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The Renewable Electron Economy XII: The “Cheap Energy Contract”…Bedrock or Dinosaur? January 14, 2008

Posted by Michael Hoexter in Energy Policy, Green Marketing, Renewable Energy, Sustainable Thinking.
Tags: cap and trade, Carbon Pricing, Coal Pricing, Energy Pricing, Feed In Tariffs, Financing Energy, Oil Subsidies, Renewable Energy
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Other than functional differences between renewable and fossil fuel generators, one of the main issues related to green and renewable energy are the capital and the per unit energy costs of new, cleaner energy systems. While the prices of oil and natural gas will certainly go up, the comparison with more plentiful coal remains the most challenging. The target or acceptable price for market entry of clean energy is a subject of heated debate among people who agree that we should move to renewable energy. Clean energy debates mirror most discussions of energy in this regard, as the decisive argument for the commercial value of an energy source is in most contexts its cost per unit energy to the buyer.

At the OpenEco camp/un-conference last week in San Francisco sponsored by Sun Microsystems, activists in the area of sustainability came together to brainstorm, discuss and network around a number of issues. One of the topics that came up frequently in different contexts was the target price or acceptable cost for energy, though there were other worthy topics discussed in parallel at this generally excellent multi-focus un-conference.

Among those presenting, Ted Nordhaus and Michael Shellenberger, the authors of the new, fairly controversial book BreakThrough, covered a range of topics, one being that government and technology companies should be working together to make clean energy cheap. In other contexts, the price of energy came up again in a discussion about whether the new cap and dividend idea (distributing the proceeds of selling carbon credits as dividends to people to offset the impact of energy costs) works. In still other sessions, the issues of subsidies for energy were discussed as both a political and an economic issue.

These discussions have resonated with concerns that I have had about whether we are pricing energy correctly given our very legitimate interest in switching from polluting to non-polluting forms of energy production. Can the United States and other industrialized nations, afford a new energy infrastructure if we continue to value energy at the price levels we are used to? For a long time, particularly since WWII, we in the US have been operating under a society-wide “Cheap Energy Contract.”

What is the “Cheap Energy Contract”?

The Cheap Energy Contract is an unwritten multilateral contract between the governments, citizens, and energy companies in industrial countries, but is in particular force in the United States. What the Cheap Energy Contract says in approximation is:

1) Government, Consumers, and Energy Producers are parties to this Contract

2) Energy costs for consumers and industry must be negligible for all but the most energy-intensive industries (think aluminum or logistics).

3) Per unit energy costs must be low enough to allow temporarily doubled or tripled rates of energy use not to “bust the bank”.

4) Real or artificial energy shortages are unacceptable

5) Government is ultimately responsible for guaranteeing that energy is cheap and available; elected officials risk being voted out of office if energy prices rise substantially or energy availability is reduced either through government action or independent of government action.

6) Depending on which political ideology vis-à-vis regulation is currently dominant, government subsidy of energy may need to be hidden in indirect forms.

7) Dominant players in energy markets sacrifice some freedom to set prices for political influence and subsidies: oil companies have more pricing power though more competition than electricity retailers who are regulated by public utilities commissions.

It is surprising how durable and pervasive the Cheap Energy Contract is, even though no one has written it down, nor is there an official enforcement procedure. Though the word “entitlement” is usually used to describe official government sponsored programs, cheap energy is generally considered to be an entitlement by American consumers and American businesses.

The founders of the oil business realized that their business depended upon scaling up rapidly and defeating whale oil and other competitors in the marketplace. In addition to canny business calculation, John D. Rockefeller believed he had a mission of bringing cheap illumination via kerosene to the masses by keeping prices low and pushing competitors out of the business. Recognizing the political sensitivity of electricity’s natural monopoly, the founders of the electricity business, in particular Samuel Insull, tried to pre-empt anti-trust actions by transparently negotiating the cost of electricity with public officials and keeping it low. To reach economies of scale in both businesses required mass acceptance and therefore low prices. Maintaining the low prices and supply of these energy sources however was sometimes beyond the power of private corporations, which led to more active involvement of the US government.

The Cheap Energy Contract is one of the “third-rails” of American politics: if you touch it, you risk (political) “death”. While the price of electricity has been heavily regulated, the price of oil is more variable and also potentially more capable of inflicting economic pain on consumers. Observations of the outcomes of Presidential elections in the last 40 years indicate that one-term Presidents Ford, Carter, Bush Sr., lost their re-election bids during a time of higher oil prices. Political manipulation of oil prices to win or lose elections through direct or indirect means is one topic of conspiratorial theories that may or may not have a basis in reality.

Carbon Pricing and the Cheap Energy Contract

As both buyers and sellers of energy were happy with the Cheap Energy Contract in an era of abundant fossil fuels and government was happy that they were happy, there has historically been little opposition to the Contract. The first full-scale assault on the Cheap Energy Contract has come recently as concern over global warming has led to first environmental leaders then broader sectors of our society questioning the wisdom of using fossil fuels to power our civilization. Most concerned politicians and activists now agree that assigning some price on carbon emissions and therefore on energy consumption may slow the consumption of fossil energy and support the development of greener, largely renewable energy.

Carbon pricing therefore threatens to break the Cheap Energy Contract and this has ignited a firestorm of controversy from energy producers, energy-intensive businesses, as well as elements of government that see the maintenance of the Contract as their fundamental duty or in their own political self-interest. While most proposals currently being aired are on the side of modest or low prices for carbon ($20-$30/tonne), the institution of mechanisms for pricing carbon set up a means by which future increases might seriously boost the price of energy. Even in countries where the Kyoto protocol is in force, the effect of the cap-and-trade system has not significantly affected the price of energy due to mistakes made in administering the system in its first iteration.

While one can expect political resistance from the energy industry and mass consumers of energy, the Cheap Energy Contract has shown its durability even among those concerned about the planet’s future. Google’s recent announcement of RE<C takes as its target a price of electricity equivalent to that of depreciated coal plants or at least a price that would compete in China or India with coal. Shellenberger and Nordhaus advocate government subsidies for clean energy research and development until it is “cheap”. In this they are following the early pricing strategy of John D. Rockefeller in requiring that the new energy be as cheaper or cheaper than the old energy (though Rockefeller was always concerned that pricing would dip below his costs “drowning” his enterprise). While it is not clear that these supporters of clean energy are opposed to carbon pricing, there is clearly a different focus than those who see a carbon price as the entering wedge in pushing out fossil fuels. While it might be argued that those who seek to promote research and development into cheaper clean energy and those who seek to raise the price of dirty energy can work together, there is implicitly and explicitly a disagreement about the future of the Cheap Energy Contract and therefore what will be an acceptable price for clean energy.

Post-Carbon Pricing Rebate Systems

It is conceivable that carbon pricing can be instituted that raises energy prices for those who can afford it and compensates more economically vulnerable individuals and sectors for the increased prices at least on a national level. One such idea, cap and dividend, has been put forward by UMass Amherst’s James K. Boyce and Matthew Riddle, a plan that suggests distributing the proceeds of carbon permit auctions to the population in payments that will lessen the impact of increased energy prices especially on those who use less energy. One can imagine other systems of attempting adjustments in which exceptions can and will be made in various forms for vulnerable industries, critical sectors and the poorest. On the other hand, to make an exception of whole nations such as China in a carbon pricing system would seem to defeat a good portion of the intention of that system.

Fuel Taxes and the Cheap Energy Contract

In certain areas of the world, particularly Europe and Japan, the Cheap Energy Contract has never been in force to the degree that it has been in the United States and Canada. While the American and Canadian industrial economies grew in an environment of cheap, domestically produced energy, Europe and Japan have had to fight and bargain more for fossil energy sources, in particular oil, from the beginning. Compact settlement patterns have also enabled greater use of public transportation in Europe and Japan, so automobile use can be viewed as a luxury in those countries.

Fuel taxes while they exist in the US and Canada, have been for many years much higher in Europe and Japan leading to pump prices for the same petroleum products to be almost twice as expensive as they are in the US and Canada. Along with market factors that boost the price of energy, Japanese and European consumers and citizens have never shown the sensitivity to energy pricing that Americans have. Additionally the Europeans and Japanese have accepted taxation as an instrument to fund government services more readily than Americans have in the last 3 decades. Thus it is difficult to assert that a Cheap Energy Contract now exists in those countries, though there are clearly political and economic upper bounds to the pricing of energy set at higher levels per unit energy than in North America.

Clean Energy Incentives and the Cheap Energy Contract

While taxes function as a disincentive, many countries with aggressive goals for renewable energy have now adopted premium price controls for renewably generated electricity. Advanced feed in tariffs or premium payments for renewable energy, were introduced in Germany in 1992 and have since been adopted in other European countries, Ontario, and are under consideration in several US states. Not a tax or a source of revenue for government but a pay for performance premium, an advanced feed-in tariff for electricity sets a menu of higher prices per kWh for different renewable technologies that decrease gradually over the years to encourage innovation and efficiency. As the price of electricity is already regulated, feed-in tariffs are folded into existing regulatory structures for energy. Retail customers pay slightly more for their electricity, as the electric utility is charging them for a mixed bundle of electricity generated from conventional and renewable sources. When the pricing of these tariffs is set accordingly, investment in renewable energy becomes a solid long-term investment for individuals and energy investors, as a favorable return on investment can be projected for 20 years into the future. Though utilities may have concerns that they will be left holding the bag with regard to paying higher prices for clean energy and then not being able to pass the cost on to ratepayers, these laws allow all related increases in cost to be passed on to the consumer.

An advanced feed-in tariff arrangement is then a new Energy Contract that expresses that consumers are to pay more for clean energy to support its growth. Though this new form of agreement originated in countries where low energy prices have not been viewed as an entitlement, they may yet be applied in the US and Canada on a broader scale. Feed-in tariffs are not taxes but price controls so may be more politically palatable in the US but they are a departure from the Cheap Energy Contract. They also have the advantage of stimulating supply and demand simultaneously and therefore jobs and investment in the area of renewable energy.

Government Subsidy and Energy Pricing

Though the image of the oilman is that of a rugged individualist, the energy business is a business where some form of help from the government has become an historical norm. The recent defeat of the attempt to switch subsidies away from the fossil fuels to renewable energy in the Energy bill of 2007, lead to a net loss of support for renewable energy. Among the negative consequences that the oil industry’s lobby group the American Petroleum Institute raised was the potential for shortages of oil if subsidies did not continue.

It makes sense that as the government is on the hook for keeping energy prices low and cheap energy available, that energy subsidies would be part of the game. Furthermore, finding and protecting energy resources, in particular oil and gas fields, is a risky business that would ordinarily lead to unacceptably high fuel prices if the government did not cover many of the externalities.

While many politicians have been pursuing or holding up a “free” market, libertarian style ideal of autonomous market functioning, the reality of energy markets and the Cheap Energy Contract leads to a state of consistent energy subsidy to keep energy prices at politically acceptable levels. An open recognition of the costs of energy both those currently recognized and unaccounted-for environmental costs, might allow political debates about direct and indirect energy subsidies to be carried out in a more transparent way. Furthermore a recognition that paying those costs will ultimately come through some form of taxes or through the price of energy may allow the public to consider what kind of subsidy it prefers at this point in time.

The Cheap Energy Contract and the Built Environment

As noted above, America’s physical infrastructure in the 20^th Century was designed upon the basis of the Cheap Energy Contract, something that Peak Oilers have been pointing out for some time. Urban and suburban sprawl as well as widely dispersed settlement in rural areas is based on cheap energy. Likewise, cheap energy subsidizes the long distances between production and consumption of goods as well as a particularly widely dispersed distribution network for those goods. While Peak Oilers predict the collapse of this way of life as petroleum gets scarcer, it is not clear what efficiency measures and clean and/or “alternative” energy solutions might help to ease the transition to an oil-independent way of life. When these solutions may emerge, what their political and market appeal would be, and at what price, remains to be determined.

The Cheap Energy Contract and Energy “Addiction”

The above suggests that Americans and Canadians in particular are compelled to demand cheap energy, in particular cheap transport fuels, or face the possible collapse of many sectors of the economy and population shrinkage. Uncharacteristically for a former oilman, President Bush declared that America is “Addicted to Oil” in his State of the Union address of 2 years ago. The addiction metaphor has been overused to describe a whole variety of social and psychological ills but it may very well be appropriate in relationship to cheap fossil energy. Unlike various mood-altering substances, the elements of individual choice and behavior are not as decisive as society-wide trends and decisions that can change our economy and way of life. On the other hand, the addiction metaphor might help individuals to be able to see how energy use supports their lifestyle and thus make more intelligent decisions about lifestyle based on the realization that our historical patterns of living are overdependent upon unsustainable fuels.

The Cheap Energy Contract: Pro and Con

There are intelligent people of good will on both sides of this sometimes stealth and sometimes open debate about what is an acceptable price for clean energy. It makes sense then to outline what are the factors that speak for and against accepting the energy pricing status quo and what speaks for and against breaking the Cheap Energy Contract.

Continuing with the Cheap Energy Contract

Pro

“Guaranteed” cheap energy enables energy-dependent economic and social activity
“Guaranteed” cheap energy maintains the current infrastructure in the US and Canada
Cheap energy keeps energy markets accessible to most economic players, discourages formation of a segmented energy market.
Clean cheap energy would be affordable for developing countries
Clean cheap energy may address traditional objections to it in the current market
Cheap energy maintains an abundant food supply and low food prices
Cheap energy pricing encourages economies of scale, technological development in the area of cost-reduction, and/or business efficiency in the energy business
The Cheap Energy Contract attunes government and energy producers to the economic needs of energy consumers.

Con

Cheap “dirty” energy does not price in environmental costs including carbon emissions
In the case of oil, the Cheap Energy Contract will be broken or become prohibitively expensive by geophysical realities and rising worldwide demand.
A Cheap Energy Contract encourages an attitude of entitlement among consumers and businesses as consumers.
A Cheap Energy Contract may discourage investment in more expensive but promising clean energy sources.
A Cheap Energy Contract may require high levels of government subsidy
Cheap Energy Contract in combination with a lack of government transparency risks corruption or influence of government officials by energy interests in favor of subsidies.
The Cheap Energy Contract excludes most clean sources of energy that are as of early 2008 not “cheap”
Cheap energy does not encourage consumer energy efficiency
Cheap energy maintains the current infrastructure in the US and Canada (which may encourage social fragmentation and discourage community)

Breaking the Cheap Energy Contract

Pro

Opens the possibility to price in environmental externalities including greenhouse gas effects
May reduce pollution and greenhouse gas emissions
Will tend to encourage an attitude of responsibility in energy consumers toward energy use
Will encourage investment in energy efficiency
Will increase the likelihood that energy investors can recover and profit from their investment in new clean energy infrastructure
Allows pricing for cleanly produced energy to be adjusted to more closely reflect its current 2008 costs.
May open the discussion to whether energy production can be autonomous from government subsidy.
May open the discussion as to which mechanism of paying for energy is most efficient: pure pricing (price controls plus market), taxation (subsidy) plus price mechanisms, etc.
May encourage transparency in government energy policy

Con

Certain implementations may have negative economic effects on low-income high energy users and industrial sectors without rebate mechanisms or other allowances.
May encourage inefficiency in energy production if pricing signals are too favorable to waste and complacency
New clean energy technologies may remain in their first generations unaffordable for rapidly developing industrial economies like China and India
Certain implementations of a New Energy Contract may encourage accusations of political favoritism.
Food prices may require additional subsidy if energy input costs go up.
Writing a New Energy Contract will require detailed data collection, hard-headed analysis even wisdom which are sometimes in short supply.

Cheap Energy Contract or New Energy Contract?

Is the future an “Expensive Energy Contract”? Probably not: Expensive energy will shut down much economic activity and is an unrealistic goal in a commodity business. Peak Oil theorists are in some senses projecting an “Expensive Energy” future in the scenarios they paint of the contraction of suburbia and a petroleum dependent economy.

Does this analysis favor the continuance of the “Cheap Energy Contract” in a carbon restricted future? If history is any guide, cheap energy may be able to be maintained with increased subsidy paid via taxes or with less subsidy, in the event of some immediate technological breakthrough or breakthroughs in the area of renewable energy. The latter events cannot be excluded from the realm of the possible and this is certainly a hope. The commitment of private and public funds to clean energy research and development is one prong of any movement towards a clean energy future. On the other hand, maintaining the Cheap Energy Contract with a revolutionary or heavily subsidized clean technology does not bring in the positive effects of higher price that encourage energy efficiency. If the “Cheap Energy Contract” does continue in force, we can all hope for and work towards greater transparency in the area of energy subsidy, so the consuming public understands what they are actually paying for the energy they consume and don’t consume.

Do we need a “New Energy Contract”? Probably. Certainly we need to bring the interests of future generations and the health of our natural environment to the negotiating table that were shut out of the original “Cheap Energy Contract”. It may be that a period of increased energy prices will help finance a transition from a carbon-dependent to a carbon-free energy system that once paid for, will allow for energy prices to once again decrease relative to the overall costs of living and doing business. A full accounting of the probable and actual costs of our current energy system and a future one will be a help in determining how we build a new energy future.

Renewable Electron Economy Part X: Revolution in Power Engineering December 25, 2007

Posted by Michael Hoexter in Renewable Energy, Sustainable Thinking.
Tags: Distributed Energy, Electric Utilities, Electrical Engineering, power engineering, Renewable Energy
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In my previous post in this series, I discussed the characteristic differences between renewable energy sources and the largely fossil energy that fuels our current societies. A fundamental difference between the fuels for our current energy system and the strongest renewable sources of energy is that the former are natural but non-renewable energy stores that we are in the process of exhausting and the latter are based upon today’s energy flux. There are a number of practical differences that follow from using an energy store versus tapping into natural energy flux as a means of generating electricity.

If the primary energy, the fuel, for the entire electric energy system will be switched from exhaustible energy stores to renewable primary energy, creating one of the foundations for a more sustainable society, there are a number of technical and organizational challenges that face the profession of power engineering.

What is Power Engineering?

Power engineering or power systems engineering is a branch of electrical engineering that concerns itself with technical challenges related to the generation and transmission of electricity as well as power related issues in end-use electrical devices like motors and computers. Power engineers are responsible for the always-on power grid that we have come to rely upon to power our convenience-filled lifestyle. Despite its vital role, power engineering has languished in universities around the world as its cousins, computer engineering and computer science have flourished. Power engineers in the US are now one of the “grayest” of engineering professions, with average age in some specialities in their 50’s.

An argument can be made that Thomas Edison was one of the first power engineers in his role as the inventor of the electric power industry. Early electric grids were built around coal driven heat engines, like Edison’s first plant, the Pearl Street Station in New York, or around hydropower, like the world’s first public electric power plant in Godalming, Surrey, England in 1881. While hydropower is, in terms of power quality and cost of fuel, superior to coal, it has suffered from geographical inflexibility and vulnerability to drought and seasonal variation. Coal’s relative abundance, independence from changes in the weather, and portability made it the choice for most generating stations.

In the contemporary electrical system, for most power engineers, the focus is on electrical reliability: maintaining energy throughput, control of systems, and distribution of electrical energy while minimizing new capital investment. On a daily basis, power plants are scheduled to turn on and off or ramp up and down to meet power demand. Grid operators monitor and regulate voltage levels and the AC frequency of the grid. More voltage sensitive equipment is now plugged into the grid, so tolerance for variations in power quality have been reduced. On a more intermittent basis, infrastructure needs to be overhauled and/or upgraded. Finally, new power plants and infrastructure are designed and sometimes implemented to meet the rising demand for power. In the developing world, electric infrastructure is being built at a quicker pace, commensurate with rapid increases in demand for electricity.

Vested with the mandate to maintain and improve stepwise the world’s largest and most capital-intensive machines, the modern power grids, power engineers focus on options that protect the substantial investment of shareholders and governments in the electrical system while delivering power to users on a largely uninterrupted basis. It is no accident that a number of the primary organizations that run the electric grid in the US have the word “reliability” in their title: The North American Electric Reliability Corporation (NERC), Department of Energy Office of Electric Delivery and Energy Reliability, etc. With a focus on “not failing” in a complex business, power engineers want to eliminate risk and uncertainty whenever possible.

An additional impetus towards conservatism originates in key characteristics of the grid as a massive set of electrical circuits: it is a tightly-coupled system with many interconnections and high degree of complexity. Dodging cascading service interruptions, i.e. blackouts, from often minor causes, is a struggle and increases with growing power demand based upon limited infrastructure growth and change. An awareness of risk helps condition the operational culture of electric utilities and grid operators.

Given this environment, there is a preference among the leaders of electrical utilities for primary energy sources that will maintain reliability and build on the existing knowledge base. Primary energy is the amount of fuel needed as input to produce a given amount of electricity using a particular set of generators. Energy stores such as coal, natural gas, oil, nuclear, and existing hydroelectric dams are favored because of the ability to project within a timescale of months and the next few years, available primary energy and time its release. The existence of established coal, gas, oil, uranium mining and refining, rail and shipping industries allows the electric industry to relegate the work of supplying primary energy to other industries.

Since the days of Samuel Insull, the designer of the modern electric utility, utilities and power engineers have insulated (sorry about the pun) users of power from the workings of the power grid, allowing them to consume electricity without much thought about its origin, availability and, for the most part, its price. As electric grids have become overtaxed and environmental concerns have mounted in the last couple decades, increasingly consumers have been brought into thinking about electricity a little more, though the workings of the electric world are still opaque and far away from most people’s everyday awareness.

The Distributed Energy Rebellion

The first challenge to large utility-based power engineering emerged during the cultural revolutions and energy crisis of the late 1960’s and 70’s. At first more theory than fact, the idea of “un-plugging” from the grid attracted attention among the counter-culture as it would mean becoming independent of the corrupt “system”, against which many would come to define themselves. The resurgent environmental movement fought against pollution that often came from power plants as well as the destruction of natural habitats by damming projects. Peace movements thought of nuclear power as tainted by its association with nuclear weapons.

The vision of a society of small-scale grids or no grids at all, emerged first from the social imagination rather than from technical feasibility. For some, a retreat from any power use at all was considered preferable to being complicit in pollution and modern society. E.F. Schumacher wrote an influential book, “Small is Beautiful” that identified large size as one of the cultural malaises of industrial society. Solar photovoltaics, stimulated by the space program, and wind energy were thought to be the more environmentally friendly ways to generate electricity even though those technologies remained prohibitively expensive until the last two decades. The hope and eventually the demand by mavericks and political leaders for cleaner solutions to generating power kept inventors and small investors working on these technologies, as did continuing demand for photovoltaic cells by the space industry to power the growing number of communications satellites.

Paradoxically, another impetus towards distributed energy came from the opposite end of the political spectrum, at least in the US. Following the Reagan Revolution of the 1980’s, a movement against regulation of markets spurred some limited organizational de-centralization in the power industry. The idea of deregulating and breaking up the vertically integrated utilities in favor of competition at least in generating electricity opened the electricity market to merchant generators. Though not explicitly supportive of renewable energy, an opening was created by deregulation for commercialization of independent renewable energy generators in addition to utility-owned generators.

The ideal of distributed energy still animates aspects of the renewable energy industry including much of the market for photovoltaic technology, small wind turbines and micro hydroelectric. Distributed energy does not yet compete directly with a professionally run, massively interconnected grid in most locations because as power demand continues to climb, capital costs to electricity self-generators would still be high and distributed electricity storage is still relatively expensive. If electrical storage and various small renewable generators were cheaper and more widely available, one can imagine that a more decentralized grid would result. On the other hand, it is doubtful that power users will want to forego access to the resources of a widely distributed interconnected group of generators or the services of a corps of professionals who insulate them from the vagaries of an electrical system and changes in availability of primary energy. Whether you identify it as a sign of industrial and environmental malaise or a positive social good, the grid will probably live on in some form in an age of distributed and renewable energy.

Revolution in Power Engineering

Whether the grid of the future will fragment into local grids or develop into a more widely interconnected hypergrid with both distributed and centralized generators, the grid(s) of the future will require some form of professional design and management and will most decisively be fueled by renewable energy sources. The efforts to clean up coal and revive nuclear will only delay this fundamental shift to sustainable fuels; they are understandable attempts to re-use the knowledge base of contemporary power engineering in a carbon-constrained world. While sticking with what you know is understandable, a delay in grasping what I am calling a revolution in power engineering only sets us all back as we grapple with the challenges of climate change, increased worldwide demand for energy and oil depletion.

In my previous post in this series, I highlighted how energy stores as opposed to energy flux were central in the organization of the contemporary electric grid: energy stores such as hydroelectric reservoirs, fossil or nuclear fuels allow for an inventory of primary energy supply and the timing and control of energy output. On the other hand energy stores can be depleted by people, while natural energy flux cannot. Natural energy flux is the key element that explains the renewable part of renewable energy. Types of natural energy flux, like solar radiation, wind, or geothermal heat are also the strongest and most widely distributed types of natural renewable energy. On the other hand, on earth’s surface, natural energy flux is not constant nor with the exception of the tides, entirely predictable. Natural energy stores replenished by renewable flux (mostly biomass) are insufficient for our current energy needs without major ecological disruptions or at the moment present technical hurdles to their extraction (geothermal heat in the crust’s basement rock).

Harnessing renewable energy flux, with all the associated challenges, is then one of the core future tasks for the power industry and the basis for a future sustainable energy system. Transferring the primary energy of the power grid from exhaustible energy stores to a primary reliance upon energy flux will then mean a revolution in power engineering, a new way to meet energy demand with many new challenges associated. This is analogous to the scientific revolutions of the Kuhnian type: a paradigm shift that does not throw out existing knowledge and skills but puts them in a new light and context. The existing knowledge base and skills of power engineering remain valuable in a renewable electron economy. The addition of new challenges and a new framework means making a difficult job even harder but also means added prestige, opportunities for enhanced public service, opportunities for financial gain, and intellectual challenge.

Associated with the change in primary fuels for electrical generators are six challenges that will necessitate substantial re-thinking of generator and grid design and operation:

1. New Primary Energy Supply Chain

The first new challenge for power engineering is realizing that the supply chain for primary energy will be radically different and more closely integrated with the delivery of electricity itself. By using renewable flux comes the need to build a whole new set of capture devices (wind turbines, solar panels, geothermal wells) that are positioned to intercept renewable energy where it is strongest. Instead of a separate coal, petroleum products or uranium extraction industries, the capture of renewable energy will most often be integrated directly with the delivery of electricity or its generation. This means changes in investment strategy in equipment (wind turbines, etc.) that replace the function of entire (supplier) industries. As it happened historically, the electrical power industry was able to inherit or share these suppliers with other buyers of coal, uranium, natural gas, and oil. Hydroelectric dams have also had multiple uses beyond power supply that have helped spread out or divert the initial investment costs from the sellers of electrical services themselves. Alliances with new equipment suppliers, merchant generators and/or new sources of investment capital will be required.

2. New Technical Understanding of Energy Capture Devices/New Generator Technologies

The second new challenge is that the capture devices for renewable flux (wind turbines, solar collectors, wave power generators, etc.) are a diverse set of technologies, some of them new to the world and many of them new or unknown to many power engineers. Whole new technical and business competencies will need to be developed to be able to interact with the makers of these new devices or to participate in inventing and or refining new renewable flux capture devices/generators.

3. Integration with Meteorology and Geophysics

One of the features of renewable energy flux that complicates harnessing it for power production is that it is not constant or entirely predictable. The third new challenge for power engineering is forming a much deeper disciplinary alliance with meteorology and geophysics that would allow grid operators a wider operational window to plan the deployment of generators. Currently grid operators rely on weather reports to predict power demand but in the renewable grid of the future, power supply will be critically affected by weather and, in the case of geothermal, subsurface events. The renewable grid will motivate the already rapidly advancing science of weather prediction to make more accurate forecasts days and weeks in advance to help power engineers manage power output.

4. New Energy Storage

The fourth new challenge for power engineers is building adequate energy storage to further bridge renewable energy supply with demand, replacing the controlled timing of energy release from the natural-supplied energy stores of fossil and nuclear fuels by constructing artificial stores. While hydroelectric dams are a notable early and, from the point of view of the power generated, successful example of a successful artificial energy storage, most of the major rivers in the developed world that offer hydroelectric potential have already been exploited. In addition to any environmental problems associated with dam building, growth in hydroelectric capacity has a natural ceiling that is below that of world-wide energy demand. I have discussed existing alternatives in energy storage in an earlier post in this series. The growth and implementation of these types of storage will take increased research and development on the storage technologies themselves, as well as willingness to invest and apply existing storage technologies that have both some technical or financial advantage and are carbon neutral.

5. New Transmission Infrastructure

A fifth challenge for power engineering is the modification of transmission infrastructure to allow for access to the strongest renewable energy flux in remote and/or hostile environments. Some all-renewable energy proposals suggest that distances of 5000 miles (8000 km) or more from source to load are conceivable, if the variability in time and space of renewable energy flux is to be balanced to meet energy demand. Conventional high voltage DC, the long distance electricity carrier of choice, may need to be further developed with new conductor technology to be able to more efficiently transport electrical energy long distances. Research into cheaper and more efficient underground cabling technology may help speed regulatory approval of transmission projects, saving time and thereby money. Building transmission facilities in hostile marine conditions far from shore or in the middle of frozen lakes represent new engineering challenges. Proposals to tap into high altitude wind would require strong but light conductors to reach high into the atmosphere. Furthermore, renewable energy generators generally have lower capacity factors (produce power only a portion of the time) than conventional power plants, leading to challenges related to designing transmission to be used most efficiently by renewable energy; combined planning of transmission and generation capacity might need to take place on a regional or national level to insure the most efficient design of transmission lines.

6. New Grid Management and Information Systems

Finally, the sixth challenge, as implied above, integrating renewable generators require a higher level of coordination and information about micro and macro-events on the grid that will require new communication and information technologies. Already on the agenda of power engineers is the building of the “smart grid” which will bring the use of current information technology, two-way communication between power users and power generators, a system of addressable nodes not unlike the Internet. Beyond smart grid proposals, an all-renewable grid will need to have the ability to communicate with and manage a multiplicity of generators with different capacities and power output profiles, factoring in weather data on both supply and demand sides. In constructing such a grid, planning for energy flows and fuel availability will include consideration of an extraordinary number of factors, also requiring the capacity to develop massively multi-factor models of natural energy flux, generator capacity, existing and future generators, security concerns and back-up generators.

Political Will and Market Demand

Power engineers may be able to help move us towards the renewable future within their profession and industry but ultimately some of the conditions for this eminently do-able transformation reside outside engineering in the centers of political and economic power. Motivated by a public concerned about sustainability and climate change, political leaders would need to add and re-frame regulations that a transition from fossil and exhaustible fuels to renewable ones were national and international priorities. Cap and trade or carbon tax proposals are one form such expressions of political will can take. Feed in tariffs, a way to explicitly promote renewable energy through offering guaranteed premium pricing to renewable energy generators, have boosted the renewable energy industry in a number of European countries and have received support most recently from the California Energy Commission.

Despite the importance of better policy, individuals and individual firms can get out ahead of policy and the market by investing now in renewable, transmission, and grid management technologies that can meet the requirements of power engineers and electricity consumers. Over the last several years, venture capitalists have been anticipating the shape of future electricity markets in their cleantech investment strategies, focused largely on new technology. Google’s RE<C announcement appears to be a similar effort. Large diversified electric equipment suppliers like General Electric and Siemens, with a diversity of commitments to many different types of generation, may increase investment in these areas if market and political leaders show resolve in steering us towards a renewable future.

Defeat of Tax Credits/Bali — A Day of Shame for the US December 14, 2007

Posted by Michael Hoexter in Green Activism, Renewable Energy.
Tags: Production Tax Credits, Renewable Energy, Solar Energy, US Congress, Wind Energy
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By a single vote, the Senate today failed to pass the tax credit package for renewable energy.

http://www.renewableenergyaccess.com/rea/news/story?id=50843

There are dinosaurs still alive in the US.

To those who contacted their Senators/Congresspeople…thank you!

Also, the news from Bali is not good either.

http://www.nytimes.com/2007/12/14/world/14climate.html?hp

Just as the old energy economy has relied on massive subsidies and favorable policy conditions to continue to mine and drill for fossil fuels around the world, the building of a renewable electron economy is going to require a policy environment that adequately prices in the externalities of climate, geopolitical uncertainty, and environmental degradation into markets. We in the US are continuing to lag behind other countries in taking steps to re-orient ourselves.

We have just taken a step back, but maybe this is an occasion to re-group and connect with the American people about the value of renewable energy and investment in our common future. From this may come a determination to create policy that is more durable and more transparent to everyday people, so lawmakers can no longer play with our common future without repercussion.

The Renewable Electron Economy Part IX: What is Renewable Energy Anyway? December 9, 2007

Posted by Michael Hoexter in Renewable Energy, Sustainable Thinking.
Tags: Definitions of Renewable Energy, energy storage, Renewable Energy, Solar Energy, Wind Energy
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I’ve been posting on the Electron Economy/Renewable Electron Economy for the past 9 months but have been relying on the Justice Potter Stewart definition (“knowing it when I see it”) of renewable energy. Most people tend to define renewable energy by listing certain natural resources: “Oh, its wind, solar, geothermal, wave, tides, etc.” Some hopefully more illuminating definitions do exist: a Google Web search reveals the following range:

“a naturally occurring raw material or form of energy that will be replenished through natural ecological cycles or sound management practices”

“an energy resource that is replaced rapidly by natural processes”

“a natural resource that can replenish itself over time”

I think it is possible to come up with a more rigorous, more specific definition that gets closer to the reality of renewable energy, even though there will always be an element of complexity and imprecision in the definition.

Interactive Definitions of Energy

Renewable energy is one of a group of terms that you might call interactive definitions of energy: energy as it matters to people, not the energy concepts that are usually taught in basic physics and chemistry classes.

Pure physicists have no use, for instance, for the concept of “primary energy”, which is useful in power engineering and energy economics. “Primary energy” means the type and amount of energy or fuel that needs to be input to produce a certain finished “secondary” energy product. Coal, natural gas, or uranium can function as the primary energy to produce electricity and crude oil or tar sands can function as the primary energy for finished petroleum fuels. Renewable fuels can function as primary energy too: incoming sun, wind or water falling can be seen as the primary energy for electricity or bio-energy. The efficiency of an energy conversion process is measured by how much of the incoming energy is converted to the useful output form of energy (secondary, tertiary, quaternary).

The “primary”-ness of primary energy has only to do with the fact that this is the form in which humans first find the energy resource. It is an interactive definition of energy; in pure physics the only primary energy is that of the Big Bang 13 billion years ago. In the practical world, humans are interested in energy as a resource not as simply an object of scientific study.

The assessment whether something can function as primary energy, an energy resource and furthermore what type of resource it is, renewable or non-renewable, is an interaction between the human variables and the natural or given variables. People need to have discovered or invented a technology to convert primary energy into a usable secondary form and the energy needs to in some way improve upon human beings natural capabilities.

To make a clear definition of naturally occurring energy types, it helps to differentiate a few concepts in interactive energy, the energy that matters for human use.

Energy Flux, Energy Stores and Energy Events

To arrive at a more precise definition of renewables, I’ve worked out three broad categories that differentiate energy in relationship to human use and timescale: energy flux, energy stores, and energy events.

Energy flux is good scientific concept that describes the flow of energy or matter in any number of different ways. Flux is the Latin word for flow but flux has the advantage of not have the concrete image of a flowing liquid or river associated with it. Fluxes can come and go. Gravitational and electromagnetic fields can be described as having a flux. Material in a liquid or gas can be described as having a flux or flow rate. Best of all, the strength of energy flux can be measured in watts per square meter: energy flow through a cross-section of space. Energy flux is not necessarily constant but can vary over time. Energy flux can be naturally occurring or manmade (light from a bulb, for instance).

Energy stores are what they sound like, a place or substance where energy is stored. An energy store is only an energy store (for human use) if humans have a technology to convert the store into useful energy: uranium 235 is only an energy store if people have a nuclear reactor and uranium 238 would only be an energy store if there is a fast neutron reactor and a fuel reprocessing cycle. The total mass-energy of a substance, i.e. the “E” in E=mc^2, is a huge number but is not an energy store as we humans do not yet have the technology to completely annihilate matter into energy. All energy stores are potential energy but not all potential energy can function as an energy store (think of rocks on the tops of mountains, for instance). Energy stores allow people to time the energy conversion to approximately when or exactly when the energy use is required; they are also exhaustible. Energy stores can be natural or artificial, the latter being “energy storage”. Energy stores can be measured in units of energy like joules, BTUs, kWh, barrels of oil equivalent etc.

Energy events are irregular but not necessarily uncommon events with a strong energetic dimension like lightning, hurricanes, tornadoes, earthquakes, volcanic eruptions even meteor impacts. People cannot count on energy events happening though some are more common than others; they are however very important for the history of the earth and life. Energy events tend to have a disruptive effect upon human plans and occupy a disproportionate place in our imaginations and mythology. Energy events are not as important in defining useful energy types as they are, as yet, not useable by human beings. Energy events can theoretically be measured in units of energy (joules, etc.) and also as a function of units of power (watts, etc.) over time.

While these concepts might seem abstract I’ll demonstrate below how they can be used to define renewable and non-renewable energy.

Characterizing Energy

Non-renewable Energy

Fossil Fuel – All fossil fuels are energy stores given our current technology. We have the technology to tap into the energy of most fossil fuels and can time the release of their energy according to our timetable.

Fissionable Fuels – Uranium and plutonium can both function as energy stores with current technology. We have the technology to time the release of their energy, though they are not as responsive to control as fossil fuels

As non-renewable energy is exhaustible, it makes sense that it functions as an energy store.

Renewable Energy

Solar – Solar energy is natural energy flux from the sun in the form of electromagnetic radiation measurable in watts per square meter. On earth’s surface it is periodic, variable but consistently available within the course of days, weeks and months. The energy is not exhausted by use.

Wind – Wind energy is also a recurrent natural energy flux, measurable in w/m2 and variable over time. Wind energy is derived from solar energy flux that replenishes wind energy. Theoretically one can capture 100% of the energy of wind in a given place but it will return with sufficient atmospheric heating.

Hydropower – hydropower is a recurrent natural energy flux, potentially measurable in w/m^2 that is often paired with an artificial energy store. It is dependent upon two opposing natural energy fluxes, solar radiation (water evaporation) and earth’s gravitational field. In the era of fossil fuels, hydropower has been easily integrated into our energy system because it so readily lends itself to artificial storage (dams).

Biomass – biomass functions a natural energy store that is replenished by renewable energy flux (solar energy) but limited by availability of water and the fertility of the local soil. People and other living things compete for the energy contained in biomass so its usable energy content can deteriorate quickly depending on local conditions. Biogas and biofuels, both derivative of biomass can also function as energy stores. The energy content of biomass can be measured in joules, BTUs, etc.

Wave – Wave energy is recurrent natural energy flux derivative of wind energy occuring on the surface of bodies of water. Though measureable in watts/m^2, it is better measured by watts/m wavefront, as most energy is contained at or near the surface.

Tidal – Tidal energy is recurrent periodic natural energy flux derivative of the interaction of the gravitational field (also energy flux) of the moon and the earth. With a tidal barrage, tidal energy can be stored. It can be measured in watts/m^2

While the above are fairly easy to characterize the two below are a little more controversial and complicated:

Geothermal – Geothermal is a complex phenomenon derivative of radioactive decay of elements in earth’s core, mantle and crust that heat rock and water in the crust. A geothermal well taps into a combination of geothermal heat flux from the mantle and crust and stored heat in the rock that is slowly replenished by heat flux through the rock. There is controversy about whether geothermal is renewable because the rate of heat extraction by people sometimes exceeds the rate that it is replenished by heat from the surrounding rock and the mantle below. Geothermal is both an energy store and energy flux. Geothermal energy is expressed both as a rock temperature (which could be converted into joules) and as a heat flow in watts/m^2. Geothermal energy flux can also diminish or stop in a given location as conditions change in earth’s mantle.

Ocean Thermal Energy Conversion (OTEC) – OTEC has not yet been commercialized but uses the difference in temperature in tropical ocean waters between the surface water and deep water to run a heat engine. OTEC could be considered “cold mining” of the deep waters and the question remains whether warmer water will cool and sink fast enough to replenish water extracted from the depths: whether the downward flux replenished the stored cold of the deep water. There may be serious climate consequences if deep water gets too warm because of this type of cold extraction. In the current terminology, OTEC taps into an energy store that may or may not be replenished by natural energy flux within a human usable time scale.

Defining Renewable and Non-Renewable Energy

Using these categories, one can define non-renewable energy more easily than renewable energy.

“Non-renewable energy sources are energy stores with zero or a minute rate of replenishment relative to its depletion by human beings. Most non-renewable energy sources are converted to usable energy by thermal or nuclear reactions. Non-renewable energy sources have stored the natural energy flux of Earth’s biological and geological past or of the formation of elements in the early history of the Universe”

Renewable energy on the other hand, appears both as natural energy flux and as an energy store. It is interesting to note that the types of renewable energy that, in the course of the 20^th century were most well integrated into the customary energy mix (hydroelectric, geothermal, and biomass) are both either energy stores or have traditionally been integrated with an energy store.

Here is a hopefully more rigorous if somewhat long definition of renewable energy that only resorts to using a list in the second sentence:

“Renewable energy sources are types of natural energy flux useful for human ends regularly occurring on or near Earth’s surface and, additionally, useful natural energy stores that are replenished by natural flux within the timeframe of conceivable human use. All known renewable energy sources originate in, or are close derivatives of, electromagnetic radiation of our Sun, the Earth’s and Moon’s gravitational fields and heat radiating from earth’s interior. Renewable energy sources are practically inexhaustible though some sources such as geothermal and ocean thermal energy conversion may become locally depleted by human use at a rate that exceeds replenishment by natural flux.”

I believe the first sentence is sufficient but the next sentences add a little more detail.

A Paradigm Shift in Power Engineering

Have we learned anything by drawing the distinction between energy flux and energy stores? One pattern that becomes very clear is that conventional energy system is heavily dependent and focused upon energy stores. The ability to time the release of energy from coal, natural gas, uranium, petroleum, dammed rivers or biomass has been a key support for how we manage our energy system and the electric power grid. We can call this the conventional energy paradigm, where energy is defined as a stockpile of fuel in tandem with the appropriate energy conversion devices.

If we are going to build a renewable electron economy, there needs instead to be a focus on how to capture and monitor the strongest or most readily available renewable energy flux and also how to supplement this with non-polluting energy stores where possible. The management of an electric grid with renewable energy flux means investment and innovation in three areas: energy capture devices, storage devices, and more sophisticated natural flux monitoring. The latter has been used already for demand forecasting (weather effects power and energy demand) but now it will also forecast supply, doubling or tripling its importance in the equation. This means more collaboration than ever between meteorology, geology and power engineering. It also means a paradigm shift in how the managers and planners of the electric system and grid discuss energy: changing from the relatively static world of naturally occurring energy stores to deal with the dynamic world of energy flux will take time, effort, and innovation.

‘Nuther Action Alert for US Readers: Renewable Energy Support December 4, 2007

Posted by Michael Hoexter in Efficiency/Conservation, Green Activism, News and Events, Renewable Energy.
Tags: Production Tax Credits, Renewable Energy, Solar Energy, US Congress, Wind Energy
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Luckily, and in part through the work of Nancy Pelosi, the Renewable Energy provisions have gotten back into the Energy Bills and now it’s time for Congress to vote on them. What is contained in these bills is the bare minimum support that renewable energy projects need in the form of tax credits and a national Renewable Portfolio Standard.

http://capwiz.com/re-action/issues/alert/?alertid=10616351&type=co

Solar Nation, the activist organization in favor of solar energy, has a neat little gizmo that sends the letter of support to your congresspeople. It’s just about a minute of your time to keep the US, kinda sorta in line with the intentions that most of us have to depend more on renewable sources of energy. We are lagging many of our European friends in this regard, so we need all the help we can get.

The Renewable Electron Economy Part VIII.2: The Electric Farm – 2 November 30, 2007

Posted by Michael Hoexter in Green Transport, Renewable Energy, Sustainable Thinking.
Tags: Agricultural Sustainability, Electric Farm, Electric Tractor, Farm Energy Efficiency, Lead Acid Battery, Lithium Ion Battery, Renewable Energy, Solar Energy, Wind Energy
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In Part 1 of this post, I started to construct a scenario where a medium-sized farm would do most or all of its work using electric farm equipment. This model of a farm had 1 large tractor with 250kW(335 hp) maximum power output and 4 smaller tractors with 50kW (67hp) maximum power output (though working at 50% power on the peak energy day). I started to sketch out what would be the electric power demand on the peak day of the year and how many battery packs and battery pack exchanges (assuming that a quick battery exchange system was part of the tractor design) would be required to fulfill that demand within a workday of 10 to 14 hours. I have put to one side claims of companies that suggest that they have high energy density ultracapacitors that can charge and discharge very rapidly (EEStor for one). If such ultracapacitors were more than vaporware, a recharge tender vehicle rather than a battery exchange tender would be preferable as tons of batteries would not need to be changed in the field during the workday.

I figured that on this day all tractors would be required to do work for 10 hours and that the large tractor would work at 100% power while the 4 smaller tractors would work at 50% power. Road vehicles do not operate at anywhere near maximum power for most of the time they operate, so farm vehicles in certain tasks (deep plowing in particular or driving a heavy piece of machinery through its power take off drive shaft) are mass energy and power consumers. The diesel equivalent of the large tractor might consume 150-200 gallons of diesel fuel in a 10 hour day if it worked continuously at maximum power.

In actuality most farm tasks do not require maximum power but some do, therefore the variations in power among the tractors even on this peak energy use day. I assumed that half the weight of the tractor could be battery weight as the electric motor would be much smaller and lighter than the equivalent diesel motors it would replace. I assumed the total weight of these tractors would be the same weight as fully ballasted diesel tractors of a similar power rating. Using current lead-acid technology, there would need to be many battery exchanges with the high power tractor operating at full power all day (13 exchanges) but less with smaller tractors working at half-power (3-4 exchanges). Using current lithium-ion technology, there were much fewer if any battery exchanges per workday but of course much greater expense to purchase the battery packs using approximate pricing for 2007.

A table of the calculations for this scenario can be found here.

Charge Infrastructure

The type of battery makes a big difference in the amount of in-field battery exchange required and it also makes a difference in the size and power of the available charge infrastructure. We will assume that the tractors can plug in and recharge their onboard batteries at the same rate as battery packs on the external charger.

The charger and spare battery packs would be installed inside a vehicle-accessible shed or barn, especially in colder and wetter climates; in warmer, drier climates, a open shed with a roof may be sufficient. The battery tender or tractors would need to be able to dock on the recharge racks and have access to the batteries so that the battery enclosures or transport sleeves could interface without unnecessary lifting of the tonne or half-tonne battery packs. The battery packs might be stored on recharge racks with fittings that allow easy lock and release of the packs by horizontal sliding on rollers. A hydraulic mechanism might push and pull the packs in and out of the charge racks into either the battery tender or the tractors themselves.

The number and size of the farm’s battery inventory would depend in this example on the battery technology (lead-acid and lithium ion), its quick-charge potential, and the power of the charge unit. We will assume that all batteries, battery packs and vehicles have the power electronics and wiring to allow complete recharge within 60 minutes, which is within the claims of makers of the current generation of nanostructured batteries. Let’s say the charger operates on a 480V 220 amp circuit with a 106 kW power capacity. This means that the charger can recharge 4 of the lead-acid (25 kWh) packs per hour or takes a little over 70 minutes to recharge one of the 125 kWh lithium ion packs. In my calculations, I’ve allowed for there to be three times as many offboard as onboard lead acid batteries, with a one to one ratio for lithium ion packs as they carry more charge and therefore last much longer in the field than the lead acid packs.

Battery Inventory

The all-electric farm, in order to handle a total peak day energy use for the 5 tractors of 3.5 MWh (3.5 million watt hours) would use an electric tender vehicle (a specially designed truck with cranes or hydraulic battery pack tubes that remove and “inject” battery packs into the tractors or the charger stand) that also uses the same type of battery packs as an energy source to do the work of exchanging and carrying the heavy batteries to and from the charger to the tractors in the fields. I have assumed that the battery tender would need 25 kWh of energy to do one complete exchange whether for a smaller or a larger tractor (though in reality there would be somewhat less energy required to exchange 2.5 {small tractor} rather than 8 {large tractor} tonnes of batteries). The farm total, for all mobile uses, will have energy needs that vary then from 3.55 MWh for lithium ion to the much higher 4.225 MWh for lead acid, the difference being made up by the 25-29 battery exchanges performed by the battery tender with the lead acid batteries versus 2 exchanges with the lithium ion battery packs.

The farm’s battery inventory will vary by number, weight and cost of batteries, depending on battery chemistry, given that we are planning for 3 times the number of offboard charging batteries for the lead acid chemistry while just a one-to-one ratio for the lithium ion batteries. The battery packs in this scenario are either one metric tonne (2200 lbs) or a half tonne, for either chemistry. The large 250kW tractor would carry 8 metric tonnes while the smaller 50 kW tractors would carry 2.5 metric tonnes of batteries (we will assume that the larger tonne-sized packs are exchanged on the smaller tractors rather than a single half tonne pack).

As the lithium ion batteries on the four smaller tractors do not need exchanging on our peak day, we will only allow for a single tonne-sized battery pack to remain in reserve for these tractors. The 250kW tractor is working at peak power all day in this peak energy day scenario (on other days, the smaller tractors might work harder and therefore use extra batteries that on the peak day are used by the larger tractor) so requires reserves for all 8 of its battery packs. We are then looking at 12 metric tonne-sized battery packs off the tractors on the chargers with 18 metric tonnes of battery packs on the tractors. The tender requires one metric tonne sized battery pack to do its work (more than enough for 2 battery exchanges). We are then looking at 31 metric tonnes worth of lithium ion batteries for the entire farm distributed in 29 tonne-sized packs and 4 half-tonne packs with a total capacity of 3.87 MWh. Assuming an energy density of 125 Wh/kg (the energy density of the Tesla motors ESS) and a 2007 cost of $.48 per Wh, the 2007 battery cost for the lithium-ion based farm would be $1.857 million dollars.

The battery inventory picture is somewhat different for the lead acid battery-based system. More exchanges, more offboard battery reserve, and lower energy per unit weight means greater total battery inventory tonnage to supply the tractors and a much harder working battery tender. The onboard battery capacity for the 5 tractors will be 450 kWh and offboard will be 1.35 MWh. The battery tender will need to carry two tonnes of batteries for its own use in order to be able have the energy to do 25kWh battery exchanges and exchange its own batteries after pretty much every exchange (the capacity of the lead acid pack is 25 kWh). The battery tender would need to work at a frenetic pace all day to be able to effect 25-29 exchanges. Offboard, then there would need to be 60 tonnes of batteries on the charger and onboard 20 tonnes on the 5 tractors and the battery tender for a total of 80 tonnes of batteries. Despite the increased tonnage of batteries needed, the 2007 cost of the lead acid battery inventory is relative to the cost of the lithium ion battery inventory, favorable: with lead acid batteries at $.12 per Wh and 25 Wh/kg, the 80 tonnes of batteries with a capacity of 2.00 MWh would cost just $240,000. The lower capacity requirement and therefore much lower than 1/4^th the total cost of the lead acid batteries is due to the more complete usage of the lead-acid capacity through more battery exchanges; in the lithium ion scenario there is excess battery charge both on the battery charger and onboard the smaller tractors.

Farm Energy Requirements and Renewable Energy

One of the major advantages of using electricity is that it is a highly flexible energy carrier that is particularly suited to using renewable energy as its primary energy source. In addition electric motors are about 3 times as efficient as internal combustion engines, and have high torque at low rpm, perfect for farm work. On a given farm there may the opportunity to use wind, solar, biogas, or waste biomass to generate electricity, beyond the use of the latter two to generate process heat for crop drying and barn-heating. Before we design any renewable energy systems for the electric farm, we first need to determine what are its overall energy requirements. As this is an idealized scenario we are free to make assumptions that would need in the future to be modified by more accurate statistics and real-world prototyping of a renewable and sustainable farm energy system. We will assume that non-mobile energy use on a farm is one-third of mobile farm energy use, which is slightly higher than the 20% of farm energy that was delivered in the form of electricity in 2002.

We have found that a lead-acid based battery-exchange system will require more battery exchanges which on our peak day scenario leads to a total mobile energy usage for our electric farm of 4.225 MWh while for the lithium-ion based scenario the usage is 3.55 MWh, barely over the energy needed by the tractors themselves. For the sake of simplicity, we will take a value in the midpoint between these two numbers and divide it by 3 to arrive at an average daily mobile energy use on a farm, which we will say is 1.4 MWh. We will assume that tractors are used 200 days/year, so annual mobile energy use for the farm will be 280 MWh. If non-mobile use of the energy on the farm is 1/3 of that of mobile usage, then we come up with 450 kWh/day, and assuming that stationary systems must operate 300 days/year we come up with annual non-mobile energy usage of 135 MWh. The proportions and total amounts of these figures will vary greatly depending upon the type of agriculture that is being practiced on the farm, the amount of on-farm processing that goes on, the climatic zone, and the types of crops. Using this scenario we come up with a total yearly energy requirement of 415 MWh.

What size of renewable energy system would deliver this amount of energy per year to the farm?

While in reality, to supply this energy, farms will have access to some combination of wind, solar and biomass energy, as well as grid electricity, we will design this model electric farm using solar arrays for comparative purposes to show how much farm land would be needed to generate the energy needed. While often, solar systems tied to the electric grid are sized to cover the energy costs rather than the actual site energy needs in kilowatt hours, here I will size the system to produce enough energy to cover all on-farm energy needs, assuming that the utility will credit the farmer for excess production. In net metering schemes, the electric utility credits a customer who uses a solar array to generate electricity at the daytime rate that is higher than average per kilowatt-hour costs. So solar arrays are sized to zero-out the bill, even though often this means that in net energy terms, the customer is using more than they are producing. Net metering does not allow system owners to make money from their installation, only to cover costs. The goal here is zero net energy.

A small innovation in the area of switches might take advantage of the PV solar array’s DC output, which is the same current type that batteries need. Sending current through an inverter to transform it to AC can lose from 4 to 8% of the energy. Ideally, a solar array on a farm with high battery recharging requirements would have a smart switch that directs current to the charger or to the grid depending upon the state of charge of the battery packs. For the purposes of this simplified model we are assuming negligible inverter losses in outputting AC to the grid.

To generate 415 MWh per year, the size of solar array depends on where the farm is located and what type of solar array is chosen. In agricultural settings, a typical larger array is mounted on the ground if there is not sufficient space on top of farm buildings. Arrays are usually mounted at a fixed angle to maximize production while minimizing the land footprint, while larger arrays sometimes use a motorized tracking system to follow the sun from east to west every day. Rob Erlichman of Sunlight Electric counsels agricultural customers to use a 10 percent fixed tilt or less to cut down on valuable land usage (higher tilt angles require substantially more spacing between them. Alternatively, arrays mounted on livestock-proof racks at sufficient height would allow grazing and sun shelter for animals below the solar array. In California’s Central Valley, an array rated at 200-250 kW could generate 415 MWh of energy per year. An array such as this would occupy anywhere from 1 to 3 acres depending on the spacing and the angle of installation of the units. In the Northeast an array of around 275-325 kW would be required to generate the same amount of power.

Photovoltaic arrays are very handy sources of power but remain expensive because of a shortage of crystalline silicon. On the other hand, the purchase or long-term lease of a solar array (or wind turbine) locks in energy prices (payments on the purchase of the array as the sunlight is free) for a period of at least 20 to 30 years, when fossil energy and grid electric prices will no doubt rise. Current costs for crystalline silicon PV arrays are somewhere in the area of $8/watt with the additional costs of $1 to $2 per watt being incurred for more distant connections to the grid. Taking a middle course of $9/watt for 2007, the array in California would cost before rebates $1.8 to $2.25 million and assuming a rebate of $2.5/watt, $1.3 to $1.6 million net. In the Northeast, the larger array required would cost from $2.48 to $ 2.92 million at current prices. We would expect pricing in 2009 to be significantly less, when more silicon production capacity is online. Cost projections by manufacturers of new thin film materials, like Nanosolar’s Powersheet, are hoping to reduce the cost of panels to $1/watt or less that may yield installed costs of less than $3/watt. Installations with these less expensive materials may occupy a larger footprint depending on their efficiency which is sometimes half that of the more expensive crystalline silicon arrays.

A farm with these energy and equipment requirements will probably occupy several hundred acres depending of course on the type of agriculture and crops. The solar array, depending on where it is installed and whether the land it occupies can be used for other uses, will use less than 1 or maybe 2% of the farm’s land. Generating electricity on the farm may not be the most efficient use of the footprint of the farm, especially if the farm contains no marginal or unproductive land. On the other hand, using farm buildings or pasture for energy production will duplex energy use upon the primary use, reducing the energy generation footprint to near zero.

Summary and Evaluation of the Electric Farm Concept

Farming will remain dependent on petroleum derivatives or biofuels with questionable environmental effects and efficiency until farm equipment manufacturers apply contemporary and near future electric vehicle technology to tractors, harvesters and other powered farming implements. Somewhat ambitiously, I have taken on a moderately difficult farming task, a peak energy use day on a middle sized farm, to see whether currently available electrical power systems might be able to handle the task requirements with no revolutionary technology breakthroughs.

Working through this scenario has yielded a number of crucial results.

Lithium ion batteries, now revolutionizing electric vehicle development, also would make a huge difference in high-energy, high-power requirement farm tasks. Because of the five fold advantage in energy content of these batteries versus lead acid, it may be possible to forgo the use of a battery tender and in-field battery exchange: of the 5 mobile farm vehicles, only the large tractor working constantly at full power all day required 2 battery exchanges, leaving the battery tender idle most of the day. While not ideal, it would be more economical for the tractor to travel back to the battery charger for an exchange even though it would interrupt work flow for perhaps 45-60 minutes twice during the peak-use day. While I haven’t worked out a price for the battery tender, eliminating this aspect of the farm’s workflow would be a large savings; all farm vehicles would either refuel directly from a high voltage charger or by exchanging batteries directly at the charge stand. By contrast lead acid batteries would either require multiple battery exchanges during busy workdays or curtailment of energy intensive tasks.

As energy dense as lithium-ion batteries are in the battery universe, lead acid remain by contrast extremely affordable. The 80 tonnes of lead acid batteries might cost around $240,000 while the 31 tonnes of lithium ion batteries might cost $1.9 million. Despite the tonnage of lead acid batteries required and the frequent changes, they cost in this scenario less than 1/7^th of the lithium ion battery cost, because, in part, we have allowed spare lithium ion capacity in this scenario.

Reducing the power and energy requirements of farm tasks, especially as designed for electricity-powered machines, remains an area of huge potential savings and triple bottom line benefit. No- and low-till agriculture has been a big success as they both save energy and preserve soil integrity. Future modifications of farm tasks may allow farmers to produce as much food with less energy expenditure, less environmental damage, and lower capital expenditures on overpowered machinery.

Speculative high energy density ultracapacitors (read the always optimistic EEStor) would if their claimed attributes are real have a revolutionary impact on mobile re-charging of farm vehicles via a re-charge tender vehicle.

Reducing peak energy needs, at planting, at harvest, or during other energy-intensive tasks, will have a crucial effect on capital expenditures for energy storage or energy conversion devices. The experience of utility companies in instituting demand response programs may in part translate to helping farmers shift tasks to avoid excess capital expenditures, though the unique needs of plants, animals and the ecosystems in which they live may not be as flexible as commercial and industrial utility customers.

Land area required to generate electricity for the farm on the farm was calculated to show symbolically how the use of power implements need not require massive inputs of energy from outside the farm. The land area requirements for an on-farm solar array would under all but the most land-constrained and energy intensive farming conditions be negligible if electric farm equipment is used.

At least in the beginning, the capital investment in electric farm equipment is going to be substantially more expensive than that in its diesel brethren, especially if the more energetic lithium ion batteries are used. The lead acid tractor system (5 tractors plus spare batteries) with battery tender, would cost substantially more than 5 diesel tractors of the same size. A 330 hp diesel tractor costs around $200,000 USD while a 65 hp diesel tractor costs maybe $50,000 USD: just the batteries alone for the 5-tractor group would cost $240,000 USD. Despite this expense, costs of lead acid battery driven tractors will be within the same order of magnitude as diesel tractors, especially when the relative simplicity of their drive systems are taken into account. With lithium ion batteries, the costs at the present time are multiplied by sevenfold over the lead-acid option and probably 10 times the cost of the diesel tractor.

Energy Paths to a Sustainable Agriculture

The often-overlooked area of agricultural energy may yield a key area for developing large-scale battery powered or grid-optional work vehicles. In the early 20^th Century, over a period of decades, agriculture in industrialized nations became dependent upon fossil fuels; it will not be easy to wean agriculture and by extension our civilization off its dependence on these fuels to produce food. While current arguments about agriculture focus on the size of the farm, its use of toxics, diversity and regional appropriateness of food species and its proximity to its market, the Electric Farm concept is applicable to almost every size of farm, from the market gardener to the largest agribusiness, no matter what their cultivation practices and proximity to markets. Despite the focus on energy here, I hope that all food businesses will continue to move towards sustainability in the use of inputs other than energy.

Analysis of the Electric Farm concept has highlighted some key areas where agriculture can move to greater sustainability and minimize energy and climate risk.

Reduction of Farm Energy Requirements

The movement of the last few decades towards low- and no-tillage farming is a bright sign pointing towards the future of farm energy use. Plowing/tilling the soil has been historically one of the most energy and power-intensive farm activities, for which first animal power was used and in the last century fossil fuel powered tractors. No-till and low-till farming was originally paired with increased use of chemical inputs to control weeds and pest formerly controlled by turning the soil. There are now efforts underway to develop organic no- and low-till techniques; previously organic agriculture has substituted physical and therefore energy intensive methods for chemicals.

Agricultural scientists and farmers might be able to work together to further reduce energy use by developing agricultural machines and implements that use energy more efficiently. Electric farm implements will have greater flexibility than fossil fuel driven implements as electric motors are much easier to scale to the appropriate size and power for a task. Furthermore, automated and robotic farm equipment may facilitate the development of new, more energy effective farm tasks that are less disruptive to the farm ecosystem.

Plug-In, Battery-Exchange Serial Hybrids

The all-electric farm may be a vision for a time in the future when batteries or ultracapacitors increase in energy density and down in price: to bridge the gap, it may be necessary to reduce but not eliminate dependence upon fossil fuels by using flexible fuel electric vehicles. The ultimate flex-fuel farm equipment that would minimize fossil fuel inputs would be a serial, battery-exchange, biofuel-capable hybrid tractor or harvester. Such a machine would be able to use grid electricity, charged batteries, biofuels and petroleum to do farm work. An internal combustion engine or a fuel cell would generate electricity for the electric traction and implement drive motors when the substantial batteries, charged from the grid or from local farm generators, are exhausted. The amount of onboard batteries would be limited by weight considerations and cost but these batteries could also be exchanged as in the Electric Farm scenario.

The addition of an electric generator to the battery-exchange electric tractor outlined in the scenario allows for a significant reduction or elimination of off-board battery inventory as tasks that require more energy can supplement battery energy with biofuel or fossil energy. Lead-acid or lithium ion battery capacity could be sized for all-electric use for 60-80% of farm tasks, reserving fossil or biofuel to cover peak energy use. The cost of the generator, fuel tank and its mount would be small in comparison to the overall cost of the tractor or several battery packs.

Commercialization of Electric Farm Equipment

A market for electric farm equipment will emerge in ethically motivated agricultural concerns that have lower daily power and energy requirements for one or more of their tractors. In addition, air quality regulators in intensive agricultural areas like California’s Central Valley may offer incentives to develop zero or near-zero emissions agricultural equipment.

Initial models of electric farm equipment will probably be serial plug-in hybrids with lead acid batteries at a size that will offer most of the functionality of a 40 to 80 hp diesel tractor. Because of cost concerns and the lesser emphasis on weight reduction in tractors than in road vehicles, lead-acid batteries will be an early choice. Generators for this equipment may be either gasoline or diesel engines capable of using biofuels.

Machine designers may start by mimicking the functions of internal combustion tractors but soon realize that electric drive offers additional flexibility that will lead to a new “no-compromise” farm vehicle that can do more than the equivalent traditional tractor. Another path to commercialization may be for equipment manufacturers to start by building small multi-use vehicles like electric ATVs and garden tractors like the Elec-Trak and gradually build up power and functionality as demand arises. With substantial decreases in cost for lithium ion or other high energy-density mobile electric storage, electric farm equipment will gain greater applicability as most farm tasks will be able to be achieved without emissions, especially when paired with renewable energy.

To speed commercialization efforts, a zero-emissions agriculture consortium could be formed by equipment manufacturers, farmers, farm advocates, inventors, engineers, and agricultural scientists which might help develop a research and development program. This program will help locate the most promising niches for growth in this area and best address issues of farm productivity, energy efficiency, and ecological sustainability as regards farm machinery and mechanization.

US Readers: Action Alert – Renewable Energy Support Endangered November 14, 2007

Posted by Michael Hoexter in Green Activism, News and Events, Renewable Energy.
Tags: 2007 Energy Act, Legislative Action, Policy, Production Tax Credit, Renewable Energy, Renewable Portfolio Standard, RPS, US Congress
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The climate of short-sighted compromise and legislative solipsism in the US Congress is endangering important provisions of the 2007 Energy Bill that was supposed to put US Energy policy on a new footing. Subsidies for gas and oil exploration were to be cut while renewable energy was to get new support in the form of a national Renewable Portfolio Standard/RPS (rule that utilities need to supply a certain percentage of their energy from renewable energy) and production tax credits for renewable energy generated, a key incentive to renewable energy investors.

The US House of Representatives has passed two bills: HR 3221 (the New Direction for Energy Independence) and HR 2776 (the Renewable Energy and Energy Conservation Tax Act) but they need to be jointly passed by both House and Senate to become law. These bills jointly would see a transfer of the $23 billion subsidy of the fossil fuel industry to renewable energy projects. Over the weekend, rumor has it that the renewable energy provisions of these bills will be cut, including the tax credits and RPS provisions.

While these bills are not the absolutely ideal ways to promote renewable energy (a feed-in tariff is most effective as witnessed by the growth of renewable energy investment in Europe) they are good starts. Also, the US Southeast with diffuse sunlight and low wind speeds will need extra technical and policy help in developing a renewable infrastructure and/or means of investing in renewable energy outside the region. For Southeasterners, biomass to electricity with carbon capture (carbon negative) might be a way to get extra credit for renewable electric generation capacity in those states that actually subtracts existing carbon from the atmosphere.

So, please, US readers, call your Senators and Congresspeople! Here is the legislative action page of the website of the American Wind Energy association:

http://capwiz.com/windenergy/home/

And here is the website of Solar Nation with a similar feature:

http://www.solar-nation.org/

You can read more about the bills here:

http://energypriorities.com/entries/2007/11/energy_bill_2007.php

The Renewable Electron Economy Part VII: Stationary Energy Storage…Key to the Renewable Grid October 7, 2007

Posted by Michael Hoexter in Efficiency/Conservation, Renewable Energy.
Tags: batteries, Beacon Power, Compressed Air Energy Storage, Electric Grid, Electricity Storage Association, energy storage, flywheels, hydroelectricity, KEMA, lead acid batteries, molten salt energy storage, power engineering, pumped storage, Renewable Energy, Sandia National Labs, solar power, vanadium redox batteries, VRB, wind power
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A few posts back in this series I reviewed the state of mobile energy storage in the form of batteries and ultracapacitors, which are in the process of getting smaller and more powerful. However, if you don’t need to move around while using energy, the amount of energy stored per unit weight and volume becomes less of a challenge, therefore the separate category of stationary energy storage. I will include in this category “transportable” energy storage meaning that the energy storage unit can be moved by crane or forklift but is not meant to operate while in transit.

Why is stationary energy storage so important for a future, renewably-based grid? We have come to rely on fossil and fissionable fuels to power our on-demand electric grid. These fuels are in their natural state large energy stores: through a thermal or nuclear reaction the stored energy in fuel is released to power generators or do mechanical work in an engine. The advantages of this method of harnessing energy are that energy providers and users can accumulate and measure reserves of fuel and more or less control the timing of the reaction that releases the energy meeting the demand for electricity or mechanical work in real time. Renewable energy for the most part is opposite in that the primary energy for electricity is often intermittent natural energy flux: storage and control of energy output is something that in many cases needs to be added on. Biomass is the one exception, though as discussed in an earlier post, biomass or its refined products (biofuels) will have insufficient energy content to be the energy mainstay of advanced societies.

As already explored in previous posts, most renewable energy sources, with the exception of geothermal and tidal energy, are not constant or precisely predictable sources of energy. If paired with sufficient energy storage, most of these disadvantages in the production of renewable electricity go away. So, energy storage will be an essential part of the renewable energy grid of the future as well as a smarter transitional mixed fossil and renewably powered grid.

A helpful overview of some of these technologies can be found at the Electricity Storage Association’s website where there a number of diagrams that compare the different strengths of kinetic and electrochemical storage technologies (thermal storage is not covered). Having recently attended the 2007 EESAT conference co-sponsored by the US DOE, Sandia National Labs and the ESA, I am indebted to the presenters and participants at that conference for new insight into this market.

Functions of Energy Storage

Energy storage, whether used with fossil or renewable resources, can have a number of functions on or off the grid. Energy storage can be used to maintain continuity of service either in the form of an uninterruptible power supply (UPS) for a firm or facility or to plug a gap in electricity generation for the wholesale delivery of power to retail customers, particularly valuable for intermittent energy sources. If voltage sags or spikes for any number of reasons, energy storage systems can be used to compensate for the unevenness in voltage on a given power line. Energy storage can be used to regulate the AC frequency in the power system (measured in Hertz or cycles per second) to save power and protect sensitive electrical equipment. Furthermore energy storage can be used to make money or save costs by storing energy during low cost times and discharging energy during high cost periods (called arbitrage). Energy storage can also store kinetic energy for use later on, as with regenerative braking systems for large-scale electric bus and train systems.

Thermal Storage

One common and potentially game-changing form of storage is thermal storage, storing energy as either heat or cold. One current common use of thermal storage is cooling chilled water with nighttime electricity, storing the cool as either ice or cold water and then using that water to run refrigeration and air conditioning during the day. This use for large buildings and corporate facilities has, under current rate structures in most markets, financial benefits as most utilities want to reduce peak demand during the day and use underutilized capital equipment during the night. However, the shifting of loads may not yield a net carbon emission benefit as night-time electricity might be more carbon intensive than daytime electricity.

A greener alternative is an experimental technology where the heat of the summer sun is stored underground and used during the winter for space heating or road de-icing. This technology has not yet been widely applied nor proven as an economic alternative but a communities in Canada and in Germany have created district heating systems for storing heat for months in underground storage that promise to defray some or all of the winter domestic space heating load. One storage technique is called borehole thermal storage where a thermal fluid transfers heat to the ground through a series of holes.

Most promising for the renewable grid is the use of molten salt or other thermal storage media to store the heat of the sun in the context of a solar thermal electric plant (sometimes called CSP or concentrating solar power), which use mirrors arrayed in parabolic troughs or power tower designs to concentrate solar radiation on a thermal fluid. While these solar thermal electric generation plants can be built without storage facilities, with storage included generation can be postponed for as much as a week and potentially more by releasing the heat from the storage medium when electricity is needed. This technology was developed in the 1970’s and 80’s but has only recently been the subject of renewed interest and investment. Solar thermal plants with storage can operate as either baseload or peak-load plants; the main limitation for this technology is siting these plants in regions with intense direct sunlight such as the US Southwest, Southern Spain, Sicily, North Africa, Namibia, the Australian Outback, the Middle East, and the Atacama Desert. If only parts of these areas were covered with solar thermal plants with adequate storage and there were sufficient electric transmission to load centers (cities), most of the world’s electric demand could be served by solar thermal electric/CSP plants that would, in their output profile, most closely meet the demands of grid managers and energy users. In the current regime without substantial carbon pricing, incentives or subsidies are needed to finance the building of storage facilities as these add cost to the already substantial capital requirements of building a solar thermal plant.

Pumped Hydroelectric Storage

The value of one of the highest capacity and highest power storage technologies has been recognized for many years: shuttling water between two reservoirs at different heights by means of a pumping system and a hydroelectric generation plant. Called pumped storage, electricity is generated as water flows downhill and stored when it is pumped uphill. This arrangement loses somewhere between 15 and 30% of the power to friction, evaporation, and pumping losses. In addition to a dedicated pumped storage reservoir, storage can be a component of typical hydroelectric power station with the addition of a pumping facility and a connection to the excess or cheaper power to be stored. There are over 100 pumped storage facilities in the world, the largest of which can output over a gigawatt of electricity for days at a time. Drawbacks to pumped storage are its high capital cost, geographical and environmental restrictions on siting a reservoir or dam, and sensitivity to drought conditions.

Pumped storage facilities, due to their capacity and power output are being considered as one of the key technologies to help integrate large amounts of wind power into the grid, storing the output of wind turbines until it is needed. Most pumped storage is located in hilly or mountainous regions with sufficient rainfall or other water resource. An interesting pumped-storage alternative has been suggested by KEMA, a Netherlands-based energy consultancy, as a way to increase the value of the output of offshore windfarms in the North Sea. Northern European countries are increasing their use of wind power, their strongest renewable resource. Holland has no mountains to speak of but a long tradition of massive earthworks by the sea to control flooding. KEMA has proposed an “Energy Island” which would create an circular dike in the North Sea which would have a central inner “lake” at a level 32 to 40 meters below sea level. Energy would be generated from the island by hydroelectric facilities that would use seawater falling into the inner lake as their primary energy. Wind from offshore turbines or from turbines on the dikes would be used to pump water out of the inner lake. This facility would store 20 GWh of power and have an output of at least 1.5 GW for 12 hours.

Compressed Air Storage

Somewhat smaller in capacity than pumped hydro and more complicated is compressed air energy storage or CAES. There now 2 operational compressed air storage facilities, one in Germany and one in Alabama with two more planned in the US. In compressed air storage, a large underground space (usually a disused mine) is used to contain air at a high pressure. Excess power from the grid is used to compress air and inject it into the container or underground cavity. When power is needed, the air is released, expanded with the force of expansion used to drive turbines. The complexity of CAES enters in issues of dealing with the changes in the heat of gases as they are compressed or expand. Compressing air or any gas, heats up the gas, while expanding a gas, especially rapidly, requires the addition of heat to prevent excessive cooling. There are also so called adiabatic methods of compression and expansion that expand the gas more slowly and do not require heat but they will output less power.

Existing compressed air storage facilities are paired with a natural gas heat source to drive the turbines to avoid the inefficiencies of adiabatic expansion. The compressed air plus natural gas turbine uses 40% of the natural gas that an ordinary natural gas plant would to generate the same amount of electricity so the compressed air might be viewed as a supercharger for a natural gas generation plant. CAES is currently used to store nighttime electricity for use during peak periods but CAES has also been discussed in connection with wind power. The key with CAES is deciding upon the ultimate design of the compression and expansion scheme including the ultimate heat source.

For a renewably powered grid, CAES would need to either use biomass, geothermal or concentrated solar thermal to heat the expanding air or settle for the lower power of adiabatic expansion of the gas. If the former were the choice, the siting of the CAES plant would be restricted to where these resources were easily available. General Compression, a start up in the wind industry, is marketing a compressed air solution that uses wind turbines that output compressed air rather than electricity. A General Compression wind farm would need to be located over a geological storage cavity and also, in most cases, would need a heat source to help re-expand the gas. General Compression markets its product as “dispatchable wind”. Obviously, as with all CAES proposals, siting and the ultimate efficiency and economics of this new type of wind farm would need to be carefully examined. CAES may also compete for underground storage cavities with carbon sequestration and storage schemes if these are developed further.

There are novel ideas from EnisWindgen that suggest that compressed air can be conducted to points of use through pipelines and used as both a refrigerant and a power source, thereby utilizing the cold of compressed air expansion as an air conditioner and a driver of an electrical generator.

Electrochemical Storage (Batteries)

While most of us think of batteries as rather small, there are some very big batteries and battery banks out there. With increasing demand for electrical storage, some specialized batteries will just get bigger and more inexpensive per unit energy and power stored. The market for stationary batteries will also benefit from the drive to improve mobile battery storage for the electric and hybrid electric vehicle market. Batteries require and generate DC current, so conversion to AC is required through inverters to output to the grid.

Lead-Acid Batteries

The cheapest batteries are still the lead-acid batteries that power typical vehicle starter motors as well as most current battery electric vehicles, including forklifts and neighborhood electric vehicles. When put together in large battery banks, these are often used as part of a backup power (UPS) system for facilities that need to maintain power to sensitive and business critical equipment. Electric utilities can use these battery systems instead of quick-dispatch fossil fuel power plants to regulate voltage or line frequency and utilize their generation plants more efficiently, thereby reducing carbon emissions. Lead acid battery banks with energy capacities of 10-20 megawatt-hours and power output of 2-4 megawatts may make economic sense depending upon the application. Lead acid batteries have efficiencies of somewhere between 75-85% meaning that 15-25% of the DC electric current is lost from recharge to discharge.

With renewable energy, lead acid batteries can be applied as an off-grid or on-grid facility UPS by storing the output of windmills and photovoltaic panels. Battery banks are necessary for off-grid facilities if power is to be available on-demand. On-grid, utilities could use lead-acid battery banks to smooth the output of wind or solar farms though other technologies with higher energy densities and efficiencies are now available

There are innovations in the use of lead-acid and lead batteries that may make them more durable and increase their charge to weight ratio. Firefly Energy is about to commercialize a lead-acid battery with longer life, higher energy density, and higher power by using “foam” structured electrodes. Axion Power is also in the process of developing a lead-carbon hybrid battery-supercapacitor that will lengthen lead acid battery life, increase their power and allow faster recharge.

Sodium Sulfur Batteries

Less well known but more energy-dense and efficient are large sodium-sulfur batteries (NaS) which are not available in smaller sizes due to the high heat required. In an NaS battery, molten metallic sodium gives off electrons during discharge (electric current) to sulfur which forms a negative sulfide ion, a reaction which then reverses with the application of current during the charge phase. The efficiency of these batteries is around 90% but if two AC/DC conversions are included the roundtrip efficiency is around 76%. NaS batteries become more economical and more efficient the larger they are with an installation in Japan as large as 58 megawatt-hours and 8 megawatts power output used to reduce peak demand. American Electric Power, the largest utility in the US, has bought some NaS batteries and is projecting buying at least 25 MWs of these batteries by the end of the decade to increase power quality. In current applications AEP is focusing on the ability of these batteries to increase the lifetime of a transformer, postponing capital expenditures but in the future hopes to pair these batteries with wind farms to enable more reliable green power output. Calculations by AEP indicate an acceptable return on the investment.

In Japan, the sole manufacturer of NaS batteries, NGK Insulators is building a 34MW NaS storage facility (with a 255 MWh energy capacity) in combination with a 51MW wind farm to store the wind farm’s power and output the electricity when the grid needs the power. As this is still an experimental arrangement, a large portion of the battery costs were covered by the Japanese Ministry of Energy.

Flow Batteries

A flow battery stores electrolytes in tanks and can therefore have a flexible energy capacity depending on how many electrolyte tanks one connects to the power input/output unit. The most well-known and widely applied flow battery is the vanadium redox battery or VRB. VRB’s are very efficient and respond very quickly to demand for electricity and can have a high power rating. There are currently less than 10 large VRB battery installations in the world, a few of which are paired with wind farms to balance output. VRB’s can be used as a UPS as well. VRB Power Systems of Vancouver, BC, the primary manufacturer of vanadium redox battery, claims that VRBs have the lowest environmental impact of any battery system and could have outputs of at least 10MW with multiple hours of energy.

Lithium Ion Batteries

Lithium ion batteries have traditionally not been produced in large sizes and are considered too expensive for stationary storage at this time. However as there is a huge push to produce more energy dense and less expensive lithium ion batteries for electric vehicle market, some of this development effort may eventually make lithium an economic choice for stationary applications.

Vehicle to Grid and Used Battery Storage

As battery electric vehicles in their various forms (EV and PHEV) become more common, they may be able to act as an energy reservoir for the grid, if technical and economic institutions are invented that support this practice, called vehicle to grid or V2G. If many thousands and millions of vehicles are plugged into the grid at any one time, the batteries in these vehicles would be in various states of charge and might be able to send electricity back to the grid within a preset limits dictated by the vehicle owner. The vehicle owner would get payment per kilowatt-hour as well as probably some form of monthly participation payment as these withdrawals of charge are of value to the grid operators. In theory, the massed battery electric vehicles on the grid could function as an additional gigawatt-sized storage device to help smooth the functioning of a grid powered by more renewables.

V2G requires the development of a smart grid, a set of technologies that allows among other things two-way communication between electricity generation and electric load. In addition V2G would require owners to set their preferences perhaps on a daily basis in terms of how much charge they need from their vehicle batteries. Compensation and/or the sense of contributing to a larger purpose would have to outweigh the inconvenience of communicating preferences to the utility and the uncertainty of the exact amount of charge remaining in the vehicle’s batteries.

Less complex is the commitment by, as a leading example, Pacific Gas and Electric, the Northern California utility, to buy functioning used vehicle batteries that would otherwise be recycled. PG&E is collecting these batteries for use as an energy storage facility, thereby 1) increasing the resale value of used electric vehicles and vehicle parts, 2) reusing rather than recycling material and 3) creating a new source of on-grid storage for a low price.

Kinetic Energy Storage – Flywheels

Flywheels use the kinetic energy of a rapidly rotating wheel or ring to store energy. Flywheels are being investigated for use in modern electric vehicles but most current applications are in the stationary energy storage market. Flywheels were used in early industrial systems to store energy and smooth the output of early power generation systems.

Modern flywheels rotate at much higher speeds than the traditional flywheels of the 19^th and early 20^th centuries; current technology allows flywheels to spin in evacuated containment vessels at speeds of up to 50,000 rpm. The newest designs use magnetic levitation to decrease friction even further. A flywheel is attached to a motor/generator that adds power and energy to the flywheel by speeding it up and taps power from the flywheel by generating electricity when needed which slows the wheel down. Flywheels are very responsive and able to deliver very high power pulses so are ideal for conditioning spikes and dips in power from power plants and renewable resources. Also flywheels are able to supply peak power to devices that need brief very high power to do their work.

Beacon Power, one of the leading flywheel manufacturers, ~~has been commissioned by the US Department of Energy~~ to build a 20 MW flywheel power plant test facility containing 200 of their 100 kW flywheels [Correction: I've received a correction from Beacon that DOE has helped fund the design work for the plant and may offer loan guarantees as well...to be determined]. These power plants if widely used would have the capacity to substitute for fossil burning power plants in the area of frequency regulation, which requires accurate calibration of power pulses to the grid to maintain the optimal AC frequency. A study by the energy consultancy KEMA suggests that the use of flywheels in the frequency regulation market could reduce CO2 emissions by as much as 80%.

Hydrogen fuel cells

Hydrogen Fuel Cells have received attention in excess of their current usefulness as energy storage devices. The may have a role in a regime of grid-wide excess production of renewable energy but are currently oversold by advocates that seem to have overlooked the inefficiency of converting electricity into hydrogen and then back again into electricity. Figures for the efficiency of the cycle range between 25% and 40%, yielding net losses of energy in the area of 60 to 75%. Current rational uses would be limited to niche applications or where oil refineries produce an excess of hydrogen as part of the petroleum refining processes. It is unfortunate that research funding for hydrogen fuel cells has over the past decade diverted attention from research into higher efficiency energy storage technologies with greater immediate or near-term usefulness.

Overview of Energy Storage

Energy storage is still a rapidly developing field with certain growth in the future, especially in a carbon constrained world. As we exploited as a society the stored energy characteristics of fossil and fissionable fuels for the last century, energy storage as a concept has not received the research and investment attention it deserves: the realization of the externalized costs of carbon-based fuels is leading to refinement of existing technologies and the potential for lowered costs. Already, energy storage technology can pay off in the higher cost areas of frequency regulation and power quality. Deferment of replacement cost for aging equipment can also pay off within several years in the use of appropriate energy storage technology.

Breakthroughs in commercializing energy storage technologies will be spurred most rapidly by the introduction of realistic pricing for carbon-emissions, which will lead to investment in both renewable energy and in energy storage technologies. The liberal disbursement of pollution credits during Kyoto’s first round has not yet signaled the true cost of carbon to electricity generators and users. Higher energy tariffs for renewable energy in Spain and other European countries may help finance storage to be built alongside renewable generation capacity as part of the payment per kWh for electricity.

Some energy storage technologies require investment in infrastructure that goes beyond the time horizon of most private enterprises, even utilities that manage equipment over 40 or 50 year life cycles. Such investment is typical for the massive earthworks and long-lived transmission lines that compose the conventional electric grids in most developed countries. Public-private partnerships, as has already been the case, will be required in at least the immediate future to build pumped hydroelectric projects or build massive thermal storage facilities in tandem with solar thermal plants. Planning for these facilities, while central to the grid of the future, will not yet be able to assign numbers to the value created by them, so it cannot be expected that private firms take on all the risk in building them. On the other hand, we need to start today in planning, siting and building these facilities, as well as speed the commercialization and development of existing smaller scale storage alternatives.

newer posts »

Green Thoughts

The Renewable Electron Economy XII: The “Cheap Energy Contract”…Bedrock or Dinosaur? January 14, 2008

Renewable Electron Economy Part X: Revolution in Power Engineering December 25, 2007

Defeat of Tax Credits/Bali — A Day of Shame for the US December 14, 2007

The Renewable Electron Economy Part IX: What is Renewable Energy Anyway? December 9, 2007

‘Nuther Action Alert for US Readers: Renewable Energy Support December 4, 2007

The Renewable Electron Economy Part VIII.2: The Electric Farm – 2 November 30, 2007

US Readers: Action Alert – Renewable Energy Support Endangered November 14, 2007

The Renewable Electron Economy Part VII: Stationary Energy Storage…Key to the Renewable Grid October 7, 2007

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