Cellulosic Ethanol: Running Cars On Lawn Cuttings  

Posted by Big Gav in , , , ,

Its been over a year since I last did a roundup of cellulosic ethanol news - time for another one.

Wired has a good introductory article on the subject (albeit one viewing the subject through rose coloured glasses) - "One Molecule Could Cure Our Addiction to Oil" which looks at some of the companies pioneering the underlying technology - Mascoma, Novozymes and Verenium. In the sidebar there are 4 Alternative Technologies On The Brink, courtesy of Dave Roberts - Energy storage with ultracapacitors, geothermal power, thin film solar and synfuel. While the article thinks biofuels are a better bet than transitioning electric powered vehicles in the medium term, I'd have to say that this seems both incorrect and a far less than optimal way to proceed.

On a blackboard, it looks so simple: Take a plant and extract the cellulose. Add some enzymes and convert the cellulose molecules into sugars. Ferment the sugar into alcohol. Then distill the alcohol into fuel. One, two, three, four — and we're powering our cars with lawn cuttings, wood chips, and prairie grasses instead of Middle East oil.

Unfortunately, passing chemistry class doesn't mean acing economics. Scientists have long known how to turn trees into ethanol, but doing it profitably is another matter. We can run our cars on lawn cuttings today; we just can't do it at a price people are willing to pay.

The problem is cellulose. Found in plant cell walls, it's the most abundant naturally occurring organic molecule on the planet, a potentially limitless source of energy. But it's a tough molecule to break down. Bacteria and other microorganisms use specialized enzymes to do the job, scouring lawns, fields, and forest floors, hunting out cellulose and dining on it. Evolution has given other animals elegant ways to do the same: Cows, goats, and deer maintain a special stomach full of bugs to digest the molecule; termites harbor hundreds of unique microorganisms in their guts that help them process it. For scientists, though, figuring out how to convert cellulose into a usable form on a budget driven by gas-pump prices has been neither elegant nor easy. To tap that potential energy, they're harnessing nature's tools, tweaking them in the lab to make them work much faster than nature intended.

While researchers work to bring down the costs of alternative energy sources, in the past two years policymakers have finally reached consensus that it's time to move past oil. The reasoning varies — reducing our dependence on unstable oil-producing regions, cutting greenhouse gases, avoiding ever-increasing prices — but it's clear that the US needs to replace billions of gallons of gasoline with alternative fuels, and fast. Even oil industry veteran George W. Bush has declared that "America is addicted to oil" and set a target of replacing 20 percent of the nation's annual gasoline consumption — 35 billion gallons — with renewable fuels by 2017.

But how? Hydrogen is too far-out, and it's no easy task to power our cars with wind- or solar-generated electricity. The answer, then, is ethanol. Unfortunately, the ethanol we can make today — from corn kernels — is a mediocre fuel source. Corn ethanol is easier to produce than the cellulosic kind (convert the sugar to alcohol and you're basically done), but it generates at best 30 percent more energy than is required to grow and process the corn — hardly worth the trouble. Plus, the crop's fertilizer- intensive cultivation pollutes waterways, and increased demand drives up food costs (corn prices doubled last year). And anyway, the corn ethanol industry is projected to produce, at most, the equivalent of only 15 billion gallons of fuel by 2017. "We can't make 35 billion gallons' worth of gasoline out of ethanol from corn," says Dartmouth engineering and biology professor Lee Lynd, "and we probably don't want to."

Cellulosic ethanol, in theory, is a much better bet. Most of the plant species suitable for producing this kind of ethanol — like switchgrass, a fast- growing plant found throughout the Great Plains, and farmed poplar trees — aren't food crops. And according to a joint study by the US Departments of Agriculture and Energy, we can sustainably grow more than 1 billion tons of such biomass on available farmland, using minimal fertilizer. In fact, about two-thirds of what we throw into our landfills today contains cellulose and thus potential fuel. Better still: Cellulosic ethanol yields roughly 80 percent more energy than is required to grow and convert it.

So a wave of public and private funding, bringing newfound optimism, is pouring into research labs. Venture capitalists have invested hundreds of millions of dollars in cellulosic-technology startups. BP has announced that it's giving $500 million for an Energy Biosciences Institute run by the University of Illinois and UC Berkeley. The Department of Energy pledged $385 million to six companies building cellulosic demonstration plants. In June the DOE added awards for three $125 million bioenergy centers to pursue new research on cellulosic biofuels.

There's just one catch: No one has yet figured out how to generate energy from plant matter at a competitive price. The result is that no car on the road today uses a drop of cellulosic ethanol.

Cellulose is a tough molecule by design, a fact that dates back 400 million years to when plants made the move from ocean to land and required sturdy cell walls to keep themselves upright and protected against microbes, the elements, and eventually animals. Turning that defensive armor into fuel involves pretreating the plant material with chemicals to strip off cell-wall protections. Then there are two complicated steps: first, introducing enzymes, called cellulases, to break the cellulose down into glucose and xylose; and second, using yeast and other microorganisms to ferment those sugars into ethanol.

The step that has perplexed scientists is the one involving enzymes — proteins that come in an almost infinite variety of three-dimensional structures. They are at work everywhere in living cells, usually speeding up the chemical reactions that break down complex molecules. Because they're hard to make from scratch, scientists generally extract them from microorganisms that produce them naturally. But the trick is producing the enzymes cheaply enough at an industrial scale and speed.

Today's cellulases are the enzyme equivalent of vacuum tubes: clunky, slow, and expensive. Now, flush with cash, scientists and companies are racing to develop the cellulosic transistor. Some researchers are trying to build the ultimate microbe in the lab, one that could combine the two key steps of the process. Others are using "directed evolution" and genetic engineering to improve the enzyme-producing microorganisms currently in use. Still others are combing the globe in search of new and better bugs. It's bio-construction versus bio-tinkering versus bio-prospecting, all with the single goal of creating the perfect enzyme cocktail. ...

Wired also outlines the formula for turning grass to gas.
Step 1: Thermochemical treatment The raw plant feedstock is treated with chemicals — often dilute sulfuric acid — to break down cell walls and make the cellulose accessible. Step 2: Enzymes A mix of cellulase enzymes is then added to convert the cellulose and hemicellulose molecules into the simple sugars glucose and xylose. Step 3: Fermentation Yeast or bacteria are added, converting the sugar into a mixture of ethanol and water, what refineries call "the beer." Step 4: Distillation The ethanol is refined and purified, producing a fuel that could one day end up in your gas tank.

After Gutenberg also has a look at cellulosic ethanol company Mascoma in "Tenessee Sipping Cellulosic".
The U.S. uses about 9.2 million barrels (219,000 gallons) of Finished Motor Gasoline a day. Automobile engines can run on an E10 blend, i.e., fuel that is 10% ethanol, with the only difference, a barely discernible reduction in mileage. “Regular” gasoline has a value of 85-92 g CO2 eq / MJ, while cellulosic ethanol, when derived from municipal solid waste, has a value of about 5 g CO2 eq / MJ. ...

There are approximately 4.5 million E85 capable motor vehicles now on American roads. If that many vehicles were operating on an E-85 blend, with ethanol made from cellulosic feedstock — Okeelanta bagasse or otherwise, then Americans might be able to make some claim to responsible action toward the mitigation of climate change.

Autoblog Green relays an announcement from Mascoma Corporation about the five-million-gallon-a-year cellulosic ethanol Tennessee plant to open in 2009. The company intends that this facility be the first in the country to produce cellulosic ethanol from switchgrass.
Mascoma’s partner in the plant is the University of Tennessee, which has been conducting research that suggests “that Tennessee is capable of generating over one billion gallons of cellulosic ethanol from switchgrass alone.”

Note that while the research was with switchgrass alone, the push is for relatively small amounts of cellulosic feedstock mixed with a coal slurry. With East Tennessee in the Eastern coal belt, it would be difficult to imagine that this effort is something other than another CBTL (Coal / Biomass To Liquids) greenwash.

The Energy Blog reports that Poet Biorefining has become the largest ethanol producer in the world, and may be first to produce cellulosic ethanol using technology from DuPont and Novozymes. I think its worthwhile keeping the Seven Commandments of Biofuel in mind whenever evaluating these kinds of schemes.
On September 14 POET Biorefining, formerly the Broin Companies, opened their 21st ethanol production facility, a 65 million gallon per year plant that brings Poet's total capacity to 1.1 billion gallons per year of corn ethanol, making POET the largest producer of ethanol in the world.

The facility, the 27th (including administrative facilites) constructed by POET since they were founded 20 years ago, is equipped with technology that decreases its environmental footprint. That technology includes POET’s patent-pending BPX™ process that eliminates the need for heat in the cooking process of producing ethanol, reducing energy usage by 8-15 percent in comparison with conventional plants. It will also be outfitted with a regenerative thermal oxidizer that eliminates up to 99.9 percent of air emissions.

The BPX process is a patent-pending raw starch hydrolysis process that converts starch to sugar, which then ferments to ethanol without heat. The process not only reduces energy costs, but also releases additional starch content for conversion to ethanol, increases protein content and quality of co-products, increases co-product flowability, potentially increases plant throughput and significantly decreases plant emissions.

POET Biorefining - Portland, IN will utilize 22 million bushels of corn from the area to produce 65 million gallons of ethanol and 178,000 tons of Dakota Gold Enhanced Nutrition Distillers Products™ per year. The $105 million facility will provide around 40 jobs with an annual payroll of about $2 million.

In February 2007 POET and the U.S. Department of Energy (DOE) agreed to jointly fund the development of a cellulosic ethanol plant. The DOE announced a grant that will fund a portion of Poet's $200 million expansion of a conventional corn dry mill facility in Emmetsburg, Iowa into a bio-refinery that will include production of cellulosic ethanol from corn cobs and stover.

The project will convert a conventional corn dry mill facility in Emmetsburg, Iowa into a commercial scale biorefinery designed to utilize advanced corn fractionation and lignocellulosic conversion technologies to produce ethanol from corn fiber and corn cobs and stover. Known as Project LIBERTY, the expansion will utilize an existing infrastructure with projected costs for the increased capabilities at just over $200 million dollars. The expansion will take approximately 30 months and is slated to begin as soon as the terms of the agreement with the DOE are finalized. Discusions of the final details of that agreement are still underway.

Poet is currently able to produce about 435 gallons of ethanol per acre (based on 150 bushels per acre). Cellulosic ethanol production from corn cobs adds another 80 gallons per acre and fractionated fiber adds another 40 gallons per acre, potentially bringing each acre’s ethanol production to more than 550 gallons.

To complement their own technology, POET has forged relationships with other leaders in the cellulosic ethanol field. It has licensed a unique integrated lignocellulose conversion technology package developed by DuPont that converts high volumes of both the cellulose and hemicellulose in corn plants into ethanol. They are also collaborating with Novozymes, a world leader in industrial biotechnology, on providing state-of-the-art enzyme technology in the cellulosic biomass field.

POET is taking two phases to producing cellulosic ethanol, the first phase will use only the cobs and the second phase will use as much of the rest of the plant as possible without comprimising soil quality.

By adding cellulosic production to an existing grain ethanol plant, POET will be able to produce 11 percent more ethanol from a bushel of corn, 27 percent more from an acre of corn, while almost completely eliminating fossil fuel consumption and decreasing water usage by 24 percent. In the future, in cellulosic plants, they will use some of the leftover lignin to power the entire facility and almost, or possibly completely, eliminate the need to power the facility with any fossil energy.

Robert Rapier has been a critic of ethanol and other biofuels in their various forms for some time. His latest post takes a look at Ted Patzek's new paper on biofuels - "Review: How Can We Outlive Our Way of Life?".
I believe our generation faces a sobering choice: Take serious steps to reduce our fossil fuel usage now - and this will undoubtedly entail some amount of hardship - or leave it to our children to face a great deal of hardship. I firmly believe this is our choice, and we must look to solutions that move us in that direction. I also believe that if most people understood that we are pushing a very serious problem onto our children - instead of assuming scientists and engineers will solve the problem - then we would collectively pursue a solution with far greater urgency.

Berkeley Professor Tad Patzek, who has written many articles that are critical of our present attempts to replace fossil fuels with biofuels, has just published a new article in which he also discusses solutions - "How Can We Outlive Our Way of Life?"

Many of you know Tad Patzek as the co-author of a number of papers with David Pimentel. If you are pro corn-ethanol, then you have probably been conditioned to discount everything Professor Patzek writes. But even if you disagree with his corn ethanol position, there is still a lot to take away from this paper. Patzek's conclusion on cellulosic ethanol is the same as my own: The status of cellulosic ethanol has been exaggerated and over-hyped, and the solution that we really ought to be pursuing is electric. The abstract of the paper reads:
In this paper I outline the rational, science-based arguments that question current wisdom of replacing fossil plant fuels (coal, oil and natural gas) with fresh plant agrofuels. This 1:1 replacement is absolutely impossible for more than a few years, because of the ways the planet Earth works and maintains life. After these few years, the denuded Earth will be a different planet, hostile to human life. I argue that with the current set of objective constraints a continuous stable solution to human life cannot exist in the near-future, unless we all rapidly implement much more limited ways of using the Earth’s resources, while reducing the global populations of cars, trucks, livestock and, eventually, also humans. To avoid economic and ecological disasters, I recommend to decrease all automotive fuel use in Europe by up to 6 percent per year in 8 years, while switching to the increasingly rechargeable hybrid and all-electric cars, progressively driven by photovoltaic cells. The actual schedule of the rate of decrease should also depend on the exigencies of greenhouse gas abatement. The photovoltaic cell-battery-electric motor system is some 100 times more efficient than major agrofuel systems.

The paper is highly technical, which will turn off many people. But what I enjoy - and I believe is one of my strengths - is to distill technical information and present it so that it is more readily digestible for the layperson. My hope is that this essay succeeds in doing that.

The paper was presented at the 20th Round Table on Sustainable Development of Biofuels in Paris, and therefore contains a lot of Europe-specific discussion and recommendations. The paper covers a lot of ground. Petroleum depletion is discussed, and the business-as-usual scenario is discarded as simply not possible. Cellulosic ethanol is covered, with a close examination of the energy efficiency of Iogen's plant in Ottawa. This result is then compared to the energy efficiency claims of the six proposed demonstration plants in the U.S. The last section compares the potential of photovoltaic cells to biofuels for mitigating our depleting fossil fuel reserves.

Summarizing the Paper


In the introduction, Professor Patzek states that world production of conventional petroleum peaked in 2006, and will decline exponentially within a decade. He suggests that heroic measures such as infill drilling, horizontal wells, and enhanced oil recovery methods can stem the decline initially, but this will lead to a steeper decline rate later on. He extrapolates the current per capita use of petroleum with the growth of population in the U.S., and concludes "that the US and the rest of the world soon will be on a head-on collision course." He also states that the U.S. currently uses 33 times as much energy in transportation fuels than is required to feed the population.


In this section, Professor Patzek outlines five constraints that impact humanity's survival, followed by possible solutions given these constraints. The constraints include exponential population growth, overuse of the earth's resources, and our current political structure in which "more is better." He presents two solutions to our current situation: 1). Go extinct; or 2). Fundamentally and abruptly change. The status quo is not an option, as Patzek believes it will lead to solution (1). I understand that many doubt that (2) is possible, which is why they believe we are doomed. Personally, I believe the most likely solution is a combination of the two. People will go extinct as food and energy become unaffordable (this is happening even now), but there will be pockets of fundamental and abrupt change. Fast recognition and adaptation - both on a personal and governmental level - are going to be very important.

Patzek examines the impact of fossil fuel usage on population growth, and concludes that of the present world population, "4.5 billion people owe their existence to the Haber-Bosch ammonia process and the fossil fuel-driven, fundamentally unstable 'green revolution,' as well as to vaccines and antibiotics."

He comments that too many in society consider themselves more knowledgeable about energy matters than they really are, and this is why we aren't urgently confronting the problem. As his 2nd conclusion of the paper, he writes:
Business as usual will lead to a complete and practically immediate crash of the technically advanced societies and, perhaps, all humanity. This outcome will not be much different from a collapse of an overgrown colony of bacteria on a petri dish when its sugar food runs out and waste products build up.

He concludes this section by pointing out that we have been conditioned to think that technology is almost magic and will solve our problems. He quoted a biofuels expert who suggested "Biotechnology is not subject to the same laws of chemistry and physics as other technologies. In biology anything is possible, and the sky is the limit!”

Efficiency of Cellulosic Ethanol Refineries

This section was extremely interesting to me. Real energy efficiencies of cellulosic ethanol plants (which presently exist only on paper or in demonstration scale) are hard to come by. Those 4:1 or 8:1 energy returns that you often see claimed are hypothetical; nobody in the cellulosic ethanol business has demonstrated anything like this. Professor Patzek attempts to shed some light on this subject. In his words:
I start from a “reverse-engineering” calculation of energy efficiency of cellulosic ethanol production in an existing Iogen pilot plant, Ottawa, Canada. I then discuss the inflated energy efficiency claims of five out-of-six recipients of $385 millions of DOE grants to develop cellulosic ethanol refineries.

Using published information, Professor Patzek calculated the efficiency of the Iogen plant. He defined the efficiency (albeit by an equation that could have been more clear) as the BTUs of ethanol produced, divided by the theoretical maximum. His calculated efficiency of the process was 20%; input 1 BTU into the process and return 0.2 BTUs, for a net of -0.8 BTUs. This calculation is in the same form as Dr. Wang's gasoline efficiency calculations - the initial BTUs of the feedstock are counted as an input into the process, and then the processing energy is counted against it. In simple terms, if you take 1 kilogram of wheat straw, add in the distillation energy and take credit for the heating value of the lignin, you have the denominator of the equation. The numerator is the heating value of the ethanol that was produced from that kilogram of wheat straw. If you started with 1 BTU of straw, and produced 1 BTU of ethanol, the efficiency is then governed purely by the distillation energy (essentially the amount of external energy required to drive the process).

Of particular note, the equation did take a credit for the lignin, which is always the assumption that cellulosic ethanol proponents use to obtain inflated energy returns. However, the most significant piece of the calculation for me - and one that Patzek did not call attention to - is that if you look at only the distillation energy (the 2nd term in the denominator of Eqn 1), it is 55% greater than the ethanol that is yielded from the distillation. That means that production of 1 BTU of cellulosic ethanol requires a distillation step that consumes 1.55 BTUs.

The reason for this is one I have stated numerous times. As Patzek writes "there is ca. 4% of alcohol in a batch of industrial wheat-straw beer, in contrast to 12 to 16% of ethanol in corn-ethanol refinery beers."

I do note that if you take full credit for the heating value of the lignin, it just barely satisifies the distillation requirement. If you run through the math, the lignin BTU credit gives an energy balance of 1.05, which is worse than the 1.3 of corn ethanol plus by-product credits. But remember, the lignin in the process is not dry. It is very wet. Drying co-products in a corn ethanol plant requires a substantial input of energy. If lignin is to be used in a cellulosic ethanol plant, it will have to be dried.

Furthermore, even if the lignin is dry, no other energy inputs into the process have been considered (so this is not a complete energy balance calculation). In other words, if those inputs were all free (of course trucking the biomass back and forth will require significant energy inputs), and the lignin was dry, you would get 1.05 BTUs of cellulosic ethanol out for a lignin input of 1 BTU. Even presuming that Iogen has made major advances recently, it is not surprising why they have been slow to build a commercial facility; they know the score. Patzek concludes:
The Iogen plant in Ottawa, Canada, has operated well below name plate capacity for three years. Iogen should retain their trade secrets, but in exchange for the significant subsidies from the US and Canadian taxpayers they should tell us what the annual production of alcohols was, how much straw was used, and what the fossil fuel and electricity inputs were. The ethanol yield coefficient in kg of ethanol per kg straw dmb is key to public assessments of the new technology. Similar remarks pertain to the Novozymes projects heavily subsidized by the Danes. Until an existing pilot plant provides real, independently verified data on yield coefficients, mash ethanol concentrations, etc., all proposed cellulosic ethanol refinery designs are speculation.

Patzek then addresses the six proposed cellulosic ethanol plants that were awarded $385 million USD by the US Department of Energy. For reference, he gives the energy efficiency of Sasol's coal-to-liquids (CTL) process as 42%, the efficiency of an average oil refinery as 88% (and I can verify that this number is spot on), and that of an optimized corn ethanol refinery as 37%.

Figure 1, from Patzek's paper, compares the claimed efficiencies of the various cellulosic ventures. Of the six proposed plants, only Abengoa, reporting 25% estimated energy efficiency, was close to Patzek's reverse-engineered efficiency for Iogen. The other five all claimed energy efficiencies in the 40-60% range. The most optimistic was Vinod Khosla's former Kergy (now Range Fuels) venture. See the last section of Cellulosic Ethanol vs. Biomass Gasification for some discussion on Kergy. This process is actually a gasification process, and as such won't have the same sorts of issues that Patzek documented for Iogen. But I don't think in an apples-to-apples comparison they can beat a CTL process on efficiency, because it is much easier to handle coal than biomass (not that I endorse CTL). They are also going to have one problem that the others don't, and that is the production of significant amounts of various mixed alcohols.

There are theoretical reasons why cellulose is unlikely to produce an ethanol concentration in the range of corn ethanol. Patzek writes that at "about 0.2 to 0.25 kg of straw/L, the mash is barely pumpable", and states that this straw concentration will result in a fermentation beer of 4.4% ethanol at a maximum. Yet five of the proposed plants are claiming energy efficiencies that are as great or greater than those of corn ethanol plants.

Where Will the Agrofuel Biomass Come From?

In this section, Patzek tackles an issue that I have also addressed: Where could we get that much biomass to begin with? Patzek asks and answers: "Where, how much, and for how long will the Earth produce the extra biomass to quench our unending thirst to drive 1 billion cars and trucks? The answer to this question is immediate and unequivocal: Nowhere, close to nothing, and for a very short time indeed." ...

Professor Patzek's Conclusions

I will let Professor Patzek's conclusions speak for themselves. Here are some excerpts:
In this paper I have painted a radical vision of a world in which fossil fuels and agrofuels will be used increasingly less in transportation vehicles. Gradually, these fuels will be replaced by electricity stored in the vehicle batteries. With time the batteries will get better, and electric motors will take over powering the vehicles. The sources of electricity for the batteries will be increasingly solar photovoltaic cells and wind turbines. The vagaries of cloudy skies and irregular winds will be alleviated to a large degree by the surplus batteries being recharged and shared locally, with no transmission lines out of a neighborhood or city.

I have shown that even mediocre solar cells that cost 1/3 of their life-time electricity production to be manufactured are at least 100 times more efficient than the current major agrofuel systems. When deployed these cells will not burn forests; kill living things on land, in the air, and in the oceans; erode soil; contaminate water; and emit astronomic quantities of greenhouse gases.

Finally, no future transportation system will allow complete “freedom of personal transportation” for everyone. I suggest that good public transportation systems will free many, if not most people from personal transportation.

My Conclusions

I am not sure whether Professor Patzek believes that biofuels have no place at all among our future energy options. In my opinion, there is a place for them, albeit in niche applications and not as a major energy source. I think we will continue to have a need for some long-range transportation options (e.g., shipping, airline transportation) that would be difficult to electrify. But for the most part, the future has to be electric. The sooner we shift focus from biofuels to electric transportation, the better.

I should note I'm very dubious about the prophets of overshoot like Patzek and David Pimental - however, while I remain cautiously optimistic about the prospects for some types of biofuel production replacing a portion of our current oil consumption, I am in complete agreement with the conclusion that we need to move to an electric transport system and fuel it with renewable energy sources - primarily solar (along with wind, ocean and geothermal) energy.

As long time readers know, I'm rather less enthralled by his thoughts about population levels.

Commenter David Morris adds some further cautionary words.
As someone who has debated Tad Patzek, I think his views about biofuels are less important than the remarkably pessimistic view he has of humanity’s future that results from his methodology. He and his mentor and sometime co-author David Pimentel seem to believe that the planet’s human population has long since overshot its carrying capacity and that renewable energy can play only a minor role in meeting our energy needs.

This is where the debate should take place, not about the application of his thermodynamic methodology to what all but Vinod Khosla thinks will be a tiny slice of our energy future.


David Pimentel has written, “the optimum(world) population should be less than…2 billion”( David Pimentel and Marcia Pimentel, Land, Energy and Water: The Constraints Governing Ideal U.S. Population Size. Negative Population Growth. 2004.) and “For the United States to be self-sustaining in solar energy, given our land, water and biological resources, our population should be less than 100 million…”( David Pimentel, Xuewen Huang, Ana Cordova, Marcia Pimentel, Impact of Population Growth on Food Supplies and Environment. Presented at the American Academy for the Advancement of Science Annual Meeting, February 9, 1996. Citing David Pimentel, R. Harman, M. Pacenza, J. Pecarsky and M. Pimentel, “Natural resources and an optimum human population”, Population and Environment. 1994.)

Patzek’s writings on thermodynamics would seem to lead him to the same conclusion. He and Pimentel, in a co-authored piece recently concluded,“We want to be very clear: solar cells, wind turbines, and biomass-for-energy plantations can never replace even a small fraction of the highly reliable, 24-hours-a-day, 365-days-a-year, nuclear, fossil, and hydroelectric power stations. Claims to the contrary are popular, but irresponsible…new nuclear power stations must be considered.”(Tad W. Patzek and David Pimentel, “Thermodynamics of Energy Production from Biomass,” accepted by Critical Reviews in Plant Sciences, March 14, 2005)

I'd also note that I consider the idea that you can't replace existing energy sources with 100% renewable equivalents ridiculous.

Mobjectivist's latest peak oil modelling post is up - "Global Update of Dispersive Discovery + Oil Shock Model".
Jean Laherrere of ASPO France last year presented a paper entitled "Uncertainty on data and forecasts". A TOD commenter grabbed the following figures from Pp.58 and 59:

I finally put two and two together and realized that the NGL portion of the data really had little to do with typical crude oil discoveries, which only occasionally coincides with natural gas findings. Khebab has duly noted this as he always references the Shock Oil model with the caption "Crude Oil + NGL". Taking the hint, I refit the shock model to better represent the lower peak of crude-only production data. This essentially scales back the peak by about 10% as shown in the second figure above.

So I restarted with the assumption that the discoveries comprised only crude oil, and any NGL would come from separate natural gas discoveries. This meant that that I could use the same discovery model on discovery data, but needed to reduce the overcompensation on extraction rate to remove the "phantom" NGL production that crept into the oil shock production profile. This essentially will defer the peak because of the decreased extractive force on the discovered reserves.

I fit the discovery plot by Laherrere to the dispersive discovery model with a cumulative limit of 2800 GB and a cubic-quadratic rate of 0.01. This gives the blue line in the following figure.

... I still find it endlessly fascinating how the peak position of the models do not show the huge sensitivity to changes that one would expect with the large differences in the underlying URR. When it comes down to it, shifts of a few years don't mean much in the greater scheme of things. However, how we conserve and transition on the backside will make all the difference in the world.

Tom Konrad at Alt Energy Stocks has an excellent article on the various uses solar power can be put to in "A Solar Technology for Every Application". See the link for some useful tables.
Acciona's financing of Nevada Solar One, and a recent series of a financing, a prominent hire, and a big announcement from Concentrating Linear Fresnel Reflector (CLFR) developer Ausra has been keeping long-underappreciated Concentrating Solar Power (CSP) technology in the news recently. I consider this great news, because the potential for cheap thermal storage of CSP and the gigantic size of the available resource means that CSP is likely to provide the backbone of reliability for any future decarbonized electric grid [Word Doc] where the clear skies which it requires to operate properly and sufficient transmission are available.

But CSP is only one of a broad range of Solar technologies, and here I will outline the framework which helps me understand and predict which ones are likely to be most successful.

To understand the future of any technology, you first need to understand its applications, which will lead to an understanding of the characteristics necessary to meet them. Broadly, solar power is used to produce heat for climate control and process heat, and for electricity, both on the grid and off.


The oldest solar application is daylighting, the use of windows and other means allowing indirect sunlight to provide effective internal illumination inside buildings. For individual homes, window and skylights are usually sufficient for the job, but there also exist architectural features such as light shelves and even active sun tracking systems which combine with fiber optics or mirrors [pdf] to provide light to the interior of large buildings. Such systems can provide significant energy and maintenance cost savings, as well as increase worker productivity. They are particularly popular in schools because of studies which show enhanced student learning under natural light.

Thermal Applications

Solar thermal, when used for space heating is needed mostly in the winter in cold and temperate climates. Because of the fact that it is only useful for part of the year, it needs to be simple and inexpensive to be practical. Here, passive solar design and proper orientation of buildings is the hands down winner, because passive solar measures are inexpensive to free, with one of the most expensive steps being adding extra thermal mass, something which greatly enhances performance where daily temperature swings are large, and tends to remain fairly inexpensive given its low tech nature. Passive solar design is almost certain to be a long term winner, although it is unlikely to be a big winner for investors because it does not require special products or materials. Active solar thermal systems are typically too expensive to economically be used for only the part of the year when the heat is necessary, although when the heat from the system can be switched between multiple applications, such as domestic hot water or electricity generation, it can be economic for an active solar thermal system for at least part of a building's space heating load.

For process heat, which includes solar domestic hot water, as well as heat for industrial processes [pdf], the active solar thermal systems shine because year round usage can make these still relatively inexpensive systems easily economic. These systems tend to be either flat plate collector systems, which circulate a working fluid under a black heat collector, or evacuated tube systems, which are somewhat more expensive, but can reach higher temperatures because the heat collector is a solid wire, which avoids problems with boiling the working fluid. Solar parabolic trough systems are also sometimes used in large scale, high temperature industrial applications.

Electricity Generation

With electricity generation, both time and location become important. Electric transmission is constrained by infrastructure, and and electric storage is often more expensive than the power being stored, leading to large price premiums for power delivered where and when it's needed most.

The right place

For off-grid applications flat plate photovoltaic (PV) panels, which can be either thin-film or the more traditional crystalline silicon with a battery backup tend to be suitable despite the relatively high cost of power because of the scalability, relative simplicity, lack of moving parts, and low maintenance of the systems. Concentrating photovoltaic (CPV) is seldome used in off grid homes to reduce up-front costs, because it tends not to work as well as flat plate collectors when there are clouds, and the need for a solar tracking system adds to maintenance costs which can be especially critical in the remote locations where off grid power is usually needed. Another form of practical off grid application is small scale power for lighting or equipment in areas where the grid is available but where the savings from avoided wiring make an investment in PV and a battery pack economical. A common example of this are the now ubiquitous solar garden lights.

Photovoltaic technologies also have an advantage in distributed generation: placing the power source at the point of use. The main advantage here is in their simplicity (which allows for low maintenance) and scalability, allowing the sizing of the power source to fit the need. For instance, an electric utility might place west-facing PV on a transmission base station which is near capacity during times of peak load, thereby meeting a portion of that load and avoiding an expensive upgrade to the base station.

The right time

Since electricity typically requires expensive batteries for storage, technologies which can have inexpensive, built in storage have a cost advantage over ones that only produce power when the sun is shining. Most solar electric technologies conveniently produce power on sunny summer afternoons, a time which normally corresponds to peak load in climates where air conditioning drives peak load. This effect can often be enhanced by orienting the panels towards the west or southwest so that they are producing their greatest output in the afternoon. This produces intermediate power, which is available when electric demand is high, but is also often available at non peak times, such as during the day in the winter. Although such power is more valuable than other forms of intermittent power generation, which often have no correlation with the load profile, they also cannot be relied on to be available when needed, and are less valued by utilities which are responsible for providing power whenever customers want it.

Dispatchable power is the most valuable form of generation (per kWh) on the electric grid, because the utility can use it only when demand is high and cannot be met with cheaper resources, while utilities also value base load power, which is almost always available and can be relied on at any time. Since the sun is not always shining, these forms of power require some form of storage, and this means that they are best met with Concentrating Solar Power, which can be built with thermal storage, a much less expensive way to store power than batteries and other forms of electric storage (with the possible exception of Pumped Hydro, which is limited in its available capacity and location.)

Thin film vs. CPV

The incumbent photovoltaic technology, crystalline silicon is typically very expensive per watt, and there are two approaches currently being taken to cut costs: thin film and concentrating PV. Thin film is another form of flat plate PV that requires much less and less specialized materials but typically has lower conversion efficiencies and durability than crystalline PV, which makes it inappropriate for applications that require a large amount of power generation in a small area, while concentrating photovoltaic (CPV) uses lenses or mirrors in to focus sunlight on small but very high efficiency cells to generate power at a lower cost. CPV usually requires the ability to track the sun and few clouds, which means that it is unlikely to be as economic in distributed applications, although some companies are working to overcome these limitations.

Central Power Generation

For central power generation, the main factor in choosing between technologies is cost. Here, the concentrating technologies (CSP and Concentrating PV) tend to have the advantage, and the ability to use transmission to bring the power to the point of use means that the generation can be placed in areas with a lot of sun and very few clouds where these technologies perform best. The need for additional maintenance for solar trackers is less of an issue at a central solar plant, and this also give and advantage to the concentrating technologies.

Concentrating Parabolic Trough plants, Solar Tower, and Concentrating Linear Fresnel Reflector generators need large scale (in the hundreds of megawatts) to achieve their superior economics, while Dish Stirling and Concentrating photovoltaic (CPV) technologies achieve their economies of scale at less than a megawatt. The superior scalability of Dish Stirling and CPV is largely negated by the cheap thermal storage (referenced earlier) available with the first three technologies which is not available with Dish Stirling or CPV.


Whenever a company announces a new technology with higher efficiency, lower cost, or better storage, it's easy to get carried away and think that that one technology is destined to win out over all the others. I hope you now appreciate that there are as many or more applications as there are technologies, and which technology has the upper hand will depend on the intended use. When evaluating companies, it's most important to consider the target market, and compare the technology to its true competitors. This article and the following tables should provide a useful cheat-sheet when you do so. ...

Jeremy Faludi at WorldChanging has a roundup of news on electric vehicles.
It's been a while since we've looked at the state of the electric vehicle market. Everyone has heard of Tesla, but what else is coming down the road? And what's out there already?

Last year in Worldchanging, Joel Makower wrote a roundup mentioning the Wrightspeed and Tesla vehicles -- but there are also practical utility vehicles, neighborhood vehicles, and more from the likes of Phoenix Motors, Javlon Electric, and Zap. Plus, the first commercially available solar-powered cars by Venturi, and other fun toys.

The Venturi Fetish

Sports Cars

VenturiFetish.jpgVenturi Motors, in Monaco, would like to make it very clear that it did the electric roadster before Tesla did -- Venturi's Fetish vehicle spent two years on a round-the-world tour before going into production, and has been on sale for a couple years now. It also costs four times what the Tesla does.

The Wrightspeed X1 roadster (almost dragster) is still just a prototype at this point, but founder Ian Wright is trying to raise money to make a production car that would have more impressive performance than any other commercial EV roadster: 0-60 mph in 3 seconds at 170 mpg equivalent. Tesla has delayed its first run of shipping vehicles, but the company is promising vehicles will hit the road by Q1 of 2008.

Zap, perhaps the longest-lived electric vehicle company, which has eked out an existence since 1994, claims to have a sports car in the works as well. Zap's Zap-X is being developed with help from Lotus Engineering (note that Lotus was the company that designed the Tesla's body, though the Zap-X's styling doesn't have the same sex appeal). The list of features is long enough and impressive enough to be implausible, so I wouldn't hold your breath on this one, but I'll be delighted if it does come out with everything advertised: photovoltaic glass, a 10-minute recharge time, 155mph top speed, an onboard computer with HD video, iPod, bluetooth, Firewire, and USB ports. All for just $25K.

Phoenix Motors's truck and the Corbin Sparrow, now Myers Motors NmG

Practical Cars

Phoenix_n_Sparrow.jpgPhoenix Motorcars sells electric trucks and SUVs, mostly to companies that run fleets of vehicles. Phoenix's vehicles go full freeway speeds, have good battery ranges, and can carry cargo. AutoBlogGreen says the company's cars have unique batteries with an amazing lifetime:
Recently, the company conducted an in-house test on their NanoSafe batteries and found that after 15,000 (not a typo) deep charge and discharge cycles, the product retained over 85 percent of its charge capacity. In theory that would push the life of these batteries beyond 40 years if you recharged everyday, though, the company admits that under real-world wear and tear a battery life of 20 years is more realistic.

That's easily four times the life of most current EV batteries.

Miles Automotive Group has a number of cars which, despite golf cart speeds, have real car size and style. Here's a pretty interesting video interview with the company, about the Javlon model.

ZENN is the name of both the car and the company for a Toronto-based neighborhood EV maker. Another slow speed but full size car, this won the Michelin Bibendum Challenge's Top Urban Vehicle award in 2006.

Venturi's Eclectic is a neighborhood vehicle which has such a futurismo design that you can't call it a golf cart. Its' claim to fame is the ability to generate its' own power, from the solar panels on the roof as well as a wind turbine that comes attached. (And no, you can't power it on the wind generated by driving the car; it's not a perpetual motion machine.)

Sexier than that, though, is the Venturi Astrolab, a two-seater solar car featured at this past month's Wired NextFest in Los Angeles.

For urbanites, a truly practical car is a mini-car. Zap does have a number of real neighborhood mini-cars on the road with top speeds around 40 mph, and they're pretty cute: check out the Xebra sedan, for instance.

Indian-made Reva is supposedly the best selling EV in the world. Another micro-car, it has a top speed of around 50mph, can fit four snugly, and has boxy-but cute styling that reminds me of plastic toy dinosaurs. (It's imported into the United Kingdom under the name G-Wiz.)

My favorite micro-car is the Myers Motors NmG--formerly the Corbin Sparrow. Just a one-seater, as small as a fat motorcycle with room for a couple bags of groceries in the back, it is the ultimate commuter vehicle: not limited to neighborhood streets, it can go 75mph on the freeway. And it's the cutest car ever.

The Tango is an impressively engineered micro-car. Like the NmG, it's about half the width of a normal car, but it can carry a passenger and go a startling 130mph, accelerating off the line almost as fast as the roadsters mentioned above. It's not pretty--actually it's miserably boxy-looking--but it's both fast and safe. Not in production yet, the Tango has been around for a few years, gathering advance-order deposits to demonstrate to investors that the market demand is there. ...

Heading back to Wired once more, an article on a Bacteria that turns toxins into plastic
Irish scientists have isolated a bacterium that can convert a toxic waste product into safe, biodegradable plastic.

This week, scientists Kevin O'Connor and Patrick Ward, of the Department of Industrial Microbiology at University College Dublin, announced that they have discovered a bacterial strain that uses styrene, a toxic byproduct of the polystyrene industry (which produces Styrofoam, among other things), as fuel to make a type of biodegradable plastic, polyhydroxyalkanoate, known as PHA.

Bacteria can live and grow pretty much anywhere, from boiling springs to deep sea, solid rock to stomach acid. Their versatility is at the heart of countless past successes of the biotech industry as well as current efforts, including several by scientists striving to develop toxin-reducing strains such as oil-eating bacteria. But O'Connor and Ward's bacteria go a step further and produce a useful end product.

"Our bacteria detoxify styrene and return it to us as a green plastic," said O'Connor.

Styrene is found in many types of industrial effluent, and in the United States alone it accounts for 55 million pounds of hazardous waste every year. It causes lung irritation and muscle weakness, and affects the brain and nervous system in people and animals. Up to 90,000 workers in the polystyrene industry are potentially exposed to styrene, so a method of disposing of it safely would have health, as well as economic, benefits.

"The current methods of dealing with waste styrene include underground injection, spreading it on land or burning it in incinerators to generate energy, which results in toxic emissions," said Ward. "We all use plastics in our everyday lives, from disposable drinking cups to car parts, so millions of tons are made, used and discarded every year. But the slow rate of degradation of polystyrene means that it can last thousands of years in our environment."

To tackle the problem, the Irish scientists turned to a species of bacterium, Pseudomonas putida, that occurs naturally in soil and can live on styrene. They grew it in a bioreactor with styrene as the sole source of carbon and energy. Their efforts resulted in the isolation of the styrene-eating Pseudomonas putida strain CA-3, which converts styrene into the plastic polymer PHA as a stored energy source.


* WSJ Energy Roundup - The Great Ethanol Squeeze
* Technology Review - Display Technology Promises Cheaper Solar. Applied Materials bringing their manufacturing expertise to bear on thin film solar.
* After Gutenberg - EERE encourages thin-film solar farms
* The Energy Blog - Thin Film Solar Company Miasolé Raises $50 million, Has Started Production
* The Energy Blog - EnerDel Lithium-ion Battery for Plug-in Hybrids will cost $1,500
* The Australian - Galaxy digs in for shot of green power. "Electric cars mean lithium batteries. Sixty per cent of world supply comes from Australia and Chile". However around 50% of global reserves are in Bolivia.
* Dow Jones - The Shift To Alternative Fuels Is Moving Beyond Ethanol. A dinosaur's eye view of the near term energy future.
* Next Energy News - Scientists Invent 30 Year Continuous Power Laptop Battery. Betavolatic batteries ? Powered by radioisotopes ? Why do I fear putting these into my laptop ?
* The Australian - Climate change inevitable, says CSIRO
* The Australian - Australia in climate crisis: Garrett
* WorldChanging - On Climate Change, Is Critical Mass in Word Turning to Critical Mass in Deed?
* Grist - This week in ocean news. "The Bangladeshi head of state said a one-meter rise would displace 25 to 30 million of the low-lying country's population, calling it 'climate Armageddon'"
* Grist - Why $100-per-barrel oil would be no big deal. Unless you are concerned about carbon emissions.
* The Australian - Eneabba Gas aims for carbon-neutral plant. Agrichar process combined with gas fired power station ?
* The Australian - Reindeer pair look for gas supply tenders
* Venezuela Analysis - Interview With Noam Chomsky
* TPM - We're outsourcing our investigations of Blackwater to Blackwater
* WhiteHouse.gov - Unfortunately, intimidation and force can chill peaceful demonstrations. And reports about very innocent people being thrown into detention, where they could be held for years without any representation or charges, is distressing. Now, obviously, this has, again, a chilling effect on protestors. Talking about Burma (just in case it wasn't clear from the text). I wonder if they are being tortured.
* Salon - Can you accidentally strangle yourself with handcuffs?
* The Onion - God Angrily Clarifies 'Don't Kill' Rule


Betavolatic batteries ? Powered by radioisotopes ? Why do I fear putting these into my laptop ?

Probably because many radioisotopes from the transuranium period on the periodic table decay into radon before they get to bismuth or lead.

I don't know what material they are planning on using however, since they don't actually report that...
I have a hard time believing that beta-decay batteries could actually provide enough power to run a modern processor. A pacemaker is one thing, but a modern CPU?

Oh yeah - I'm dubious about the power bit too, but I just found the idea of chucking radioactive material into consumer electronics so alarming it seemed immaterial...

Anonymous   says 9:49 PM

But Gav, our very own industry funded boffoons over at the Physics Dept. at Melbourne Uni Inc. insist that nuclear is all good. Remember they even set up that web site just in time for the PMs nuclear announcements. Wasn't that a nice coincidence?

On the bacteria, it's good that they can detoxify the styrene; bacteria have amazing metabolic diversity. I'm not sure, were you using the article to hint at bioplastics? Not via styrene?

You might want to cross post Roberts article on sodium as a potential replacement for Lithium in this style of battery. I suspect that there isn't enough Li for car batteries, fusion reactor blankets AND antidepressant drugs...

I wouldn't call that bacteria transformed styrene a bioplastic (its more a recycled waste) but it sounds like they produce a plastic feedstock.

More on an interesting science note than something I'd sconsider industrial sclae chemistry though.

but will the power remain the same?

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