Has crop ethanol met its Waterloo?

It should be obvious by now that I think today's is one of the best issues of Science in recent memory. This will be my last post out of this issue, but even these three posts don't come close to covering everything in there that I think is cool. If you don't work at an institution that has a subscription, you could do a lot worse for your brain than buying a copy online or at a newsstand or bookstore. So to wrap up my blogging on this one, I'll cover some papers that support my extreme distaste for biofuel mania, especially with respect to food crops such as corn and soybeans. A pair of articles today find that using food crops for ethanol is even worse in terms of carbon balance than continuing to use fossil fuels.

My regular readers will no doubt be aware that I positively loathe the idea of using corn for ethanol, and am somewhat dubious of the benefits of using even cellulosic ethanol as a biofuel. These are at best stopgaps on the way to fully clean energy sources, do not in general remove a great deal of carbon from the atmosphere, and may have significant adverse effects on the environment and carbon balance. So you should consider this post in light of the significant potential for confirmation bias. That said, these papers seemingly end the debate on the carbon balance benefits of corn or soybean ethanol, and raise serious questions about the benefit of any form of monoculture intended to replace petroleum, especially if they take over cropland or forest.

The fundamental problem with previous models of greenhouse gas reductions due to biofuels, according to the authors of these papers, is that they do not take into account the carbon debt incurred by altered land use. For instance, clearing land to allow the planting of biofuel monocultures has the effect of releasing all or almost all of the carbon presently fixed in plants in those areas (1). Moreover, forward-looking economic models were not previously employed to judge the likely effects of shifting food crops into fuel production. For instance, the increased cost of corn might induce clear-cutting intended to free up more cropland to grow the now more-profitable food crop (2).

What happens when you start taking those "carbon costs" into account? Searchinger et al. find that corn ethanol doubles greenhouse emissions versus petroleum over a period of 30 years and doesn't break even for 167 years. Fargione et al. predict that it takes 48-93 years, depending on what kind of source land is used, before corn ethanol pays back its carbon debt. And it's not even the worst: biodiesel derived from lands that used to be rainforest take more than 250 years to balance the carbon sheet, on average. Even cellulosic energy sources, if they are grown on viable cropland, produce more greenhouse gases over the next 30 years than petroleum does (2).

So, are we totally screwed? Not exactly. Both papers suggest that cellulosic sources grown on marginal croplands or prairie, or derived from existing biomass waste (i.e. inedible cornstalks) still end up on the right side of the carbon balance sheet. This is consistent with estimates from a study I discussed previously.

The ideal response to both global warming and oil dependence is to depress petroleum usage (by increasing fuel mileage and encouraging public transit) while transitioning to a completely green transportation system that doesn't rely on combustion at all. Stretching out oil and growing forests is the best option for slowing emissions short term, and does not require an additional construction of infrastructure to produce and distribute ethanol. If biofuels are unavoidable, however, then they should be derived from non-food crops grown on marginal land if at all possible.

It's still not clear that biofuels can replace petroleum, so they may not help us as much as we'd like. However, if they are not to hurt us, we must make sure that we make wise choices about what kinds of sources to use and where to grow them. The best evidence now conclusively indicates that ethanol from corn and soybeans (except for cellulosic derived from their spare biomass) is not the way.

1. Fargione, J., Hill, J., Tilman, D., Polasky, S., Hawthorne, P. (2008). Land Clearing and the Biofuel Carbon Debt. Science, 319(5867), 1235-1238. DOI: 10.1126/science.1152747

2. Searchinger, T., Heimlich, R., Houghton, R.A., Dong, F., Elobeid, A., Fabiosa, J., Tokgoz, S., Hayes, D., Yu, T. (2008). Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change. Science, 319(5867), 1238-1240. DOI: 10.1126/science.1151861

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Ethanol from switchgrass: the answer?

With the Iowa caucuses over, the corn ethanol mania that seized the campaigns of candidates from both major parties appears to have passed. This can only be a good thing, because producing ethanol from corn starch is an ecological and agricultural dead end. But the siren song of biofuels continues to beckon, with cellulosic ethanol from switchgrass now being the alcohol du jour. Cellulosic ethanol has tremendous advantages, not least that if cellulosic facilities are the basis of our alcohol infrastructure then practically any vegetation can be used to supply them. Switchgrass, because it is high in cellulose, simple to cultivate, and can be grown on reserve plots, is a tremendously attractive plant to serve as the backbone for such a system. However, research on the full-scale feasibility and energy output from switchgrass cultivation has been lacking. Last week, that deficiency was addressed when PNAS released a study from the U.S. Department of Agriculture and University of Nebraska claiming that the energy output from switchgrass ethanol was more than 500% of the energy put into making it. The article is open access, so you can go on over to PNAS and read it yourself if you like. The findings of this article are encouraging and promising, but it is the start, not the end, of the necessary research.

Assuming that the production and distribution of a biofuel are feasible—this is not a minor assumption—the ultimate decision of whether we should wholeheartedly pursue biofuel production and if so what approach to use should be decided by the answers to the following questions, based on our strategic and environmental needs:

1. Does the biofuel produce substantially more energy than is needed to generate it?
   
2. Can the biofuel significantly reduce or eliminate our dependence on petroleum?
3. Do production and use of the biofuel add less greenhouse gases to the environment than they remove?
4. Does the biofuel produce fewer non-greenhouse pollutants than petroleum products?
5. Can the biofuel be produced without significant disruptions to agriculture or the food supply?
6. Are the other negative environmental effects of biofuel monoculture manageable?
   

Obviously, we want every answer to be "yes", and a little quick thinking will show that switchgrass scores higher than corn ethanol on questions 5 & 6, with a tie on question 4, and less clarity on questions 1-3. Question 2 doesn't really get a good answer in this paper (so far the answer is "no"), but questions 1 & 3 are treated, albeit incompletely.

The authors of this study answer question 1 with a resounding yes, claiming that the switchgrass fields produced an astonishing 540% more energy than was used in seeding and maintaining them. Given that it is still not clear whether corn ethanol is capable of breaking even on this kind of energy balance, that seems like an end to the question. It's important to realize, however, that no energy was actually produced in this study, because no large scale cellulosic ethanol plants actually exist. This would appear to be a significant advantage for corn—although its production is less energy efficient, such production is at least not fictional. The energy numbers and ethanol yields in this study emerge from a computer model based on pilot studies; the efficiency of cellulosic ethanol plants on a large scale, though promising, has yet to be demonstrated. As such, this number should be taken with a grain of salt.

The energy numbers for this comparison also do not appear to include the diesel used in agriculture or any estimates of energy costs involved in transporting the substantial quantities of biomass to ethanol plants. The latter is either totally outrageous or completely fair; one of the uncertainties in treating this question is the infrastructure that would be developed. If most ethanol production ends up in large centralized plants the transport costs will be high and the energy efficiency per year will be less. On the other hand, if ethanol production is distributed to many small local plants the energy costs of transport will be diminished while the costs of start-up in terms of materials, money, and energy will be high. This question is significant and one that needs an answer quickly; fortunately, given ballpark figures for energy consumption and output it should be relatively easy to model computationally. That said, I doubt any two models will agree.

So, this study has many nice things to say about the energy yield of switchgrass ethanol, but no experimental proof. But what about question 3? Here again the authors have nice things to say. Most of the plots were carbon-neutral, with slight deviations up or down in different years. Of course, this is again the result of a model; the final answer will depend to a large degree on how effectively carbon can be sequestered in the soil and how much energy the burning of the lignaceous or woody portion of the biomass can contribute to the production process and energy grid.

However, our joy at finding a carbon-neutral fuel should be tempered by remembering that the problem with greenhouse gases is that they are too concentrated in our atmosphere. This is important, so I will repeat it in larger text with a color accent:

The problem with greenhouse gases is that they are too concentrated in our atmosphere.

That is to say, the problem is not that we are adding more greenhouse gases, the problem is that the atmosphere has too much greenhouse gas already. While adding more certainly makes that problem worse, adding nothing does not make it better. Those poor plants and animals got buried underground and hid their carbon away from the world for millions of years; until we put it back where we got it, our climate will be altered. Thus, what we require is permanent sequestration, something that cannot be achieved to any meaningful degree by biofuels.

I'm being mean to switchgrass, of course. Every biofuel fails this test, but so far switchgrass comes closest to success, and the most optimistic estimates certainly seem to indicate that a substantial quantity of carbon would be sequestered in the soil. As the transit system switched over to renewable fuels that advantage would be increased. Biofuels can stop or slow global warming, but they cannot turn back the carbon clock.

So, is this study worthless? Not by a long shot. However, the real contribution of this study is not in its publicized conclusions: they are largely based on modeling and possibly overstated. No, the great contribution here is the substantially more detailed assessment of the required inputs for producing switchgrass biomass on a large scale. The ratio of inputs to outputs was far smaller than expected; from this work it appears that switchgrass cultivation will be more energy-efficient than previously suspected. However, even in this regard the study is limited: the geographic area studied was small and not particularly diverse in climate. It remains to be seen whether switchgrass cultivation will be as effective in warmer or drier climates.

Nonetheless, this study, and others like it, are precisely what we need: detailed research dedicated to finding the best answer. Yet this sort of critical assessment will be all too infrequent in the coming year, as bloviating presidential candidates lurch from hot topic to hot topic, and our useless, brainless Congress lards the budget with pork based on speculation rather than research to find facts.

M. R. Schmer, K. P. Vogel, R. B. Mitchell, and R. K. Perrin, "Net energy of cellulosic ethanol from switchgrass." Proceedings of the National Academy of Sciences 15 January 2008 pp. 464-469 DOI: 10.1073/pnas.0704767105

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Light and peppery, with a finish reminiscent of an archaeal cytochrome P450...

As will be reported in this week's Nature, French and Italian scientists have completely sequenced the genome of the common pinot noir wine grape (subscription required). As most wine connoisseurs would expect, the vitis vinifera genome is fairly complex, containing about 30,000 genes. While this is several thousand more than human beings, it is significantly lower than the number of genes noted in some earlier plant genomes, such as the poplar or rice. The most relevant comparisons cannot yet be made because the grape is the first fruit plant to be sequenced. However, some aspects of the annotations that can be made stand out noticeably. Relative to known genomes, the grape has a large number of stilbene synthases (responsible for the synthesis of resveratol) and terpene synthases (which produce compounds that give rise to wine's complex flavors).

For the present, this sequencing effort is unlikely to produce any great revolutions in the wine industry—a significant body of work is required to relate flavor profiles to genetics, especially so considering the influence that soil chemistry, water abundance, and climate have on grapes and the resulting wines. As this research develops, however, it may prove possible by transplanting cassettes of synthetic genes from one grape to another, to introduce flavors currently unique to poorly-dispersed or finicky strains into hardier grapes that can be grown anywhere. Moreover, this research may provide a means to protect grape monocultures from diseases or climate change by identifying (and possibly correcting) genetic weaknesses.

The thing that strikes me is how overdue this kind of research is. I've already written in this space on the importance of agricultural research in the context of climate change; this is particularly true with regards to fruits. Most grains are grasses, and while this does not mean they are invincible, it does mean they're likely to be relatively hardy—this is part of why they became so widely cultivated in the first place. By contrast, fruits and vegetables can be difficult to cultivate even in relatively good conditions. While grains are sufficient to sustain life, to ensure proper nutrition it will be important to make fruits and vegetables available. Understanding the genetics of these organisms is essential to that task.

It's important to emphasize that sequencing a genome is only the beginning of understanding an organism's genetics. Knowing what the genes you've sequenced produce, what stimuli control their expression, and what can be safely done to manipulate those stimuli or genes is the true aim of a genetic study. In this regard, plant studies lag significantly behind those in animals—the fact that many animals are significant models for human illness is a major reason for this. However, plants are the basis of our entire food supply, and therefore understanding their biochemistry may be of much greater importance in the near future. Research funding bodies, especially at the government level where the results will not be proprietary, should begin putting a greater emphasis on crop plant research in order to ensure the integrity of the food supply in light of climate change, declining diversity, and other challenges.

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A Program for Response to Climate Change

The recent news that polar bears might disappear by 2050 shouldn't really shock anyone, but it does serve as a reminder that the global warming policies being proposed by our political elites are failures-in-waiting. That the Republicans have presented a suite of jokes as policy proposals is par for the course, but the Democratic approaches are equally weak. Most of them advocate cuts in greenhouse gas emissions, but that ship has already left port -- no cuts made over the next 40 years can prevent global warming, they can merely limit it. That's still a noble goal, and carbon cuts should be made, but the belief that we can do something to stop warming and then all will be well is fundamentally misguided. What we need and deserve to see from our candidates is not just their promises to reduce emissions, but their plan for mitigating global warming's impact.

Climate change will alter the temperature schedule and rainfall levels in many agricultural regions, producing novel climates in some portions of the country. Water may become scarce in some areas of the country now thickly populated. Sea levels will probably rise, threatening coastal regions. As supplies are exhausted, petroleum prices will begin to increase, making the modern suburban lifestyle less tenable for the middle class, especially when those price increases percolate through every other sector of the economy.

The response has to be multifaceted and nimble -- years of effort have not yet yielded any certainty on the precise effects of warming on the environment. So it would be a mistake for anyone to plan on the basis of any particular model. However, there are general steps that could be taken for preparedness.

Agricultural research and readiness: The United States has a plethora of agricultural universities, and now is the time to strengthen their research programs, with the aim of producing hardier, more efficient strains of our workhorse foods. Make use of the powerful techniques developed in the study of human health and bend them to the study and improvement of plants. Technical development should also be a focus: particular attention should be paid to the devising of more efficient irrigation systems. Pest control and topsoil management should also be priorities. Existing technologies should be pushed into use wherever possible; agricultural schools should be used as distribution centers to help local farmers put novel techniques into use. The government should take an active role in helping farmers adapt to the changes in local climate. The Department of Agriculture, in conjunction with local agricultural universities, should help farmers change what they grow and when they grow it so as to maximize productivity. This will have to come at the expense of tradition, and I'll miss Chilton County peaches if they have to go, but it's better for the food supply and better for the farmers if they're growing crops suitable for the climate they're experiencing.

Alternative fuels: By which I do not mean biofuels. In fact, biofuel initiatives should be abandoned immediately, not only because cutting forest to make way for biofuel monocultures is harmful to the environment, but also because biofuels will not substantially help carbon balance or warming in the long term. The simple fact is that burning biofuels is still burning something, and the additional CO2 and NO2 released during their cultivation will seriously diminish their potential to affect global warming. A recent (non-research) article in Science (subscription required) points out that sequestration of carbon in forests is superior to the use of biofuels from the pure greenhouse-gas perspective. Moreover, using arable land for biofuel monocultures will be a losing proposition when climate change stresses the food supply. Food prices in the United States and Mexico have already suffered some disruption from the proposed use of ethanol; when food itself starts being difficult to come by, the growing of corn for fuel (or even animal feed) is likely to be untenable.

If biofuels are to be used, then it ought only be when they can be produced exclusively from the refuse of existing food crops (cellulosic ethanol from cornstalks, for instance). Barring this, the government should enforce increasingly stiff fuel-efficiency requirements while pushing forward on research into non-carbon fuel sources for transportation. Simultaneously, every effort should be made to reduce the amount of automotive traffic required in everyday life...

Re-urbanization: Cities are crowded, messy, polluted, and filled with crime, but suburbs sprawl, destroy forests, promote excessive use of automobiles, and spread vile environmental impacts over a large area. As forests are our best friends in the fight against warming, anything that destroys them must be anathema. However, there is no way that any mandate of the government could shove everyone back into the cities. Rather, the government must work diligently to support the cities in their efforts to call people back by reducing crime and producing more family-friendly spaces. At the same time, the cities themselves must be revamped so that they are more environmentally friendly. "Green" buildings must be economically encouraged or enforced by statute. Public transit must be made as attractive and efficient as possible. Suburban sprawl must be curtailed, by inviting the nation back into the cities if possible, by forbidding further development in wooded areas if necessary. Increased property taxes encourage living in small spaces while providing additional revenues to support urban redevelopment.

Water Policy: Water management beyond the local level has largely been ad hoc up to this point, but with increasing populations in some major urban areas stressing the water supply of multiple states or large regions, a comprehensive higher-level policy must be put in place. The government should provide assistance to those wishing to move away from areas experiencing significant strains on the water supply, and help develop economic opportunities in areas where water is plentiful in order to make such moves desirable.

Disaster preparedness: One likely consequence of the development of novel climates is the destruction of the previous climates. In cases where temperatures rise and rainfall decreases, this will probably take the form of extensive forest fires. Even now it seems like every year brings a record number, and it's probably not because so many kids are playing with matches these days. The government will need to come up with a comprehensive plan for dealing with these fires without completely exhausting the men and women who fight them on our behalf. Trying to imagine and then plan for every possible contingency is a good way to get completely lost in details, but nothing DHS and FEMA have done since the Katrina disaster suggests that they have grown more nimble or capable. These agencies should be shaken up from top to bottom, and if necessary FEMA should be removed from the bloated and apparently completely ineffectual DHS.

This isn't everything that such a plan needs by half, and by this time next week I may have 3-4 more headings of components that are necessary. But it's telling that even the most environmentally conscious candidates seem to have only thought of one.

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