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Researchers Outline Consensus Position on “Beneficial Biofuels”

Noting that society “cannot afford to miss out” on the multiple benefits of biofuels “done right”, but that society also “cannot accept the undesirable impacts of biofuels done wrong,” eleven researchers suggest what they describe as a consensus position on beneficial biofuels in a paper published 17 July in Science.

Lead author is David Tilman of the University of Minnesota. Co-authors include the U of M’s Jonathan Foley and Jason Hill; Princeton’s Robert Socolow, Eric Larson, Stephen Pacala, Tim Searchinger and Robert Williams; Dartmouth’s Lee Lynd; MIT’s John Reilly; and the University of California, Berkeley’s Chris Somerville.

Biofuels can be produced in large quantities and still offer multiple benefits, but only if they come from feedstocks produced with low life-cycle greenhouse gas emissions, as well as minimal competition with food production, they state. The biofuels industry should focus on five major sources of renewable biomass:

  • Perennial plants grown on degraded lands abandoned from agricultural use
  • Crop residues
  • Sustainably harvested wood and forest residues
  • Double crops and mixed cropping systems
  • Municipal and industrial wastes

Biofuels should receive policy support as substitutes for fossil energy only when they make a positive impact on four important objectives, they suggest: energy security, greenhouse-gas emissions, biodiversity, and the sustainability of the food supply. Evaluation of the greenhouse gas impact should include consideration of the effects of indirect land-use change.

The recent biofuels policy dialogue in the United States is troubling. It has become increasingly polarized, and political influence seems to be trumping science. The best available science, continually updated, should be used to evaluate the extent to which various biofuels achieve their multiple objectives, and policy should reward achievement. Three steps should be taken: meaningful science-based environmental safeguards should be adopted, a robust biofuels industry should be enabled, and those who have invested in first-generation biofuels should have a viable path forward.

In support of such policy, rigorous accounting rules will need to be developed that measure the impacts of biofuels on the efficiency of the global food system, greenhouse-gas emissions, soil fertility, water and air quality, and biodiversity. Accounting rules should consider the full life cycle of biofuels production, transformation, and combustion.

A central issue for the coming decades, then, is how the environmental impacts and potential benefits associated with meeting the global demand for food and energy can be internalized into our economic systems. This is a complex question that cannot be addressed with simplistic solutions and sound bites. It needs a new collaboration between environmentalists, economists, technologists, the agricultural community, engaged citizens, and governments around the world.

—Tilman et al. (2009)

The discussions that led to the paper began in June 2008 at a workshop on biofuels and food hosted by the Carbon Mitigation Initiative (CMI), supported by BP and Ford. The CMI is a Princeton center headed by Socolow and Stephen Pacala, the Frederick D. Petrie Professor in Ecology and Evolutionary Biology and director of the Princeton Environmental Institute.

Individuals whose backgrounds span a broad range of perspectives gathered in Princeton, NJ, to exchange views about the sustainability of biofuels, food, and the environment. After considerable back-and-forth, we arrived at the consensus presented above. We are hopeful that colleagues charged with developing biofuels policies, who are likely to span a similarly broad range of views, will benefit from our deliberations.

—Tilman et al. (2009)


  • David Tilman, Robert Socolow, Jonathan A. Foley, Jason Hill, Eric Larson, Lee Lynd, Stephen Pacala, John Reilly, Tim Searchinger, Chris Somerville, Robert Williams (2009) Beneficial Biofuels—The Food, Energy, and Environment Trilemma. Science Vol. 325. no. 5938, pp. 270 - 271 doi: 10.1126/science.1177970



Rational biofuels probably does not include ethanol, if these researchers are going to be honest with themselves and others. Ethanol is too costly to produce from low level crop residues as they suggest as feedstocks.

This leaves biomethane. The upside is that we have an extant infrastructure to support it in the form of our natural gas pipelines. The downside is its problematic nature as a vehicle fuel and the cost competition from NG supplies (at least for this year....).

Perhaps the best fate for biofuel production is to allocate considerable space at our landfills for low cost (but enhanced) biomethane production from organic wastes. It's already done now with our landfills that tap methane emissions from decomposing waste, but I can only assume this method is quite inefficient compared with a strategy which is more proactive using selected waste streams.


Landfill gas contains lots of stuff that you do not want burned. It has to be cleaned up way too much to make it cost effective for pipelines. They use it to generate electricity at the site.

Renewable methane can be used and turned into other fuels. If you want to make it into methanol at the fueling station and put it in cars, that would work. The delivery of methane in pipes seems to me to be the way to go.

Ole Grampa

@ Jim:
"Rational biofuels probably does not include ethanol, if these researchers are going to be honest with themselves"

Ethanol can be made from wood chips and garbage for $ 1.00 / gallon.

Aureon Kwolek

This “Concensus Position on Biofuels” is a step in the right direction, however it is not a complete analysis of all the issues. The biofuel slash and burn witch-hunt mentality is gone, and in its place is a willingness to work to improve the biofuel path that we are already on.

We should talk about individual biofuels, not biofuels in general. Ethanol and biodiesel are way different animals. They are made from different feedstocks using different processes. They have very different fuel characteristics and are used in different engines. They have different emissions and different environmental footprints. They have different economic impacts on the food supply.

Biofuel engine technology has recently taken a giant leap forward, and this will dramatically enhance its environmental impact. “Ethanol optimized” engines are now being developed that get better mileage than gasoline, but have all the power and efficiency as diesel, at a much lower cost and a much higher power to weight ratio. This is made possible because ethanol has 25% higher octane and faster flame speed than gasoline, eventhough it has 30% less btu’s.

Whereas biodiesel is oil based, ethanol can be blended with up to 50% water and still combust. That is significant, because we have technology that can distill a gallon of ethanol with 3 kilowatts, blend it half and half with water, and then combust it in a genset that produces 23 kilowatts per gallon (MicroFueler “grid-buster”). These new ethanol technologies are viable for charging batteries onboard the coming plug-in hybrids, and what you get is a vehicle design that eliminates imported oil entirely.

Onsite ethanol-water (waste water) could also replace natural gas used for production power at ethanol refineries. That would significantly impact their environmental footprint, by replacing newly mined CO2 in the natural gas - with recycled CO2 embodied in the ethanol.

There are also plans to grow Algae on the corn ethanol refinery waste stream. Again, this would greatly improve the environmental footprint, while mitigating waste heat, nutrient-rich waste water effluent called “centrate”, and recycle CO2 through the algae, instead of releasing it into the atmosphere. This will likely be very concentrated heterotrophic algae grown in dark, insulated tanks, on a very small footprint of adjacent land. The sugars and nutrients in the waste water centrate will feed the algae, enhanced by CO2 feeding, and what we’ll get is algae biomass doubling every 6 hours under optimal conditions. Strains of heterotrophic chlorella have been documented to double every five hours. That is if you grow it for maximum speed and biomass, rather than stress it for much slower oil production. This obsession with oil is what’s slowing down algae development. Instead, grow algae for maximum speed and biomass. You get a smaller overall percentage of oil, but from a much bigger volume of biomass. You come out way ahead, because you get massive quantities of starch and proteins. Five different companies are reporting algal biomass yields of 65-300-220-270-330 TONS per acre per year.

Algae grown on the corn ethanol waste stream will provide additional onsite co-products: The carbohydrates will drop-in to the fermentation process, providing additional onsite ethanol feedstock. The oils can go to The proteins are complete amino acids that will enhance animal feeds and complement corn ethanol distillers grains. Algae as a high-quality complete protein feed supplement, is also a green chlorophyll hemoglobin oxygen carrier that will improve the health and productivity of dairy cows, hogs, poultry, meat cattle, and farm-raised fish and “seafood”. Chorella, which can be grown at corn ethanol refineries, is currently selling in bulk on the internet for about $18 per pound. And medicinal and nutriceutical Omega Oils derived from algae are now selling for up to $500 per pound. Nutritional supplements for humans are another revenue stream.

Another cutting edge plan is the “Farmer’s Ethanol” integration system, that will also dramatically improve the environmental footprint of corn ethanol, while mitigating methane released from manure and instead using it as an onsite resource. We will also be integrating algae and/or duckweed production into the “Farmer’s Ethanol” flow chart. This may give us a new generation of corn ethanol with a 5 to 10 fold return and an environmental footprint that is totally acceptable.

There is also a plan to purify corn ethanol byproduct distillers grains for human consumption, so you may soon see it mixed-in with other foods as a protein booster. Distillers grains may also become a global food staple that will help alleviate hunger. We are currently only taking the starch to make ethanol from 1 out of 4 bushels of corn. Every acre of corn used for ethanol also produces about 50 bushels of animal feed, which goes to producing food. The fuel vs food debate has been debunked, and so has indirect land use change.

Look at biofuels in the context of how they compare with conventional petroleum based fuels. Biofuels, such as ethanol and biodiesel, are derived from “recycled CO2” which is already in the air. That’s what sets them apart from petroleum based fuels. Biofuels also release far less particulate soot.

In contrast, dirty fuels such as gasoline, diesel fuel, jet fuel, heating oil, kerosene, and bunker fuel are all extracted from crude oil, which is constantly bringing-up new CO2 from deep underground. Thus, fossil fuels are causing additional CO2 to accumulate in the atmosphere. Biofuels are not. Credit the footprint of biofuels for replacing “newly mined CO2” with “recycled CO2”. These two types of CO2 belong in two different categories.

Conventional fossil fuels also produce massive amounts of Black Carbon Soot, which heats the air and then settles out on water, snow and ice, where it causes additional solar thermal absorption. This could be a much bigger climate change factor than CO2.

You also need to accurately measure the impact of conventional fuels, before you go comparing them to biofuels. The EPA disguises the true environmental impact of Petroleum based fuels by using old or slanted information. For the footprint of petroleum, the EPA used pre tar sands data. This does not reflect more recent crude oil extracted from Canadian tar sands – which consumes twice the amount of energy as conventional ground wells. And we import more crude oil from Canada than any other country. Tar sands oil extraction is also a major source of deforestation. Shale oil and deep water offshore drilling is also more energy intensive. Yet the EPA low-balls the environmental footprint of petroleum based fuels, and gives them preferential treatment over cleaner burning biofuels.

Imported Oil is also transported thousands of miles - from the Middle East and numerous foreign countries - by ocean going ships burning Bunker Fuel, a major cause of global pollution and Black Carbon Soot. Compare this with domestic biofuels that can be produced and consumed locally. The EPA has no accounting method for that comparison. See “Commercial Shipping Emits Almost Half as Much Particulate Pollution as Total Released by World’s Cars”. Ocean going ships burning bunker fuel are showering the water’s surface with black soot, which absorbs heat, rather than reflecting it.

According to a recent Rand Report, we are spending 12-15% of our entire defense budget every year to protect our supply of foreign oil. We burn through a huge amount of money, resources, bunker fuel and diesel fuel, over a long-distance supply line, in order to protect foreign oil. This problem can be solved by implementing alternative energy, including domestic biofuels. What is the yearly bill for protecting biofuels? Zero.


Fermenting waste to produce biomethane has a much better energy return than distilation to make ethanol and can use a wide variety of feedstocks.

Duckweed or water hyacinth might work as well as algae and be for more reliable under the conditions they are likely to be grown in.

The direct injection, turbo charged engines which are moving towards the industry standard work very well with methane, and diesel engines can be made to 'dual fuel' with methane with minimal modification.

A small range extender running on methane is also an instant backup generator and co-generation system.

Roger Pham

To sum it up in one sentence: Put environmental sustainability and science over self-interest and politic. This consensus idea is a very worthy goal.


As usual late and stupid.

Ethanol corn as in corn made ONLY to produce ethanol is now being planted. In fact its about 300 feet from my house. Oh and no its not food.

As time goes on that ethanol corn will be improved to produce more and more fuel per field just as they said it would and all this gibbering blather will be ignored as so much standard ignorant blather.

What will decide its continued success is as always if it can make money and frankly its making more money then cattle feed thats for sure.



Very nice summary. All too often, critics take a very narrow-sighted approach with biofuels. When you factor in the entire supply chain and use the proper benchmarks, it is very clear that biofuels can have a very important role in our future.


It seems that there are lots better ways of running a modern economy on renewable energy, but there is a static inertia that keeps things going the way they have been, until they can not any more.

I would like to see us use more renewable and less fossil energy. Renewable energy is made continuously and does not require using precious finite fossil fuels that took millions of years to create.

It makes more sense to use the renewable energy and save the fossil fuels. Once the fossil fuels are gone, they are gone forever. We have it backwards, use renewable energy now as much as possible and save the fossil fuels for later if needed.


Aureon, thanks for the detailed overview. I tend to think that most of the resistance to biofuels of all type (including ethanol) comes from the energy establishment. The counter to this is not environmental but economics. Every dollar NOT sent to buy foreign oil is a dollar that can revitalize domestic economies. And save the 10-15% of defense budget to protect foreign resources.

It would be interesting to see how the processing cost of increased algal yields compares to higher lipid content processing. If handling larger volume does not offset lower oil content - it seems like the way to go.


"Every dollar NOT sent to buy foreign oil is a dollar that can revitalize domestic economies."

That says it about as well as it can be said. Save $500 billion per year on imported oil and another $100 billion on the defense of imported oil supplies and we can afford lots of great things for this country.


"Every dollar NOT sent to buy foreign oil is a dollar that can revitalize domestic economies."

Good idea but is it possible with our global economy set up the way it is? We live in a WalMart world where everybody is looking for the lowest price and the Saudis can supply you with oil at the cheapest price. Please note I said 'price' and not 'cost' because COST is something else. Price is what you pay at the pumps, cost includes things like hidden taxes, lost jobs spilled blood, etc.


It costs very little for the Saudis to produce a barrel of oil but they charge a high price, when you add up the external costs it is even higher.

At some point we may decide that FFV PHEVs running cellulose biofuels is a MUCH better way to go. You can take short cuts that get you in the long run, or you can do it the better way and eliminate future problems.


"or you can do it the better way and eliminate future problems."

Yeah, and we have a long history of doing that don't we? Not!

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