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Two Science articles make the risk of bad biofuels clear

Nathanael Greene

Posted February 7, 2008

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Two articles appearing today in Science Magazine make the risk of bad biofuels clearer than ever. The first article, "Land Clearing and the Biofuel Carbon Debt," addresses the direct greenhouse gas emissions from growing biofuel feedstocks on land recently converted from natural ecosystems to managed agriculture. This article is by a team from the Nature Conservancy and the University of Minnesota including David Tilman. The second article, "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land Use Change," addresses the emissions from land use change induced by the economic pressures when crops and land are diverted from food, feed, and fiber to fuels. This article is by a team lead by Tim Searchinger now from Princeton, the Woods Hole Research Center, and Iowa State's CARD.

While these two article will no doubt stir a lot of debate about the specific amounts of carbon released from different land types, the amounts of different lands being cleared, and the exact economics driven by growth in biofuels production, three conclusions are crystal clear now: 1) Under business of usual, these two dynamics make it very likely that most biofuels would be responsible for greenhouse gas emissions significantly higher than gasoline or diesel; 2) The fundamental dynamics addressed by these two articles (direct land use emissions and economically induced land use emissions) are undeniable; and 3) Because of these dynamics, the importance of minimum GHG emissions standards and land-use safeguards (see this post) in the recently adopted renewable fuel standard is clearer than ever.

Unfortunately, before EPA has even launched a formal rulemaking, some in Congress appear to be itching to gut the standards and safeguards. Today, the Senate Committee on Energy and Natural Resources held a hearing on the renewable fuel standard and a number of Senators raised questions about the standards and safeguards and the need for "technical fixes." (See this article regarding recent comments by Sen. Thune about his desire to use the Farm Bill to start the gutting around some of the forest protections.)

Let's be clear: the environmental protection provisions in the RFS make it possible for the 36 billion gallon goal to be good for our climate and not destructive of our forests, prairies, and wild places. Obviously, whether it works out this way depending on how well we implement these safeguards. Fortunately, while these articles are just running today, the threats they enumerate shaped the RFS protections. We need to go further; we need to adopt a federal low-carbon fuel standard, but definitely at the head of the class now.

But if we gut these protections, these articles make it clear that the RFS will make global warming worse and lead to greater clearing of rainforests, savannas, and millions of acres of natural ecosystems. Without these protections, it's not that the RFS will be less good--it will be very bad!

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Jim BullisFeb 7 2008 04:39 PM

I had a moment of euphoria.

I finally figured out the Argonne study on cellulosic ethanol. It began to make sense when they explained how they took credit for 'lignin' as a coproduct of the process which was 'useable to fire gas turbine engines.' The process sounded good, where all the co2 released by burning the stuff, either as ethanol or lignin, would have been previously taken in from the atmosphere.

Maybe lignin would actually work in gas turbines and the transportation infrastructure could get that lignin to those gas turbines. Well, maybe. It looks like a lot of roads through forests will be needed to get it done.

Then I remembered seeing the 100 year old growth on the root structure of a giant redwood cut that long time ago. That new growth might be capable of sinking co2 like that giant did it, but I doubt it.

Then I realized that we would probably clear-cut the Northern Boreal forests, in North America at least, to fuel our SUV's. I believe that these forests are major defense against global warming. Would it be possible to manage that in a sustainable way?

So then I realized that the correct measure of efficiency would be miles traveled by the car per acre-year of forest land. If those miles are in an SUV, lots of luck. Even 35 MPG cars will be quite a drain.

Ok maybe it will work with switch grass. Whatever that is, somehow, I think this will require cropland that might otherwise be used for food production.

Thus ended euphoria.

The only way this can begin to make sense is if our cars operate far more efficiently than even the 35 MPG standard. Such operation is possible if we begin to make cars that fit our actual requirement for transportation, rather than a 90 year old, misguided notion. In 1916, tandem seating in cars was being introduced in ‘cycle cars’. There were many ‘start-up’ companies using this approach. Henry Ford did a worse killing job on these cycle cars than ever was done by GM on the electric car. We have since been stuck with the notion that riding in cars was a social occasion and that energy waste due to a usually empty right front seat was unavoidable. An example of a car designed around our real requirements is shown at With cars like this we could be thinking in terms of 200 MPG rather than 35 MPG.

If 200 MPG cars were widely used, the quantity of ethanol might be reasonable. Then,it might be possible to keep effective environmental protections in place.

No goods or services are offered at the above referenced web site. However, I have an interest in Miastrada Corporation.

Best regards, Jim Bullis

Tim RaphaelFeb 8 2008 06:21 PM

The analyses are fundamentally flawed because:

• The reports attribute “secondary land use impacts” to biofuels that are not supportable;
• The reports fail to account for ongoing improvements in agricultural yields and technology improvements in biofuel production; and
• The reports fail to account for upstream environmental impacts of oil extraction.

The current first-generation biofuels (corn-based ethanol and soy-based biodiesel) are not perfect and alone will not solve all our problems, but what is clear is that current and future use of renewable fuels reduce carbon compared to conventional gasoline. In addition, the environmental performance of biofuels continues to improve and the next generation of biofuels based on agriculture and other wastes will provide even further CO2 reductions.

“Secondary Land Use Impacts” – A Flawed Concept
The reports assert that increasing production of biofuels in the US is driving destruction of ecosystems in South America and Asia for food production and attributes a carbon debt to biofuels from the clearcutting of rainforests and cultivation of native ecosystems. This assertion is based on assumptions and models that are not and cannot be verified. This “Secondary Land Use Impacts” assumption counters all current, verified analyses showing substantial greenhouse gas emission reductions for biofuels.

Why should US-based corn ethanol, other crop-based biofuels, or advanced cellulosic fuels take a carbon hit for international land use changes for food or housing or other non-fuel related production? By that logic,

• Any US farmland not growing food crops is creating a carbon debt by increasing demand for international food production—What are the “secondary land use impacts” of US grass seed farmers? Or tobacco farmers? Or nursery owners? Or cotton, tomatoes grapes and a myriad of other non-food related agricultural acreage in the US?
• Every new subdivision and greenfield commercial, industrial or residential development creates a carbon debt by taking potential food-producing land out of production and shifting that demand to sensitive, international native ecosystems; and
• Any effort in the US to protect ancient forests or native ecosystems creates a carbon debt by increasing demand for international sources of wood products.

Any analysis that shifts away from a life cycle analysis of the carbon potential for a single product or fuel and attempts to distribute carbon potential to “secondary” or “tertiary” impacts will create a dead-end, through-the-looking-glass scenario that is inaccurate and unworkable.

The real implication of accepting “secondary land use impacts” is an on-going dependence on CO2 intensive, polluting, imported fossil fuels. Inclusion of secondary impacts is the wrong approach—each product should stand on its own.

It’s Not Acre for Acre – Productivity Gains Means We Get More From Less

The analyses of land use impacts assume that for every acre of land dedicated to renewable energy feedstocks, another acre of land must be put into production elsewhere in the world. This assumption is flawed for several reasons:

• It fails to account for advances in seed and processing technology that are providing greater yields for each acre of feedstock.
o Corn acreage in the US peaked in 1917 with 116 million acres planted, compared to 93 million acres in 2007. During that period yields have increased by more than 1 bushel/acre/year, from 29 bushels/acre to 200 bushels/acre. This year the US will harvest more than 10 billion bushels of corn, and exports are rising, so certainly US corn ethanol production is not causing a need for increased grain production in the world.

• It ignores the value of the feed co-products that are produced at today’s biorefineries.
o The food value of corn is not lost in ethanol production—distillers grain is a high protein, high nutrient co-product that is sold back into the food market.

• It inappropriately assigns all of the impact to growth in renewable fuels, ignoring the effects of a growing world economy, increased demand for food, and urban sprawl.

The Environmental Impacts of Fossil Fuels are Increasing
The reports fail to account for the fact that every gallon of biofuel produced today requires less land, requires less water and is less energy intensive than a decade ago, while the opposite is true for oil production. Every new gallon of oil produced is more energy intensive and requires much more water than before.

The “easy” sources of oil have been found and are being depleted. What is left are more remote, costlier and more environmentally damaging nontraditional sources like Canadian tar sands or Rocky Mountain oil shale. By failing to capitalize on the opportunity renewable fuels offer to begin breaking our adherence to the oil standard, the world would be forced to develop these nontraditional sources of oil that carry significant environmental price tags.

Even traditional sources of oil have steep environmental costs that are not accounted for in the land use reports. Where is the accounting for oil drilling in the Amazon? Oil spills in San Francisco Bay? Or asthma deaths from air pollution?

Peter KelleyFeb 11 2008 06:58 PM

We've been looking at these studies with the United Nations Foundation. As their blogger Matt Cordell wrote about them:

"Judging renewable fuels on a snapshot of what they're capable of now is like judging aviation based on the Wright brothers' flyer. Within 65 years, we'd broken the sound barrier and landed on the moon. In the last five years alone, we've been able to increase switchgrass yields by 50 percent. Everyday, less and less land can be used for more and more fuel, promising to reduce the carbon footprint dramatically. In less than a decade, it is highly likely that converting that grass to fuel will become economically viable and therefore widespread. Similar technology could be used to produce fuel from waste like yard clippings, brush, animal fats, scrap paper, algae, and sawdust -- all of which requires no additional land use. And that's only the tip of the iceberg."

More at:

Disclosure: I also work with SunEthanol on their microbe that makes ethanol from plant material.

fred schumacherFeb 13 2008 09:53 AM

Quick disclaimer--I haven't yet had a chance to get access to a copy of the two Science articles by Searchinger and Tilman,, but my immmediate reaction to the media reports was there must be something fundamentally wrong with the research methodologies used.

One immediate thought is that they are comparing apples and coal briquets. Saying that destruction of forests and grasslands to plant biofuel crops result in higher carbon emissions than fossil fuels is equating botanical carbon with fossil carbon. These are not the same. Botanical carbon is already a part of the earth's carbon cycle. Fossil carbon is new carbon being introduced into the cycle. All things die, whether sooner or later, and carbon tied up in above ground biomass is not sequestered carbon.

Regarding Tilman's dire message on plowing up grasslands: if carbon is sequestered underground in an 8 feet deep layer of soil (I'm a retired native grass seed farmer, so I'm very cognizant of how deep the root system of my plants were), how does tearing up the top 6 inches suddenly release so much carbon?

I looked at historical CO2 levels, especially the latter half of the 19th century when millions and millions of acres of native prairie were put to the plow in the U.S., Canada, Russia, Brazil, Argentina and Australia. The only correlation I could find in rising CO2 levels fit exactly with the rate of coal burning. I could see no bubble in CO2 levels I could ascribe to land use change.

I think there's a scaling error in their calculations.

Also, the primary pressure on food resources worldwide is not biofuels but meat production. Increased income in east Asia due to globalization is creating a voracious demand for higher quality and quantity of food.

Eric KarpFeb 13 2008 05:10 PM

It seems unwise to take the position that biofuels do not have a large impact on the price of commodities.

That being said, I do not believe biofuels are the only cause of the increase, but they certainly play a significant role. One that shouldn't be ignored.

In regards to the validity of the research articles, I believe it doesn't matter whether or not they make accurate claims. The price of feedstock for biodiesel has risen so much that it is uneconomical to produce fuel (even with the 1$ tax credit). Ethanol, as you know, is following the same trend. But this doesn't mean biofuels are worthless. Government subsidies should be diverted towards R&D projects designed to make fuel from non-foodstock sources (Algae, cellulosic, etc.). That's where the real future of biofuels is going to be, because the current scheme is failing at an astounding rate.

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