New study concludes that biofuels can be part of climate-energy solution.

The debate has been raging for years. Can biofuels, fuels derived from recently alive plant materials (or manure), serve as the fuel of choice to power our nation’s huge fleet of automobiles and trucks and power plants without adding to our climate change woes?  (Take a quiz: “What You Don’t Know About Biofuel.”)

A Look at Biofuels in Principle and in Practice

In principle the answer should be yes. Because the carbon in plants is produced from taking carbon dioxide (CO2) out of the atmosphere via photosynthesis, burning those plant-derived fuels simply puts the same amount of CO2 back in the atmosphere — sort of like no harm, no foul. (See comprehensive coverage: “Biofuels at a Crossroads.”)

Burning fossil fuels, on the other hand — fuels derived from the remains of plants and animals that lived between a million and hundreds of millions of years ago (way before the dinosaurs, by the way) — adds carbon to the atmosphere, carbon that was buried long, long ago, and so results in a net gain of CO2, and in the climate change game, most definitely a foul.

But being a winner in principle and being a winner in practice are two different things. In the first place, growing the biofuel feedstock and converting it to a biofuel consumes energy and emits some CO2. This arises from the energy needed to manufacture fertilizers and fossil fuels used to plant, harvest and transport. But calculations indicate that even after taking that into account, biofuels do better than fossil fuels from a climate point of view. So all is copacetic on biofuels?

Enter the ‘Searchinger Hypothesis’

Not so fast, say a host of papers. (See here, here, here, here and this paper here on which I am a co-author.) Advancing an idea based on the so-called Searchinger Hypothesis after Tim Searchinger (a former colleague who is “generally … credited with reshaping the world debate on bioenergy”), these papers argue that, once one takes land conversion into account, the biofuels climate picture goes from a positive to a negative.

More specifically, the argument goes something like this: When we take crops normally used for food, and use them as feedstock for biofuels instead (e.g., corn ethanol or soybean biodiesel), that can create a food supply deficit. To make up for this deficit, farmers somewhere will cultivate more crops, and to cultivate more crops, the farmers must farm on land not currently under cultivation. And that conversion of land from non-agricultural to agricultural can effectively create carbon emissions.

For example, when a forest is cut down to grow those new crops, there are significant releases of carbon, carbon that would have otherwise been stored in the forest. Thus this scenario represents a heretofore unaccounted for flow of CO2 into the atmosphere (a case of indirect land use). Accounting for these emissions, the advancers of the Searchinger Hypothesis claim, tends to make biofuels no better than, or even worse than, just using fossil fuels.

How to Solve the Biofuel Conundrum?

Some have attempted to solve this conundrum by proposing to use only marginal lands to grow advanced biofuels — leaving prime agricultural land for food. Sounds good, but I’m not sure this will work — it’s simple economics. If farmers can earn more income by growing fuel than crops, it’s hard to believe they wouldn’t convert prime croplands to grow fuels. Certainly, as these headlines indicate, U.S. farmers in recent years have been producing more corn in response to the U.S. mandate for ethanol (except in 2012 because of the drought): “2007 Corn Crop a Record Breaker, USDA Reports,” “2009 Crop Year is One for the Record Books, USDA Reports” and “U.S. CORN ACREAGE IS UP IN 2011.” And here’s the latest corn report for 2013. (Not only has growing more corn affected food production, a recent report by The Associated Press found that “As farmers rushed to find new places to plant corn, they wiped out millions of acres of conservation land, destroyed habitat and polluted water supplies.”)

Of course this rush to corn ethanol in the United States is being driven by the ethanol mandates in the Energy Policy Act of 2005 and the Energy Independence and Security Act of 2007. Ironically, because demand for gasoline in the United States is dropping, there is no longer enough gasoline being used to consume all the ethanol produced to meet the mandate (when the ethanol content is limited to 10 percent). In response, EPA is now proposing to relax the ethanol mandate. (See related post: “U.S. Proposes First Reduction in Ethanol Mandate.”)

Rosy Biofuel Future Predicted

It would appear that our recent biofuel journey has been problematic. Disrupted food markets, concerns about emissions from land conversion, and mandates that are in search of demands. But a new report released by the nonprofit think tank Resources for the Future foresees a stronger future for biofuels. Specifically, Roger Sedjo and his co-authors conclude that, based on two modeled scenarios,

“industrial forests and supplemental dedicated fuelwood plantations … can economically produce large levels of biomass [to provide biofuels] without compromising crop production, thereby mitigating the land conversion and carbon emissions effects posited by the Searchinger Hypothesis.”

The authors’ conclusions are predicated on their argument that there are more than enough non-agricultural and marginal lands available to produce enough biomass to meet their modeled biofuel demand*, keeping the price for biomass feedstocks low enough to make it unprofitable for farmers to switch from growing food crops to growing biomass for biofuels. (See Sedjo and others discuss biofuels in this series of clips.)

A Linchpin to this Counterargument: Economically Viable Cellulosic Ethanol

A key and critical assumption underpinning the Sedjo et al. argument is that the technology for producing biofuels from cellulosic material (as opposed to sugars from crops like corn) will advance enough to make biofuels generated from cellulose economically viable. If this occurs, the models used by Sedjo et al. predict there would be large amounts of biomass from grasses and trees grown on marginal lands; this biomass along with biomass from the pulpwood sector could meet the demand for biofuels without driving land conversion.* (See related story: “Drop-In Biofuels Squeeze Gasoline from Plants.”)

Will cellulosic-based technologies be able to bring biofuels to the marketplace? It remains to be seen, but there are encouraging signs. At least two cellulosic ethanol plants are up and running in the United States with three more expected to come online in 2014. And while it remains to be seen if production can match this year’s EPA target of 6 million gallons [pdf], next year’s goal of 17 million gallons has been called “realistic.” ($ub req’ed)

So it may turn out, with cellulosic ethanol in play, that biofuels are preferable to fossil fuels. But I’ve got something that beats out both: Cars that drive with fewer gallons per mile and drivers that drive fewer miles. (Vote and comment: “Are Biofuels Worth the Investment?“)


End Note

* The demand for biofuels modeled by the authors is significantly less than the cellulosic biofuel production specified in the Renewable Fuel Standard.

Post corrected 11/21/2013
The original version of the post neglected to mention that the demand modeled by Sedjo et al. is significantly less than the Renewable Fuel Standard specified in the Energy Independence and Security Act. Also left out were two of the primary sources of biomass for the paper’s scenarios (which, along with the biomass from marginal lands, which was mentioned, would be the means to meeting the demand specified in the paper): biomass derived from residues and the pulpwood sector.


  1. Bill Chameides
    February 3, 2014, 3:37 pm

    Groundthinking: Food for thought indeed; using sugars for biofuels probably means taking that sugar out of someone’s possibly hungry mouth.

  2. Deepi Makwana
    December 22, 2013, 6:46 am

    Bio fuel is the alternative source of energy and highly growing. other fossil fuels are very expensive and polluted environment that’s why we have to use renewable sources like bio fuel, solar energy, wind energy, geothermal energy etc…

  3. Martin Bostock
    Coventry, England
    December 12, 2013, 11:13 am

    Why this assumption that ‘biofuels’ are only liquid biofuels? The US has bands of both cool temperate and warm temperate climate and already has a super sufficiency of woody biomass that neither displaces food crops nor requires fossil carbon release for fertiliser.

    Even Canada with no warm temperate achieves a tremendous output of woody biomass without displacing food crops. As paper and saw lumber demand declines so fuel uses for pulpwood increase. We in Europe will happily take millions of tons of your wood for electricity generation.

    With efficient husbandry the US (and other regions including lands where presently lack of opportunity for economic activity is encouraging disorder) can grow woody biomass on all sorts of marginal lands and not only canes, like the sugar canes mentioned by another commentator, but fast growing hardwoods and softwoods can deliver fibre at several times the rate of present wood crops . . . .

    Add to that developments in gasification and further processing into liquid fuels plus use of the heat and carbon dioxide in the stack gasses from processing to grow oil rich algae and even more energy is captured for use in the whole range of types of fuels.

    Come on guys, the debate is too narrow, the science is rudimentary, the concepts and metrics too old and the lack of imagination, well, it simply appalls.

    Well used the land that presently grows plantation timber (plantation timber please, not forests because then a spurious emotional need to protect arises) plus much post industrial land, scrubland and marginal land could satisfy the need for energy security by providing solid fuels capable of generating the ‘base load’ when wind and sun are unavailable, domestic fuels, gas and liquid transportation fuels. Remember, much European transport ran on ‘producer gas’ during WW2. We could do it but we need to get enthusiastic about it and stop the narrow quibbling!

  4. John Edwards
    December 11, 2013, 12:01 pm

    Good balanced article and good comments. I do not think biofuels should be used for large-scale electrical power generation. Current wood-based projects will only result in deforestation, for negligible benefit.

    I do agree with D Sutherland that motor vehicles are being scrapped far too soon , before they have even become obsolete due to high fuel consumption.

    The work on fusion reactors is going well but i fear that they will be far too expensive to build and maintain.

    However there are fission reactors that we know will work and are crying out for full scale development and deployment which can both recycle existing ‘spent fuel’ and utilise thorium, guaranteeing a long-term future.

    There will still be a need for fuels for transport and biotech research should concentrate on producing hydrocarbons.

  5. Dave Sutherland
    December 10, 2013, 12:32 am

    Why haven’t these guys figured out that we put more carbon into the atmosphere just to manufacture a vehicle than it ever burns in it’s lifetime. Make the vehicles last longer and we could reduce carbon emissions a lot faster. Also, if standardized parts were legislated we could chop our massive parts inventory by 60 to 80% and reduce maintenance costs. Then maybe we could focus on building more reliable and cost effective alternative energy machines. Why is there so little effort being focused on fusion research? Oh, I forgot, we’re just pretending to find solutions. When 10 billion people run out of petroleum in the next 50 years or so, then we’ll do something about it… LIKE DIE.

  6. Groundthinking
    December 9, 2013, 6:48 pm

    Sugar cane ethanol has an energy balance of 8. Meaning its energy output is 8 times the amount used to grow and process it.
    In contrast corn ethanol has an energy balance of 1.3. Which makes it a poor feedstock for ethanol. One of the reasons the energy balance is so low is because unlike sugarcane, corn first needs to be processed to access its sugars which are then processed into ethanol.
    When the world figures out how to economically produce cellulosic ethanol, grass and wood pulp will be the last things to be considered as a fuel feedstock.
    Instead the other parts of the crop of sugar cane and corn will be used, as approximately 2/3 of the energy of sugar cane is locked up in its cellulosic residue.
    Food for thought.