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Biofuels Baling corn residue at a University of Nebraska-Lincoln field experiment site in Saunders County, Neb.
Image Credit: UNL

Published on April 27th, 2014 | by James Ayre


Cornstalk Biofuels Can Generate More Greenhouse Gases Than Gasoline, Research Finds

April 27th, 2014 by  

Biofuels created from corn crop residues — such as stalks, leaves, cobs, etc — can generate higher levels of greenhouse gases than gasoline, according to new research from the University of Nebraska-Lincoln.

The production of these biofuels — including ethanol — also works to reduce soil carbon, further contributing to greenhouse gas emissions via that pathway.

Baling corn residue at a University of Nebraska-Lincoln field experiment site in Saunders County, Neb. Image Credit: UNL

Baling corn residue at a University of Nebraska-Lincoln field experiment site in Saunders County, Nebraska.
Image Credit: UNL

This new work casts yet further doubt on the usefulness of biofuels with regard to reducing greenhouse gas emissions. Of course, biofuels have a number of other advantages over conventional fuels that will likely see them used in some capacities for some time to come — especially by militaries, and/or governmental agencies.

The work also casts doubt on whether or not “corn residue can be used to meet federal mandates to ramp up ethanol production.”

The press release from the University of Nebraska-Lincoln provides more:

Corn stover — the stalks, leaves and cobs in cornfields after harvest — has been considered a ready resource for cellulosic ethanol production. The US Department of Energy has provided more than $1 billion in federal funds to support research to develop cellulosic biofuels, including ethanol made from corn stover. While the cellulosic biofuel production process has yet to be extensively commercialized, several private companies are developing specialized biorefineries capable of converting tough corn fibers into fuel.

The researchers, led by assistant professor Adam Liska, used a supercomputer model at UNL’s Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced (a joule is a measure of energy and is roughly equivalent to 1 BTU). Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule — which is 7% greater than gasoline emissions and 62 grams above the 60% reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act.

Importantly, they found the rate of carbon emissions is constant whether a small amount of stover is removed or nearly all of it is stripped.

“If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield,” Liska explained.

According to the research, the way to limit increased carbon dioxide emissions and to reduce soil carbon, would be to increase the planting of cover crops — in order to fix more carbon in the soil.

According to Liska, the researchers tried their best to poke holes in the study — but without success. The work appears to be quite solid.

“If this research is accurate, and nearly all evidence suggests so, then it should be known sooner rather than later, as it will be shown by others to be true regardless,” he continued. “Many others have come close recently to accurately quantifying this emission.”

Of course, the findings aren’t all that surprising to many people — most especially farmers, who have long noted the need to retain crop residue on their fields to protect against soil erosion and to preserve soil quality.

Some more specifics on the work:

Until now, scientists have not been able to fully quantify how much soil carbon is lost to carbon dioxide emissions after removing crop residue. They’ve been hampered by limited carbon dioxide measurements in cornfields, by the fact that annual carbon losses are comparatively small and difficult to measure, and the lack of a proven model to estimate carbon dioxide emissions that could be coupled with a geospatial analysis.

Liska’s study, which was funded through a three-year, $500,000 grant from the US Department of Energy, used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America, Europe, Africa and Asia.

Using USDA soil maps and crop yields, they extrapolated potential carbon dioxide emissions across 580 million 30-meter by 30-meter “geospatial cells” in Corn Belt states. It showed that the states of Minnesota, Iowa and Wisconsin had the highest net loss of carbon from residue removal because they have cooler temperatures and more carbon in the soil.

The new findings were just published in the journal Nature Climate Change
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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • swinging voter

    “Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule — which is 7% greater than gasoline emissions ”
    This is not correct and IT is pretty obviously INCORRECT to anyone that stayed awake in the high school science class about the carbon cycle. Gasoline is derived 100% from sequestered carbon whilst ethanol sources the majority of its carbon for plant growth from carbon dioxide in the atmosphere in a process called photosynthesis and respiration… Its possible that a small amount may be derived from soil based carbon although the above statement is deceptive ,grossly misleading and ignores the carbon cycle fundamentals
    no university studies required! its high school science on the carbon cycle!

  • Benjamin Nead

    Stepping away from the issue of choosing the right crop for biofuel production and scaling up production output for a nation’s vehicular fuel supply (I do read you 5 by 5, agelbert,) I’d like to mention that I keep about a gallon of pure (B100) biodiesel around the house for cleaning rust off of metal tools and removing the gunked-up grease off of bicycle chains. Pure biodiesel is also a excellent oil for rejuvenating non-finished hardwoods, like ebony and teak. Marvelous stuff.

  • Jouni Valkonen

    There is still another point that is not usually considered… if that agricultural field had regrown as forest, it would store some 1–2 tons carbon (3–5 tons carbondioxide) per hectare per year. This is very significant fraction from the productivity of soil as biofuel feedstock.

    Forests can store carbon at least some 100 maybe 200 years at fast rate. Then it slows down and old growth forests are acting perhaps some 300 to 600 years as carbon sinks, before equilibrium is reached. Trees themselves has typical lifespan some 400 to 1200 years and it takes as long as 100 years from dead tree to decay.

    This underlines how horrible invention biofuel in in any larger scale than what can be recovered by recycling e.g. spent cooking oil.

    Biofuels as solution for global warming is the holocaust of Nature!

    • LookingForward

      A little dramatic, but that’s what I’ve been thinking.
      The best we can do to keep everyone happy is plant trees for decarbonisation and put grass and weeds in between them for biofuels, I think it can be done if you keep enough space in between the trees to harvest the grass and weeds.

    • Mythbuster

      Sorry – any non-managed forest will frequently burn – not totally, but partially – more frequent the closer to the equator – and over and over lose parts of its carbon. While we in the meantime will have to use coal and oil for our energy need. Result is increased climate gas emissions.

      The best carbon storage is instead to keep the fossil fuels in the ground and use all the superfluous land we have to capture solar energy – both as PVs, as wind, and as biofuels – and listen carefully to reports like these on how to grow sustainable biofuels.

      BTW – there is an answer by Michael Wong (NREL) on the article – pointing out all the exaggerations the researchers made. These researchers pointed to an important factor that needs to be taken into consideration, but they overdid it many times. It is a huge systematic error in our research system that you need to exaggerate to get someone to listen.

      • Jouni Valkonen

        there is no such thing as sustainable biofuels. Biofuel production at any larger scale will lead local holocaust of nature and also erosion of top soil.

        Therefore there is no such thing as superfluous land for biofuel production, but it is better to live nature as it is.

        Also biofuels has weak carbon economy. It is easier to improved ICE efficiency than to improve the carbon efficiency of biofuel production.

        You are exaggerating the role of forest fires. Most of the large scale forest fires are due to human intervention. When humans put down the small fires that are no threat for the trees, but only dead plant material is burning, this sows the seeds for large scale forest fires that neither humans nor nature cannot no longer control.

        • Bob_Wallace



          • Jouni Valkonen

            Not yet commercially feasible, but I agree that algae has good promise, but I cannot estimate the time scale. I would root rather artificial photosynthesis than algae based biofuels.

  • agelbert

    This is grossly erroneous information. But just for the hell of it, let’s say it is true. Hello? Have you morons heard of Duckweed or Azolla (mosquito fern, duckweed fern, fairy moss, water fern)? Never mind sugar cane, which beats the stuffing out of corn (a crop set up as a biofuel source by big oil deliberately to fail!), both Azolla and Duckweed have higher growth rates, actually sequester carbon rather than simply being carbon neutral and can grow in just about any place that humans live on this planet, including non-arable land because you grow them with water that does not ever have to be replenished from the initial shallow tank amount, thank you very much.

    Sorry folks, spare me the hemming and hawing about “unproven” crops and biofuels, this is really another Koch funded piece of clever half truth.

    Do you remember how our ancestors crowded the native Americans and Blacks into the worst living conditions imaginable, took away their quality of life, pride of ownership and any hope for a decent future and then “lamented” how “genetically lazy and prone to theft and immoral behavior” said people were as compared to whitey? Sure you do! Well, guess what? Big oil has been doing that with renewable energy in general and biofuel crops in particular for several decades. Have you ever heard of hemp? Did you know you can make any plastic there is from it cheaper than from fossil fuels? Did you know we were doing just that in the 1930s until a strange serious of fires destroyed out chemurgy refinery? Get real people. Big oil is just “doing what the have done for over 100 years! . We need fossil fuels like a hole in the head.
    Corn was always a poor ,lousy, stupid choice for biofuels because you need to plow a field – you need lots of fuel for the machinery in a self defeating loop of irrationality when you are looking for biofuels, it’s an annual instead of a perennial l- a guarantee of leaking carbon into the atmosphere!. The Kansas Land Institute proved all this (and provided a thorough laundry list of perennial grasses that don’t require plowing or pesticides – all much more cost efficient for biofuel stock than stupid corn) and told it to Congress over 15 years ago and Congress would not listen. -[I]And that’s the big oil wanted it!

    Full Chemurgy crushing by big oil story here:

  • Benjamin Nead

    It’s possible to recycle old cooking oil into biodiesel and, although this might not be able to scale to the massive volumes needed, it would seem that this would be a win/win scenario, as the crops would start life as food product (cooking oil) and, after the oil would otherwise simply be dumped into the sewer, turned into a fuel source. Is recycled corn or soy oil factored into this study?

    • Bob_Wallace

      We should do it, we are doing it. But it won’t make a significant part of our fuel needs.

      We’ve got semi-long shots such as algae and duckweed.

      ​We also may be able to grow a crop of canola in between annual wheat crops. The canola will thrive on the leftover ​fertilizer from the wheat, it slows erosion, the roots add to the organic matter in the soil and it provides additional income for farmers.

      The solution may be a little from here, a little from there, stir it all together with as much electrification as possible and top it off with generous amounts of efficiency.

  • JamesWimberley

    Oops. This is big bad news. We can’t assume any biomass energy is carbon-neutral without a full analysis of the effect on soils. Imagine a woodchip plant in a sustainably managed forest. Is it recycling carbon freshly fixed by the trees, or drawing down the capital of buried carbon?

    Zach: it’s a lot to ask, but land use – deforestation, energy crops – is a very big deal, of the same order of magnitude as transport an electricity generation. Worse, the trends are all in the wrong direction. Brazil say needs a U-turn to go from net deforestation to net reafforestation,. Only the hippies are talking about this, it’s outside the Overton window.

    • Omega Centauri

      I never thought it would be carbon neutral, I would expect some decrease in soil carbon. But if the effect is so large there is no benefit versus using oil, it is bad indeed. Incrementally how much soil carbon is lost by taking the corn as well?

      I suppose maybe, if a few years later, the practice is stopped, some of the soil carbon might gradually be restored, i.e. perhaps less soil carbon is lost over decadal or longer scales? But we need to also remember that the oil that wasn’t burned because of the biofuel, is still available for someone else.

      • Bob_Wallace

        Some biofuels could be carbon negative. (Assuming renewable harvesting/processing.)

        Plants like switchgrass produce extensive root systems and take carbon from the atmosphere, fix it in their roots.

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