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From Kansas State University's:

Consortium for Agricultural Soils Mitigation of Greenhouse Gases (CASMGS)



Charles W. Rice, K-State Department of Agronomy, National CASMGS Director

(785) 532-7217 cwrice@ksu.edu

Scott Staggenborg, K-State Department of Agronomy (785) 532-7214 sstaggen@ksu.edu

Steve Watson, CASMGS Communications (785) 532-7105 swatson@ksu.edu




Climate Impact of Starch-Based

vs. Cellulosic bioEthanol


Biofuels: an energy- and climate-saver, or a climate-heating money trap? There is no single answer to this question. Biofuels are carbon neutral in some ways, in that burning a biofuel simply releases a portion of the carbon back into the atmosphere that the plants absorbed during their lifetime.


But there’s more to the analysis than that. Whether a particular biofuel source can reduce greenhouse gas (GHG) emissions also depends on how the biofuel crop is grown, where it is grown, and how it is converted from the feedstock into the biofuel, according to some researchers. There is no question that some biofuels can lead to substantial greenhouse gas (GHG) emission reductions when compared to fossil fuels. But some may not.


To know for sure, it is necessary to figure in all the emissions that occur in the production and processing of the fuel source.


In large part, the ultimate answer may depend on whether the feedstock for the biofuel is “first generation,” using only the high-starch or oil-rich parts of the plant, or “second generation,” using the entire plant biomass, according to a newly released report from the British House of Commons. The report is titled “Are Biofuels Sustainable?” See:


The European Union is actively promoting the production of biofuels as a means of reducing greenhouse gas emissions, among other goals. This report was done to evaluate the climate effects and energy balance of biofuel production.


The main area of discussion involves the “life cycle analysis” of biofuel crops. In a “life cycle analysis,” the climate impact of all the inputs used in producing and utilizing a crop for ethanol or biodiesel production are taken into account.


Biomass crops to be used for cellulosic ethanol production are considered to reduce GHG emissions, and the life cycle analysis is favorable.


Other biofuel sources are still being debated, however. Production of ethanol from corn, for example, may contribute to global warming by increasing nitrous oxide emissions, which would more than offset the benefits that come from fossil fuel savings, according to a report by Dr. Paul Crutzen, 1995 Nobel Chemistry Prize recipient and atmospheric chemist at the Max Planck Institute for Chemistry, in Germany. Crutzen’s report, released in summer 2007, discusses the adverse effect on GHG emissions of increased nitrogen applications to farm fields. His report is at: http://www.atmos-chem-phys-discuss.net/7/11191/2007/acpd-7-11191-2007.pdf


Nitrous oxide (N2O) is about 300 times more effective at warming the atmosphere than carbon dioxide, making it the most powerful greenhouse gas.


Through hundreds of field measurements and evaluations, Crutzen and his staff discovered that the global warming impact of nitrous oxide emissions from corn fields for ethanol production is up to 1.5 times greater than the saved CO2 emissions. For biodiesel produced from rapeseed, the emissions are up to 1.7 times larger. These studies did not include CO2 emissions from farm equipment or fertilizer/herbicide production.


Crutzen’s report states that the increase in N2O emissions from biofuel production will also destroy more of the beneficial ozone layer in the stratosphere.


Cellulosic plants like switchgrass, elephantgrass, and other plants that require less nitrogen fertilization may be a better option for producing biofuels, claims Crutzen, but more research is needed in that area.


The House of Commons report “Are Biofuels Sustainable,” released on January 21, 2008, concludes that N2O emissions from the nitrogen fertilizer used in the production of ethanol are just one factor to consider when evaluating the climate impact of biofuels. Other considerations include:


* Agricultural production practices. If biofuel crops are grown using tillage, the soil will release carbon to the atmosphere. If the crops are grown using no-till systems, this is not a concern. The emissions from farm equipment used in production of the biofuel crop also needs to be taken into account. Here again, no-till has an advantage because less fuel is used.


* The amount of energy consumed (and greenhouse gases released) in the transportation of corn to the ethanol plants, the process of converting corn to ethanol, and the transportation of ethanol to the end user.


* Whether tree clearing was done to make land available for biofuel crop production.


The House of Commons report refers to another study released by the Organization for Economic Cooperation and Development (OECD), an international trade organization consisting of 30 countries – primarily developed economies. The OECD specializes in studying issues of sustainable economic growth and financial stability. The OECD study concludes that growing second-generation cellulosic biofuels is better than developing traditional sugar- and starch-based biofuels, partly because marginal lands can be used for biomass crop production instead of land that could otherwise be used for food production.


Richard Doornbosch, Principal Advisor, Round Table on Sustainable Development, OECD, and Ronald Steenblik, Director of Research, Global Subsidies Initiative, International Institute for Sustainable Development, stated in the September 2007 OECD report that if ethanol and biodiesel become significant contributors to the transportation sector, food prices along with the environment will most likely be compromised. The report is at: http://media.ft.com/cms/fb8b5078-5fdb-11dc-b0fe-0000779fd2ac.pdf


They said that in theory, there might be enough land available around the globe to feed an ever-increasing world population and produce sufficient biomass feedstock simultaneously, but it is more likely that land-use constraints will lead to a “food-versus-fuel” debate. Because food production and biofuel production compete for the same resources, the rapid growth of the biofuels industry is likely to keep food prices high and rising throughout at least the next decade, the report stated.


Doornbosch and Steenblik also pointed out that if value is not placed on the environment, biofuel demands will result in natural ecosystems like forests, wetlands, and grasslands being replaced by cropland -- making biofuels less environmentally friendly. 


One potential benefit of producing biofuels is that biofuels could give developing countries an opportunity to develop their own source of energy, the report stated. Biomass could provide electricity to people who have been living in the dark. Bioenergy could also boost developing economies with increased exports to industrialized nations. They said that more research needs to be done about this subject to determine its importance.


-- Steve Watson, CASMGS Communications



-- Katie Starzec, CASMGS Communications, Kansas State University



Soil Carbon and Climate Change News

Read the latest issue of Soil Carbon and Climate Change News here. You'll also find all past issues of this newsletter.


Conference Proceedings: 2007 USDA Greenhouse Gas Symposium

February 6-8, 2007


Past Conference Proceedings: 2005 USDA Greenhouse Gas Symposium

March 21 - 24, 2005

Past Conference Proceedings: CASMGS 2003 Fall Forum

Conference information, presentations, and papers are available at http://www.oznet.ksu.edu/ctec/Fall_Forum.htm

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