"Biofuels would be actually worse than conventional gasoline"
1 Dec, 2009 10:27 am
According to a new study titled "Indirect Emissions from Biofuels: How Important, published online in Science on October 22, biofuels programs aimed at curbing greenhouse gases could do just the opposite without proper regulation. Dr John Reilly from the MIT, one of the co-authors of the study, answers Scitizen's questions.
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Our approach allowed us to derive better estimates of the indirect CO2 emissions from land use change than previous estimates. We also showed the impact of N2O emissions from nitrogen fertilizer use to be substantial. Previous work has not estimated the impact of N2O emissions. Our results emphasized the fact that the indirect emissions depend on the willingness of land owners to convert natural forest land - if they are less willing to convert land than there is greater intensification of use on existing pasture and grazing land and on cropland and biofuels are not so damaging. In fact, in some areas intensification could lead to increased CO2 storage on land.
Did you make a distinction between the first and second generations of biofuels and the third generation - algal biofuels - which doesn't need arable land?
We focused mostly on what we called - second generation - biofuels. By these we mean technologies that would convert cellulosic material in plants to biofuels. Our focus was limited to analysis of land-based plant material. Cellulosic conversion technologies (and other technologies) could produce biofuels from algae. We did not consider those in this work. While algal based biofuels production likely would not compete directly for land that otherwise could be cropped, the water requirements of algal based systems would be substantial.
Is the impact of biofuels on climate change somewhat more harmful than those of fossil fuels because of its hidden aspect?
Absent effective protection of forests, a big expansion of biofuels would likely lead to deforestation and as a result for the first 20 to 40 years, biofuels, even if not emitting any CO2 during the processing of the biomass, would be actually worse than conventional gasoline in terms of greenhouse gas emissions. Once the major expansion period was over, then repeated biomass crops on the same land would not lead to further land use emissions, and biofuels would be less-GHG emitting than gasoline. The continued need for nitrogen fertilizer would mean that there would still be GHGs emitted even in the long run mainly in the form of N2O. The CO2-equivalent N2O emissions alone associated with producing a gallon-equivalent of biofuels would be about 20% of the CO2 released when a gallon of gasoline is burned by our estimate. This assumes that fossil fuels are not used in the processing of biofuels.
Whether biofuels are better or worse than fossil fuels thus depends on (1) whether forests are protected (2) how they are processed (3) what material is used to produce them.
In the light of your study, could the negative impact of nitrous oxide emissions on climate change supplant those of carbon dioxide emissions in the eye of public opinion?
Both are important. In the near term the big issue is CO2 from land use change, in the longer term we need to not lose sight of the N2O emissions associated with fertilizer use, and possible look for ways to reduce those emissions through more efficient use of fertilizer.
In what way can a cap-and-trade system tackle the issue of indirect emissions from biofuels?
If a cap and trade system were extended to cover emissions and sequestration from land use, and such a system could be applied globally, then most of the negative consequences of biofuels on greenhouse gas emissions could be eliminated. This would, however, put greater pressure on food prices. Partial protection in some regions might however worsen the situation by further encouraging deforestation in regions without effective forest protection, especially if regions without protection are those in tropics. While extending a cap and trade to land use emissions and sequestration is one way to solve the problem, simply protecting forests through any means, as long as it is effective, would greatly reduce indirect land use emissions associated with biofuels production.
Do you call for a global legal framework to protect natural ecosystems with high carbon storage in the course of the Copenhagen process?
Effective protection of forests and natural ecosystems generally is very important because of the large store of carbon in these systems, and also because of the value of biodiversity and other important functions of these systems such as moderating the hydrological cycle. Their protection should be sought through whatever means might effective - certainly through the Copenhagen process. The hugely multilateral nature of the COP process can make it hard to reach agreement among all parties. Other bilateral agreements, or forest protection agreements outside of the climate negotiations should also be pursued.
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the nitrous oxide piece is really under-appreciated, and I'm glad Mr. Reilly highlights it. if you want the basics on nitrous oxide, check out this fact sheet: http://www.nitrogennews.com/factsheets_and_studies-nitrousoxide/