Busting Big Oil Myths on the RFS and Ethanol, Part III: ILUC and Greenhouse Gases

Source: Geoff Cooper, RFA’s Vice President of Research and Analysis. Energy Collecive • Posted: Monday, June 10, 2013

biofuels and ethanol mandate

As part of an aggressive effort to stifle ethanol use and repeal the Renewable Fuel Standard (RFS), Big Oil and its allies have launched a campaign of half-truths and misinformation about the economic and environmental impacts of biofuels. I previously addressed two of the oil industry’s go-to myths here and here. In this post, I’ll address the false notion that ethanol does not reduce greenhouse gas (GHG) emissions compared to gasoline.Incredibly, the American Petroleum Institute’s anti-RFS “training center” (yes, Big Oil has a “training center” apparently intended to spawn an army of certified RFS haters) has the audacity to claim, “If you thought ‘at least ethanol is environmentally friendlier than gasoline,’ think again.” The module goes on to raise the specter of biofuels-induced land conversion and “ecosystem disruption.”  API’s recent comments to the House Energy & Commerce Committee also made the claim that the RFS is not reducing GHG emissions. The irony of ethanol’s environmental impacts being called into question by the purveyors of tar sands, shale oil, benzene and other toxics, MTBE, petroleum coke, and other not-so-environmentally-friendly products would be downright laughable if it weren’t so disgusting.Myth #3: Ethanol and the RFS are not leading to reduced greenhouse gas emissions from transportation

Prior to 2008, there was broad consensus among the scientific and regulatory communities around the fact that modern corn ethanol generates considerably lower GHG emissions than gasoline. Much of the GHG benefit associated with ethanol stems from the fundamental difference between the carbon cycle of biomass and the carbon cycle of fossil fuels. As eloquently explained in a recent paper by scientists from Duke University, Oak Ridge National Laboratory, and the University of Minnesota (note: this is a fascinating paper that compares, head-to-head, the potential lifecycle environment impacts of ethanol and gasoline):

A critical temporal distinction exists when comparing ethanol and gasoline life-cycles. Oil deposits were established millions of years in the past. The use of oil transfers into today’s atmosphere GHGs that had been sequestered and secured for millennia and would have remained out of Earth’s atmosphere if not for human intervention. While the production and use of bioenergy also releases GHGs, there is an intrinsic difference between the two fuels, for GHG emissions associated with biofuels occur at temporal scales that would occur naturally, with or without human intervention. …Hence, a bioenergy cycle can be managed while maintaining atmospheric conditions similar to those that allowed humans to evolve and thrive on Earth. In contrast, massive release of fossil fuel carbon alters this balance, and the resulting changes to atmospheric concentrations of GHGs will impact Earth’s climate for eons. [1]

In other words, biofuels essentially recycle atmospheric carbon. In the case of corn ethanol, for instance, the same amount of CO2 released when the fuel is combusted in an engine has been previously removed from the atmosphere via photosynthesis during growth of corn plant. Although there may be temporary shifts between atmospheric and terrestrial stocks of carbon within the active carbon cycle, the carbon released into the atmosphere during this process is not “new” carbon being introduced into the earth’s carbon cycle. Biogenic carbon emissions then are considered “carbon neutral” based on the feedstock’s carbon uptake. For annual crops like corn, this carbon cycle occurs rapidly (i.e., every year with each new harvest).

While COemissions from fuel ethanol combustion are carbon neutral, there are some GHG emissions associated with the production and distribution of the fuel. These supply chain emissions are the primary focus of well-to-wheels “lifecycle analysis.” In the case of corn ethanol, lifecycle analysis includes the emissions related to: the production and use of fertilizers, seed, and other inputs; fuel use by farm machinery; fuel use by trucks/trains hauling corn to ethanol plants; energy use by the ethanol plant (typically natural gas and electricity); and fuel use by trains/trucks to distribute ethanol to blending terminals, and eventually to consumers. Most lifecycle GHG analyses conducted from the mid-1990s through 2007 (including a seminal 2001 study executed by General Motors, Shell, ExxonMobil, BP, and Argonne National Laboratory) concluded that corn ethanol offered well-to-wheels GHG savings in the range 20-30% compared to gasoline.

But the understanding of ethanol’s GHG benefits was substantially (and strategically) muddled in early 2008. That’s when former Environmental Defense Fund attorney Timothy Searchinger published an article claiming that corn ethanol expansion in the U.S. would induce “indirect land use changes” (ILUC) in the Amazon rainforest, and that when the emissions from land clearing are allocated to ethanol’s lifecycle, its total GHG profile would be worse than that of gasoline. In essence, Searchinger’s theory posited that increased demand for U.S. corn (for ethanol) would displace U.S. soybean acres, and that farmers in South America would respond by clearing rainforest and expanding soybean acres there. Searchinger’s assumption-driven scenario analysis and slapdash, opaque methods suggested corn ethanol would reduce GHG emissions by 20% compared to gasoline if ILUC is not considered, but would increase GHG emissions by 93% when his hypothetical ILUC scenario was included.

The Searchinger paper sparked significant controversy about the actual occurrence and magnitude of ILUC. It also launched a contentious debate about whether ILUC could be appropriately simulated with existing methodologies and economic modeling tools, all of which were designed for other purposes. Unfortunately, the debate over ILUC was not confined to the ivory towers of academia—it quickly bled into the regulatory sphere as rules for the federal RFS2 and California Low Carbon Fuel Standard (LCFS) were being drafted. Despite the high uncertainty of modeling simulations, the unsettled debate over estimation methods, and a complete lack of validation or ground-truthing, ILUC penalties prematurely found their way into the RFS2 and LCFS regulations (due in no small part to the relentless lobbying of Big Oil and environmental NGOs).

In the five years since Searchinger’s paper was published, more sophisticated models and methodologies have been developed for examining potential ILUCs, more robust input data sets have been assembled, and empirical data has been reviewed (incidentally, in 2012 deforestation in the Amazon hit its lowest point since at least 1988). While ILUC analysis remains highly uncertain and driven by assumptions, the most recent analyses have exposed Searchinger’s initial estimates as being egregiously inflated, terribly exaggerated, and irrelevant to the current debate over ethanol’s GHG impacts.

Retrospective analyses of land use patterns since adoption of the RFS have concluded that there is little or no evidence that the program has induced ILUC. [2] Other analyses have produced corn ethanol ILUC emissions estimates that are a full order of magnitude lower than Searchinger’s estimate and well below the levels estimated for the RFS2 and LCFS. The improved estimates primarily result from better data and enhanced understanding of: the types of land most likely to be converted, the most likely location of predicted conversions, crop yields on newly converted lands, crop yield responses to changes in prices, carbon stocks and emissions from land conversion, the effects of animal feed co-products on land use, and crop switching/cross-commodity effects. New and improved methodologies for accounting for land use emissions over time (i.e., “time accounting”) have also been established. [3] (EPA’s time accounting method was a particularly controversial element of its ILUC analysis).  Image

Based on newer data and improved methodologies, the independent estimates of corn ethanol LUC produced in the last several years have generally trended in the range of 7-15 grams CO2 equivalent/Mega joule (g/MJ), compared to Searchinger’s outrageous 104 g/MJ, and estimates of about 30 g/MJ by both EPA and the California Air Resources Board (CARB).

The most recent lifecycle analysis of corn ethanol, published in the journal Environmental Research Letters, found that corn ethanol produced in the 2008-2012 timeframe reduced GHG emissions by an average of 34% compared to baseline gasoline. [4] Importantly, that figure includes hypothetical ILUC emissions. If ILUC emissions are excluded from the calculation (i.e., if an equitable comparison of only direct emissions is made), today’s average corn ethanol reduces GHG emissions by 44% relative to gasoline, according to the paper.

These results are consistent with several other independent lifecycle analyses of corn ethanol. For example, Liska et al. (2009) in Yale’s Journal of Industrial Ecology found modern corn ethanol reduces direct GHG emissions by 48-59% compared to gasoline. [5] Meanwhile, a report by O’Connor for the International Energy Agency found 2005-era corn ethanol reduced direct GHG emissions by 39% compared to gasoline, with reductions of up to 55% expected in the near future. [6] Further, CARB has certified individual pathways for nearly 30 grain ethanol plants that serve the California market for the state’s Low Carbon Fuels Standard (LCFS). The ethanol produced by these plants reduces direct GHGs by an average of 40-45% relative to baseline gasoline, according to CARB. Incidentally, CARB recently reported that ethanol has provided 80% of the GHG emissions reductions required under the LCFS to date—despite the application of a punitive an indefensible ILUC penalty.

It’s unfortunate (but unsurprising) that critics of biofuels still cling to the Searchinger analysis in a desperate attempt to perpetuate the ridiculous myth that corn ethanol is somehow worse for the climate than gasoline. Any unbiased and impartial review of the lifecycle GHG studies and predictive ILUC scenario analyses conducted over the past several years could only lead to the conclusion that corn ethanol undoubtedly reduces GHG emissions relative to petroleum fuels. This is especially true when one considers the increasing GHG intensity of the petroleum fuels used in the U.S. today and in the future, like Canadian tar sands and tight oil from fracking. Consider that CARB recently estimated that the carbon intensity of California gasoline increased from 95.9 g/MJ in 2006 to 99.2 in 2010—an increase of 3.4% in just four years! The carbon footprint of producing and using crude oil will continue to worsen, as unconventional sources make up a larger share of the crude oil slate. Meanwhile, the GHG impacts of ethanol will only get better as crop yields increase, energy inputs decrease, ethanol plants continue to adopt new technologies and efficiencies, and new cellulosic feedstocks are commercialized.

  1. Parish et al. (2012). “Comparing Scales of Environmental Effects from Gasoline and Ethanol Production.” Environmental Management, 50 (6): 979-1246.
  2. See, for example, Oladosu et al. (2011). “Sources of corn for ethanol production in the United States: a decomposition analysis of the empirical data.” Biofuels, Bioprod. Bioref. 5:640–653 (2011).
  3. See, for example, Kloverpris, J. & Mueller, S. (2012). Baseline time accounting: Considering global land use dynamics when estimating the climate impact of indirect land use change caused by biofuels. Int J Life Cycle Assess, online Sep. 11, 2012.
  4. Wang et al. (2012). “Well-to-wheels energy use and greenhouse gas emissions of ethanol from corn, sugarcane and cellulosic biomass for US use.” Environ. Res. Lett., 7 (2012) 045905 (13pp).
  5. Liska, A.J., H.S. Yang, V.R. Bremer, T.J. Klopfenstein, D.T. Walters, G.E. Erickson, and K.G. Cassman (2009). “Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol.”  Journal of Industrial Ecology. 13(1): 58-74.
  6. O’Connor, D., for International Energy Agency (2009). “An examination of the potential for improving carbon/energy balance of bioethanol.” IEA Task 39 Report T39-TR1, 72 pp.

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