Biomedical Engineering and Bioengineering Commons^™

Accounting For Indirect Land-Use Change In The Life Cycle Assessment Of Biofuel Supply Chains, Susan Tarka Sanchez, Jeremy Woods, Mark Akhurst, Matthew Brander, Michael O'Hare, Terence P. Dawson, Robert Edwards, Adam J. Liska, Rick Malpas

Adam Liska Papers

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions; and other economic, social and environmental effects. We analyze the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued; direct, attributional life cycle analysis (ALCA) and consequential life cycle analysis (CLCA). A proposed hybrid “combined model” of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modeling methodology (economic equilibrium or cause-effect), data inputs, …

Energy Issues Affecting Corn/Soybean Systems: Challenges For Sustainable Production, Douglas L. Karlen, David Archer, Adam Liska, Seth Meyer

Adam Liska Papers

Quantifying energy issues associated with agricultural systems, even for a two-crop corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) rotation, is not a simple task. It becomes even more complicated if the goal is to include all aspects of sustainability (i.e., economic, environmental, and social). This Issue Paper examines energy issues associated with and affecting corn/soybean rotations by first defining the size of the system from both a U.S. and global perspective and then establishing boundaries based on the Farm Bill definition of sustainability. This structured approach is essential to help quantify energy issues within corn/soybean …

Climate Change Policy Could Make Keystone Xl Obsolete, Adam Liska

Adam Liska Papers

Clearly the Keystone XL pipeline threatens both surface and ground water that sustains the agricultural economy of Nebraska, but the projected profitability of tar sands oil and the pipeline operation are dependent on the future economics of climate change. Three recent scientific studies estimate the total carbon intensity of tar sands-based gasoline from Alberta (from both production and burning of the fuel) at an average of roughly 22 percent higher than U.S. gasoline in 2005, with the range of average carbon intensities for tar sands-gasoline at 16 to 27 percent higher than most other sources.

Life Cycle Assessment Of Greenhouse Gas Emissions From Ethanol And Biopolymers, Adam J. Liska, Xiao Xue Fang

Adam Liska Papers

Conclusions

• Regulatory LCA is not likely to be used for non‐fuel chemicals alone in the near future

• Significant GHG emission credits for corn‐ethanol can be obtained by using only roughly 6‐9% of initial starch for production of biopolymers based on previous LCA theory

• Pay close attention to values in calculating credits per kg—these have to stand up in litigation to ensure the credit

• Credits are proportional to the mass of polymer produced

• Many theoretical issues are uncertain and credits will only be determined in conjunction with EPA

• Indirect emissions are uncertain and are a …

Effect Of Distillers Grains Moisture And Inclusion Level In Livestock Diets On Greenhouse Gas Emissions In The Corn-Ethanol-Livestock Life Cycle, Virgil R. Bremer, Andrea K. Watson, Adam J. Liska, Galen Erickson, Kenneth Cassman, Kathryn J. Hanford, Terry Klopfenstein

Adam Liska Papers

A model was previously developed (Biofuel Energy Systems Simulator; www. bess.unl.edu) to predict greenhouse gas (GHG) emissions and net energy yield when ethanol is produced from corn. The model also predicts feedlot cattle, dairy cattle, and swine performance and feed replacement value of ethanol coproducts. Updated equations that predict performance of feedlot cattle fed 0 to 40% of dietary DM as corn wet (WDGS), modified (MDGS), or dry (DDGS) distillers grains plus solubles replacing dry-rolled and high-moisture corn were developed and incorporated into the model. Equations were derived from pen-level performance for 20 finishing studies evaluating WDGS, 4 evaluating MDGS, …

Energy And Climate Implications For Agricultural Nutrient Use Efficiency, Adam J. Liska, Richard K. Perrin

Adam Liska Papers

Energy and climate change are beginning to dominate the global political agenda and will drive policy formation that will shape the future of agriculture. Energy issues threaten national security and economic stability, as well as access to low-cost nutrient inputs for agriculture. Climate change has the potential to cause serious disruption to agricultural productivity. Paradoxically, nutrient use in agriculture to increase crop yields has the potential to negatively impact climate. This chapter will discuss recent and future energy and climate trends, the relationships between agricultural nutrient use efficiency and biofuels, and how global land limitations will shape agriculture in the …

Uncertainty In Indirect Land Use Change Emissions In The Life Cycle Of Biofuels: Implications For Legislation, Adam Liska

Adam Liska Papers

Current EPA life cycle analysis (LCA) of greenhouse gas (GHG) emissions from corn-ethanol will be the foundation for regulations for advanced biofuels. It appears regulatory policies that include emissions from indirect land use change (and other indirect emissions) in the biofuel life cycle are moving faster than the underlying science; there is no comparable scientific study that approaches the complexity in methods currently used by the EPA. There is substantial uncertainty in quantifying direct and indirect emissions from fuels, as evidenced by conflicting results from state and federal regulators and from within the scientific community. If indirect emissions from land …

Life Cycle Greenhouse Gas Emissions From Biofuels: Variability, Uncertainty, And Steps Toward Accurate Regulation, Adam J. Liska, Bruce E. Dale

Adam Liska Papers

a)Variability in life cycle greenhouse gas (GHG) emissions from corn-ethanol:
biorefineries
cropping systems
co-product feeding to livestock

b) EPA regulation of life cycle GHG emissions from biofuels & use of life cycle analysis (LCA):
uncertainties & inaccuracies
indirect effects

c) Building accurate knowledge infrastructure, theory, and research teams for accurate LCA methods for biofuels

Responses To “Comment On ‘Response To Plevin: Implications For Life Cycle Emissions Regulations’” And “Assessing Corn Ethanol: Relevance And Responsibility”, Adam Liska, Kenneth Cassman

Adam Liska Papers

This letter responds to two issues concerning the greenhouse gas (GHG) emissions intensity of corn-ethanol that were raised in discussions of our response (Liska and Cassman 2009) to Plevin’s article (2009), which critiques our original research (Liska et al. 2009) published in the Journal of Industrial Ecology. ... The suggestion by Anex and Lifset (2009) that corn-ethanol does not reduce GHG emissions by 47% compared to gasoline, but instead by “somewhere between” 35 to 40%, is unsubstantiated.

Bess: BIofuel ENergy SYstems SImulator: Life Cycle Energy & Emissions Analysis Model For Corn-Ethanol Biofuel Production Systems -- User’S Guide For The Bess Model, Adam Liska, Haishun Yang, Daniel T. Walters, Kenneth Cassman, Terry Klopfenstein, Galen Erickson, Virgil R. Bremer, Richard K. Koelsch, Dan Kenney, Patrick Tracy

Adam Liska Papers

The BESS model is a software tool to calculate the energy efficiency, greenhouse gas (GHG) emissions, and natural resource requirements of corn–to-ethanol biofuel production systems. The model provides a “cradle-to-grave” analysis of the production life cycle of biofuels from the creation of material inputs to finished products, producing an inventory of distributed GHG emissions from fossil fuels and a few key indirect emissions in the production life cycle. The model parameters can be set by the user to achieve the highest accuracy in evaluating a single corn-ethanol biorefinery and its surrounding feedstock crop production zone. The model equations and summary …

Magnitude And Variability In Emissions Savings In The Corn-Ethanol Life Cycle From Feeding Co-Products To Livestock, Virgil R. Bremer, Adam Liska, Terry J. Klopfenstein, Galen E. Erickson, Haishun Yang, Daniel T. Walters, Kenneth G. Cassman

Adam Liska Papers

Conclusions

• Co-product GHG emissions credit varied by >2-fold, from 11.5 to 28.3 gCO₂e per MJ of ethanol produced

• Co-product GHG emissions credit depend on
-types of co-products produced
-proportion fed to beef cattle vs. diary or swine
-location of corn production; the CP credit is highest in regions where GHG kg^-1grain are highest

• Depending on CP production types and feeding livestock classes, corn-ethanol net life cycle GHG intensity is 44-56 gCO₂e per MJ

• Midwest corn-ethanol reduces GHG emissions compared to gasoline by 47% on average, with co-products offsetting 23% of …

Developing Lcfs For Biofuels: Getting It Right For Corn Ethanol, Kenneth Cassman, Adam Liska

Adam Liska Papers

• Corn ethanol will be first to test the newly developed LCFS assessment methods; substantial amounts of other biofuels will come several years later

• Accurate valuation of direct-effect GHG emissions from corn ethanol is the foundation of the LCFS process; these affects vary with ethanol biorefinery type and corn feedstock supply

• Different reference GHG emissions values are needed for each major class of ethanol plants

• The BESS model provides the most up-to-date, scientifically sound estimate of corn-ethanol GHG emissions; can BESS and GREET reach agreement?

• Certification and compliance tools are also needed

Energy And Environmental Contributions Of Corn-Ethanol, Adam Liska, Kenneth Cassman, Haishun Yang

Adam Liska Papers

Rapid development of regulatory mechanisms to mitigate greenhouse gas (GHG) emissions requires that the biofuel industry employ standard methods to evaluate biofuel systems comprising both crop production systems and biorefineries. Biofuel systems associated with a variety of organic feedstocks have a range of performance capabilities, and recent life-cycle assessment studies of these different systems have used inconsistent methods, leading to confusion about biofuel energy efficiency and GHG mitigation. Hence, there is a critical need for well documented life-cycle metrics for consistent biofuel evaluation that are established and supported by a national or international governing body. Standardization of net energy and …