1. Biofuels: Comparing New Sources with Coal, Gas, and Kerosene
Bruce Babcock
Madhu Khanna
Puneet Dwivedi

4. Bruce Babcock Iowa State University
Plausibility of CO2 Emissions from Corn Ethanol Being Higher than Gasoline
Bruce Babcock
Iowa State University
Presented at ICABR conference, Berkeley, CA June 1, 2017.

7. LCA Accounting Rules (grams CO2e/MJ)
Corn Ethanol
Fossil Gasoline
Ag inputs and N2O
Distillery 31
Transport & other 5
Subtotal 68
DDGS credit -14
Total Emissions 52
Refinery 11
Crude production 6
Transport 3
Subtotal 20
Tailpipe emissions 74
Total emissions 94
45% emission reduction from corn ethanol

9. Biogenic emissions do not get counted with LCA
Ethanol emissions from tailpipe 74
Emissions from ethanol plant 33
Total emissions not counted 107

10. Alternative Accounting Method*
Track physical carbon flows on an annual basis (ABC).
Any additional flow of carbon to atmosphere is an emission
Any additional flow of carbon from the atmosphere into crops is a negative emissions
*Plevin, RJ, MA Delucchi, and F. Creutzig “Using attributional life cycle assessment to estimate climate-change mitigation benefits misleads policy makers.” J. of Industrial Ecology 18:73-83.
DeCicco, et al “Carbon balance effects of U.S. biofuel production and use.” Climatic Change 138:

14. CO2 Emissions
CO2 Crop Uptake

16. ABC Accounting Rules (grams CO2e/MJ)
Corn Ethanol
Fossil Gasoline
Total LCA Emissions 52
Tailpipe emissions 74
Fermentation
Total emissions 159
Net crop uptake offset 40
Total Emissions 119
Refinery 11
Crude production 6
Transport 3
Subtotal 20
Tailpipe emissions 74
Total emissions 94
27% emission increase from corn ethanol

18. Policy-relevant question about GHGs and ethanol that DiCiccho, et al try to answer
What would atmospheric GHG levels (or net flows) be if ethanol held constant at 2005 levels?
Not the question they address in their analysis.

19. DiCiccho’s Increased Crop Uptake Attributed to Ethanol
Price
DiCiccho’s Increased Crop Uptake Attributed to Ethanol
Ag Output/ Crop Uptake of CO2
Q2005
Qobserved in 2013

20. Assumption 1. Behind DeCicco’s Answers
All changes in crop uptake of CO2 relative to 2005 should be attributed to corn ethanol.
Strong implication about counterfactual:
Crop uptake of CO2 would have stayed constant at 2005 levels had ethanol production not increased.

22. 59% of increased biogenic emissions offset by increased crop uptake since 2005.

25. Some of the factors that caused ag output to change from 2005 to 2013
Ethanol production
Weather
Demand for domestic food (income, changes in demand composition)
Export demand
Government policy (eg CRP)
Input prices
Technological change

26. Conclusion 1:
No basis for DiCiccho et al’s attribution of annual changes in crop uptake of CO2 to ethanol.

27. Policy-relevant questions about GHGs and ethanol
What would atmospheric GHG levels (or net flows) be without ethanol?
What would they be without the Renewable Fuel Standard?

28. Alternative Counterfactual
What would have crop uptake of CO2 been had growth in ethanol/RFS not occurred?
Need to construct a world without ethanol/RFS to answer this question.

29. Demand shift from ethanol
Price
Ex post Supply2013
Demand shift from ethanol
Consumption increase due to lower price
2013 demand
2013 demand without ethanol
Ag Output/ Crop Uptake of CO2 Q*
Qobserved

30. No ethanol Ex post Supply2013
Price
Ex post Supply2013
Supply shift due to ethanol
2013 demand
2013 demand without ethanol
Ag Output/ Crop Uptake of CO2 Q*
Qobserved

31. Realized change in ag output due to ethanol.
No ethanol Ex post Supply2013
Price
Ex post Supply2013
Realized change in ag output due to ethanol.
2013 demand
2013 demand without ethanol
Ag Output/ Crop Uptake of CO2
Q**
Qobserved

32. Observations Nothing inherently wrong with the ABC approach
Problem is with the only published implementation
Modeling and computational burden quite large to estimate change in ag output and resulting change in carbon flows that should be attributed to ethanol
Change in land use
Change in farming intensity
Change in all components of demand
Change in movement along supply and demand curves
Also requires a dynamic model because of path dependence and future implications on carbon flows of actions taken today

33. Does ethanol emit more CO2 than gasoline?
Following the ABC approach requires bigger and better models and more insight
Concept that only “additional” carbon uptake should count is false
Movement along non-biofuel demand curves creates offsets that are just as real as increased crop uptake.