Ethanol Can Contribute to Energy and Environmental Goals

SUMMARY OF RESULTS

Alexander E. Farrell¹, Richard J. Plevin¹, Brian T. Turner^1,2, Andrew D. Jones¹, Michael O'Hare², Daniel M. Kammen^1,2,3

27 JANUARY 2006 VOL 311 SCIENCE www.sciencemag.org

Figure 2. Metrics for evaluating ethanol based on the intensity of primary energy inputs (MJ) per MJ of fuel and of net greenhouse gas emissions (g CO2-equivalent) per MJ of fuel.

	Net Fossil Inputs	Net Fossil Ratio	Petroleum Input	GHG Emissions
	MJ_fossil needed for each MJ_fuel	MJ_fuel produced for each MJ_fossil input	MJ_petroleum needed for each MJ_fuel	g CO₂-equivalent per MJ_fuel**
Gasoline	1.19	0.84	1.10	94
Ethanol Today	0.774	1.30	0.04	77*
CO₂ Intensive Ethanol	0.94	1.06	0.18	91*
Cellulosic Ethanol	0.10	10.0	0.08	11

MJ = Mega Joule, an energy unit. ^*These values are highly uncertain and may be greater than gasoline-related emissions. ^**GHG emissions include combustion.

Notes: Current agricultural production creates soil erosion, nutrient runoff, and other environmental impacts that cannot be accurately represented in energy units. Progress toward attaining energy and environmental goals will require new technologies and practices, such as sustainable agriculture and cellulosic ethanol production. In addition, the conversion of land to agriculture for ethanol production also has environmental consequences.

See http://rael.berkeley.edu/ebamm for more information.

¹Energy and Resources Group, ²Goldman School of Public Policy, ³Renewable and Appropriate Energy Laboratory, University of California, Berkeley