1. Bullard M, Metcalfe P (2001) Estimating the energy requirement and CO2 emissions from production of the perennial grasses miscanthus, switchgrass and reed canary grass. ETSU B/U1/00645/REP
2. Energy Information Administration (2009) International Energy Outlook. U.S. Department of Energy, Washington, DC. Available online: http://www.eia.doe.gov/oiaf/ieo/index.html
3. European Commission (2009) Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC
4. Faaij APC (2006) Bio-energy in Europe: changing technology choices. Energy Policy 34:322–342
5. Fargione J, Hill J, Tilman D, Polasky S, Hawthorne P (2008) Land clearing and the biofuel carbon debt. Science 319:1235–1238