Biofuels and the conundrum of sustainability

Sustainable energy is the problem of the 21st century. If biofuels want to be part of the solution they must accept a degree of scrutiny unprecedented in the development of a new industry. That is because sustainability deals explicitly with the role of biofuels in ensuring the well-being of our planet, our economy, and our society both today and in the future. Life cycle assessment (LCA) has been the standard framework for assessing sustainability of biofuels. These assessments show that corn ethanol has a marginally lower fossil energy and greenhouse gas footprint compared to petroleum fuel. Sugarcane ethanol and some forms of biodiesel offer substantially lower footprints. New biofuels may offer low footprints. The science of LCA is being stretched to its limits as policy makers consider direct and indirect effects of biofuels on global land and water resources, global ecosystems, air quality, public health, and social justice.