Are renewable sources green enough?

Abstract

The world is waking up to the reality that the limited fossil fuel reserves cannot satisfy its energy needs indefinitely. Also, the harmful environmental impacts of burning fossil fuels have resulted in climate change and global warming. A shift from fossil fuels to renewable energy (RE) sources has been universally proposed as the solution, but the environmental benefits of RE seem to have been accepted at face value, and evidence is emerging that it may not be ‘green enough’. Among contemporary RE sources, biofuels have attracted tremendous attention and are starting to be widely produced and deployed. This project aims at assessing the environmental impact of biofuels. The author invoked the technique of life-cycle assessment to study two metrics: Net Energy and Greenhouse Gas (GHG) Emissions. Various published studies from all over world were found to have widely divergent results. Detailed investigation of six representative analyses of the most common biofuel, corn ethanol, revealed that these differences arose due to difference in treatment of co-products, application of inconsistent system boundaries and use of variable figures for farm inputs. After adjusting for these differences, the author was able to reduce the variation in these studies by 33% and 23% for net energy and GHG emissions respectively, enabling a more holistic and complete idea of the benefits and drawbacks of corn ethanol. The net energy balance of corn ethanol was found out to be positive and favourable overall and it would improve in the future with increased production efficiency. The GHG emissions of corn ethanol were similar to that for gasoline. The author concluded that corn ethanol is an environmentally viable alternative to fossil fuels, but further improvements with respect to GHG emissions would require a move towards cellulosic ethanol.