How environmentally sustainable are current biofuels?

Mr Jeremie Mercier, Imperial College 

Today’s liquid transport biofuels are mostly bioethanol and biodiesel, commonly used in low blends with their fossil fuel equivalents gasoline and diesel. Current feedstocks for bioethanol include maize (US), sugar cane (Brazil), wheat and sugar beet (Europe). The major biodiesel feedstocks are soybeans (Argentina, Brazil and the US), oil palm (South-East Asia), sunflower and oilseed rape (Europe).

Biofuels are widely promoted for their presumed role in tackling climate change, by virtue of their CO2 emissions reduction potential compared to their fossil fuels equivalents. Thanks to an increased public awareness of climate change and pollution in general, many consumers are ready to buy biofuels, or cars that can run on higher biofuel blends, if it is proven that these biofuels truly help the environment.

But depending on practices and feedstocks, biofuels can have significant impacts on the environment at every step of their life-cycle: farming, industrial processing, distribution, combustion…

In an effort to raise consumer awareness, more information and transparency is needed, allowing consumers to assess the environmental impact of biofuel use compared to fossil fuels.

Purpose of the work

The goal of this research is to clearly identify, on a life-cycle basis, the most significant direct impacts of biofuels on Greenhouse Gas (GHG) emissions and air pollution, soil and water pollution, biodiversity, but also to identify indirect impacts (displacement, real allocation of by-products…).

Approach

A framework is developed in which relevant indicators are chosen for every group of impacts. A grade is given for each of these groups and the final grade describes the overall sustainability of the specific biofuel. In addition, the levelised costs of production are analysed in order to compare the economic competitiveness of biofuels with different grades. Case studies focus on biofuels made from European feedstocks.

Scientific innovation and relevance

Most research on biofuels’ sustainability emphasises net GHG emissions assessed using Life-Cycle Analysis (LCA) but little work is done looking at the wider environmental impacts. Furthermore, reference scenarios chosen for the allocation of credits from co-products commonly do not describe actual co-product destinations. Finally, much of the literature on biofuel certification lacks precise environmental requirements allowing the majority of current biofuels to be certified under the suggested certification schemes. This paper provides new insight by specifically targeting the areas of LCA that are not typically examined with great care, despite being crucial to the overall sustainability of biofuels.

Results

Using a novel process of analysis this research accurately compares the complete environmental impacts of selected biofuels together with their costs of production. In doing so the research provides better information and easier comparison between production practices – something not easily available from suggested certification schemes to date.

Conclusions

The environmental and economic costs and benefits of biofuels compared to fossil fuels must be listed and assessed so that governments and consumers can make accurate choices regarding the type of fuels they use. Until now this has not been possible.