The Environmental Footprint of Biofuels

A new UN report emphasizes the importance of addressing land use, water, and biodiversity impacts of biofuels.
The jury is now in on biofuels: Current government mandates in the  United States, Europe and other countries to blend biofuels into  ordinary car fuels cause substantial environmental damage, do little to  reduce greenhouse gas emissions, and have a questionable contribution to  energy security. A new UN report and a new book document  many, sometimes fascinating facets of this intricate issue. There are  many types of biomass, different options for growing this biomass, a few  technologies for converting the biomass to various liquid fuels. It is  not surprising that the environmental impacts depend on the  particularities of the growing, harvesting, transporting, converting and  use of the fuels. However, there are only very few production routes  currently used, and these routes are harmful to the environment in  several ways.

The report “Towards sustainable production and use of resources: Assessing Biofuels” was  produced by the International Panel for Sustainable Resource Management  (IPSRM) and relased by the head of the United Nations Environment  Program Achim Steiner on 23 October. I am also a member of IPSRM, but  have not contributed to this report. The book ‘”Biofuels for Road Transport: A Seed to Wheel Perspective”,  was written by the Dutch environmental scientists Lucas Reijnders and  Mark Huijbregts. Both works present an extensive review of scientific  work on biofuels.

To understand biofuels, one must look at thermodynamics, that is, to  account for energy flows in a biomass system similar to how one would  account for money flows. Already in 1982, Perezblanco and Hannon published  an analysis of the energy required to produce one unit of energy in the  form of corn-ethanol and wood-methanol. They showed that the energy  used to run tractors, produce fertilizers, and convert corn to ethanol  is more or less equal to the energy in the ethanol produced – so that  there is little point in whole exercise. Methanol from wood, however,  has a substantial net energy gain. These results have since then been  confirmed by a great number of studies, also for other biofuel products  derived from these biomass resources.

If there is little energy gain, there is also little benefits in  terms of greenhouse gas emissions. The figure illustrates the reduction  GHG emissions reductions – or the lack thereof – achieved by different  biofuel production routes. Today’s biofuel comes all from food crops –  maize, wheat, vegetable oil, and sugar cane, which are easy to convert  but require high inputs of fertilizer and machine power to produce –  with the exception of sugar cane.

The substantial insights of the two new publications, however, is the insight of the high  ecological impacts that come from converting land for biofuel  production, emissions from land use, as well as the runoff of fertilizer  and pesticides. These effects are often not sufficiently considered  in life-cycle assessment. In the United States, it is reported that  increased fertilizer application for biofuels has lead to increased  runoff of phosphorus and nitrogen, which stimulates increased algae  growth in waterways and leads to oxygen depletion and fish death as a  result.

The issue of land conversion and its effect on carbon stored in soil  and plants has been discussed prominently in recent years and months. It  is central to determining the greenhouse gas benefit of biofuels. The  report underlines that declining yield increases and increasing food  demand imply that the current global cropland needs to expand further.  Increase biofuels product will hence inevitably require the conversion  of virgin land to cropland. Certifying biofuels grown on already  established agricultural land has hence little effect, as this only  displaces food production to previously marginal land.

The effect of this is quite clear, as the report underlines: “Increased  biofuel production is expected to have large impacts on biological  diversity in the coming decades, mostly as a result of habitat loss,  increased invasive species and nutrient pollution. Habitat loss will  mainly result from cropland expansion. Species and genotypes of grasses  suggested as future feedstocks of biofuels may become critical as  invaders. Nutrient emissions to water and air resulting from intensive  fuel cropping will impact species composition in aquatic and terrestrial  systems.
We afford climate mitigation measures that are so ineffective in  reducing greenhouse gas emissions but destroy ecosystems and  biodiversity. It is time to reconsider biofuel mandates!