Not a Lexis+ subscriber? Try it out for free.


The rush into biofuels may be a major error

Prior posts have noted that EPA is conducting an assessment of biofuels to ascertain if they are truly "renewable", and that the so-called GHG emission benefits of ethanol appear to disappear if the "indirect" land-use effects are taken into account. [See, for example, the Nov. 5, 2008 post.] Recent analysis of the N2O (nitrous oxide) effect that derives from biofuel production is adding another layer of complication. First, some history, then a review of the issue.
The theory of biofuels is that plants such as sugar cane, corn (aka maize), canola (aka rape seed), and wheat take up CO2 during their growth; thus, so the theory goes, burning fuels made from them should have no net effect on the amount of that gas in the atmosphere. Biofuels, therefore, should not contribute to global warming. Were it only so.
Questions have recently been raised by the International Council for Science, a federation of worldwide scientific associations. The ICSU report concludes that, so far, the production of biofuels has aggravated rather than ameliorated global warming. In particular, it supports some earlier controversial findings by German scientists that most analyses of global warming have underestimated the importance N2O by a factor of between three and five. The report argues that the amount of this gas released by farming biofuel crops, such as corn and canola, probably negates by itself any advantage offered by reduced emissions of CO2.
How does this offset occur? First, it is important to understand the production of N20. N2O is made by bacteria that live in soil and water, and one of their favorite raw materials is the nitrogen-rich fertilizer that modern farming requires. Since the 1960's, the amount of fertilizer used by farmers has increased six-fold, and not all of that extra nitrogen ends up in their crops. Corn in particular is described by experts as a "nitrogen-leaky" plant because it has shallow roots and takes up nitrogen for only a few months of the year. There is thus lots of extra nitrogen around for the bacertia to use to make N20. [The loss of nitrogen (along with phosphorus) is also a key factor in the creation of dead zones, such as the one in the Gulf of Mexico, as noted in prior posts.] This would make corn (which is one of the main sources of biofuel in the U.S.) a particularly bad contributor to global N2O emissions.
Second, although N2O is not common in the Earth's atmosphere, it is a more potent greenhouse gas than CO2 and lasts longer. Its global warming effect is almost 300 times that of an equivalent mass of CO2. Because the report argues that the IPCC has miscalculated the significance of N2O as part of the GHG problem, the failure to consider this effect as a component of the rush to biofuels is a serious error in both judgment and analysis.
Because this problem has only recently come to the forefront of scientific thinking, an assessment of its parameters is still underway. However, it suggests that the rush to biofuels may be entirely self-defeating.
A summary of the overall assessment to date and a link to the ICSU report can be found at