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Monday, 10 December 2012

Biofuels – Why bother?

A while ago someone figured out that the Earth's ever fluctuating climate was now changing too quickly and blamed it on excessive emissions of carbon dioxide from human activities. The scientific community, policy makers and the general public more or less agreed that something ought to be done to prevent a global catastrophe. One of the main sources of such climate-harming gases is burning fossil fuels for our transport and industries. Conveniently, such fuels are also a cause of great economical and geopolitical distress in the whole world, since every country needs them but only a handful are able to supply them.

One possible solution for these issues is the use of "biofuels". Biofuels are burned to release energy, much like conventional fuels, but whose energy was stored by consuming (sequestering) carbon dioxide in the first place.  In other words, using biofuels only releases the carbon dioxide that was removed from the atmosphere by making it, resulting in no overall increase. The most obvious example of biofuel is wood.

Grass grown as a biofuel crop for Drax power station
This grass is grown as an annual crop for biofuel, burned at Drax power station in Northern England.
Photo credit: Allan Harris (Creative Commons)

Biofuels are as old as the domestication of fire - and that is pretty old! However, today it is not only about small-scale collection and use of available wood, but also about covering extensive patches of land with crops and trees meant to supply energy. There are also developments in using wastes from agriculture, forests and households, in integrating different ecosystem services with energy and in making energy crops supply chains as efficient as possible. All of this with the prospect that building up a steady supply of liquid and solid biofuels would reduce our need for diesel and gasoline for our vehicles and coal for our power plants.

Controversy followed suit, with the core concern being that there is a limit to the land currently available on which to grow bioenergy feedstocks. Market forces may push biofuel crops onto land used for other purposes, which might be food production or natural ecosystems. Putting pressure on food and natural resources is an intricate trade-off with environmental and socioeconomic aspects other than greenhouse gas emission reduction.

In order to ensure that biofuels would meet the overall goal of reducing emissions from energy production, scientists and policy makers worked together to make guidelines and standards to determine, case by case, whether or not that happens. The primary tool for this is life cycle assessment, which, in essence, accounts for all the flows of energy and materials involved in a production chain and analyzes the global warming potential of all its combined emissions.

Biofuel photo by Steve Jurvetson
People often associate "fuel" with liquids, but biofuel may be liquid or solid. Photo Credit: Steve Jurvetson (Creative Commons)
There is however, one flow which many claim is not being handled properly in the biofuel life cycle: carbon, ironically. In particular, the transfer of carbon from the atmosphere to the bioenergy crop through photosynthesis and back to the atmosphere during the combustion of the biofuel. The default assumption is that the balance of this transfer is neutral, but land was once again left out of the sustainability equation. A portion of land in a given moment has a carbon stock in its vegetation and soil. When a given land use is replaced with biofuel feedstock production, there is a shift in those carbon stocks. To complicate matters, if the previous land use is displaced, it can be argued that the demand for that biofuel crop will cause indirect land use change as well. No one can predict for sure how this happens and the magnitude of the shift of carbon stocks is highly case specific. In addition, the timescale of these shifts is hard to couple with that of the conventional production chain and the overall calculations of the potential global warming.

Renewable energy sources are relatively immature technologies and are yet to prove their worth, although it is unlikely that all will prevail. Many private enterprises, governments and academics around the world are thinking about how to make carbon accounting work, in order to determine which feedstock should be grown where to minimize the impacts on the environment. Many other people are working on improving bioenergy crops and conversion techniques, and even in using biofuels on a small scale to improve livelihoods in impoverished communities.

There remain a number of open questions relating to the impact a large scale adoption of biofuel would have on third world economies, such as whether a shift in land use from growing food to biofuel crops would lead to increases in food costs. In 2006, BP's chief scientist Steven Koonin claimed1 in an editorial that "studies show that with plausible technology developments, biofuels could supply some 30% of global demand in an environmentally responsible manner without affecting food production", and a year later the Overseas Development Institute2 concluded "the development of biofuels has potentially important roles to play in poverty reduction – through employment effects, wider growth multipliers and energy price effects".

This article was written by Joana Almeida - Doctoral student at the Forest Ecology and Management Research Group of KU Leuven, Belgium.

References
why don't all these papers have links? 
1 Koonin, Science 27 January 2006 Vol. 311 no. 5760 p. 435
2 Peskett et al. Natural Resource Perspectives, June 2007