Sep 2, 2009
Biofuels are not much better than fossil fuels in terms of the impact on atmospheric pollution levels and effects on climate change, according to Mark Jacobson professor of civil and environmental engineering at Stanford University. This is especially true when making claims about the sustainability of biofuels in comparison with hydrogen fuel cells and battery-driven electric vehicles charged up using solar, wind, tidal or other truly renewable energy sources.
To quote from his web page, the main goal of Jacobson’s research is to…
…understand physical, chemical, and dynamical processes in the atmosphere better in order to address atmospheric problems, such as climate change and urban air pollution, with improved scientific insight and more accurate predictive tools. He also evaluates the atmospheric effects of proposed solutions to climate change and air pollution, examines resource availability of renewable energies, and studies optimal methods of combining renewables.
In order to accomplish these important goals Jacobson has developed and applied various models to simulate gas, aerosol, cloud, radiative, and land/ocean-surface processes that could give scientists and engineers a much more overarching perspective on the climate than other simpler models.
Jacobson points out that the use of biofuels, particularly ethanol, has expanded in the last few years, although in South America biofuels have been popular and successful for decades. This more recent and rapid expansion of biofuel use in transport across North America and elsewhere is based on the notion that by replacing fossil fuels with biofuels we may somehow ameliorate global warming and air pollution. After all, he growing plants absorb carbon dioxide from the atmosphere, they are then converted into biofuels, which are burned in modified vehicle internal combustion engines, which releases the carbon dioxide into the atmosphere again, where it is used by the next generation of biofuel crop plants to grow and so on.
This claim is still being hotly debated, especially given the impact on agriculture and the environment of turning over vast tracts of land to biofuel crops rather than growing food. However, Jacobson believes that, “the real comparison should be between biofuels and other emerging technologies.” He reports that corn-E85 (85% ethanol/15% gasoline) and cellulosic-E85 both degrade air quality and climate by up to two orders of magnitude more than electric vehicles ultimately powered by solar photovoltaic cells, wind, geothermal, hydroelectric, wave, or tidal power. “As such, the use of cellulosic or corn ethanol at the expense of the other options will cause certain damage to health, climate, land, and water supply in the future,” he asserts.
Moreover, the land required for cellulosic-E85 may also exceed that of corn-E85 and the land required for both will exceed that required for the footprint on the ground of wind powering battery electric vehicles by a factor of 500,000 to 1 million, adds Jacobson. He suggests that we should be considering very carefully the notion that replacing fossil fuels with biofuels could save us from catastrophic climate change given that this is not only unlikely, but will also have a negative impact on land and water supply relative to genuinely renewable energy sources.
I asked Jacobson for his thoughts on how vested interests might be persuaded that biofuels are no panacea. “The biofuels interests will go out of their way to dismiss or distort results from any study that comes out that makes their product look bad,” he told me. “It is mostly politicians and the public who can be persuaded,” he added. “The best approach is to focus on what is better, such as electric hydrogen fuel-cell vehicles powered by renewables, and to try to push people more in that direction.”
Mark Z. Jacobson (2009). Effects of biofuels vs. other new vehicle technologies on air pollution, global warming, land use and water International Journal of Biotechnology, 11 (1/2), 14-59