Biofuels ‘worse than petrol’ for climate change, study says

Ethanol and biodiesel are not inherently carbon neutral as the widely held assumption states, s new study from University of Michigan (U-M) researchers says.

Contrary to popular belief, the heat-trapping CO₂ gas emitted when biofuels are burned is not fully balanced by the CO₂ uptake that occurs as the plants grow, according to a study by research professor John DeCicco and co-authors at the U-M Energy Institute.

The study, based on US Department of Agriculture (DOA) crop production data, shows that during the period when US biofuel production rapidly ramped up, the increased CO₂ uptake by the crops was only enough to offset 37% of the CO­₂ emissions due to biofuel combustion.

The researchers conclude that rising biofuel use has been associated with a net increase rather than a net decrease in the CO₂ emissions that cause global warming.

"This is the first study to carefully examine the carbon on farmland when biofuels are grown, instead of just making assumptions about it," DeCicco said.

"When you look at what's actually happening on the land, you find that not enough carbon is being removed from the atmosphere to balance what's coming out of the tailpipe."

The use of biofuels to displace petroleum has expanded over the last decade in response to policies, such as the US Renewable Fuel Standard, that promote their use for transportation.

Consumption of liquid biofuels – mainly corn ethanol and biodiesel – has grown in the US from 4.2 billion gallons in 2005 to 14.6 billion gallons in 2013.

The environmental justification rests on the assumption that biofuels, as renewable alternatives to fossil fuels, are inherently carbon neutral because the CO₂ released when they are burned was derived from CO₂ that the growing corn or soybean plants pulled from the atmosphere through photosynthesis.

DeCicco and his colleagues analysed real-world data on crop production, biofuel production, fossil fuel production, and vehicle emissions without presuming that that biofuels are carbon neutral.

"When it comes to the emissions that cause global warming, it turns out that biofuels are worse than petrol," DeCicco said.

"So the underpinnings of policies used to promote biofuels for reasons of climate have now been proven to be scientifically incorrect.

Some funding for the study was provided by the American Petroleum Institute.

‘Flawed methodology, fallacious result’

In a response to the study’s publishing, Renewable Fuels Association’s president and CEO Bob Dinneen said the the research, which has been partly funded by the American Petroleum Institute, “obscures and confuses” scientific facts.

“This is the same study, same flawed methodology, and same fallacious result that Professor DeCicco has churned out multiple times in the past,” said Dinneen. “He has been making these arguments for years, and for years they have been rejected by climate scientists, regulatory bodies and governments around the world, and reputable lifecycle analysis experts.”

According to Dinneen, current science supports the view that biomass crops used to produce energy act as temporary carbon sinks, and the CO₂ their burning emits is offset by that absorbed while they grow.

“According to researchers at Duke University, the University of Minnesota, and Oak Ridge National Laboratory, a critical temporal distinction exists when comparing ethanol and petrol lifecycles,” Dinneed said.

“While the production and use of bioenergy also releases GHGs, there is an intrinsic difference between the two fuels, for GHG emissions associated with biofuels occur at temporal scales that would occur naturally.”