Biofuels such as ethanol and biodiesel are not anywhere near as environmentally friendly as previously thought.
A study by researchers at the University of Michigan, published today in the open-access journal Climactic Change, has found that biofuels actually increase the heat-trapping carbon dioxide emissions responsible for global warming, despite their reputation for being a ‘clean’ fuel source.
It was previously thought that such fuels were carbon-neutral, based on the premise that the CO₂ they produce when burnt was balanced by the CO₂ the plants absorbed as they grew. However, this study has found that the crops’ CO₂ absorption only mitigated a fraction of its emissions.
Using extensive crop production data from the US Department of Agriculture, alongside data on fossil fuel production and vehicle emissions, the researchers found that during a time when biofuel use rapidly increased in the US, the biofuel crops’ CO₂ absorption only offset 37% of their emissions when burnt.
“This is the first study to carefully examine the carbon on farmland when biofuels are grown, instead of just making assumptions about it,” explained research professor and study lead author John DeCicco, from the University of Michigan Energy Institute.
“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 findings have significant ramifications for climate change mitigation approaches, as biofuels have increasingly been used as a cleaner alternative to petroleum. In many parts of the world they form a vital part of government-backed plans to reduce carbon emissions; a role that may well need to be reconsidered now that such strong doubt has been cast on their effectiveness.
In the US, for example, they are recommended for transportation purposes by the US Renewable Fuel Standard, which has helped to spur growth in production in the country from 4.2 billion gallons in 2005 to 14.6 billion gallons in 2013.
The researchers have even gone so far as to argue biofuels are worse than other traditional fuel sources, due to the false sense of security they provide to policymakers.
“When it comes to the emissions that cause global warming, it turns out that biofuels are worse than gasoline,” said DeCicco.
“So the underpinnings of policies used to promote biofuels for reasons of climate have now been proven to be scientifically incorrect.”
As a result of the shocking findings, the researchers are now recommending that policymakers reconsider their use of biofuels to mitigate climate change.
“Policymakers should reconsider their support for biofuels,” said DeCicco.
“This issue has been debated for many years. What’s new here is that hard data, straight from America’s croplands, now confirm the worst fears about the harm that biofuels do to the planet.”