A new generation of biofuels, meant to be a low-carbon alternative, will on average emit more carbon dioxide than burning gasoline over the next few decades, a study published in Science found on Thursday.
Governments and companies are pouring billions of research dollars into advanced fuels made from wood and grass, meant to cut carbon emissions compared with gasoline, and not compete with food as corn-based biofuels do now.
But such advanced, "cellulosic" biofuels will actually lead to higher carbon emissions than gasoline per unit of energy, averaged over the 2000-2030 time period, the study found.
That is because the land required to plant fast-growing poplar trees and tropical grasses would displace food crops, and so drive deforestation to create more farmland, a powerful source of carbon emissions.
Biofuel crops also require nitrogen fertilizers, a source of two greenhouse gases: carbon dioxide (CO2) and the more powerful nitrous oxide.
"In the near-term I think, irrespective of how you go about the cellulosic biofuels program, you're going to have greenhouse gas emissions exacerbating the climate change problem," said lead author, Jerry Melillo, from the U.S. Marine Biological Laboratory.
Without steps to protect forests and cut fertilizer use, gasoline out-performs biofuels from 2000-2050 as well.
How far we have fallen from the biofuel craze of just a couple of years ago.