True or False: Biofuels

(CNN) -- True or False: Burning biofuel instead of gasoline produces less greenhouse gases

The answer is: FALSE

Despite the fact that biofuels have been promoted as a green alternative to powering cars, some say they are not as environmentally-friendly as they first appear.

According to the U.K's Times newspaper, quoting an Edinburgh University study, "rapeseed and maize biodiesels...produce up to 70 percent and 50 percent more greenhouse gases respectively than fossil fuels". In Europe, 80 percent of biofuels come from rapeseed.

The University also calculated that if the U.S. increases its maize ethanol productions "sevenfold by 2022" the country's transportation-related greenhouse gas emissions will actually increase by as much as 6 percent.

According to Alternet, when one considers the entire lifecycle of biofuels -- from deforestation to cultivation to burning -- their environmental credentials come in for question. "Every ton of palm oil produced results in 33 tons of carbon dioxide emissions -- 10 times more than petroleum," it points out, while clearing vast areas of forest to grow sugarcane ethanol "emits 50 percent more greenhouse gases than the production and use of the same amount of gasoline."

Biofuels can also be a drain on water supplies and treating the waste produce is not necessarily energy-efficient, it argues. "To produce a liter of ethanol takes three to five liters of irrigation water and produces up to 13 liters of waste water," it says. Treating this waste takes the energy equivalent of 113 liters of natural gas, it adds.