Most biofuels are worse for the environment than gasoline, according to the Swiss Federal Laboratories for Materials Science and Technology (Empa).
Since biofuels stem predominantly from agricultural products, there can be negative effects, for example on the supply of food in times of drought, or whether arable land is oversupplied with nutrients.
And, says Empa, many biofuels based on agricultural products do indeed lead to other environmental pollution, such as too much acid in the soil and polluted lakes and rivers.
"Most biofuels therefore just deflect the environmental impact: fewer greenhouse gases, thus more growth-related pollution for land used for agriculture," says researcher Rainer Zah.
This results in only a few biofuels having an overall better ecobalance than petrol. One such is biogas from residues and waste materials, which – depending on the source material – impacts on the environment up to half as much as petrol.
Ethanol-based fuels tend to have a better ecobalance than those with an oil base - although this is very much dependent on manufacturing processes.
Biofuels from deforested areas usually emit more greenhouse gases than fossil fuels, says Zah, pointing out that even when the deforested area has already been used as agricultural land, switching to biofuel often means clearing more land for food.
On the other hand, positive effects can be achieved if energy plant cultivation increases the carbon content of the soil, for example via the cultivation of oil palms on unused grazing land in Columbia or via jatropha plantations in India and eastern Africa, making deserted land arable again.
"Despite this, you can’t speak in general terms of jatropha as being a 'wonder plant', as its ecobalance is very much dependent on the agricultural practices at the site in question and the land’s previous use," says Zah.