Biodiesel is extremely low in sulphur, and has a high lubricity and fast biodegradability. These advantages have been confirmed by various programmes and tests of independent research institutes.

In specific cases, used vegetable oils can be recycled as feedstock for biodiesel production. This can reduce the loss of used oils in the environment and provides a competitive and advantageous way of transforming waste into transport energy. Biodiesel production also plays a useful role in agriculture. The arable raw materials needed for biodiesel production may be grown on set-aside land, land which would otherwise be taken out of production. [1]

Policymakers in the European Union and the US have identified Biofuels as a tool to fight global warming, as they emit less greenhouse gases than burning fossil fuels.

The US recently enacted legislation boosting Biofuel production to 36 billion gallons in 2022 from 7.5 billion gallons in 2012. EU requires 10 per cent of the transportation to use Biofuels by 2020.

 
Converting forests and peatlands that absorb carbon dioxide from the atmosphere to grow the crops may cause emissions that may far outweigh the annual benefits of burning the new fuels, creating a "carbon debt" lasting centuries, the researchers at the University of Minnesota, St Paul and the Minneapolis-based Nature Conservancy said in the journal Science.
 
"If you're trying to mitigate global warming, it simply does not make sense to convert land for Biofuels production," lead author Joe Fargione said in a statement. "All the Biofuels we use now cause habitat destruction, either directly or indirectly."

 
The scientists studied different cases of natural habitat conversion, and used data from previous studies to determine the carbon debt accrued.

 
They found that converting Indonesian or Malaysian peatlands into palm plantations incurred a carbon debt that took 423 years to neutralize. Replacing tropical rainforests in those two nations with the same crop led to an 86-year debt. [2]

 
While the U.S. and others race to expand the use and production of biofuels, two new studies suggest these gasoline alternatives actually will increase carbon-dioxide levels.
 
A study published in the latest issue of Science finds that corn-based ethanol; a type of biofuel pushed heavily in the U.S., and will nearly double the output of greenhouse-gas emissions instead of reducing them by about one-fifth by some estimates. A separate paper in Science concludes that clearing native habitats to grow crops for biofuel generally will lead to more carbon emissions.

 
The Renewable Fuels Association in the U.S. said that "biofuels alone are not the silver bullet" for the world's energy or environmental challenges. It said earlier analyses of greenhouse-gas reductions show corn-derived ethanol reduces greenhouse gas emissions by 22% on average, though those studies didn't include the effect of changing land use. [3]
 
A quick calculation needs to be done on each farm land to grow crops for biofuel - how much energy is needed to produce 1 kg of Biofuel and what is the input and output ratio. Even if it is true that Biofuel burning emits less GHG than fossil fuel then how much emission takes place while producing 1 kg of Biofuel needs to be calculated.
 
A calculation showed that even if all the farmland in the United States were converted to growing Switch grass, it would not produce enough ethanol for the country's fossil fuel use. Switch grass takes several years to mature. The yield ranges from 0 for complete failure of the crop to take hold to 20 t or more per ha, a lot depending on the rainfall. A yield of 15 t /ha is optimistic; and would provide some 250 GJ/ha of raw chemical energy a year. If that energy could be converted with 70 percent efficiency into electricity, ethanol, methanol etc., it would take about 460 m ha to produce the 80EJ (ExaJoule = 1018J) fossil fuel energy used in the USA each year. The total farmland in the USA is 380 m ha, of which 175 m ha is harvested cropland. [4]