The biofuels industry received a lift this week after a report emerged showing that fuels made from a type of fast-growing grass can produce over six times more energy than it takes to manufacture.

The five-year study of 'switchgrass' - a type of tall-growing field grass that grows in North America - showed that the biofuels made from the crops resulted in 94 per cent less CO2 emissions than gasoline.

The report, which appeared in the Proceedings of the National Academy of Sciences and was backed by the US Department of Agriculture, found that just 0.4 hectares of grassland would be needed to produce 320 barrels of bioethanol - making it far more efficient than corn-based ethanol.

Co-author of the report, Ken Vogel, said the study was more comprehensive than those conducted previously, whereby the viability of using grass for fuel had been brought under question.

"Unlike corn, for which long-term data on grain yield and agricultural inputs are available, data for switchgrass and other perennial herbaceous plants are limited and are based largely on small-plot research," he said. "To obtain relevant field-scale information for switchgrass managed as a biomass energy crop, we conducted trials using fields on 10 farms in the mid-continental US."

Vogel added: "Improved genetics and agronomics may further enhance energy sustainability and biofuel yield of switchgrass."

The report will be welcomed by the biofuel industry which has faced consistent criticism over the past year for failing to deliver promised carbon emission savings. Numerous studies have argued that far from being carbon neutral emissions from the production and transport of biofuels as well as the deforestation of land to make way for fuel crop plantations have resulted in a significant carbon footprint.

However, advocates of the technology argue that the emergence of second generation fuel crops such as switchgrass that grow rapidly, boast high yields and do not require prime agricultural land means the controversial fuel can ultimately deliver on its promise of major carbon savings.