Oil company Shell and bioscience specialist Virent Energy Systems have joined forces in a five-year venture to come up with a sustainable alternative to petrol.

The two companies plan to synthesize new biofuels from plant sugars that in contrast to ethanol - currently the leading biofuel alternative to petrol - will not affect food prices or require engines to be modified.

The collaboration aims to extract sugars from non-food sources such as switchgrass, the leaves and stalks of maize, wheat straw or sugar-cane pulp, as well as more conventional biofuel feedstock such as wheat, corn and sugar cane.

Ethanol is typically created by fermentation of these plant sugars, followed by distillation. When burned in an engine, ethanol releases about a third less energy per litre than petrol. In contrast, Shell and Virent’s proposed new “biogasoline” is intended to more closely match petrol’s energy density.

“The technical properties of today’s biofuels pose some challenges to widespread adoption,” said Graeme Sweeney, Shell executive vice president for future fuels and CO2. “Fuel distribution infrastructure and vehicle engines are being modified to cope - but new fuels on the horizon, such as Virent’s, with characteristics similar or even superior to petrol and diesel, are very exciting,” he added.

The companies said that future efforts will focus on making the technology available for larger volume commercial production. Shell and Virent did not reveal the financial sums invested in the project, nor did they offer a target date for the commercial availability of the new fuel.

The announcement follows multiple initiatives by oil companies, including Chevron and BP, aimed at producing second-generation biofuels from non-food crops.

Environmentalists, however, have argued that investments by oil companies thus far are little more than a public-relations smokescreen aimed at drawing media attention away from their ongoing focus on fossil fuels.

Last year, Shell itself drew criticism for backing away from some of its green technology investments, including the sale of its photovoltaic operations in India and Sri Lanka.

Shell said the decision, which followed the 2006 sale of its solar module production business unit, was prompted by the operation’s lack of profitability.