London, Sep 23 (IANS): Researchers have found a way to manufacture cheaper and sustainable bio-fuels from food crop by-products such as straw.

They have discovered variant straw plants whose cell walls are more easily broken down to make bio-fuels, but which are not significantly smaller or weaker than regular plants.

Increased digestibility can be achieved through a range of changes in the cell wall where the majority of sugar is contained in woody biomass, analysis of the plants showed.

Currently bio-fuel production from non-food parts of plants such as straw is too expensive because of the cost of breaking down the woody tissues into simple sugars.

"Using plant by-products such as straw provides a double benefit as we can harvest the food from the plant, then use the straw to produce a carbon neutral fuel," said lead researcher Simon McQueen-Mason, a professor at the University of York in Britain.

The discovery could help ease pressure on global food security as bio-fuels from non-food crops become easier and cheaper to make.

"This research is another important step towards making carbon-neutral bio-fuels both easier and cheaper to produce," said professor Melanie Welham from the Biotechnology and Biological Sciences Research Council (BBSRC) in Britain.

The impact of carbon emissions on global warming is driving the need for carbon neutral bio-fuels.

Many existing bio-fuels are produced from crops which can be used for food and therefore have a negative impact on global food security.

The findings appeared in the journal Proceedings of the National Academy of Sciences.