UK boffins give biofuels a roasting

'Torrefaction' can boost the energy potential of bio fuel crops by 20 per cent

Scientists have unveiled details of a technique that could boost the energy of the UK's most popular biofuels by a fifth.

A study carried out by engineers from the University of Leeds suggests that exposing biofuel crops to a mild thermal process known as 'torrefaction' can boost their energy potential by 20 per cent.

The process is more usually associated with coffee production, but is increasingly seen as a desirable treatment for biomass because it creates a solid product which is easier to store and transport.

The scientists examined energy crops including willow, canary grass and agricultural residue wheat straw to see what happened when they went through the torrefaction process.

Results showed that the treated materials needed less time and energy to heat to burning point, and that they offered increased energy yields on burning.

"Raw biomass takes up a lot of space and has a low energy density," said Professor Jenny Jones who worked on the study with PhD student Toby Bridgeman.

"This makes it environmentally and economically costly to transport, and you need more of it than, say, coal to produce energy efficiently.

"Torrefaction is not currently used in the UK in either the agricultural or the energy sectors. But our paper shows that it has a lot of benefits, besides those to do with fuel handling, so it is definitely something we would like to explore further."