Plant waste might soon help make flying a little greener. A fuel made from cellulose has such a high energy density that it could make an even better jet fuel than those made from fossil fuels.

Flying produces 2 per cent of global carbon emissions, a figure projected to soar to in excess of 10 per cent by 2050. So numerous groups are working on ways of limiting the emissions generated by flying .

Ning Li of the Dalian Institute of Chemical Physics in China …