Why there is serious money in kitchen fumes.

On the windy roof of a Burger King in Malmo, southern Sweden, Maggad Khalidy points to a large metal box attached to a jungle of pipes and wires. From the outside, it's far from an eye-catching innovation, but Mr Khalidy, who owns the fast food franchise that runs this restaurant, says it has saved the branch the equivalent of around $16,000 (APS13,000) a year in heating bills. The box contains a new form of heat exchange equipment called Lepido, developed by a Malmo start-up called Enjay. It spotted a gap in the market for recovering energy from kitchen fumes, and using it to heat other areas inside restaurant buildings - helping to cut bills for conventional heating, and reduce emissions in the process. "We were a bit sceptical in the...