The Royal Free Hampstead trust is saving £780,000 a year with a combined heat and power plant that allows 70 per cent of fuel to be conver ted into energy. The trust says 27 per cent of fuel is conver ted into energy in a conventional power station. Some of the savings from the £3.7m plant installed in 1997 come from selling excess electrical power to London Electricity.The trust calculates that it also cuts carbon dioxide emissions by 14,000 tonnes.The plant and other new facilities at the Royal Free Hospital were on display during a royal visit last week.