Process — Electricity from household waste

The diagram shows the eight stages by which non-recyclable household waste is converted into electricity.

Overall, the plant wastes almost nothing: the rubbish itself becomes fuel, the heat becomes power, the flue gases are cleaned before release, and even the leftover ash is put to use in road building.

The process starts when rubbish lorries deliver non-recyclable waste and tip it into a deep storage bunker. A giant crane grab then lifts the waste and feeds it into the furnace, where it is burned at about 850 degrees Celsius — a temperature high enough to cut the volume of the rubbish by ninety per cent.

The energy recovery follows the classic power-station pattern. The intense heat boils water inside pipes, producing high-pressure steam, which spins a turbine connected to a generator, and the electricity flows out to the grid. Meanwhile the combustion gases pass through a series of filters in the chimney, which remove pollutants before the cleaned gases escape. The ash that remains is collected and used as material for road building, completing a process in which one tonne of rubbish yields roughly a month''s electricity for a home.