At several factories, more electricity is generated than the factory requires and the excess is sold to the electricity supply companies and is probably the cleanest electricity available.
The beet and cane sugar factories all utilise power generation systems (known as combined heat & power, CHP) that produces both steam and electricity. A mixture of renewable & fossil fuel (bagasse, coal, oil or gas) are used in water boilers to produce steam at high pressure. This steam is used to drive turbo-alternators which generate electricity to power the sugar factory. In many cases electricity is also sold to the local grid network.
Forty-eight percent of the fuel is derived from renewable sources, cane bagasse, and 25% is from natural gas, the cleanest fossil fuel. Of the fuel, about 80 per cent of the energy in the fuel is put to beneficial use in the sugar manufacturing process. This efficiency compares favourably to 30-45 per cent for conventional power stations.
Having generated electricity, the resultant lower pressure steam is then used many times over in the sugar production process i.e. in highly integrated & efficient multiple effect evaporators.
At several factories, more electricity is generated than the factory requires and the excess is sold to the electricity supply companies and is probably the cleanest electricity available. This principle is taken furthest in the UK, where 2 high performance combined cycle gas turbines have been installed at the Bury St Edmunds and Wissington factories, each efficiently generating 50MW electricity for sale.