heat-generating plants 45 biomass 21 cogeneration of electric power and heat 15 power engineering 12 energy sources 10 heating 10 fuels (chemistry) 9 more ... heat supply 8 district heating 7 power stations 7 combustion 7 thermal networks 7 untraditional sources heating 7 calculations 7 history 6 steam-boiler plants 6 unconventional energy sources 6 steam boilers 5 energy sources operation 5 consumption 5 electric current 4 solar energy sources 4 imissions 4 air-conditioning 4 pipelines 4 European union 3 price 3 price control 3 corrosion of material 3 environment protection 3 less ...