□ □ □ □ □
[□] □ □ □ □
□+ □ □ □ □
Combustion of solid fuels ( coal , peat , biomass , waste ) is a common way to produce power and heat . In the reduction of briquets to coal equivalent , different conversion factors are applied according to their origin from hard coal , peat , brown coal , or lignite . The fuels studied include coal , peat , wood-based fuels , biomasses , waste-derived fuels , and wastes .