ABSTRACT
Solar energy has always been used on a large scale in agriculture and forestry. Plants absorb the energy in sunlight and store some of it chemically – as biomass. When animals eat these plants, another type of biomass is created as a byproduct: manure. Overall, biomass can be divided into three categories in terms of energy use:
Wet biomass (manure in particular, but also freshly cut plants) can be used to create biogas when allowed to ferment in an oxygen-free environment. The biogas can then be used to generate electricity, heat or both. Waste gas from trash and water purification can also be used in this way, and organic waste can also be fermented (see 5.2 and 5.3).
Dry biomass (wood and straw) can be burned to generate electricity and heat. In addition to straw (a waste product from agriculture), waste wood from forestry and timber byproducts from industry (sawdust, wood chips, etc.) can also be used (see 5.4 and 5.5).
Dedicated energy crops (rapeseed, corn, poplars, miscanthus, etc.) can also be planted to provide additional biomass, which can be used in a number of ways to make electricity, heat and fuels (see 5.6–5.9).
