Energy crop

Energy crops are low-cost and low-maintenance crops grown solely for renewable bioenergy production (not for food). The crops are processed into solid, liquid or gaseous fuels, such as pellets, bioethanol or biogas. The fuels are burned to generate electrical power or heat. The plants are generally categorized as woody or herbaceous. Woody plants include willow and poplar, herbaceous plants include Miscanthus x giganteus and Pennisetum purpureum (both known as elephant grass). Herbaceous crops, while physically smaller than trees, store roughly twice the amount of CO2 (in the form of carbon) below ground compared to woody crops. Through biotechnological procedures such as genetic modification, plants can be manipulated to create higher yields. Relatively high yields can also be realized with existing cultivars. However, some additional advantages such as reduced associated costs (i.e. costs during the manufacturing process) and less water use can only be accomplished by using genetically modified crops. TOC Solid biomass, often pelletized, is used for combustion in thermal power stations, either alone or co-fired with other fuels. Alternatively it may be used for heat or combined heat and power (CHP) production. In short rotation coppice (SRC) agriculture, fast growing tree species like willow and poplar are grown and harvested in short cycles of three to five years. These trees grow best in wet soil conditions. An influence on local water conditions can not be excluded. Establishment close to vulnerable wetland should be avoided. Whole crops such as maize, Sudan grass, millet, white sweet clover, and many others can be made into silage and then converted into biogas. Anaerobic digesters or biogas plants can be directly supplemented with energy crops once they have been ensiled into silage. The fastest-growing sector of German biofarming has been in the area of "Renewable Energy Crops" on nearly of land (2006). Energy crops can also be grown to boost gas yields where feedstocks have a low energy content, such as manures and spoiled grain.