Types of Biomass energy
Wood Wood is the conventional biomass energy used in the home - though it can be used for much larger buildings or even communities.
Woody biomass production comprises forestry products, waste wood, cardboard, waste pellets and straw. A farmer in Northamptonshire now crops miscanthus, or elephant grass, which produces 12ft high canes for use in power stations or as horse bedding.
Used on its own or in conjunction with fossil fuels it is possible for woody biomass fuel to reduce carbon dioxide emisssions, whilst in some instances can also reduce waste treatment costs.
Biogas Sewage or manure is used to generate biogas. After feeding slurry into a digester, conversion can take from 10days to several weeks.
In Nepal a cow dung biogas project won the Ashden Award for Sustainable Energy in 2005 where 66 of the 75 districts are running the scheme. In Sweden cow entrails are used to power the trains system.
Landfill gas Landfill sites produce a 50:50 mix of carbon dioxide and methane as organic materials decompose. Sites which hold less organic material produce less gas. The methane is used to generate electricity or to provide process heat. 33% of the UK's renewable energy in 2003 came from landfill gas.
This form of energy generation is symptomatic of a society that cannot deal with its waste. Hopefully, as local authorities become adept at separating waste, and householders compost where possible, this form of renewable energy will subside.
FermentationBioethanol and Biodiesel are forms of fermented biomass. To produce bioethanol sugars are converted into ethanol. Bioethanol can be mixed with petrol or used directly if an adapted engine is used. The most efficient sources are sugar cane and beet, though potatoes, corn, wheat and barley can also be used. Forestry waste, energy crops and waste paper are all in the research phase to produce bioethanol.
Vegetable oils, animal fats or recycled cooking oil can be made into biodiesel. The refining process does have a carbon cost, but typical carbon dioxide emissions are still reduced, as compared to fossil fuels, by 60%.