Biomass refers to any fuel which is derived from organic matter of recent origin, and hence does not extend to fossil fuels. Essentially, burning biomass fuel is carbon neutral, since the CO2 which is released during the combustion process is equivalent to that absorbed during the growing process.
Fuel tends to fall into two main categories, forest dried chips and cuttings (from coppicing) and pellets. Chips are the cheaper fuel, but have a lower calorific value, and therefore require more storage space for the same heat output. For domestic systems, fuel can also include dried logs, which can be burnt in log fires, with or without back boilers, or purpose designed log burning boilers.
Non-woody biomass fuels are also available, which include animal wastes, industrial and biodegradable municipal products from food processing and high energy crops such as rape, sugar cane and maize.
Wood boilers are particularly well suited to rural and semi-rural locations, off the gas grid, where they can replace oil, LPG, electricity or solid fuel in the form of coal, as the main form of fuel.
Paybacks vary depending on the size and complexity of the installation and the cost of the displaced fuel, but with the application of grant funding tend to vary between 4 to 8 years. Where there is fuel available on the site in the form of tree waste, then fuel costs can be lowered and payback times shortened.
Whether the system is for a house or for a larger commercial building, careful system design needs to be undertaken in order to ensure that the biomass boiler and associated system operate as efficiently as possible.
In rural and semi-rural application, biomass boilers offer an excellent alternative to other fuels, and the plant and equipment is readily available in the U.K.