Biomass (often called bioenergy or biofuels) is organic matter of recent origin.

It doesn't include fossil fuels, which have taken millions of years to evolve.

The CO₂ released when energy is generated from biomass is balanced by that absorbed during the fuel's production. We call this a carbon neutral process.

Biofuels are produced from organic materials, either directly from plants or indirectly from industrial, commercial, domestic or agricultural products, and fall into two main categories:

• Woody biomass includes forest products, untreated wood products, energy crops, short rotation coppice (SRC), e.g. willow.

• Non-woody biomass includes animal waste, industrial and biodegradable municipal products from food processing and high energy crops, e.g. rape, sugar cane, maize.

For small-scale domestic applications of biomass the fuel usually takes the form of wood pellets, wood chips and wood logs.

Made from a mixture of sawdust and wood shavings, wood pellets provide high energy at low cost and are smoke-free and leave virtually no residue for easy cleaning. A renewable source of energy (they are made from wood from sustainable forests) they are good for the environment cutting your energy bills, as opposed to oil and gas, theyre pretty good for your bank balance too!

There are two main ways of using biomass to heat a domestic property:

• Stand-alone stoves providing space heating for a room. These can be fuelled by logs or pellets but only pellets are suitable for automatic feed. Generally they are 6-12 kW in output, and some models can be fitted with a back boiler to provide water heating.

• Boilers connected to central heating and hot water systems. These are suitable for pellets, logs or chips, and are generally larger than 15 kW.

Stoves can be 80% efficient. They're normally used for background heating. They also add aesthetic value in the living area of the house itself. Many wood burning stoves act as space heaters only. But the higher output versions can be fitted with an integral back boiler to provide domestic hot water and central heating through radiators, if needed.

Capital costs: Depend on the type and size of system you choose. But installation and commissioning costs tend to be fairly fixed. Stand alone room heaters generally cost around 3000 installed. The cost for boilers varies depending on the fuel choice; a typical 20kW (average size required for a three-bedroom semi-detached house) pellet boiler would cost around 5,5000 - 12,000 installed, including the cost of the flue and commissioning. A manual log feed system of the same size would be slightly cheaper.

Running costs: Unlike other forms of renewable energy, biomass systems require you to pay for the fuel. Fuel costs generally depend on the distance from your supplier. As a general rule the running costs will be more favourable if you live in an area that doesn't have a gas supply.

Payback: This depends on the fuel being replaced and the type of wood fuel being used. It too is more favourable in areas that don't have a gas supply.