Biomass fall into two main categories:

• Woody biomass includes forest products, untreated wood products, energy crops and short rotation coppice (SRC), which are quick-growing trees like willow.
• Non-woody biomass includes animal waste, industrial and biodegradable municipal products from food processing and high energy crops. Examples are rape, sugar cane, maize.

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

Producing energy from biomass has both environmental and economic advantages.

Although biomass produces CO₂ it only releases the same amount that it absorbed whilst growing making it a carbon neutral process. Furthermore, biomass can contribute to waste management by harnessing energy from products that are often disposed of at landfill sites.

It is most cost effective when a local fuel source is used, which results in local investment and employment and also minimises transport miles to your home.

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.

There are many domestic log, wood chip and wood pellet burning central heating boilers available. Log boilers must be loaded by hand and may be unsuitable for some situations. Automatic pellet and wood chip systems can be more expensive. Many boilers will dual fire both wood chips and pellets, although the wood chip boilers need larger hoppers to provide the same time interval between refuelling.

You should consider the following issues if you're thinking about a biomass boiler or stove. Green Refurb can provide more detailed advice about specific issues on request.

• Fuel
  It's important to have storage space for the fuel, appropriate access to the boiler for loading and a local fuel supplier.
• Flue
  The vent material must be specifically designed for wood fuel appliances and there must be sufficient air movement for proper operation of the stove. Chimneys can be fitted with a lined flue.
• Regulations
  The installation must comply with all safety and building regulations.
• Smokeless zones
  Wood can only be burnt in exempted appliances, under the Clean Air Act.
• Planning
  If the building is listed or in an area of outstanding natural beauty (AONB), then we will need to check with your Local Authority Planning Department before a flue is fitted.

A typical 15kW (average size required for a three-bedroom semi detached house) pellet boiler could save you around 8 tonnes of C0₂ per year.

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 and whether you can buy in large quantities.