Biomass and biofuel
Biomass is a type of organic matter, often referred to as 'bioenergy' or 'biofuel', which is used as an alternative, green source of energy.
Biofuels are produced from organic materials, either directly from plants or indirectly from industrial, commercial, domestic or agricultural products. These materials fall into two main categories:
- Woody biomass includes forest products, untreated wood products, energy crops, and 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. sugar cane and maize.
Biomass and your home
For small-scale, domestic applications of biomass, the fuel usually takes the form of wood pellets, wood chips and wood logs.
There are two main ways of using biomass to heat a domestic property:
Standalone stoves 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.
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.
There are many domestic log, wood-chip and wood pellet burning central heating boilers available that can be connected to central heating and hot water systems.
Boilers can be designed with an integral hot water energy storage or accumulator tank that stores water up to 90ºC, enabling the supply of heat to be further decoupled from the combustion of the fuel.
Is my house suitable?
You should consider the following points if you're thinking about installing a biomass boiler or stove in your home:
- 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.
- Regulations: The installation must comply with all safety and building regulations your home might be governed by.
- Smokeless zone: Wood can only be burnt on exempted appliances, under the Clean Air Act.
- Planning: If the building is listed or in an area of outstanding natural beauty (AONB), then you will need to check with your Local Authority Planning Department before a flue is fitted.
An accredited installer will be able to provide more detailed advice on whether any of the above applies to your property.
This will depend on the type and size of system you choose, but installation and commissioning costs tend to be fairly fixed.
Standalone room heaters generally cost between £1,500 - £3000 for purchase and installation. 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 £5000 installed, including the cost of the flue and commissioning. A manual log feed system of the same size would be slightly cheaper.
Unlike other forms of renewable energy, biomass systems require you to pay for the fuel. Fuel costs generally depend on the distance your home is 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.
This depends on the fuel being replaced and the type of wood fuel being used. As is the case with most other aspects of biomass installations, the ‘cashback’ is more favourable in areas that don't have a gas supply.
Producing energy from biomass has both environmental and economic advantages. It is most cost-effective when a local fuel source is used, which results in local investment and employment. Furthermore, biomass can contribute to waste management by harnessing energy from products that are often disposed of at landfill sites.
Source: The Energy Saving Trust January 2007.
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