Wood fuel
Until about 150 years ago, wood was the main fuel for heating on Exmoor and woodland and hedgerow management was related to this demand. Coppicing also led to the production of charcoal, which was used in South Wales for smelting minerals. Coal only took over as the main source of heating with the introduction of cooking ranges in the late 19th century. Now oil and electricity are more common, but many Exmoor houses have wood burners. Changes came both with new fuels and more efficient heaters. Open fires and primitive stoves burned very inefficiently, with up to 85% of the heat going up the chimney. Such fires were also polluting. Modern wood stoves still give off carbon dioxide, contributing to greenhouse gasses but growing trees to replace the wood reabsorbs the carbon dioxide and burning the wood gives off no more carbon dioxide than the wood would if it decayed naturally. Modern wood heating is clean, efficient and competes on cost with most other heating systems. This has been achieved through controlling airflow, boiler insulation and re-burning flue gasses. There is a constant supply of wood, making it less susceptible to price changes than fossil fuels.
Exmoor has great potential for renewable energy from wood products. A recent study estimated that there are about 16,000 tonnes of dry wood available now and 8,000 tonnes a year on a sustainable basis. This could supply 10% of Exmoor's heating requirements and half of all farms on Exmoor. There are about thirty firewood merchants across Exmoor supplying the domestic market but there is more potential for the commercial market with wood chips and pellets. At present there are only three chip fuelled units within the Greater Exmoor area. The National Park Authority uses a wood fired boiler for its heating needs at its depot at Exford and a wood pellet fired boiler at its sawmill at Simonsbath. Sustainably produced timber from the Authority’s own woodlands is used at the workshops and the waste is used in the boiler. This is not as efficient as wood chip and pellet boilers, where the rate of combustion can be carefully controlled.
Wood pellet room heater at Simonsbath Sawmill
Wood pellet burners are very efficient, although they need electricity to power a fan and auger that controls the rate of burning and delivery of the fuel. The efficiency is partly due to the dryness of the fuel and drying and compressing the fuel also requires energy, although much is saved because it is then lighter and smaller to transport. Much pelleted fuel is currently imported, although it is hoped to set up more local pelleting plants. The pellets are mainly made from waste sawdust but can also be made from 'energy crops' like miscanthus, or straw.
A lorry load of wood pellets has about three times the energy value of wood chips. This is because of the moisture content and lack of compression of the chips. However, these are easier and cheaper to produce. They can even be made at home out of garden waste. They are about the cheapest form of heating that currently exists but much depends upon the distance they have to travel and so they are best made from locally sourced timber. They are best delivered in large loads, requiring considerable storage space. The chips also tend to compact and stick together in storage, requiring robust machinery to separate them and feed them to the boiler. Thus they are more sited to large installations such as public buildings and factory units.
The National Park Authority's Sustainable development Fund has been used to support several projects to develop wood fuelled heating systems in the Exmoor area:
- A grant towards the purchasing of timber solely from woodlands under the stewardship of the Exmoor WoodCert Group to start-up “Exmoor Wood Fuels” – a proposed business producing quality seasoned logs and kindling using timber sourced from woodlands in the Exmoor WoodCert Group Certification Scheme. If successful, this business will establish a unique certified market of firewood from small timber from Exmoor’s woodlands. The premium paid for the timber should help sustain management of smaller woods.
- To work through Wood Energy Ltd to attract grant aid to carry out feasability studies for the installation of wood-chip boiler heating systems at the Calvert Trust, Wistlandpound and Nettlecombe Court, Field Studies Centre. This will be used as a demonstration for the technology and as an educational facility to help establish a biomass heating industry across Greater Exmoor and encourage biomass heating across the region.
- To support Exmoor-based South West Wood Fuels, whose aim is to increase economic activity associated with the production and utilisation of wood fuels by stimulating the automatic wood-fired heating industry within the South West.
- Grant aid for South West Wood Fuels to research and write factsheets on affordable log & woodchip boilers, aimed at the communities across Exmoor which are not connected to a mains gas supply. They are also to organise a technical training programme for potential installers of new cheaper systems. In addition grants are available until March 2006 for householders, aimed at making the cost of a modern, efficient household central heating wood boiler the same as a modern CO2-efficient fossil fuel alternative (e.g. condensing gas boiler).