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Why is it important? Burning wood does not contribute to climate change as long as the wood is from a sustainable source (i.e. one tree planted for each tree felled). Carbon Dioxide (CO2) is still released when the wood is burned, but this is approximately equivalent to the CO2 which is taken in by the trees over their lifetime. Using wood as a fuel can also help the rural economy. Wood fuel can be provided from local sources in rural areas, creating new business and employment opportunities. How does it work? Wood can be burned directly to provide heat in a central heating boiler or a room heater. Wood can also be burned to run a turbine and generate electricity. Modern wood fired heaters are highly efficient, keeping the heat inside the house much longer and burning the wood more efficiently and cleanly than older systems or open fires. Refined wood fuels, such as wood briquettes or pellets made from compressed sawdust, are now available. Using these dense fuels, more units of energy can be moved in each lorry load of wood, reducing the cost and impact of transport. Wood pellets are small and have a uniform size and shape so they are suitable for automatic feed systems like hoppers or screw feed system, which are more convenient than those which need to be hand fed. How much energy can it generate? Room heaters Direct room heaters can be sized to heat a single room, a small home or the core of an open plan house. They can be used with a back boiler to provide hot water and to heat radiators elsewhere in the building. Room heaters designed specifically to burn wood pellets tend to be efficient and clean burning as well as convenient to operate. Most room heaters are designed to provide an attractive feature within a household. Central Heating Wood fired central heating systems are also available. Heating an average 2-3 bed family home would need about 8-12 oven dry tonnes of wood per year (this is around 3 tractor loads). A wood boiler generally looks similar to a normal boiler, but wood storage space and a chimney stack are also needed. In some countries, such as Sweden, large central wood boilers are used to heat whole towns. This is know as "District Heating". Power Stations Wood fired power stations are comparable in size to a large barn or small factory. They usually provide enough electricity for between 5,000 and 30,000 households. Systems are now being developed to generate electricity at a smaller scale, for example for individual factories. The main sources for wood fuel are:
Environmental Effects Burning wood inefficiently causes smoke and air pollution. Careful operation of wood burning systems greatly reduces this and modern wood energy systems are often automated to improve efficiency and reduce pollution. Wood-fuel production needs careful management to avoid damaging wildlife habitats. Well managed wood fuel production can benefit nature conservation. Transport: Wood fuel can be transported by rail but will generally need to travel by road at some point. Using a local fuel supply keeps transport distances to a minimum. It is generally accepted that woodchips can be transported within a 40 km radius before energy use in transport becomes a major issue. Wood pellets have a higher energy density so they can be transported more economically. |
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How much does it cost? The main costs associated with supplying wood fuel are gathering and transporting the fuel. Prices for wood fuel therefore vary considerably, with local wood and by-products such as wood off-cuts being the cheapest fuel (perhaps even free). As a domestic heating fuel, wood is often cheaper than LPG, electricity or oil. Wood heating systems tend to cost slightly more to buy and install than fossil fuel systems. Generating electricity from wood fuel is usually more expensive than fossil fuels, but support grants are available and costs are reducing as the industry develops. Where can it be sited? A cheap, reliable wood fuel supply is the most important factor for a successful wood energy project. This is likely to be a local supply or even your own wood supply. You will need to plan for space and access for fuel storage and delivery. Burning fuels to generate electricity creates waste heat. This heat can be used for water or space heating which greatly improves the efficiency of the system. It is therefore important to try to find a nearby heat demand when planning a wood-fired power plant. |
For information on the various sources of funding for wood fuel projects, click here
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Further information:
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