This guide provides information about converting wood waste into fuel and energy. It is mainly applicable to joineries, sawmills and wood merchants.
There are several ways of using wood waste. It can be converted into products or used to generate “green” energy. Here we are focusing on the more mainstream and practical ways of converting wood waste into energy and will explore both fuel production and onsite energy generation.
In England and Wales 6 million tonnes of waste wood is sent to landfill every year corresponding to a massive 30 million MWhr of energy. This is equivalent to the annual production by 2 power stations like Ratcliffe-on-Soar.
Solid, liquid and gas fuel can be produced from wood. However, at small scale, only solid fuel is currently realistic. Sawdust can be turned into briquettes and pellets and off-cuts can produce wood chips and charcoal. Typically the transformation of sawdust and off-cuts into solid fuel has the main aim of reducing moisture content, increasing fuel density, and allowing automatic handling and reduction of transportation costs.
This is a robust technology and applicable for small volumes. Briquettes can be sold to individuals at the factory gate or through local outlets. The feasibility will depend on the quantity of the product and local market conditions.
Pellet making is a slightly more complex technology then briquetting and is applicable to larger volumes. One must make sure that customers are secured in order to make this viable.
This option is mainly applicable to tree surgeons and companies undertaking forestry activities but could be applied to situations where a lot of off-cuts are generated.
This is relatively messy, labour intensive and has a low return. Not advisable for joineries and wood merchants.
Biomass on-site energy generation has come a long way and can be very technologically involved, enabling users to produce heat, power and cooling, as required. However, simple solutions can also be implemented and a ‘risk benefit and economical analysis’ report would be recommended to determine the most advantageous solution.
When synergetic conditions occur, such as processes that require heat in a nearby company, heat can be sold off-site. The use of biomass is looked upon favourably in terms of CO2 emissions, but local planning authorities should be informed about a potential biomass boiler project at the earliest possible stage. The planning authority will be able to advise on the requirements for building regulations and planning permission. This is particularly important for all non-domestic installations or installations above 45 kW, and for environmental issues such as smoke control zones or air quality management areas.
Save on fuel bills during winter and avoid disposal during summer. This method is not the most efficient but can be a good solution for small volumes or where no process heat is required but there is a requirement for winter heating. Even though it diverts organic waste away from landfill, this solution is marginally environmentally friendly.
This solution provides better heat and fuel management as it allows for heat to be used in processes or to be transported to neighbouring businesses where there is a need. The heat becomes a commodity that can be sold and generate a return.
This requires equipment that is more sophisticated but is becoming more and more main stream and is nowadays feasible for relatively small scale schemes. Tri-generation; heating, cooling and power generation is possible at additional overall capital expenditure. These more advanced technologies can be advantageous if a good business case can be established.