Collecting wood fuel

If managed properly, English forestry could provide the heat requirements for approximately 500,000 homes and electricity for 1,000,000 homes.

Photo by that_james

A report from The Forestry Commission and DEFRA indicates that two million tonnes of wood is available for energy usage from established English forestry per annum. The research suggests that this figure could be raised to four million tonnes per year if currently unmanaged English forestry resources are brought into full production.

The Forestry Commission have also set up the Biomass Energy Centre, a one stop shop for people interested in biomass. It contains a database of woodfuel suppliers by region in the UK.

Four millions tons of wood per year would provide the heat requirements for approximately 500,000 homes and electricity for 1,000,000 homes. Wood fuel is already in established use by some households in rural areas and lessons can be learned from these examples.

Waste wood is available as both clean (from woodland and park management which could be used in smaller scale plants) and within the waste stream (treated wood cannot be used in low temperature combustion based technologies as it can produce dioxins and therefore has to be used in larger scale EU Waste Incineration Directive compliant Combined Heat and Power plants). The British Biomass Task Force report identified the major biomass source as currently contained within municipal solid waste. The calorific value of waste will decline with improving recycling rates but it is estimated that there is sufficient fuel of this type to last the life of the plant - about 35 years.

Locally produced wood for energy should be reserved for the use of rural developments close to the point of maximum sustainable wood production rather be taken long distances to cities. There may be potential for some cities to access locally sourced wood but care should be taken to develop policies carefully and to avoid the overuse of wood as an urban fuel given its relative scarcity in comparison to other low carbon and renewable sources.

The evidence base for local strategies (and ultimately the Local Development Framework) should be informed by the availability of wood supplies and its proximity to settlements.

Solar and wind renewable generation produces energy from a free source. Although wood is considered a carbon neutral energy source, it is not free. At the moment heat derived from the combustion of wood is more expensive than heat derived from the combustion of natural gas.

The use of wood as a significant urban fuel also risks the rejection (leakage) of heat (particularly from absorption chiller based, wood-fired combined cooling, heat and power installations) into the inner urban heat island zone, potentially increasing the urban heat island effect.

The average capital costs for a biomass/wood heating system are between £200 and £600 per kWt. This reflects the capital cost when applied to a Part L1a 2006 compliant home and is based on figures from the 2008 Communities and Local Government research. The same research also undertook an economic cost and benefit analysis of each technology. This found that the value of saving in energy costs for biomass heating systems was £968 per tonne of CO2 saved.

Wood fuel is a viable source of carbon neutral energy at the neighbourhood and building scale, and can be seen as part of a city-wide approach to energy supply alongside other sources. A key determinant in choosing this technology is the availability of wood and its proximity. The local context will therefore be central in any decisions. Opportunities to bring local woodland into active management linked to wood fuel production can have important environmental benefits. Wood fuel strategies should be closely associated with wider green infrastructure strategies.

Smaller scale plants can have potential problems with external air quality when burning biomass that larger plants avoid through high quality and guaranteed control equipment.

As fossil fuels become scarcer and more expensive, there is likely to be increasing competition for biomass as a fuel from transport and electricity generation.

In Sweden, wood fuel forms an important energy source. It is supplied to towns and cities via urban biomass ‘terminals’. A regional and sub-regional approach to wood fuel supply is also starting to emerge in the UK. The Heartwoods scheme in the West Midlands is an example of such a regional approach to sustainable woodland management, which pulls together a wide partnership to deliver across the region.

Priority: develop a low carbon and renewable energy portfolio
Tags: energy, green infrastructure, cities and towns, neighbourhoods