What has Northern WoodHeat done?

The key issue that has been constraining woodfuel market developing in this country is confidence: users lack confidence in existing supply chains, but these will not expand or proliferate until there is further evidence of demand. Northern WoodHeat has been able to utilise the experience and strengths of project partners from all three countries to develop sustainable local supply chains by researching and demonstrating woodfuel production techniques that integrate with and complement existing natural resource management goals and methods to meet local needs.

At the same time it has been able to design training programmes and produce and circulate literature to improve woodfuel expertise in addition to raising awareness and understanding of the benefits that woodfuel markets can deliver to users, producers, the wider community and the environment.

The main issues that have been addressed by Northern WoodHeat are:

Economics – The project has trialed trialed different woodfuel harvesting, production and transport techniques to determine which are economically viable at the small/medium scale, and which are most beneficial to long term forest development. Unmerchantable timber can be used for woodfuel and well developed, efficient woodfuel supply chains can greatly improve the financial viability of thinning operations. Woodfuel markets provide an opportunity to recover biomass that would otherwise be lost to competition-based mortality by providing a market for tending and early pre-commercial thinning.

Rural development – Different business models for woodfuel supply have been encouraged including those based on the estate/farm, community and co-operative formats, in order to open up woodfuel markets to as many potential suppliers as possible.

Implementation – The project has helped stimulate active long term support for woodfuel markets amongst key interest groups, such as policy makers, forest resource managers, architects, builders and housing managers, through carefully planned and co-ordinated PR strategies.

Building expertise – The findings from the project trials have been and will continue to be widely disseminated and educational material and training courses, such as the online training course, have been developed through international co-operation. This will help ensure further market development after the end of the project.

Sustainability – Through integrating woodfuel development with natural resource management, local energy markets and local socio-economic structures the project will improve the sustainability of woodfuel.

Why use Woodfuel?

Wood is a plentiful and under-exploited resource

As energy-producing technology has become increasingly sophisticated, the level of reliance on wood as a fuel in the developed world has fallen.

However, the need for renewable and sustainable energy sources is now widely accepted, and the use of wood as fuel has increased significantly in several parts of Europe. Woodfuel now accounts for 19% of primary energy production in Finland, 22% of rural domestic heating energy in Austria with plans to increase this to 40% by 2010, and approximately 35% of the Danish timber harvest is for woodfuel. As a result of this expansion, there are now well tested wood-burning technologies suitable for a range of different applications and scales.

A fundamental aspect of bioenergy systems such as woodfuel is that they must be locally centred to be economically viable. Such an approach is ideally suited to rural Northern Europe where both the resource and the population is scattered; this is particularly true of peripheral areas. It enables supply and demand sides of the market to be matched to meet local energy, timber market and employment needs. Timber prices in peripheral areas of Northern Europe are currently low and are unlikely to rise significantly in the foreseeable future. This has created a large surplus of low grade timber, much of which is very remote from current markets. A well-developed woodfuel market could make good use of this currently under-exploited resource.

Thus in terms of available technologies, resources and geography, woodfuel energy systems are an ideally suited to use in Northern Europe.

Woodfuel is environmentally sound and sustainable

Unlike other forms of renewable energy, biomass can be used to generate heat directly, rather than as electricity. This is a way of avoiding both the grid imposed limitations on energy generation in peripheral areas, and the transport costs associated with the wide fuel catchment areas required by large combined heat and power developments.

Woodfuel is effectively carbon neutral because the carbon released during combustion is equivalent to that absorbed by the tree while it was growing. Therefore, in addition to having a proven technology, a resource, and a potential market, woodfuel is also an environmentally sound energy source.

Aside from energy production, using woodfuel has wider positive effects in terms of forestry practice, employment and biodiversity. Forest thinning is often delayed or abandoned due to lack of markets for the produce. Unthinned crops can result in lower grade timber, more appropriate for large scale industrial fibre using industries than for local added value processing. The lower timber incomes from such crops are frequently exacerbated by high haulage costs to distant markets and can result in negative returns to timber growers. However, thinnings and low grade timber can be used as woodfuel. Establishing woodfuel heating schemes in peripheral areas would use this resource locally cutting the economic costs of haulage while increasing local forestry incomes and improving the value of timber crops.

Furthermore, research has shown that high stocking densities are optimal for woodfuel harvests. This gives flexibility in terms of restocking, allowing use of silviculturally beneficial mixtures of native and exotic conifer species such as spruce/birch. There is a future option to remove one or the other in response to future changes in forest management prioties and in response to changing timber markets. For instance if softwood markets deteriorated or landscape and biodiversity issues gained in importance the spruce could be removed as woodfuel leaving a native woodland to develop. Alternatively if there was a shortfall in softwood supply and biodiversity imperatives were being met adequately elsewhere the birch could be removed as woodfuel having served its purpose as a nurse crop. There is also a middle “multi-purpose” option where an intimate mix could be thinned to produce discrete single species blocks of spruce or birch.

Local employment and business opportunities can be created through operating woodfuel energy schemes at the local scale. Small scale supply chains require less specialist equipment and therefore provide opportunities for local contractors, community woodland groups and farmers to enter the market. Moreover, the improved quality of the remaining timber resource will further increase options for local added value processing.

Finally, more mixed woodlands, and increased thinning and felling will improve the biodiversity of woodlands and forests. For example, thinning is a vital part of a major project aiming to recreate woodland habitats suitable for Capercaillie. Such management techniques will also improve landscape values and recreational values.

Types of woodfuel

Woodfuel is extremely versatile, existing in a variety of forms compatible with different combustion technologies and end users, ranging from small scale domestic heating to district heating schemes and large-scale combined heat and power generation schemes.

Logs

Logs are often regarded as an inefficient, inconvenient and dirty fuel compared with the convenience of mains utilities. However, automated, highly efficient log burning stoves have been developed with a magazine that can be filled with logs. The entire magazine is burnt within a few hours, but the heat is stored in an accumulator, which in summer mode, can provide up to 14 days of hot water supply. Whilst log fires rarely exceed 15% efficiency, wood-burning stoves can reach 70-80%.

Logs are straightforward to produce. At a very small scale fuel can be gathered by hand and processed using hand tools. More usually chainsaws and agricultural tractors, or Land Rovers, and trailers are used. For the woodfuel contractor there is a range of firewood processors powered by tractor PTO/hydraulics. These range from simple log splitters to machines that will saw lengths into logs, split them and load them into a trailer.

Much of the current log market is dependent on suppliers working on a casual basis with minimal equipment. Quality is very variable, often poor, and fuel is often overpriced as a result of inefficient production methods. Also, potential customers frequently have difficulty in locating supplies. Despite these problems, well targeted support measures, focused on raising log quality, increasing mechanisation and improving customer service could yield rapid gains in this sector.

Woodchips

Woodchips are utilized at an extremely wide range of scales from the individual household to large district heating and CHP schemes. They are generally produced from poor quality final crop timber, thinnings, harvesting residues and arboricultural arisings. Equipment for producing wood chips is available at a range of operational scales. Roundwood is harvested using conventional techniques and then chipped in small hand fed, tractor mounted or self powered chippers, or large hammer mills.

The biggest limitations on chip use are variations in quality. The most important of these are inconsistencies in size and moisture content. Variations in size are often cured by correct matching of raw material and chipping technology. Moisture content has a direct effect on the available calorific value in woodfuel as part of the heat released during combustion is lost as latent heat during evaporation of the moisture.

Pellets

Pellets are usually made by compressing the sawdust and small shreds of wood produced from industrial manufacturing waste rather than from round wood or harvest residues. They are about 8 mm in diameter and look like animal feed. They are well suited to small scale auger fed systems because they are clean, dry (8-10% moisture content), easy to store, and easy to use in automated systems due to their consistent size. Pellets also have greater bulk density than other wood fuels and reduce transport costs through reducing load size.