Biomass fuel in the form of wood is the oldest known form of artificial heating. It is solar energy, stored by the process of photosynthesis, converting atmospheric carbon dioxide to woody matter. Burning wood in oxygen releases the stored energy and carbon dioxide.

Although the burning of wood and other biomass (such as biodiesel) releases carbon dioxide, the primary greenhouse gas, it is often considered to be a low carbon or carbon neutral fuel, as the amount of carbon dioxide released equates to that which was absorbed by the plant in the first place. As long as new trees are planted or new crops grown, the carbon cycle is a closed process and does not add extra carbon dioxide to the atmosphere.

In practice though, although the process is not carbon neutral as fossil fuels are commonly used in harvesting and processing the biomass fuel. It can still be counted as a low carbon fuel if produced sustainably.

The UK government sees biomass fuel as a key element in meeting the country’s carbon emissions reduction targets.
Applications

The most commonly used form of biomass heating is domestic wood burning stoves.
Wood fuel logs can be produced with very little energy input, requiring only splitting and air drying under cover. A significant quantity of waste wood suitable for log fuel is generated within urban areas such as Greater Manchester from regular work by tree surgeons and council maintenance services.

Wood stoves for use in smoke control areas, such as Greater Manchester, must be approved by DEFRA to ensure they meet the required particulate emissions standards. Many stoves are now approved and non-compliant stoves can now even be retrofitted with a relatively affordable device (around £30) to reduce smoke emissions and achieve compliance.

Wood burning stoves have been successfully used to tackle fuel poverty – many homes in fuel poor areas are older houses with fireplaces which are ideal for retrofitting with wood stoves. In Old Trafford, the 2007 Old Trafford Renewables Project received the Energy Institute’s Renewable Innovation Award for that year, reducing carbon emissions and fuel bills with wood burning stoves combined with solar hot water systems.

For domestic applications, wood burning boilers are also available. These appliances tend to be more efficient than wood stoves, but considerably more expensive. However, wood boilers qualify for a subsidy under the Renewable Heat Incentive (RHI) which currently provides an upfront grant for installation, and in the longer term will provide an income for homes using biomass fuel, along the lines of the Feed In Tariff (FIT) for solar photovoltaic panels which we are more familiar with. Wood boilers have been used by the Carbon Co-Op to help meet carbon emissions reduction targets in retrofitted properties.

Wood boilers can either use wood logs, wood pellets or wood chip as their fuel. The latter two fuel types are much more energy intensive to manufacture than logs, requiring processing to achieve precise dimensions and moisture content. However, they are more controllable and so more suited to larger applications such as schools. One consideration though is that a large fuel storage facility will be required, with regular deliveries from large trucks, so the siting of the storage is key to the appropriateness of the biomass installation.
Biomass fuel can be used to power district heat networks – where a housing estate or group of commercial buildings are connected to under-road pipes containing hot water. This is a very efficient way of using the biomass fuel, and some installations can even generate electricity for the national grid, in an arrangement known as Combined Heat and Power or CHP. The larger the boiler, generally the higher the standard of technology installed to ensure that the flue emissions are clean and free of particulates and other potentially harmful compounds.

Finally, biomass fuel can be used in power stations. These power stations tend to be much smaller than conventional power stations running on gas or coal power – typically in the region of 20 or 30MW (MegaWatts) compared to several GigaWatts which is the typical size of a fossil fuel fired power plant. Utilising the waste heat from a biomass power station wherever possible is key to maximising the environmental benefit and efficiency from such a facility.

The flue gas cleaning equipment for biomass power stations is typically the most expensive and best performing of all biomass burning appliances. Biomass power stations require that the fuel contain optimal moisture content. This is normally achieved by feeding a mixture of recycled wood (very low moisture content) and virgin timber (high moisture content) into the hopper together. Recycled wood can contain paints and other treatments, which is why the exceptionally high-performing flue gas scrubbing equipment is necessary for biomass power plants.

Typically emissions are cleaner than the equivalent coal burning power station, although air quality does not tend to be as much of an issue around large coal power stations as they are commonly situated away from residential areas. Biomass power plants, because of their small size, can be situated in urban areas, which is particularly important if the waste heat is to be used for district heating or industrial processes.
Issues Around Biomass

The Greater Manchester Low Carbon Hub views biomass as an essential element in the Greater Manchester Climate Change Strategy to meet the agreed target of a 48% cut in CO2 emissions by 2020 on a 1990 baseline.

The UK government is developing a national heat strategy which will include the widespread use of district heat networks as in continental Europe. Greater Manchester has a developing heat network programme, although biomass fuel is only one option to supply heat networks. Natural gas and even ground sourced heat are other options.

As with any technology, biomass heating will not be appropriate for all situations, with several different factors coming into play.

• Provenance and availability. Within urban areas, a certain quantity of waste wood arises from regular tree operations. This resource is truly sustainable – it does not deplete the resource base and is supplied locally without having to be transported over distance. However, only a certain quantity is available which can only be increased over time by an expansion in urban tree planting. Biomass fuel imported over distance has a larger carbon footprint and greater supply vulnerabilities in terms of potential diversion to alternative demand elsewhere. Some biomass fuel may even be sourced from unsustainable resources such as the clear-cutting of boreal forest taking place in Canada as part of the tar sands oil production process.
• Storage and access. Biomass fuel requires large storage facilities which need to be accessed by large trucks or by water such as canal. These requirements will rule out many potential sites. Also, health and safety considerations must be taken into account around sensitive sites such as schools.
• Maintenance. Biomass appliances typically require more in the way of maintenance than their gas-burning equivalent, which may mean more work for (for example) school caretakers. However, if the fuel is of sufficient quality, minimal problems should be experienced.
• Air quality. In urban areas, any appliance burning biomass fuel needs to meet strict national emissions standards for particulates, set by DEFRA and enforced by the Environment Agency. Particulates can be dangerous to health and are the reason the Clean Air Act was originally introduced. That said, the levels of pollution from coal burning open fires when the CAA was first introduced are a world away from any pollution which could be caused by wood burning in an efficient appliance. Larger facilities burning wood contaminated with paint and other treatments need extra flue gas scrubbing equipment which comes at significant cost. No wood burning power station can be built without a licence from the Environment Agency. On the plus side, wood burning can actually emit lower levels of nitrous oxides than gas burning appliances, and is certainly cleaner than burning coal or oil.

Case Studies

Greater Manchester Tree Station

Set up in 2008, Greater Manchester TreeStation was one of the first tree stations to be established in the UK, and the very first in the North West.

The TreeStation was born from the realisation that (a) tree work arisings were often wasted due to lack of adequate recycling infrastructure or scale inefficiencies and (b) the wide scale uptake of sustainable solutions like biomass heating requires a high quality and secure supply. It made sense to integrate complementary activities such as tree work and biomass production, to provide an appropriate local infrastructure on a viable scale.

As an urban tree station, it acts as a hub for a broad range of wood-related activities, such as woodland management operations, arboricultural work and consultancy.  It also provides a local, unique and innovative green solution to wood waste for the Manchester area, and produces a range of quality wood products for the local market, including wood fuels, timber and related products.

Above all, the TreeStation is led by strong ethical views, which govern the way the business is run. Sustainability is embedded in the aims of the company. The TreeStation is a not-for-profit organisation, registered as Society for the Benefit of the Community (BenCom), making it both a democratic and accountable business.

Old Trafford Renewables Project

Six family households in Old Trafford were provided with a package of innovative renewable energy measures to reduce their fuel bills and carbon footprint. Five of the families received a multi-fuel burning stove, providing whole house heating through convection with wood fuel as the primary heat source. Three of the families received a gas combination boiler with integrated solar panel and is the first of its kind in the country. During summer, the solar panel can produce over 90% of domestic hot water for the property. In winter, the solar panel will preheat the water by as much as 30% meaning the gas combination boiler does not have to work as hard. The three remaining households have received a standard solar thermal heating system with a dual immersion as back up. The project received the Energy Institute’s Renewable Innovation Award for 2007. 

Oldham

Two Oldham schools, Waterhead Academy and Failsworth Academy, have biomass boilers, and there is a small wood chip fuel production facility in Oldham operated by the Council there. The potential for heating the glasshouses at Alexandra Park with locally produced wood chip fuel is being investigated. The Council is also developing plans for a district heat network to serve civic buildings as part of the GM Heat Network Programme, which could potentially be fuelled with biomass.

Trafford Park Biomass Power Plant

A 3MW (MegaWatt) biomass burning power station has received planning permission to be built in the Trafford Park industrial estate. The power station will feed renewable electricity into the national grid, and waste heat could be utilised for industrial processes or heating business premises on the park.

A large industrial park is an ideal situation for a biomass power station, as although the same standards of flue gas cleanliness must be met in all locations, sensitivities around perceived air quality issues can be controversial when a facility is proposed near to residential areas, complicating the planning approval process. Access for fuel deliveries is also commonly much better on industrial parks.

Tameside

New Charter Housing Trust Group Cavendish Mill (Ashton-under-Lyne) Biomass District Heating System was shortlisted for the Greenbuild Awards 2013.
The Cavendish Mill project made the finals of the Greenbuild Awards in the Domestic Retrofit category. The Greenbuild Awards 2013 recognises excellence in sustainable buildings, with a particular focus on projects that can illustrate an understanding of the importance of building performance in use.
The Biomass heating installation at Cavendish Mill in Ashton-under-Lyne is linked with 40 solar thermal panels which together provide low cost, low carbon hot water and heating to the building.

Barton Renewable Energy Plant

Peel Energy’s proposal to build a 20MW biomass power station at Barton Dock is so far the most controversial proposal for a biomass burning facility in Greater Manchester.
The plant will be able to take as feedstock a mixture of recycled wood (including treated wood), virgin timber, Energy crops such as coppiced willow and miscanthus grass, and agricultural residues from harvesting or processing such as straw and husks.

The proposed renewable energy plant site occupies an area of vacant land on the south side of the Manchester Ship Canal. The United Utilities Davyhulme Wastewater Treatment Works is located west and south of the site and Barton High Level Bridge carrying the M60 motorway is located to the east.

The original application for planning permission was refused by the local council’s Planning Committee after thousands of objections from local residents were received. The Stretford & Urmston Messenger, 2nd May 2013, reports that Trafford’s Breathe Clean Air Group (BCAG) has taken its campaign to stop the proposed Peel Energy Davyhulme biomass plant to Parliament. The article states the group met Trafford MP’s Kate Green and Paul Goggins to discuss key issues and raise the profile of their campaign.

The Environment Agency granted Peel Energy an environmental permit for the plant in October, and Eric Pickles, the Secretary of State for Communities and Local Government will soon make a decision on the scheme.

A number of factors have contributed to the controversial nature of the Barton Dock proposal:-

• It is near to residential neighbourhoods in Davyhulme
• It is near to the M60 which already contributes significantly to air quality issues
• The stack height on the proposed plant has been limited due to proximity to Barton Aerodrome

The Environment Agency has however issued a permit for the plant, signalling that they are satisfied that it poses no threat to health locally. British air quality standards are amongst the highest, if not the highest, in the world. The Secretary of State will have the final decision on whether or not the development goes ahead.

Peel Energy have indicated that if the Barton plant is granted planning permission, they intend to offer to supply heat to local businesses to further increase the plant’s environmental benefit in terms of carbon dioxide emissions reduction.

Barton Renewable Energy Plant is very likely a test case for relatively large biomass-burning facilities in urban areas. It will undoubtedly reduce carbon emissions locally, contribute to local energy security and (if the biomass feedstock is produced sustainably) sustainable energy supply. The biomass fuel could potentially be delivered via the Manchester Ship Canal, avoiding the constant flow of lorries associated with delivery by road. Even if the Barton plant is eventually approved for construction, it does highlight the importance of ensuring that local communities are adequately considered and possibly recompensed for potentially controversial industrial energy production facilities nearby.