Biomass is produced from organic materials, either directly from plants or indirectly from industrial, commercial, domestic or agricultural products. Biomass includes:

• Woody biomass such as specially grown crops like short rotation coppice willow and the perennial grass Miscanthus.
• Non woody biomass such as animal waste, industrial and biodegradable municipal products from food processing and high energy crops. Examples are rape, sugar cane, maize.

Increasing the use of renewable energy in the UK, Europe and the World is gaining in importance as climate change impacts are being recognised with increasing urgency.

Biomass energy is ideal to help with reducing greenhouse gas emissions from fossil fuel burning as it can be made available as solid, liquid or gaseous fuels and can be used to generate electricity.

This flexibility as well as the large potential resource base makes the development of biomass resources a major for the UK. Advantages of using Biomass Not only does biomass help with climate change issues, but it also can provide significant local employment and can be grown profitably by farmers locally yielding long term secure income to provide some certainty in an uncertain future for the industry.

Furthermore, biomass can contribute to waste management by harnessing energy from products that are often disposed of at landfill sites. Wood fuel is carbon neutral - when wood is burnt it emits the same amount of CO2 into the atmosphere as absorbed during the life cycle of the growing plant. There are no toxic risks associated with its use, unlike other fuel sources such as oil and gas.

Biomass crops are easy to grow and blend in well with the landscape, is has been estimated that in Cornwall 38% of the current agricultural land would be suitable for energy crop growth.

Electricity and heat in the UK

Generating heat accounts for roughly 47% of the UK’s total energy consumption, and 41% of the UK’s total carbon emissions (equivalent to 61 MtC annually).  Three quarters of that energy is used for space and water heating, primarily in the domestic sector.

Diagram: Biomass - Wood Renewable Energy Cycle (taken from the Bioenergy Technology Ltd, 2007).

Around 1% of heat is currently generated from renewable sources.

Biomass has significant potential to contribute to renewable electricity and carbon abatement.

Currently around 4.6% of our electricity comes from renewable energy sources with biomass providing around half of that supply.

CHP

Combined Heat and Power (CHP) is a carbon-efficient process which puts to use the heat produced as a by-product of electricity generation. CHP increases the overall efficiency of fuel utilisation compared to conventional forms of generation, so delivering carbon savings.

Typically the process is fired by fossil fuels, though biomass CHP is growing in importance. The costs of generating electricity using CHP are often higher than for standard centralised generation, even though there is a financial return for the heat that can be sold.

Technology Biomass can be applied to a wide range of scales from 50kW domestic systems, medium 500kW plant to mega watt scale power stations. The main type of company which could benefit from biomass boiler heating would have a high heat demand, preferably all year round, such as food processing, film processing, swimming pool providers, care providers such as hospitals and nursing homes.

Fuel

This table shows the wide range of crops that can be grown and how they are processed.

Stores

Biomass is a low energy density fuel, a large volume must therefore be stored onsite to avoid an unacceptable frequency of deliveries.

Wood fuel requires a lot more storage space than fossil fuels. Wood pellets will require 3 times, and wood chips 10 times (see picture below), the storage volume of oil to provide similar amounts of heat.

A suitable area close to the intended site of the biomass boiler is needed. For a domestic house a fuel store of at least 5-6 m3 is recommended, larger for wood chips.  This would require filling approximately once or twice a year for pellets and four to six times for wood chips.

Storage can be either above or below ground of using an adapted unit such as a feed silo or shipping container.

A fuel store must be well designed and kept in good condition to protect it from moisture.

The transport of low-density materials is also a major consideration, and will greatly affect the cost of the fuel. To be economic the supply of wood fuel should be as local as possible.

Boilers at a domestic scale

There are two main ways of using biomass to heat a domestic property:

• Stand alone stoves providing space heating for a room. These can be fuelled by logs or pellets but only pellets are suitable for automatic feed. Generally they are 6-12 kW in output, and some models can be fitted with a back boiler to provide water heating.
• Boilers connected to central heating and hot water systems. These are suitable for pellets, logs or chips, and are generally larger than 15 kW.

There are many domestic log, wood chip and wood pellet burning central heating boilers available. Log boilers must be loaded by hand and may be unsuitable for some situations. Automatic pellet and wood chip systems can be more expensive. Many boilers will dual fire both wood chips and pellets.

A chip boiler may be appropriate at the very largest end of the domestic sector but sufficient space will be needed to store wood chip.

At a community scale

Above domestic scale, logs become a less likely fuel of choice since greater heat output means more frequent refuelling.

If there is sufficient space available for delivery and storage of wood chip (and a local fuel supply), then wood chip will offer greater running savings than pellet.

Pellet boilers (as seen in the picture) have their own advantages: easier fuel delivery, less space required for fuel storage, and better modulating ability than chip boilers.

Cost

Unlike other forms of renewable energy, biomass systems require you to pay for the fuel. Fuel costs generally depend on the distance from your supplier and whether you can buy in large quantities. In many cases it is likely that the fuel will be produced locally thus benefiting the local community.

At the moment the capital cost of instillations is more expensive than traditional wood stoves or fossil fuel fired boilers. Each system will also require a fuel store that will increase costs. The cost for boilers varies depending on the system choice; a typical 15kW (average size required for a three-bedroom semi detached house) pellet boiler would cost around £5,500 - £12,000 to install. A manual log feed system of the same size would be slightly cheaper, with larger wood boiler systems over 50kW costing around £100-£120 per installed kW.

A biomass powered boiler could save you around £200 a year in energy bills and around 8 tonnes of C02 per year.

Savings will depend on how much they are used and which fuel you are replacing. With wood chips being so much cheaper than traditional fuels (see graph below) the economics can work out favourably, especially for larger systems.

The graph above (taken from the biomass energy centre, November 2007) shows the difference in price per kWh between wood and fossil fuels. When changing from oil to wood chips for example a savings of over 2p per kWh can be made. In the UK, the average medium sized house uses 20.500 kWh of gas per year, by switching to wood chip fuel a saving of approximately 1p/kWh could be made resulting in a saving of at least  £205 annually. (All prices are prone to significant variation with geographical region, order quantities, delivery distance, and time etc).

Government grants and incentives are increasingly available to assist with biomass boiler installations and renewable based energy generation is exempt from the Climate Change Levy.

The Climate Change Levy is a tax on the use of energy in industry, commerce and the public sector, with offsetting cuts in employers’ National Insurance contributions and additional support for energy efficiency schemes and renewable sources of energy. The aim of the levy is to encourage users to improve energy efficiency and reduce emissions of greenhouse gases.