Biomass renewable energy is a nebulous term, covering all sorts of fuels and scales of generation. Typical biomass renewable energy fuels are specially grown crops (such as as oil seed rape or miscanthus), managed forest plantations (in the UK, normally willow or poplar) or other types of waste vegetation including waste from tree surgery, grain husks, chicken manure or straw. The largest straw-fired power station in the world is located at Ely, East Anglia, with a capacity of 38MW.

Alongside large-scale district power plants, biomass renewable energy can be employed on a much smaller scale. Individual biomass boilers to heat homes are likely to be covered by the new ‘renewable heat incentive scheme’.

Biomass can only be considered to be a renewable form of energy if there is a ‘closed loop cycle’ in the type of fuel used. This means that biomass burned to produce renewable electricity should be sustainably grown and replanted after incineration in order to absorb carbon released during combustion.

The advantages of biomass renewable energy depend to a large extent on the type of fuel crop used. When carefully managed and sustainably grown, there is much scope for biomass renewable energy to sequester carbon from the atmosphere. This useful table illustrates the varying carbon footprints of typical biomass renewable energy fuels against fossil fuels. One can see that wood pellets used as biomass renewable energy produce around 15kg of carbon-dioxide per megawatt of energy produced. Coal produces around more than thirty times this amount of carbon-dioxide at 484kg for the same amount of electricity.

There is also a lot of waste fuel that can be employed in a biomass renewable energy plant. Kitchen waste, agricultural by-products and waste wood from coppicing and forestry management can all be viable, although may require some treatment to be used as an effective biomass renewable energy source. In many cases, there is a cost incurred in disposing of these wastes, so use as biomass renewable energy would be an effective way of dealing with this.

The burning of biomass renewable energy fuels can produce an ash by-product is a very rich fertiliser.

Biomass renewable energy might have a greater impact on the generation of renewable heat rather than large scale electricity production. Check our page on the Renewable Heat Incentive scheme for more information. DECC’s 2009 renewable energy strategy suggests that much of the targeted 12% of renewable heat might come from biomass renewable energy and this seems to be supported by the Renewable Heat Incentive Scheme.

It is imperative that biomass renewable energy is sustainably grown and managed in order for the wider impact on the environment to be minimised and to ensure that net carbon emissions are balanced. In some parts of the world, deforestation for biomass renewable energy far outstrips the rate of afforestation to replace it.

Different types of fuel have different associated costs and efficiencies as a source of biomass renewable energy. Moisture content is an important consideration – the lower the moisture levels, the greater the efficiency of combustion in the renewable electricity generating process and wetter biomass renewable energy fuels will require drying or compression.

Some types of biomass renewable energy are more effective than others. Energy crops, such as oilseed rape and miscanthus are more efficient than others, like green wood or vegetable waste but have their own associated costs. Energy crops can require intensive fertilisation, which can be both expensive and damaging to the environment.