Types of bioenergy
Bioenergy is energy that comes from biological sources such as trees and plants and manure. Wood is one of the oldest forms of biofuel that can be burned to produce energy. It has been used for thousands of years. Other methods of obtaining bioenergy is the use of sugar cane to make alcohol or bagasse (the bits left over after making sugar) and anaerobic digestion of biodegradable material to make Biogas. These can all be burned.
How does it work?
Biogas and Biofuel such as alcohol, manure and bagasse (fibrous residue obtained from sugar cane) are burned and heat water into steam. The steam turns a turbine which then generates electricity, just as in power stations that use fossil fuels.How does it work?
Cost and efficiency
Plants are only at most 2% efficient at turning sunlight into energy. We then have to harvest them with machines and transport which are energy intensive and expensive. Anaerobic Digestion costs are variable depending on size and location.
Bioenergy requires large fields and land areas to grow the crops needed.
Locations around the UK
Didcot power station now burns a small amount of biomass such as sawdust. There are lots of Anaerobic Digestion sites in Europe but not many in the UK.
Burning biomass to get our electricity reduces our reliance on the use of coal, oil and gas in our power stations. In many cases, it is also a useful way of getting rid of our waste products. Anaerobic digestion produces a gas similar to North Sea gas so it can go straight into the gas grid that we already have. The by-products of bioenergy can also be used e.g. hot water and natural fertiliser. It is also possible to have smaller installations in individual homes and communities.
Growing enough biomass to sustain our energy needs will take up a lot of space and uses up the resources we need for also growing our food. Bioenergy still produces carbon dioxide like fossil fuels – but the idea is that biomass is carbon neutral so that it they produce as much as they used up when growing.
Biomass is relatively easy to store and use when required, but may not be as easy to get hold of at certain times of the year. Growing, collecting and storing enough for a year-round supply would be difficult.
We need a lot of land to grow biofuels so the uses of land may have to be changed. Deforestation or reclaiming land from the sea and other changes in land use may have an impact on the original environment, or the nature of the soil.
Growing biomass would use a lot of the agricultural land that could be used for growing food.
Is it a viable power source for the UK?
It may be useful for small communities or in farms that have direct access to the biomass and biofuel but it would not provide all the energy needs of the country.