Biomass energy means energy generated from burning living or recently living organisms such as wood, as opposed to fossilised organisms (also known as fossil fuels). The energy production process is just the same as with a coal or oil fired power station. Biomass fuel is burned to heat water which creates steam which turns turbines which produces electricity. Its supporters claim that it is an effective way of reducing carbon emissions but are they right?
It is not immediately obvious to most people why burning wood would be good for the environment, after all this releases carbon into the atmosphere, right? So what are the benefits of biomass as a fuel and should be moving toward large scale use?
What is the Environmental Effect of Burning Biomass?
Those in favour of biomass claim that it helps to reduce carbon emissions but how can this be when burning wood releases carbon? First of all the argument depends on the alternative being to be burn fossil fuels, which in fairness at present it most probably is. As trees and plants live they absorb carbon from the atmosphere. When they die and rot some carbon is released and some is trapped in the ground. As layer upon layer of trapped carbon builds up over millions of years we end up with oil and coal deposits. When fossil fuels are burned, this carbon which has been trapped for millennia is released into the atmosphere.
The theory behind biomass is that, instead of mining fossil fuels, you plant an area of woodland. As the trees grow they take carbon out of the atmosphere. When they are burned they release it back but they only release the same amount which they absorbed during life, so in very simple terms the net carbon emissions from biomass fuels are zero. If therefore the whole world suddenly switched to using biomass there would be no new carbon emissions from electricity production and the world’s natural forests and plants could absorb what was already there and so the levels of carbon in the atmosphere would eventually reduce.
Critics of large scale biomass use argue that this is far too simplistic a view and ignores several important factors. Firstly, they point out that the immediate of effect of switching from fossil to biomass fuel is an increase in emissions and that it could take decades or even centuries for the offset effect of planting new trees to have an impact. They point out that we do not have that long to solve the emissions problem. Secondly, they stress the need to look at what the land was used for previously. If it was a brownfield industrial site then turning it into forest will have a positive impact but in reality meadows and farmland are likely to be used. Since the plants in these areas absorb carbon and are not subsequently burned, they are net consumers of carbon.
Is Biomass a Sustainable Fuel?
There are question marks over the sustainability of biomass on a large scale. Is there enough spare space to actually grow all of the trees necessary to fuel the power stations? Licences have already been granted to destroy areas of rainforest and turn them into trees farms. As more and more power stations are constructed and demand for fuel increases there is a fear more and more natural forests and plains will be wiped out, thus reducing the Earth’s ability to absorb carbon and actually bring down the levels currently in the atmosphere.
Economically there are question marks too. Presently wood for biomass is relatively cheap but as its value to the consumer increases, so does its price. In the UK we have relatively low capacity to produce fuel therefore if we are to rely on biomass on a large scale we will need to import. This means the UK government will not be able to exercise any control on prices and we could end up being held to ransom in the same way as we are with oil.
Other Carbon Costs of Large Scale Biomass Energy
Biomass fuel is not carbon neutral. Although it is true that when burned it releases only the carbon it has absorbed during life, there is a cost associated with its production and transportation, particularly if it is imported from as far a field as South America. Also, waste has to be disposed of.
Biomass is seen in some areas as a simple short term solution to the carbon problem. On a small scale the advantages probably outweigh the disadvantages however on a larger scale it could be a case of out of the frying pan and into the fire.
