May 2013



1. Several UK coal-fired power stations are switching to burn biomass instead of coal. What policies have caused this to happen? (6 marks)

In 2003, Drax power station converted half of its 6 units to biomass in response to EU and UK policies that are making combusting fossil fuels particularly coal with its high carbon intensity and other pollutants less economic to run. Europe is attempting to reduce the greenhouse gas emissions of its member countries with several policies and schemes including setting greenhouse gas emissions reductions targets. For example the UK is obligated to reduce greenhouse gas emissions by 80% on 1990 levels by 2050. The EU also implemented a carbon trading scheme with a 16 billion tonnes of C02 set as a cap for industries to emit between 2013 and 2020 and which allows companies to trade set allowances between them. This scheme was unsucessful due to being overcapacity causing the carbon price to fall, however it may still provide some incentive to decrease emissions. As a result of this the UK government bought into place a UK carbon price floor with a slowly esculating levy on greenhouse gas emissions on industries burning fossil fuels for energy. Coal power stations must either pay this fine or convert to lower carbon technology, however as the price is increased it is becoming harder to justify the costs of continuing to use coal. The UK government is also keen to encourage conversion to renewable energy due to having the target of 15% of energy being sourced from renewables by 2020 according to the Renewable energy directive 2009. It therefore bought in a "ROC" scheme where ofgem would give "ROC" to renewable energy producers and energy suppliers would have to source a particular proportion of its energy from producers with ROCs or face fines. This makes it more likely that renewable energy producers will have buyers and removes some of the risk from investment. This scheme  closed to new capacity is 2013, however the new contracts for difference involving setting strike prices for power stations that produce low carbon energy may also be acting as an incentive for power stations to convert to biomass.

List two advantages and two disadvantages of the shift from coal to biomass in terms of environmental impacts of electricity generation. (6 marks) 

Biomass can often combust less efficiently than coal which may increase pollutants of black carbon and therefore particulate matter that is produced, increasing the costs of waste emissions cleaning or providing a health risk to human populations if cleaning is not carried out. Burning biomass for electricity generation may not make carbon dioxide savings depending on the land area converted for biofuel crops and how intensive the agricultural inputs are. If chemicals produced using fossil fuel intensive processes are used, biofuels may have a larger negative environmental impact and contribution to climate change. Pimental and Pimental in 2005 found that 1.08-1.32 MJ fossil fuel energy was required to produce 1 MJ biofuel energy.


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