Sunday, 23 February 2014


Measuring energy's contribution to climate change

Emissions of greenhouse gases like carbon dioxide (CO2) strengthen the greenhouse effect, accelerating global climate change. Generating electricity is one of the biggest contributors to greenhouse gas emissions worldwide.

The contribution of an energy source to climate change is measured by calculating carbon emissions over the lifetime of the generating equipment. An energy source's carbon footprint is measured in grams of CO2-equivalent  per kilowatt-hour (gCO2e/kWh) of electricity generated.
 Carbon commitments
Every energy source has strengths and weaknesses, such as its inherent carbon footprint. To meet its carbon-reduction commitments, the UK has to phase out the use of carbon-rich fuels to generate electricity, and to replace them with low-carbon equivalents.
Wind, solar, hydro and nuclear power stations all operate with close to zero CO2 emissions. Any emissions they do produce come largely from building the power station and, in the case of nuclear power, manufacturing the fuel. These emissions are amortised across the long life of the power station.
Carbon capture
Power stations that use fossil fuels, such as coal and gas, produce significantly higher levels of CO2 emissions. In the future, this problem could potentially be mitigated by fitting carbon capture and storage (CCS) technology to coal- or gas-fired power stations, but this is not yet proven to work on an industrial scale and they would still produce higher emissions than generating from renewable sources.
Furthermore, CCS will make fossil-fired power stations more expensive to build and less efficient to run, and could lead to issues in the future around storing the captured CO2.
Energy mix
In 2009, about 22% of the UK's electricity came from low-carbon energy sources. The Government recommends that by 2020 this figure should increase to around 40%, and the Committee on Climate Change recommends that by 2030 almost all the UK's electricity needs to come from low-carbon sources. Hence the UK Government favours a transition to a diverse mix of low-carbon generating technologies where the strengths of one energy source compensate for another's weaknesses.