The question Horizon missed: What might UK shale gas mean for greenhouse gas emissions?

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What could extracting shale gas in the UK mean for greenhouse gas emissions in this country – and for attempts to reduce them in response to climate change? Carbon Brief breaks it down.

Last night, BBC 2’s Horizon programme investigated shale gas – “a new power source deep beneath the earth that could change the lives of us all” – asking what it means for the planet and for us. Geologist, Professor Iain Stewart, went to the US to examine its “energy rush” and what might happen if it was repeated in the UK.

The programme addressed many of the local environmental impacts of getting shale gas out of the ground. But, perhaps surprisingly, it avoided a big question – what might UK shale gas mean for climate change?

The USA example

Natural gas releases about half the carbon emissions of coal when it is burnt. Emissions from the United States fell to a 20-year low at the beginning of 2012 – a change the International Energy Agency (IEA) partly attributed to a switch away from coal and towards cheaply produced shale gas.

The UK could emulate this experience, argue many commentators. But the US example isn’t quite as clear-cut as it might at first seem. Here’s four reasons why:

The switch from coal to gas isn’t the whole story. A report from Bloomberg new energy finance identified three trends cutting US emissions – increased energy efficiency, more power from renewables and cheaper natural gas.

The decline in gas consumption in the United States meant it exported more coal. As a result, coal prices went down in the European Union and coal consumption went up. This pushed up emissions, particularly in the UK and Germany.

There’s no guarantee that the trend in the USA will continue in the long term. Last month the IEA warned that US emissions could just as easily go up again if the market changes and there are no policies to block a move back towards coal.

‘Fugitive emissions’ of methane could put a spanner in the works. During the process of extracting shale gas – fracking – gas can leak out. Methane is approximately 25 times more powerful than carbon dioxide as a greenhouse gas over a 100 year timescale. According to academics at Cornell university, fugitive emissions may mean shale gas releases more emissions than coal. But the question is hotly contested – many other academics disagree.

Is the UK the same as the USA? Not really

Some experts argue that that shale gas could be used as a ‘transition fuel’ in this country – that is, a cheap and relatively low-emissions fossil fuel that could help meet the UK’s energy needs until (hopefully) emissions cutting renewables or nuclear take over.

But the UK has a different power system from the USA. The country is already heavily dependent on gas – so there’s less potential for a coal-to-gas switch to bring down emissions. There is a chance that cheap shale gas could outcompete renewables rather than coal, driving up emissions.

via The question Horizon missed: What might UK shale gas mean for greenhouse gas emissions? | Carbon Brief.

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