A report commissioned by the Environmental Defense Fund (EDF), a non-profit organisation, has found that leaks from natural gas and oil production on federal or tribal land in the USA in 2013 produced the equivalent in greenhouse gases of 5.6 million cars.
With 65 billion cubic feet of gas released into the air (the figure includes venting and flaring processes, in which gas is deliberately let out), many of the environmental advantages natural gas has over coal are apparently being wasted.
Researchers believe that around 2.2% of the gas produced on government-owned land is leaking. Leaks during transportation, which were not measured, could lift the total amount beyond 3% – the threshold at which scientists agree the ‘clean’ benefit of natural gas is lost.
The EDF report, which also highlighted local pollution such as smog arising from gas drilling operations, follows a Cornell University study in 2011 which questioned the green merits of natural gas.
The shift towards gas
Natural gas is largely made up of methane, which is much more efficient than carbon dioxide at trapping heat in the atmosphere and therefore, in the long-term, a more potent greenhouse gas.
Although considered the cleanest fossil fuel available, its contribution to carbon emissions is expected to grow as it becomes a more and more important part of the fossil fuel mix. The USA is enjoying a natural gas boom as drilling technology and hydraulic fracturing (‘fracking’) enables it to draw from previously inaccessible reserves.
Domestic leaks and public safety
Internal leaks that build up inside buildings can cause deadly explosions, though these are rare considering how widely gas is used.
Natural gas is odourless, so an odorant is generally added to make leaks easier to detect. In June, a utility company in Gretna, Nebraska received a flurry of calls from worried homeowners. It was later established that excessive odorant had been added to the gas, giving the impression that a few minor leaks were much more serious.
A web search for ‘natural gas leaks’ reveals a number of other incidents in the month of June, on both sides of the Atlantic. Twelve households in west London were evacuated for several hours while the source of a natural gas leak was located and fire crews ventilated homes.
Measures to minimise leakage
The EDF report comes as the Obama administration’s regulations, aimed at minimising methane leaks from the oil and natural gas industries, reach the final review stage.
The Environmental Protection Agency (EPA) has signalled that it will consider regulating methane leaks from newly drilled or modified natural gas wells. Drilling companies have responded by insisting that it is in their economic interest to reduce leaks and that efforts to do so are already underway.
Gas flow measurement has an important role to play in calculating leakage rates and managing energy supplies. For details of the flow measurement products provided by Exi Flow call the team on 01243 554920.