* Shell to limit methane emissions to 0.2 pct by 2025
* BP, Exxon have already set targets
* Methane is a potent greenhouse gas(Adds comment, details and background)
By Ron Bousso
LONDON, Sept 17 (Reuters) - Royal Dutch Shellannounced on Monday plans to limit leaks of methane, a potentgreenhouse gas, across its oil and gas operations as it tries tosharply curb carbon emissions.
Shell aims to maintain methane emissions below 0.2 percentof its total oil and gas production by 2025, it said in astatement, joining British rival BP, which last year seta similar goal. Larger rival Exxon Mobil announced in May plansto reduce methane emissions by 15 percent by 2020.
Methane is released into the atmosphere mostly from theburning of excess gas, known as flaring, as well as throughleaks in gas infrastructure such as wells, pumps and pipelines.
The gas has a bigger greenhouse impact than carbon dioxide,even though the oil and gas industry produces less methane andthe gas also has a shorter lifetime.
The methane target will be measured against a baseline leakrate, which is currently estimated at range from 0.01 percent to0.8 percent across the company's oil and gas assets, it said.
The Anglo-Dutch company set out last year an ambitious planto halve its carbon emissions by 2050, far exceeding rivals.Investors have called on the company to set binding targets toreach those goals.
Climate change and emissions, caused by burning fossilfuels, have moved to the forefront of discussions between energycompanies and investors since the signing of the 2015U.N.-backed Paris climate agreement that seeks to curb emissionsto zero by the end of the century in order to limit globalwarming.
"The race to near-zero methane emissions is on," said BenRatner, director at Environmental Defense Fund, U.S-basednon-profit climate advocacy.
"Company leadership on methane does not stop with settingtargets. Follow through with good data and transparency arevital."
Shell's methane emissions reached 123,000 tonnes last year,accounting for around 5 percent of its total greenhouse gasemissions, according to its website.(Reporting by Ron Bousso; Editing by Edmund Blair and MarkPotter)
