Much of the potent greenhouse gas could be captured with existing technologies and profitably.
Mar 3, 2014 |By Stephanie Paige Ogburn and ClimateWire
Nearly half the methane released into the atmosphere from the U.S. oil and gas industry could be eliminated using existing technologies at an affordable cost, according to a study released today.
The report, by the analyst group ICF International, was commissioned by the Environmental Defense Fund (EDF), an environmental group spearheading an effort to measure and decrease emissions of methane from natural gas.
“We can achieve a 40 percent reduction in methane emissions for less than a penny per mcf [thousand cubic feet] of gas produced. That’s a pretty good deal,” Mark Brownstein, EDF’s associate vice president and chief counsel for U.S. climate and energy, said in a conference call about the report.
Methane is a greenhouse gas about 30 times more potent than carbon dioxide over a 100-year period, according to the most recent report of the Intergovernmental Panel on Climate Change.
Reducing methane emissions from U.S. oil and gas operations, along with CO2 emissions reductions, is a cost-effective way for the country to meet its climate goals, Brownstein said.
Another important finding in the study is that about 20 percent of methane emission sources account for 80 percent of the total methane leaked, said Joel Bluestein, a senior vice president of ICF International.
This is potentially good news, since it means a significant quantity of leaks can be plugged by addressing a relatively small percentage of sources.
The report found that, by 2018, methane emissions will grow 4.5 percent from 2011 levels, with most of the growth from the oil sector. Despite the growth in emissions coming from oil drilling, natural gas will still constitute three-quarters of methane emissions from the U.S. oil and gas sector in 2018.
The 138-page report includes pie charts outlining the major types of leaks and where reductions could take place.
Mainly low-tech solutions
Just more than a third of reductions could be accomplished by leak detection and repair, where an inspector goes out quarterly to find leaks and identify them for repair.
Another 30 percent of reductions come from replacement of pneumatic devices with ones that leak less. About a quarter come from reduced methane venting from wells and equipment, and the remaining 12 percent of reductions are from capturing gas leaking from a type of equipment called a wet-seal compressor.
ICF International consulted with industry groups to ensure the costs and methods outlined in the report made sense from an industry perspective, Bluestein said.
The report also contains figures called marginal abatement cost curves, where leaky sectors of the oil and gas industry are lined up in bars representing their leakiness as well as the cost of reducing methane emissions from that sector.
As the figures show, reducing emissions in some of the sectors targeted for reduction would actually save industry money and could potentially eliminate a lot of lost methane, including by replacing high-bleed pneumatic devices with low-bleed ones and capturing the gas from wet-seal compressors.
Other areas targeted for emissions reductions, including reducing fugitive emissions from wells and reducing leaks in the natural gas distribution system, end up costing companies more than they save.
The total cost for gas companies to reduce emissions by 40 percent, adding up both savings and expenses, would be $108 million a year, according to the report.
The measure that saved gas companies the most money — $4.05 per thousand cubic feet of gas — involved replacing one type of pump known as a Kimray pump with an electric pump. The priciest measure, leak detection and response at large local gas distribution companies, was set at $19.75 per thousand cubic feet of gas.
Where fixes become expensive
Distribution, or the system of pipelines that gets gas to people’s houses, is one of the tougher areas to fix and find leaks, since some of the oldest, leakiest pipes are in dense urban areas, where finding and fixing them can be very costly, said EDF’s Brownstein — one reason that sort of leak detection and plugging was the most expensive.
In the natural gas distribution system, companies often do not lose money for what is called “lost and unaccounted-for gas” and can bill customers for that lost gas (ClimateWire, Aug. 1, 2013).
Public utilities commissions can play a role in encouraging utilities to plug these leaks, though, Brownstein said, mentioning a pilot project recently approved in New York for Con Edison to prioritize and reduce its backlog of leaks that are known but not a public health threat, and thus not a priority for repair.
Another way to look at cost savings is through economywide savings: the benefit to the overall economy from methane being captured rather than lost to the atmosphere. When the report authors took that into account, the total cost of reducing emissions was actually negative, saving the overall economy (which includes natural gas customers) $150 million a year.
Although there are still uncertainties about just how much methane is leaking into the atmosphere from oil and gas, and where the leakage is occurring, that does not preclude regulators and industry from taking action now to reduce leaking methane, Brownstein said.
“There are important scientific questions to be answered, but we already know enough to get started addressing the problem,” he said.