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Climate Change

Methane Emissions From Oil & Gas 27% Higher Than Earlier Estimates

Originally published on EDF.
By David Lyon

Methane emissions from the oil and gas industry are significantly higher than previous official estimates, according to draft revisions of the U.S. greenhouse gas emissions inventory released Monday by the Environmental Protection Agency. At 9.3 million metric tons, revised estimates of 2013 emissions are 27% percent higher than the previous tally. Over a 20-year timeframe, those emissions have the same climate impact as over 200 coal-fired power plants. The lost gas is worth $1.4 billion at 2015 prices.

2014EPAInventory2The big jump makes it crystal clear that there can be no more excuses for ignoring this huge challenge – not only controlling methane emissions from future sources, as proposed new EPA rules will do, but also controlling emissions from the tens of thousands of leaking facilities already operating now. Existing systems account for all of today’s emissions, and will generate the lion’s share of pollution for many years to come, yet federal rules so far don’t apply to them.

EPA is expected to use similar calculations to estimate 2014 emissions when it publishes the final inventory sometime between now and April 15. EPA also plans to update estimates of previous years’ emissions going back to 1990 based on revised methodologies.

The new estimate drastically exceeds modest improvements in several subsectors in prior years, which have been widely touted by industry lobbyists who oppose new rules and claim voluntary emissions reductions can get the job done.

The revised figure is based on new, more accurate accounting methods reflecting the significant improvement in scientists’ understanding of the problem in recent years. While the new figures still do not encompass the full scope of the industry’s methane footprint (see below), they paint a more thorough portrait of real world conditions. Although major gaps remain, EPA deserves credit for their efforts.

What Changed & Why?

As U.S. oil and natural gas production have soared, scientists have made great strides in their understanding of the industry’s methane emissions. EPA is updating its accounting methods to begin incorporating the latest scientific evidence by more accurately reflecting both the number and type of sources in the field, and the amounts of methane they emit.

2013 Emissions (MMT CH4)
2015 GHGI Draft 2016 GHGI % change
Production & Gathering 1.9 4.2 125%
Processing 0.9 0.9 -2%
Transmission and Storage 2.2 1.2 -47%
Distribution 1.3 0.5 -65%
Natural Gas Systems 6.3 6.7 7%
Petroleum Systems 1.0 2.5 150%
Natural Gas & Petroleum Systems 7.3 9.3 27%

SOURCE: EPA, 2015 GHGI and Draft 2016 GHGI, tables 3-37 and 3-44.

The largest leap in emissions (and second biggest percentage jump) is in the production and gathering sector. That’s because EPA is increasing their estimates of equipment counts at well pads and factoring in emissions from thousands of gathering facilities that collect gas from multiple wellheads, which had been almost completely ignored in earlier accounting. As it turns out, they’re emitting as much as 1.7 million metric tons of methane a year, almost none of which showed up on the books until now.

The biggest percentage increase is in the oil sector (petroleum systems), due to increased estimates of equipment counts at oil production sites.

Based on current research, EPA is also estimating that emissions from several segments are actually lower than previously thought. As proposed, the new figures for transmission and storage show a marked decrease (but this excludes “superemitters” – the widespread, unpredictable leaks, malfunctions or other problems – responsible for a significant share of industry emissions).

Local gas distribution also reflects progress on controlling emissions due mainly to improved technology and better operating practices on the part of local utilities, but estimates undercount emissions associated with industrial meters, and may not fully account for the number of leaks in the nation’s vast network of distribution pipes.

Until now, EPA had been relying mostly on data from the 1990s – before the start of the shale boom – to derive national emission estimates. Methane is the main ingredient in natural gas, and also a major byproduct of oil and gas production. It’s important because methane has 84 times the warming power of carbon dioxide over a 20-year timeframe.

EPA is continuing to refine their calculations and emphasizes that the numbers in the draft will likely change between now and the final version, based on stakeholder feedback on a series of detailed technical memos published by the agency. This is the fourth time in recent years that EPA has revised their accounting methods in order to get closer to the actual facts on the ground.

Emissions EPA Still Leaves Out

Over the past five years, academic and industry researchers have made extensive efforts to develop a better sense of what’s leaking where, how much, and why, and to create a better census of operating equipment. Some of that research is included in EPA’s new accounting methods, but not all. A recent study of methane in Texas’ Barnett Shale, for example, found oil and gas methane emissions could be 90% higher than estimates based on the GHG Inventory, in part because inventories often don’t count super emitters.

Case in point: the recent Aliso Canyon disaster in California released nearly 100,000 tons of methane, but operators aren’t required to report that type of pollution to regulators – nor is there a method for EPA to consider these emissions in their official estimates. Aliso Canyon is the “mother” of all super emitters, but research shows similar problems happening on a smaller scale every day throughout the supply chain.

In fact, the science suggests overall U.S. methane emissions from all sources are likely anywhere from 25- to 75% higher than EPA estimates. It is likely that a sizeable chunk of that discrepancy results from the widespread problem of super emitters and underestimated equipment counts in the oil and gas industry.

Big Step Forward

While critical gaps remain in accounting for all oil and gas methane emissions in the EPA inventory, this new draft represents important progress. The dramatic figures make it more clear than ever that the time to regulate existing sources – the sources responsible for this 9.3 million ton problem – is now.

Reprinted with permission.

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