Methane Emissions from Venting and Flaring Are Lower than Previously Thought
Mon, July 09, 2018
The Obama-era regulation, known as the Waste Prevention Rule, targeted two routine oilfield practices: venting and flaring. Venting refers to the controlled release of gas, which operators use to prevent pressure buildups that would otherwise pose a hazard to workers onsite. Flaring is the combustion of excess gas, and is also used for safety purposes. Flaring is also often performed to comply with air quality regulations. Delays in natural gas pipeline approvals, particularly on federal lands, have forced operators to vent or flare excess gas that could otherwise be delivered to market.
The U.S. Environmental Protection Agency (EPA) publishes data on methane emission levels every year, including from venting and flaring. Methane emissions from oil and natural gas production activities have declined since 1990, and new EPA data show emissions from venting and flaring specifically are lower than what previous EPA assessments concluded.
- Methane emission levels from associated gas venting and flaring during petroleum production declined 17 percent between 2013 and 2016, even as domestic oil production increased by 19 percent.
- Methane emissions from hydraulically fractured natural gas well completions declined 82 percent between 2013 and 2016.
- EPA’s estimates for associated gas venting and flaring in 2015 are now 54 percent lower than what the agency estimated last year. Emissions estimates for prior years show even larger downward revisions.
- These lower emissions estimates could raise additional questions about controversial federal regulations targeting methane (CH4) from venting and flaring on federal lands.
Between 2013 and 2016 – the most recent year included in the U.S. Environmental Protection Agency’s latest Greenhouse Gas Inventory (GHGI) – methane emissions from associated gas venting and flaring during petroleum production declined by 9,122 metric tons, or roughly 17 percent.
Over this same period, domestic oil production increased by 19 percent, or nearly 1.4 million barrels per day. Further, from 2013 to 2016, methane emissions from “miscellaneous production flaring” nationally declined by almost 1,000 metric tons, equivalent to an 11 percent decline.
A similar trend can be seen in natural gas production. EPA data show significant declines in methane emissions during various production processes, such as gas well completions and workovers.
For example, methane emissions from hydraulically fractured natural gas well completions – with venting and flaring – declined by 82 percent between 2013 and 2016.
The emissions data were also downwardly revised from previous years, as new methodologies allowed for more accurate estimates. This is significant because EPA data were used in crafting the Obama administration’s Waste Prevention Rule, more commonly referred to as the venting and flaring rule. As a result, these downward revisions could raise questions about the original justification for the regulation, which was finalized by the U.S. Bureau of Land Management in December 2016.
In EPA’s 2017 Greenhouse Gas Inventory, for example, the agency estimated associated gas venting and flaring from petroleum systems totaled 3.7 million metric tons of carbon dioxide equivalent (MMT CO2 eq.) in 2015, which was the most recent year listed in the 2017 Greenhouse Gas Inventory. However, in this year’s Greenhouse Gas Inventory (2018), EPA reduced that 2015 estimate to 1.7 MMT CO2 eq. – or 54 percent less than previously thought.
Prior years saw even larger reductions, as associated gas venting and flaring estimates for 2014, 2013, and 2012 were revised down by 73 percent, 86 percent and 93 percent respectively.
It was not just venting and flaring that saw significant downward revisions in the 2018 Greenhouse Gas Inventory. In EPA’s 2016 Greenhouse Gas Inventory, methane emissions from petroleum production were estimated to be 67.4 MMT CO2 eq. in 2014. This was revised down to 43 MMT CO2 eq. in the 2017 GHGI – a 36 percent decline – and revised down again to 34.4 MMT CO2 eq. in the 2018 Greenhouse Gas Inventory.
In just two years, EPA slashed its 2014 petroleum production methane emissions estimate by almost 50 percent. Similarly, compared to the 2016 Greenhouse Gas Inventory report, the latest data show downward revisions of 49 percent and 50 percent for the 2013 and 2012 estimates of petroleum production methane levels, respectively.
Since 1990, total methane emissions from petroleum systems have also declined, which the EPA attributed in large part to lower emissions from venting:
“Petroleum systems methane emissions decreased by 1.2 MMT CO2 Eq. (or 3.0 percent) since 1990. This decrease is due primarily to decreases in tank emissions and associated gas venting.”
Environmental Protection Agency
The Obama administration promulgated the venting and flaring rule based on older EPA data suggesting methane emissions were far higher than what current EPA estimates suggest. As BLM put it when the rule was published in the Federal Register:
“The EPA data are based on methane emissions factors that are representative rather than actual. Even though data in these programs have recently been updated, they are still incomplete, and recent studies suggest actual emissions may be somewhat, or even substantially, higher than the emissions factors suggest. Thus, we believe that the estimates of losses used to support today’s rule, while substantial, are conservative.”
Bureau of Land Management
As it turns out, those data may not have been conservative, and indeed could be inflated compared to current estimates. The EPA’s 2016 GHGI would have been the latest report on which the Obama administration could have relied for its rulemaking, and the data tables in the 2016 GHGI do not break out venting and flaring the same way as subsequent GHGIs. It is also worth noting that the venting and flaring rule only targets emissions on federal and Indian lands, and thus the BLM’s methane emissions calculations would only represent estimates for federal and Indian lands.
While this makes it difficult to create a perfect apples-to-apples comparison, the overall downward revision in methane emissions from petroleum production since 2016, including the downward revisions in venting and flaring emissions specifically, suggests the Obama administration may have overestimated methane emissions when it finalized the venting and flaring rule. Venting emissions listed in the 2016 GHGI are also far higher than emissions listed for both venting and flaring in the 2018 GHGI.
Indeed, while the methane emissions estimates in the EPA Greenhouse Gas Inventory are nationwide and include production on state and private lands, BLM specifically referenced the Greenhouse Gas Inventory as “generally representative” of what venting emissions would be on federal and Indian lands, at least for most of the individual emissions sources. In its Regulatory Impact Analysis for the venting and flaring rule, published in November 2016, BLM wrote:
The venting and flaring rule is currently stuck in a legal quagmire, although opponents of the rule have had some recent success. In April, a federal judge ruled that a temporary suspension of the rule would remain in place, and an activist-supported maneuver to revive the rule was rebuffed by a federal appeals court last month.