Natural gas is a relatively clean burning fossil fuel — relative to coal, that is. Then we figured out that natural gas could warm the planet as much as coal in the short term, due to methane leaks along the supply chain.
Methane is about 86 times more potent than carbon dioxide over a 20-year time period, and there is a point where methane emissions along the value chain could completely undo any climate benefits of switching to natural gas as a transition fuel.
As a result, the oil and gas methane emissions discussion has focussed on assessing methane emissions from gas. Both U.S. and Canadian companies are also focusing more on methane due to the anticipation of future regulatory requirements.
Recognizing that it is difficult to compare performance between companies on the basis of total emissions because production varies so significantly from company to company, industry and scientists alike sought to normalize performance on an intensity basis.
Clear and consistent methane measurement
It becomes important, however, to ensure that the selected intensity metric fairly compares performance between assets and is not biased by portfolio.
For example, a methane intensity metric that considers total methane emitted in the numerator and either gas produced or gas to market in the denominator is biased in favor of dry gas-producing assets.This is because in an oil production region, such as the Permian Basin, methane emissions are attributable to both the natural gas portion and oil production.
A metric that includes all those methane emissions normalized only by the gas production errantly attributes the methane emissions only to the gas.
This was the basis for a call for consistent metrics by David T. Allen, Qining Chen, and Jennifer B. Dunn. In their article, they illustrate the implications of the selected metric. Ultimately, they recommend:
“To promote clarity and transparency, and until a global consensus is reached regarding the most appropriate allocation method for upstream oil and gas emissions, if normalized methane emissions are reported, they should be reported on three bases: normalized by the energy content of the natural gas produced, by the energy content of the natural gas and natural gas liquids produced, and by the energy content of the oil, natural gas, and natural gas liquids produced. If a normalized emission unit expressed as a percentage is desired, the methane emissions could be reported based on their energy content.”
Having consistent metrics in place, along with the right measurement systems, will make it easier for companies to set and meet their methane emission targets.
Interested in learning more about measuring methane emissions? Speak with our experts.
Erin is the Senior Advisor, Carbon Strategies for Validere. She brings expertise on emissions estimating, measurement, and reconciliation and uses data to inform actionable emissions reduction strategies.