California Energy Commission Funds Project to Pinpoint Methane Super Emitters

The tiered methane observation program will use towers, aircraft, on-road vehicle surveys, post-meter residential and commercial measurements, and low-cost sensors to detect methane emissions. (Credit Berkeley Labs)[/caption]

Methane, an abundant greenhouse gas more than 25 times more potent than carbon dioxide in terms of its climate warming potential, is emitted from rice paddies, dairy farms, oil and gas production sites and landfills all over the world. Now the Lawrence Berkeley National Laboratory, or Berkeley Lab as it's more commonly known, has received a US$6 million grant from the California Energy Commission to pinpoint methane super emitters so that methane emissions can be quantified and potentially mitigated.

The focus area of the project is the southern San Joaquin Valley, where oil and gas production and dairy farming are the primary contributors of methane emissions to the atmosphere. The project, known as SUMMATION, short for SUper eMitters of Methane detection using Aircraft, Towers, and Intensive Observational Network, is a collaboration between Berkeley Lab and Stanford University, University California Riverside, Scientific Aviation, Central California Asthma Collaborative and Bluefield.

Berkeley Lab's new project to identify and mitigate methane "super emitters" will focus on the area in the white polygon. The smaller colored polygons show the diversity of methane emission sources in the area, with oil and gas fields in red, dairies in green, landfills in cyan, and natural gas infrastructure in purple. (Credit Berkeley Labs)[/caption]

"The existing methane accounting and monitoring frameworks in California are limited in their ability to resolve emissions at the scale of individual cities or facilities, such as an oil and gas field or a natural gas processing facility, much less individual components," said Sabastien Biraud, a Berkeley Lab scientist who leads the effort. "The idea for this project is based on the development of a tiered observation system."

The research team will monitor and quantify methane emissions at scales ranging from component and facility level to a regional scale. Various detection methods will be employed, including collection of air samples from a network of aircraft and fixed towers, onsite field campaigns where new innovations such as low-cost methane sensors are tested, transgressing the region by road using specially equipped vehicles, as well as conducting surveys of both commercial and residential buildings.

"We will show the state how methane emission quantification can be done over a complex region, and hopefully demonstrate that our approach can be replicated in a cost-effective manner to other areas of interest in California, such as the San Francisco Bay Area or the Sacramento region," Biraud said. "The goal is to design a framework, show that it works, and expand it throughout the state."

Monitoring Methane Accurately Can be a Challenge

Methane is a relatively short-lived greenhouse gas (GHG) as it only lingers in the atmosphere for around 10 years or so, compared to carbon dioxide, which is not only more prolific, but it also remains in the atmosphere far longer, around 100 years. By law, California is compelled to reduce its GHG emissions, and has earmarked short-lived GHGs such as methane as a top priority in order to see short-term positive impacts when it comes to addressing atmospheric warming as well as public health.

Last year, the State passed the California Cooling Act, which banned the use of some hydrofluorocarbons in new refrigeration and air conditioning systems. California also recently implemented atmospheric regulations that require oil and gas production sites, natural gas processing plants, as well as equipment used to process and deliver oil or natural gas to monitor methane emissions from these sites on a quarterly basis. While the state conducts regular inventories of its GHG emissions, numerous studies suggest these inventories are likely to be underestimating the actual volumes of methane being emitted. The southern San Joaquin Valley in particular lacks reliable atmospheric methane data, which in combination with the complex sources of methane in this region, leads to a significant amount of uncertainty with regards to determining the actual volume of methane emitted across the region, as well as its distribution over time, space and sector.

Super Emitters the Biggest Source of Methane

The SUMMATION project's prime target are the bigger sources or methane super emitters, Biraud points out.

"Methane emissions could be in the form of a distributed area of small leaks, which is difficult to address, or from a large super emitter, which is low-hanging fruit," Biraud said. "A statewide methane survey led by NASA's Jet Propulsion Laboratory from 2015 through 2017 found that 80% of methane emissions in California are from 25% of sources; in some cases, as few as 1% of sources contribute more than half the emissions. A super emitter could be a dairy, it could be a landfill which isn't well maintained, or it could be a leaking natural gas compressor station."

Using a variety of collection methods, including continuous and frequent field campaigns, will vastly improve methane monitoring and detection, says Biraud.

"Many sources are not persistent - they could be on for a few months, then off," Biraud said. "If you just do surveys one or two times a year, you're fishing. You might see a source, you might not. With a persistent network of towers, you address the nature of intermittent sources."

The SUMMATION project will employ tracers to help pinpoint methane sources. For example, methane emissions from the oil and gas industry contain certain alkanes (such as ethane) methane emissions from diary farms don't.

A key aspect of the project is to evaluate the effectiveness of affordable methane sensors.

"There are new technologies emerging," Biraud said. "We'll invite companies to participate, then deploy some of them over a one-year period."

Another important component of the project is community and stakeholder engagement.

"We'll be reaching out to disadvantaged communities, both to educate them on methane emissions and also to hear about their concerns in order to inform the development of future measurement systems," Biraud said. "These communities are affected disproportionately by methane and VOCs [volatile organic compounds]."