Airborne Methane Measurements to Continue Across California
The California Air Resources Board (CARB) has renewed their partnership with Scientific Aviation, an airborne atmospheric research outfit with offices in Lincoln, CA and Boulder, CO, in an ongoing effort to improve and validate the statewide methane emissions inventory.
Methane is a potent greenhouse gas that boasts a global warming potential (GWP) 84 times that of CO2 on a 20 year time horizon. Methane alone is responsible for an estimated 9% of California’s total greenhouse gas emissions. CARB estimated the 2014 statewide annual methane emissions at 40 MMT CO2e, with the majority of the total (59%) arising from agricultural activities such as dairy and beef cattle ranching; landfills (21%) and industrial activities (19%) constitute nearly all of the remainder.
The issue of methane emissions has received strong global attention, especially in the last ten years, and methane reduction plans have been at the forefront of regulatory discussions and international agreements relating to climate change. After a prolonged period of near-zero growth in the global atmospheric methane burden in the late 1990’s through early 2000’s, methane began rapidly increasing again in 2007, prompting a flurry of investigations and high-impact research seeking to uncover the sources behind this renewed growth. Hypotheses have included a range of explanations, from increasing oil and gas production or agriculture, to thawing permafrost or tropical wetlands. While a definitive answer has yet to be found, one thing that is clear is that high quality measurements of emissions fluxes from a range of sources are critical pieces to this puzzle.
Scientific Aviation has been patrolling the skies over California since 2010, measuring pollution and collecting air samples for institutions such as NOAA and the University of California Davis. Their single-engine Mooney airplanes have been modified for atmospheric research to draw in air through inlets located under the starboard wing and to analyze that air in real time for a variety of chemicals using specialized instruments housed in the rear luggage compartment. Sophisticated on-board meteorological sensors and navigation systems provide measurements of additional parameters such as temperature, humidity, and horizontal winds, allowing SA scientists to not only measure levels of atmospheric pollutants, but also to calculate the rate that those pollutants are being emitted.
When the Aliso Canyon gas storage facility in Porter Ranch suffered a catastrophic blowout in 2015, it was the Scientific Aviation aircraft, piloted by founder and CEO Stephen Conley, that the State of California called in to measure the leak rate. That leak turned out to be the largest natural gas leak in U.S. history, releasing 100,000 metric tons of methane to the atmosphere before it was repaired. SA’s ability to respond to that event and provide accurate, same-day emissions numbers to the state agencies and to SoCal Gas, demonstrated the strength of airborne emissions monitoring and the importance of conducting regular measurements for these facilities.
As coincidence would have it, only two weeks prior to the initial discovery of the Aliso Canyon gas leak, the Governor of California approved Assembly Bill 1496 (AB 1496), requiring the Air Resources Board to monitor and measure high methane emission hotspots within the state using the best available scientific and technical methods. And so, for the last two years, through a contract with CARB, Scientific Aviation has put their planes to work circling gas storage facilities, refineries, cattle ranches, landfills, and wastewater treatment plants, as well as checking up on Aliso Canyon itself, to get a better accounting of the state’s methane emissions.
On any given day, one might spot the SA Mooney flying low laps around a site, just as this Sacramento-based journalist observed at Kiefer Landfill recently.
These measurements are designed to increase our understanding of the magnitude of the methane emissions coming from these different sources, as well as shed new light on the variability of these sources over the course of months and years. After all, accurately knowing where methane emissions are coming from (and how much) is a critical part of determining the best approaches for reducing them. Now, with the renewal of this contract recently approved, these measurements are set to continue for at least another year, ensuring that SA airplanes will still be a regular sight in the sunny skies of California.