Sensing trouble

Touché Howard, standing in front of a valve from a natural gas transmission pipeline, questions the accuracy of methane emissions estimates due to faulty sensors in technology he invented.
Courtesy of Touché Howard

In the fight against global warming, both carbon dioxide and methane are known greenhouse gases that effectively trap heat in the earth’s atmosphere. Although there is disagreement on which gas contributes more significantly to global warming, experts and scientists across the spectrum conclude that methane ultimately traps heat at a rate of 20 to 100 times greater than carbon dioxide.

On Aug. 18 the U.S. Environmental Protection Agency (EPA) released proposed regulations to curb methane emissions from the oil and gas sector across the country by 40 to 45 percent from the 2012 measurements by 2025. These regulations are the first attempt by the EPA to address methane emissions specifically as the agency estimates close to 30 percent of methane emissions due to human activity in the U.S. are from the oil and gas industry.

The agency’s regulations propose emission standards for new developments for all production, processing, transmission and storage facilities associated with both oil and natural gas development. It will also require operators to find and repair leaks for these “new and modified emission sources.” The agency estimates this will result in a reduction of 400,000 short tons of methane, or the equivalent of 9 million metric tons of carbon dioxide, from oil and gas emissions by 2025, according to an email from Enesta Jones from the office of media relations. The EPA is currently taking public comment for 60 days following the regulations posting to the Federal Registrar on Aug. 27 and will consider all comments before making the final ruling, which it estimates will be released by spring 2016.

The oil and gas industry has long argued there are already enough regulations at both the state and federal level to mitigate methane emissions through voluntary programs and self-reporting mechanisms. “I don’t think industry is all too happy with the regulations,” says Harry Weis, chair of the environmental and natural resources practice at Ballard Spahr LLP, the law firm representing the oil and gas industry. “Industry would say in some places it might be hard to disagree, like in Colorado, ‘We’re already subject to regulations and the state is doing a fine job taking care of it.’”

But while the industry maintains this position, leading methane experts question the proposed EPA methane regulations as well.

Robert Howarth, professor of ecology and environmental biology at Cornell University, has been vocal about the severity of methane as a greenhouse gas for several years. Although Howarth is pleased that the EPA is directly addressing methane emissions in the proposed regulations, he still feels they fall short in two ways. First of all, the regulations only apply to new developments in the oil and gas industry — new wells, new facilities, new pipelines — without addressing the leakage from infrastructure already in use that may be anywhere from 50 to 100 years old.

The U.S. Energy Information Administration (EIA) reports 363,559 oil wells in its most recent data from 2009. Additionally, the EIA reports 487,286 producing natural gas wells in the U.S. as of 2013, making a combined estimated total of 850,845 oil and gas wells. The non-profit FracTracker Alliance reported 1,156,870 operational oil and gas wells in the U.S. as of February 2014, which they calculated from individual state reporting. Regardless of which number is accurate, none of these wells will be covered by EPA’s proposed regulations.

Secondly, Howarth contends the EPA has underestimated the extent of methane emissions and “under-characterized” methane’s contribution to overall greenhouse gas emissions on a national scale.

“They’re 10-fold off in terms of how important methane is as a starting point. And then they’re ignoring the current emissions and just looking at new infrastructure. It’s just way off the mark of what’s needed,” Howarth says.

He says the EPA has traditionally favored a bottom-up approach using source measurements to determine methane emissions rather than a topdown method, utilizing airplane flyovers to measure the amount of methane in the air at any given time. He questions this method, specifically how emissions are source-measured across the industry as the proposed regulations would rely heavily on the self-reporting of the oil and gas industry.

And Howarth’s concerns are not without merit.

In a paper released Aug. 4 in Energy Science & Engineering, Touché Howard reports sensor failures in the Bacharach high flow sampler, an EPA-approved instrument and a common device used by the oil and gas industry to report greenhouse gas emissions to the EPA through the Subpart W section of the Greenhouse Gas Reporting Program.

With a background in environmental engineering and air pollution control, Howard invented the high flow sampling system in 1993 and for the next decade any recorded measurements using the technology used either his sampler or one of his design. However, the device was not commercially available, so in 2003 Bacharach, Inc. developed the Bacharach high flow sampler for commercial use, implementing Howard’s idea but using different sensor technology.

The sampler utilizes two different sensors, a catalytic oxidation sensor and a thermal conductivity sensor. The oxidation sensor measures natural gas levels between 0 and 5 percent. If natural gas levels are higher than 5 percent, the sampler should automatically switch to the thermal sensor to accurately measure emissions. However, according to Howard’s tests, the Bacharach sampler failed to switch to the thermal sensor, meaning that the device was recording much lower emission rates than were most likely occurring.

Through further testing, Howard concluded in his paper that updating the software and frequently re-calibrating the device solves the sensor failures. Although he tells Boulder Weekly he recently saw a Bacharach sampler that still failed even after meeting these criteria. “We certainly think updated software and frequent calibration has been shown to improve performance dramatically but we still don’t understand all of the problems,” he says.

Howard says the discrepancies he’s found using the Bacharch high flow sampler has created uncertainty within the field of methane emissions based on measurements taken from the device. He also allows for variability across these measurements as not every device may be experiencing the same issues, depending on the version of software, frequency of recalibration and level of expertise of the person taking the measurements.

Howard accidentally happened upon this problem while testing a Bacharach device for a client in January 2013. He took measurements with the device and then compared those numbers to measurements done with his own sampler, at which point he noticed a difference. He didn’t do much with his knowledge at first, but in October 2013 when an Environmental Defense Fund study out of the University of Texas released its findings of methane emissions at natural gas facilities based on measurements using the Bacharach sampler, Howard realized the problem could have far-reaching consequences. Although he alerted the authors of the study to the issue he experienced with the sampler, it took him almost two more years to conduct his own study and publish his findings at the beginning of August 2015.

“If we had disclosed this in the fall of 2013, that’s a whole other year of Subpart W measurements that were made without people realizing there were problems,” Howard says. “Second, the Environmental Protection Agency could look at this issue and say, ‘Hmm maybe we could do preliminary regulations but factor in the fact that we don’t have enough data yet and allow for modifications as more data came in.’”

Howard says that if the EPA Subpart W inventories are too low based on the faulty sensors and the agency is using that data as a basis for their emission reduction goals, “They might be using the wrong target to start with. Their baseline number could be too low,” Howard says. He says his findings are important not only for methane emission measurements that go to the EPA, but also present safety risks at facilities that are using the Bacharach device to detect leaks.

Howard’s research causes Howarth to question the EPA regulations further. “How do you know it’s leaking if you’re using the sort of instrument Howard just criticized?” he asks. However, both Howard and Howarth remain unclear whether or not measurements using the Bacharach high flow sampler went into the recent proposed regulations. “They’re (EPA) not good at documenting what they’re doing,” Howarth says.

Anthony Marchese, professor of mechanical engineering at Colorado State University, has also studied natural gas emissions and proposes another theory for the data EPA uses as the 2012 baseline for emission reductions proposed by the regulations. He suggests the EPA could have used the Greenhouse Gas Inventory (GHGI) to determine emission levels in 2012 instead of reported emissions. GHGI is an annual report released by the EPA tracking greenhouse gas emissions by source and economic sector.

However, Marchese questions the validity of this approach. “We know [GHGI] is based on years of estimates without a lot of direct measurements…” Marchese says. “It’s a comparison to something that has a lot of uncertainty in it.”

Marchese says the GHGI is based on measurements taken over 20 years ago, that the EPA “tweaks” every year. “You really have to take the GHG inventory with a grain of salt,” he says.

Like Howarth, Marchese is skeptical of the numbers coming out of the EPA, specifically the leakage rates coming from natural gas, the sector he is most familiar with. “The GHGI right now, if you do the calculation, would suggest that there is an overall leakage of 1.3 percent. I’m seeing almost .5 percent from gathering and processing and that’s only one step in the process. When we add gathering and processing to transmission and storage, distribution and production, I’d be shocked if we come in at 1.3 percent. I think we’ll be coming in at a little north of 2 percent,” Marchese says. Howarth estimates a 10 percent leakage rate.

But both scientists agree that despite these discrepancies, the regulations still fall short due to the fact they would only apply to new infrastructure and don’t address leaks and other emissions at current facilities, tying the estimated reductions to production in a time when the oil and gas industry is slow. “When we’re going gangbusters and drilling new wells, those new wells are going to adhere to these new standards, but if we don’t drill any new wells there will be less changes, so it’s a little bit ironic there,” Marchese concludes.

Boulder Weekly made multiple attempts (a phone call and nine emails) to speak with someone at the EPA to answer our questions about what specific information was used to determine methane emission levels. We received the following statement via email as a response.

The proposed New Source Performance Standards would avoid future emissions from several types of new and modified equipment and processes (called “sources”). Estimating those avoided emissions involves several steps, including: estimating emissions from each type of source covered by the proposed rule; projecting industry growth, so we can estimate what emissions would be from new and modified sources without the rule; then applying the requirements of the rule to each type of source to estimate the reductions the rule would yield.

In making these estimates, EPA uses the best available information. For this proposed rule, that included the U.S. GHG inventory and EPA analyses, among other information resources.

EPA compiles the U.S. GHG Inventory annually as a requirement under the United Nations Framework Convention on Climate Change. Substantial amounts of new information on the oil and gas sector have become available recently and additional information will become available in the coming years from a number of channels, including EPA’s GHGRP, and research studies by government, academic, and industry researchers, and industry organizations. EPA will continue to refine its emission estimates to reflect the most robust and up to date information available.

EPA will host a public hearing concerning the proposed regulations at their Denver office on Sept. 23.