Better Rules for Natural Gas Leak Detection and Repair

by Robert Kleinberg
Institute for Sustainable Energy, Boston University

Methane, the main component of natural gas, is a powerful greenhouse gas agent.  Although anthropogenic emissions of methane are estimated at 0.3 gigatons per year, only 1% of the 36 gigatons of anthropogenic carbon dioxide emitted annually, the radiative forcing of methane is one-third that of carbon dioxide, relative to levels in 1750 [Etminan, Geophysical Research Letters, 2016]. 

I have for some time been concerned that the EPA regulations (40 CFR 60 Subpart OOOOa) tend to discourage technological innovation in methane leak detection and repair (LDAR) in natural gas production and transmission systems.  The original 2016 OOOOa rules lock in cumbersome and costly methods of leak detection.  

There is provision for other methods to be approved by the EPA – called “alternative means of emission limitation” (AMEL) – but these rules are also cumbersome and restrictive, and in fact no alternative means have been approved. 

In October 2018 the EPA proposed a reconsideration of the LDAR rules [Emission Standards for New, Reconstructed, and Modified Sources Reconsideration (2018), Docket ID No. EPA-HQ-OAR-2017-0483].  The reconsideration proposed weakening these rules in several respects, guaranteeing that more methane would enter the atmosphere from U.S. natural gas infrastructure.  However, I was surprised and encouraged to find improvements in the AMEL provisions.  But, in my opinion, even the improvements do not go far enough in encouraging technological innovation.

What both the original 2016 rule and the 2018 reconsideration overlook is that the underlying motivation for methane control regulations is the reduction of greenhouse gas emissions at the national level.  Although the OOOOa provisions are written to be site-specific, greenhouse gas emissions have national impact.  Therefore, an explicit goal of this regulation should be reduction of greenhouse gas emissions at the national level.

As a hypothetical, consider a methane detection system based on national technical means of verification, e.g. an earth-orbiting satellite capable of locating methane emission anomalies.  Such satellites are already in operation (e.g. GHGSat, GOSAT), though not yet necessarily capable of usefully directing repair efforts.  Foreseeable improvements may lead to satellite-based detection of super-emitters – sources of unusually large quantities of vented or fugitive methane – which may be responsible for the bulk of methane emissions [Ravikumar et al., Environ. Sci. Technol. (2017) 51 718, Supporting Information].  

Satellite or aerial surveillance is not capable of locating super-emitters at the component level, but it can eliminate facilities or groups of facilities from suspicion.  Then component-level leak detection can be focused on limited areas defined by the spatial resolution of the overhead measurement. Sites which overhead surveillance shows do not host super-emitters can be exempted from component-level inspection.

Thus, I contend that the detection and repair of super-emitters, with on-site component-level inspection triggered by overhead surveillance, may come to constitute a more effective means of mitigating anthropogenic methane emissions than sole reliance on methods specified by the 2016 OOOOa regulation, while materially  reducing the costs of compliance.  However, space-based and overflight means of surveillance are clearly outside the scope of both the 2016 and 2018 AMEL provisions.

Development and testing of new, more cost effective, methane detection paradigms and methodologies are likely to require significant research and development expenditures.  In order for innovators to make these investments, they must see the possibility of market access beyond individual sites (as specified by 2016 AMEL regulation) or even producing basins (as foreseen by the 2018 reconsideration).  Thus, regulations that permit only site-specific or even basin-specific comparison with component-focused measurements are very likely to inhibit development of some classes of technologies that could lead to larger national-level methane emission reductions at lower cost.  Therefore I propose specific changes in 40 CFR 60.5398a allowing methods to be judged based on their national impact on LDAR efficacy.  

The benefit of this national-level approach over the site specific method specified by the present and proposed AMEL provisions is, principally, a clear path to wide-spread commercialization.  This encourages innovators to invest the research and development resources required to bring genuinely new and more effective measurement paradigms and methodologies to market.  

Details about this regulation can be found at

https://www.regulations.gov/docket?D=EPA-HQ-OAR-2017-0483

My full submission to the EPA on this subject can be found at

https://www.regulations.gov/document?D=EPA-HQ-OAR-2017-0483-0760

Related post: Encouraging Congress to Enact the Best Possible Environmental Regulations

The opinions expressed herein are those of the author, and do not necessarily represent the views of the Boston University Institute for Sustainable Energy.

Robert Kleinberg is Principal of Presidio Energy Technology, a non-resident senior fellow of the Institute for Sustainable Energy at Boston University, and adjunct senior research scholar at the Center on Global Energy Policy of Columbia University.