posted on 2018-01-19, 00:00authored byArvind P. Ravikumar, Jingfan Wang, Mike McGuire, Clay S. Bell, Daniel Zimmerle, Adam R. Brandt
Methane, a key component of natural
gas, is a potent greenhouse
gas. A key feature of recent methane mitigation policies is the use
of periodic leak detection surveys, typically done with optical gas
imaging (OGI) technologies. The most common OGI technology is an infrared
camera. In this work, we experimentally develop detection probability
curves for OGI-based methane leak detection under different environmental
and imaging conditions. Controlled single blind leak detection tests
show that the median detection limit (50% detection likelihood) for
FLIR-camera based OGI technology is about 20 g CH4/h at
an imaging distance of 6 m, an order of magnitude higher than previously
reported estimates of 1.4 g CH4/h. Furthermore, we show
that median and 90% detection likelihood limit follows a power-law
relationship with imaging distance. Finally, we demonstrate that real-world
marginal effectiveness of methane mitigation through periodic surveys
approaches zero as leak detection sensitivity improves. For example,
a median detection limit of 100 g CH4/h is sufficient to
detect the maximum amount of leakage that is possible through periodic
surveys. Policy makers should take note of these limits while designing
equivalence metrics for next-generation leak detection technologies
that can trade sensitivity for cost without affecting mitigation priorities.