trace amounts (about 510 ppb). The GWP 100 for Hydrogen is 5±1, but this figure downplays its impact. GWP deemphasises the climatic importance of short-lived molecular species such as hydrogen and methane. In the troposphere, hydrogen reacts with OH radicals, the main sink for atmospheric methane and affects the chemistry of ozone. It also impacts water vapour levels in the stratosphere (see Figure 9 ), (Ocko & Hamburg, 2022). It will be crucial to minimise the leakage of hydrogen from the outset, starting with the design specifications for repurposed and new infrastructure for the synthesis, storage, distribution and use of hydrogen. Regulatory action should underpin industry voluntary actions The International Energy Agency’s (IEA) “Driving down methane leaks – A regulatory roadmap and toolkit” (IEA, 2021b) supports the design and implementation of government policies that can overcome barriers due to a lack of information, the development of infrastructure for capturing natural gas and incentivises investment for the reduction of methane emissions. IEA advocates a combination of four regulatory approaches, classified as Prescriptive, Performance based, Economic, and Information based: • Prescriptive regulations require actions by a target date, such as: a) Requirements for Leak Detection and Repair (LDAR) programmes and b) Technology standards with equipment specifications. One example used by signatories to the Global Methane Initiative is the replacement of high-bleed pneumatic devices. • Performance-based approaches that set goals based on an outcome. Examples include: a) The 30% reduction by 2030 as per the Global Methane Pledge and b) Emissions intensity (0.2%) or absolute emissions reduction targets used by companies in OGMP 2.0. • Economic approaches include carbon taxes or tradable emissions allowances and credits, such as the EU Emissions Trading System (ETS) • Information-based instruments include mandatory data collection and reporting
requirements, as well as requirements for public disclosure.
Technologies for detection and monitoring of leaks LDAR programmes aim to detect, locate, and repair fugitive leaks of volatile organic compounds, including methane. LDAR is used across the entire supply chain from upstream, midstream (pipelines and shipping) to downstream. In addition, continuous monitoring based on remote or facility-based sensors can abate emissions from large but sporadically occurring leaks. Annex VI of the “Report for the Madrid Forum in June 2019” (gie/Marcogaz, 2019) provides a review of available techniques for detection and quantification of methane leaks (and other VOCs). The gas industry typically uses a source- specific, 'bottom up' approach. A couple of examples include: On-site monitoring and detection of methane leaks Handheld devices, used by operators or maintenance engineers, utilising standard (such as EPA 21 or EN15446) methods based on: • Flame-ionisation detector (FID) to sample the concentration of methane ('sniffing') • Quantitative Optical Gas Imaging (OGI) using infra-red cameras with real-time image processing (Quantitative OGI or QOGI). A study in the US showed the importance of surveyor training to increase the detection resolution of OGI (Zimmerle, et al. , 2020). Airborne detection for pipeline monitoring Unmanned aerial vehicles or drones equipped with miniaturised gas analysers are a lower-cost alternative to helicopters to monitor pipelines and remote equipment. One example is ABB’s HoverGuard drone, equipped with laser-based Integrated Cavity Output Spectroscopy (OA-ICOS), capable of detecting variations in ambient methane gas concentrations at ppb levels (ABB, 2021). Satellites have significantly increased the world’s knowledge of emission sources. Scientific institutes and agencies are combining
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