Timelines for mitigating the methane impacts of using natural gas for carbon dioxide abatement

Abstract

Reducing carbon dioxide (CO 2 ) emissions through a reliance on natural gas can create a hidden commitment to methane (CH 4 ) leakage mitigation. While the quantity of CH 4 leakage from natural gas has been studied extensively, the magnitude and timing of the CH 4 mitigation required to meet climate policy goals is less well understood. Here we address this topic by examining the case of US electricity under a range of baseline natural gas leakage rate estimates and emissions equivalency metrics for converting CH 4 to CO 2 -equivalent emissions. We find that CH 4 emissions from the power sector would need to be reduced by 30%-90% from today's levels by 2030 in order to meet a CO 2 -equivalent climate policy target while continuing to rely on natural gas. These CH 4 emissions reductions are greater than the required CO 2 reductions under the same policy. Alternatively, expanding carbon-free sources more rapidly could meet the 2030 target without reductions in natural gas leakage rates. The results provide insight on an important policy choice in regions and sectors using natural gas, between emphasizing a natural gas supply chain clean-up effort or an accelerated transition toward carbon-free energy sources.

Consequences of equivalency metric design for energy transitions and climate change

“…Interactions between the budget design and metric selection can also lead to initially counterintuitive results, especially if metrics are time-dependent. For example, a policy that defines emissions limits based on a percent reduction relative to a base year would lead to the greatest emissions reductions if there is a large difference between initial metric values (when the base year is defined) and later metric values (when emissions must be reduced) (Klemun and Trancik 2020).…”

“…Efforts to mitigate climate change, such as replacing coal with natural gas in the energy sector (Brandt et al 2014;McJeon et al 2014;Zhang et al 2016;Alvarez et al 2012;Alvarez et al 2018;Tanaka et al 2019;Mallapragada and Mignone 2017;Klemun and Trancik 2020), may involve a tradeoff between short-lived greenhouse gases (e.g., methane, CH 4 ) and long-lived carbon dioxide (CO 2 ). Equivalency metrics are frequently used to convert emissions of various gases into equal mass emissions of CO 2 (in CO 2 -equivalent units).…”

Research priorities for supporting subnational climate policies

“…Meeting this need requires researchers to frame questions from the perspectives of actors in the field, and to present results using levers that they can directly control. New methods are needed to (a) combine large‐scale modeling with local data and perspectives to target insights to the more immediate, human scales at which decisions are made and (b) translate climate risks and energy system targets into specific decision levers in technology design, consumption choices, business strategy, agriculture planning, infrastructure management, and public policy (Cui et al, 2019; Dietz, Gardner, Gilligan, Stern, & Vandenbergh, 2009; Gurney et al, 2015; Howden et al, 2007; Iyer et al, 2017; Klemun & Trancik, 2019; Miotti et al, 2016; Trancik et al, 2014; Trancik & Cross‐Call, 2013; Weber et al, 2018; Wynes & Nicholas, 2017).…”

“…However, translating these results into decision‐relevant metrics that can be used by investors and local policymakers is critical. Some recent research has discussed a range of metrics for tracking progress in energy transitions and informing investments in new technologies (Peters et al, 2017; Trancik & Cross‐Call, 2013), including lifetime limits for coal plants (Cui et al, 2019), timelines for mitigating methane emissions from natural gas infrastructure (Klemun & Trancik, 2019), and comparisons of the costs and emissions intensities of different generation sources (Miotti et al, 2016; Trancik et al, 2014). However, further research is needed to uncover policy levers and inform decisions.…”

“…Our comments draw on a set of conversations we held with representatives in business, government, NGOs, and educational institutions actively engaged in local or regional climate action (Personal Communication, 2017), as well as our own research (Edwards et al, 2017; Edwards & Trancik, 2014; Kavlak, McNerney, & Trancik, 2018; Klemun & Trancik, 2019; Miotti, Supran, Kim, & Trancik, 2016; Needell, McNerney, Chang, & Trancik, 2016; Trancik, 2017; Trancik et al, 2015; Trancik, Chang, Karapataki, & Stokes, 2014; Trancik & Cross‐Call, 2013). The stakeholders we spoke with called for not just more but also different research to design effective subnational climate policies.…”