There is growing recognition of the value of near-term actions to reduce short-lived climate pollutants (SLCPs) such as methane, black carbon, and various hydrofluorocarbons that have large global warming potentials. Urgent actions to reduce these SLCPs are needed to avoid warming that could occur over the next few decades and irreversible (or difficult to reverse) consequences of climate change, such as the melting of artic snow cover, which in turn could trigger a further release of methane. Reducing emissions of SLCPs can also reduce air pollution and improve public health.
In September, California became first in the United States to establish statewide targets for reducing emissions of SLCPs. State Senate Bill 1383 requires the state’s Air Resource Board (ARB) to approve and begin implementing a comprehensive SLCPs mitigation strategy by January 2018. The law requires emissions reductions of methane and hydrofluorocarbon gases by 40 percent and anthropogenic black carbon by 50 percent below 2013 levels by 2030.
To achieve these goals, the law requires state agencies to develop policies and incentives to reduce methane emissions from landfill sites and livestock and dairy operations. Agencies will launch a process of public engagement, consider and adopt policies and incentives, and assess markets and infrastructure for diverting wastes to other uses, including biogas, a mixture of methane and carbon dioxide produced by the breakdown of organic matter in the absence of oxygen. The use of biogas in transportation will earn credits pursuant to regulations under the state’s Low-Carbon Fuel Standard Program. An important aspect of the landfill requirement is a 50 percent reduction in disposal of organic waste from 2014 levels by 2020, and a 75 percent reduction by 2025. It requires a 20 percent reduction in the disposal of edible food by 2025. However, the ultimate outcome and success of these policies remains uncertain because while the goals are now in statute, further legislative action may be needed to achieve them or to lower the goals. The initiative is subject to the midterm progress review in 2020.
Our previous research at RFF has assessed one of the policy pathways that could be taken by the legislature—the capture of methane from animal farm operations in California and its use in generating electricity. We used an integrated-process economic model to identify and estimate the climate and health benefits that could be achieved and to identify market-based approaches that could be adopted to provide incentives for this strategy. Three specific policy options include the use of greenhouse gas offset credits for methane control, particulate matter offset credits for ammonia control, and expanded net metering policies to provide revenue for the sale of electricity generated from captured methane gas. Individually, any of these policies appears to be sufficient to provide the economic incentive for farm operators to reduce emissions. Our research did not consider additional societal benefits associated with electricity-sector carbon dioxide emissions displaced by generation from methane digesters, or other environmental benefits, such as nutrient and resource recovery and improvements in water quality.
Given uncertainty in the economic conditions (e.g., natural gas price, economies of scale, credit price) as well as in the physical science (e.g., performance of biogas production rate), modeling analysis with considerations of these uncertainties could provide information for policymakers to set emissions reduction targets. Energy and resources recovery from diverted waste could potentially provide both private and social benefits. We are glad to see that California made the first step to explore the technical, economic, financial, and policy feasibilities.