39 research outputs found
The US government's social cost of carbon estimates after their first year: Pathways for improvement
No full textIn 2010, the U.S. government adopted its first consistent estimates of the social cost of carbon (SCC) for government-wide use in regulatory cost-benefit analysis. Here, we examine a number of the limitations of the estimates identified in the U.S. government report and elsewhere and review recent advances that could pave the way for improvements. We consider in turn socioeconomic scenarios, treatment of physical climate response, damage estimates, ways of incorporating risk aversion, and consistency between SCC estimates and broader climate policy
Supply and Demand Drivers of Global Hydrogen Deployment in the Transition toward a Decarbonized Energy System
No full textThe role of hydrogen in energy system decarbonization is being actively examined by the research and policy communities. We evaluate the potential "hydrogen economy" in global climate change mitigation scenarios using the Global Change Analysis Model (GCAM). We consider major hydrogen production methods in conjunction with delivery options to understand how hydrogen infrastructure affects its deployment. We also consider a rich set of hydrogen end-use technologies and vary their costs to understand how demand technologies affect deployment. We find that the availability of hydrogen transmission and distribution infrastructure primarily affects the hydrogen production mix, particularly the share produced centrally versus on-site, whereas assumptions about end-use technology primarily affect the scale of hydrogen deployment. In effect, hydrogen can be a source of distributed energy, enabled by on-site renewable electrolysis and, to a lesser extent, by on-site production at industrial facilities using natural gas with carbon capture and storage (CCS). While the share of hydrogen in final energy is small relative to the share of other major energy carriers in our scenarios, hydrogen enables decarbonization in difficult-to-electrify end uses, such as industrial high-temperature heat. Hydrogen deployment, and in turn its contribution to greenhouse gas mitigation, increases as the climate objective is tightened.
The National Security Dividend of Global Carbon Mitigation
No full textEnergy and environmental security objectives are often conflated in political circles and in the popular press. Results from a well-established integrated assessment model suggest that policies designed to stabilize atmospheric carbon dioxide concentrations at levels above ~500 ppm generally do not align with policies to curb global oil dependence, because these atmospheric objectives can be achieved largely through reductions in global coal consumption. Policies designed to stabilize atmospheric carbon dioxide at levels below ~500 ppm, on the other hand, directly facilitate the alignment of environmental and security objectives because atmospheric targets in this range demand significant reductions in both coal and oil use. Greater recognition that investment in carbon mitigation can yield significant security dividends may alter the political cost-benefit calculus of energy-importing nations and could increase the willingness of some key global actors to seek binding cooperative targets under any post-Kyoto climate treaty regime.
A consistent conceptual framework for applying climate metrics in technology life cycle assessment
No full textComparing the potential climate impacts of different technologies is challenging for several reasons, including the fact that any given technology may be associated with emissions of multiple greenhouse gases when evaluated on a life cycle basis. In general, analysts must decide how to aggregate the climatic effects of different technologies, taking into account differences in the properties of the gases (differences in atmospheric lifetimes and instantaneous radiative efficiencies) as well as different technology characteristics (differences in emission factors and technology lifetimes). Available metrics proposed in the literature have incorporated these features in different ways and have arrived at different conclusions. In this paper, we develop a general framework for classifying metrics based on whether they measure: (a) cumulative or end point impacts, (b) impacts over a fixed time horizon or up to a fixed end year, and (c) impacts from a single emissions pulse or from a stream of pulses over multiple years. We then use the comparison between compressed natural gas and gasoline-fueled vehicles to illustrate how the choice of metric can affect conclusions about technologies. Finally, we consider tradeoffs involved in selecting a metric, show how the choice of metric depends on the framework that is assumed for climate change mitigation, and suggest which subset of metrics are likely to be most analytically self-consistent
A theoretical basis for the equivalence between physical and economic climate metrics and implications for the choice of Global Warming Potential time horizon
No full textThe global warming potential (GWP) is widely used in policy analysis, national greenhouse gas (GHG) accounting, and technology life cycle assessment (LCA) to compare the impact of non-CO2 GHG emissions to the impact of CO2 emissions. While the GWP is simple and versatile, different views about the appropriate choice of time horizon--and the factors that affect that choice--can impede decision-making. If the GWP is viewed as an approximation to a climate metric that more directly measures economic impact--the global damage potential (GDP)--then the time horizon may be viewed as a proxy for the discount rate. However, the validity of this equivalence rests on the theoretical basis used to equate the two metrics. In this paper, we develop a new theoretical basis for relating the GWP time horizon and the economic discount rate that avoids the most restrictive assumptions of prior studies, such as an assumed linear relationship between economic damages and temperature. We validate this approach with an extensive set of numerical experiments using an up-to-date climate emulator that represents state-dependent climate-carbon cycle feedbacks. The numerical results largely confirm the theoretical finding that, under certain reasonable assumptions, time horizons in the GWP of 100 years and 20 years are most consistent with discount rates of approximately 3% and 7% (or greater), respectively
The US government's social cost of carbon estimates after their first year: Pathways for improvement
No full textIn 2010, the U.S. government adopted its first consistent estimates of the social cost of carbon (SCC) for government-wide use in regulatory cost-benefit analysis. Here, we examine a number of the limitations of the estimates identified in the U.S. government report and elsewhere and review recent advances that could pave the way for improvements. We consider in turn socioeconomic scenarios, treatment of physical climate response, damage estimates, ways of incorporating risk aversion, and consistency between SCC estimates and broader climate policy. --Climate change,social cost of carbon
Carbon offsets, reversal risk and US climate policy
No full textAbstract Background One controversial issue in the larger cap-and-trade debate is the proper use and certification of carbon offsets related to changes in land management. Advocates of an expanded offset supply claim that inclusion of such activities would expand the scope of the program and lower overall compliance costs, while opponents claim that it would weaken the environmental integrity of the program by crediting activities that yield either nonexistent or merely temporary carbon sequestration benefits. Our study starts from the premise that offsets are neither perfect mitigation instruments nor useless "hot air." Results We show that offsets provide a useful cost containment function, even when there is some threat of reversal, by injecting additional "when-flexibility" into the system. This allows market participants to shift their reduction requirements to periods of lower cost, thereby facilitating attainment of the least-cost time path without jeopardizing the cumulative environmental integrity of the system. By accounting for market conditions in conjunction with reversal risk, we develop a simple offset valuation methodology, taking into account the two most important factors that typically lead offsets to be overvalued or undervalued. Conclusion The result of this paper is a quantitative "model rule" that could be included in future legislation or used as a basis for active management by a future "carbon fed" or other regulatory authority with jurisdiction over the US carbon market to actively manage allowance prices.</p
