PREFACEThis is one report in a series that explores the costs, benefits, and other impacts of state renewable portfolio standards (RPS), both retrospectively and prospectively. The terminology applied in this series does not align precisely with the traditional concepts of costs and benefits, but rather is a function of how RPS programs have often been evaluated in practice. In particular, this analysis series evaluates RPS programs in terms of the following:• RPS compliance costs represent the incremental cost of meeting RPS compliance obligations, from the perspective of the utility or other load-serving entity, compared to the costs that would have been borne in the absence of the RPS. RPS compliance costs may be negative, if the renewable electricity used for RPS compliance is less expensive to the utility than the alternatives.• Benefits, as analyzed in this report series, consist specifically of environmental benefits that accrue to society at large, rather than to individual utilities. In theory, such benefits may be negative, representing net environmental costs, if the renewable electricity used for RPS compliance leads to more harmful environmental impacts than it avoids.• Other impacts, in the form of resource transfers from one market participant or segment to another, are also evaluated. These other impacts may also entail net costs or benefits to society at large, but our analyses focus only on the gross impacts, not the net cost or benefit. This report, the second in the series, analyzes historical benefits and impacts of all state RPS policies, in aggregate, employing a consistent and well-vetted set of methods and data sets. The analysis focuses on three specific benefits: greenhouse gas emissions, air pollution, and water use. It also analyzes three other impacts: gross job additions, wholesale electricity market price suppression, and natural gas price suppression. These are an important subset, but by no means a comprehensive set, of all possible effects associated with RPS policies. These benefits and impacts are also subject to many uncertainties, which are described and, to the extent possible, quantified within the report.The present report is intended to help policymakers, RPS administrators, and other decision-makers gauge the potential significance of a number of key benefits and impacts from state RPS programs. By noting limitations, caveats, and uncertainties in these results, the report also seeks to highlight important methodological considerations to evaluating RPS benefits and impacts. This report does not, however, provide a complete picture, and comparable information on both the costs and benefits, as well as other impacts, are ultimately needed to inform decision-making. To that end, a third report in this series is planned for the coming year to evaluate the future costs, benefits, and other impacts of state RPS policies, under both current policies and possible revisions. A prior study ) and subsequent update in this report series found that RPS compliance costs over the 2...

Renewable portfolio standards (RPS) exist in 29 US states and the District of Columbia. This article summarizes the first national-level, integrated assessment of the future costs and benefits of existing RPS policies; the same metrics are evaluated under a second scenario in which widespread expansion of these policies is assumed to occur. Depending on assumptions about renewable energy technology advancement and natural gas prices, existing RPS policies increase electric system costs by as much as $31 billion, on a present-value basis over 2015−2050. The expanded renewable deployment scenario yields incremental costs that range from $23 billion to $194 billion, depending on the assumptions employed. The monetized value of improved air quality and reduced climate damages exceed these costs. Using central assumptions, existing RPS policies yield $97 billion in air-pollution health benefits and $161 billion in climate damage reductions. Under the expanded RPS case, health benefits total $558 billion and climate benefits equal $599 billion. These scenarios also yield benefits in the form of reduced water use. RPS programs are not likely to represent the most cost effective path towards achieving air quality and climate benefits. Nonetheless, the findings suggest that US RPS programs are, on a national basis, cost effective when considering externalities.

We model scenarios of the U.S. electric sector in which wind generation reaches 10% of end-use electricity demand in 2020, 20% in 2030, and 35% in 2050. As shown in a companion paper, achieving these penetration levels would have significant implications for the wind industry and the broader electric sector. Compared to a baseline that assumes no new wind deployment, under the primary scenario modeled, achieving these penetrations imposes an incremental cost to electricity consumers of less than 1% through 2030. These cost implications, however, should be balanced against the variety of environmental and social implications of such a scenario. Relative to a baseline that assumes no new wind deployment, our analysis shows that the high-penetration wind scenario yields potential greenhouse-gas benefits of $85-$1,230 billion in present-value terms, with a central estimate of $400 billion. Air-pollution-related health benefits are estimated at $52-$272 billion, while annual electricsector water withdrawals and consumption are lower by 15% and 23% in 2050, respectively. We also find that a high-wind-energy future would have implications for the diversity and risk of energy supply, local economic development, and land use and related local impacts on communities and ecosystems; however, these additional impacts may not greatly affect aggregate social welfare owing to their nature, in part, as resource transfers.

Funding for this report came from the U.S. Department of Energy's Vehicle Technologies Office. This work has benefited from guidance and input provided through discussions and reviews with an advisory committee established through the U.S. Department of Energy and the Edison Electric Institute (EEI), which emerged as a result of the recent Memorandum of Understanding between the two organizations. Members of the EEI advisory committee include

Table of Contents 1 Methods .