Abstract: Over the last half decade, a variety of federal legislative proposals for limiting greenhouse gas (GHG) emissions have been put forward, most of which would set a price on carbon. As of early 2013, the one politically plausible policy appears to be a carbon tax, passed as part of a larger fiscal reform package. Meanwhile, the US Environmental Protection Agency has begun regulating GHG emissions from a variety of sources using its authority under the Clean Air Act. It may be necessary to choose between these two policies, however. The Waxman–Markey cap-and-trade bill that failed in 2009 would have preempted much of this authority, and it appears likely that a carbon tax law would do the same. But how can one make this choice? What are the key questions and issues to consider? The purpose of this paper is to compare these policies. Our aim here is therefore not to determine whether an exchange is wise or unwise. Instead, our intention is to give policymakers and other interested readers an impartial assessment of both policies and, in particular, the features that are important to a comparative evaluation. We don’t give answers, but hope at least to give the right questions to ask.

Abstract: There is little evidence from impact evaluation studies of ambitious residential energy conservation programs, especially in developing countries. In this paper, I investigate the short- and long-term impacts of the most ambitious electricity conservation program to date. This was an innovative program of private incentives and conservation appeals implemented by the Brazilian government in 2001-2002 in response to supply shortages of over 20%. I nd that the program reduced average electricity consumption per customer by 25% over a nine-month period in affected areas. Importantly, the program reduced consumption by 12% in the long run. Such persistent effects, which arose mostly from behavioral adjustments, may substantially improve the cost-effectiveness of ambitious conservation programs. Finally, I show that a price elasticity estimated out-of-crisis would have to be increased fivefold to rationalize conservation efforts by the private incentives alone. Appeals to social preferences likely amplify consumers' responsiveness in times of crisis.