A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49):15060–15065] argue that it is feasible to provide “low-cost solutions to the grid reliability problem with 100% penetration of WWS [wind, water and solar power] across all energy sectors in the continental United States between 2050 and 2055”, with only electricity and hydrogen as energy carriers. In this paper, we evaluate that study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power. 

Chetty, Friedman, and Rockoff (2014a, b) study value-added (VA) measures of teacher effectiveness. CFR (2014a) exploits teacher switching as a quasi-experiment, concluding that student sorting creates negligible bias in VA scores. CFR (2014b) finds VA scores are useful proxies for teachers' effects on students' long-run outcomes. I successfully reproduce each in North Carolina data. But I find that the quasi-experiment is invalid, as teacher switching is correlated with changes in student preparedness. Adjusting for this, I find moderate bias in VA scores, perhaps 10-35 percent as large, in variance terms, as teachers' causal effects. Long-run results are sensitive to controls and cannot support strong conclusions.

In this paper, we comprehensively examine the effects of the Great Recession on child poverty, with particular attention to the role of the social safety net in mitigating the adverse effects of shocks to earnings and income. Using a state panel data model and data for 2000 to 2014, we estimate the relationship between the business cycle and child poverty, and we examine how and to what extent the safety net is providing protection to at-risk children. We find compelling evidence that the safety net provides protection; that is, the cyclicality of after-tax-and-transfer child poverty is significantly attenuated relative to the cyclicality of private income poverty. We also find that the protective effect of the safety net is not similar across demographic groups, and that children from more disadvantaged backgrounds, such as those living with non-Hispanic black or Hispanic, single, or particularly immigrant household heads-or immigrant spouses, experience larger poverty cyclicality than non-Hispanic white, married, or native household heads with native spouses. Our findings hold across a host of choices for how to define poverty. These include measures based on absolute thresholds or more relative thresholds. They also hold for measures of resources that include not only cash and near cash transfers net of taxes but also several measures of medical benefits.

The cash and near cash safety net in the U.S. has undergone a dramatic transformation in the past fifteen years. Federal welfare reform has led to the “elimination of welfare as we know it” and several tax reforms have substantially increased the role of “in-work”' assistance. In 2012, we spent more than 7 dollars on the Earned Income Tax Credit (EITC) for every dollar spent on cash benefits through Temporary Assistance for Needy Families (TANF), whereas in 1994 on the eve of federal welfare reform these programs were about equal in size. In this paper, we evaluate and test whether the EITC demonstrates a defining feature of a safety net program—that it responds to economic need. In particular, we explore how EITC participation and expenditures change with the business cycle. The fact that the EITC requires earned income leads to a theoretical ambiguity in the cyclical responsiveness of the credit. We use administrative IRS data to examine the relationship between business cycles and the EITC program. Our empirical strategy relies on exploiting differences in the timing and severity of economic cycles across states. The results show that higher unemployment rates lead to an increase in EITC recipients and total dollar amounts of credits for married couples. On the other hand, the effect of business cycles on use of the EITC is insignificant for single individuals, whether measured by the number of recipients or expenditures. Estimates that further cut by education show that the protective effects of the EITC are concentrated among those with higher skills (and potential earnings). In sum, our results show that the EITC serves to mitigate the effects of income shocks for married couples with children and other groups likely to have moderate earnings, but does not do so for the majority of recipients—single parents with children. The patterns we identify are consistent with the predictions of static labor supply theory, which we confirm with an analysis of earnings, and with expectations about how economic shocks are likely to vary across family type and skill group.

The years since the 2009 end of the Great Recession have been disastrous for many workers, particularly those with low human capital or other disadvantages. One explanation attributes this to deficient aggregate labor demand, to which marginal workers are more sensitive. A second attributes it to structural changes. Cyclical explanations imply that if aggregate labor demand is increased then many of the post-2009 patterns will revert to their pre-recession trends. Structural explanations suggest recent experience is the “new normal.” This paper reviews data since 2007 for evidence. I examine wage trends to measure the relative importance of supply and demand. I find little wage pressure before 2015, pointing to demand as the binding constraint. The most recent data show some signs of tightness, but still substantial slack.

How well can democratic decision making incorporate the knowledge and expertise generated by public policy analysts? This book examines the historical development of policy analysis, as well as its use in legislative and regulatory bodies and in the federal executive branch. The essays show that policy-analytic expertise effectively improves governmental services only when it complements democratic decision making. When successful, policy analysis fosters valuable new ideas, better use of evidence, and greater transparency in decision processes.

This study identifies, characterizes, and values wind and solar electricity resources for 21 countries in the Eastern and Southern Africa Power Pools. We find that many countries possess potential many times their projected demand. However, because the most competitive wind and solar resources are spatially uneven, international transmission could allow the region as a whole to benefit from “no-regrets” or low-cost, low-impact, and highly accessible resources. International energy trade also lowers system costs by reducing the need for conventional power plants and allows lower impact, more accessible renewable energy sites to be cost competitive. Regional interconnections planned around strategic siting opportunities are crucial for realizing no-regrets wind and solar energy development that can be competitive with conventional generation in African countries.

Microgrids are a rapidly evolving and increasingly common form of local power generation used to serve the needs of both rural and urban communities. In this paper, we present a methodology to evaluate the evolution of the sustainability of stand-alone microgrids projects. The proposed methodology considers a composite sustainability index (CSI) that includes both positive and negative impacts of the operation of the microgrid in a given community. The CSI is constructed along environmental, social, economic and technical dimensions of the microgrid. The sub-indexes of each dimension are aggregated into the CSI via a set of adaptive weighting factors, which indicate the relative importance of the corresponding dimension in the sustainability goals. The proposed methodology aims to be a support instrument for policy makers especially when defining sound corrective measures to guarantee the sustainability of small, isolated microgrid projects. To validate the performance of the proposed methodology, a microgrid installed in the northern part of Chile (Huatacondo) has been used as a benchmarking project.