Research

Biofuels are promoted worldwide as a strategy to replace fossil fuels and cut greenhouse gas emissions. However, their climate benefits are uncertain because biofuel production can induce deforestation and other land use change that causes carbon emissions. Here we show that global demand for biomass-based diesel fuel between 2002 and 2018 drove the conversion of approximately 1.7 million hectares of forest to oil palm in Indonesia and Malaysia, which released more than one gigaton of CO2, giving biomass based diesel higher carbon emissions per megajoule than that of fossil diesel.  (paper link)

Commercially viable battery or fuel-cell airplanes do not yet exist and likely won't exist for a long time, so the focus has turned to liquid biofuels known as Sustainable Aviation Fuels (SAF). SAFs are liquid jet fuels produced from plant biomass, waste products, vegetable oils, or ethanol. Are they a good idea? How will proposed policies work? What will be their effects on other markets? We now have a working paper on policy options (and a blog about the working paper).

Climate policy projections typically deploy deterministic or equilibrium optimization models that produce estimates of single values for each output, rather than probabilistic ranges for those output values. Uncertainty can be tested via scenario analysis, but the selection of scenarios is not based upon any statistical analysis. We aim to produce statistically rigorous distributions of outcomes, rather than rely upon individually selected scenarios. This is ongoing work.  So far, we have published working papers on the LCFS and IRA.

Climate-smart agriculture promises to mitigate climate change by sequestering carbon in soils on working lands. However, this promise faces substantial policy challenges due to heterogeneity, costly measurement, and uncertainty. We summarize the latest scientific literature on carbon sequestration in agricultural soils, and we describe the current policy environment. With that background, we present an economic framework for policy analysis. We conclude by emphasizing (i) the need for better measurement and policy that is robust to poor measurement, and (ii) the importance of improving agricultural productivity to avoid future carbon losses from expanded agricultural land use. 

Time-of-use (TOU) electricity prices are increasingly being adopted to reduce consumption during the higher marginal cost afternoon hours. There is ample evidence that TOU rates reduce average consumption during the peak price hours of the day, but it is unknown how these energy savings are distributed across days. Using a unique dataset from households with smart thermostats, we find that adopting TOU rates causes large decreases in peak period AC usage, resulting in energy savings that are concentrated on the hottest, highest demand days when the benefits of conservation are the greatest.

The Renewable Fuel Standard (RFS) specifies the use of biofuels in the United States and thereby guides nearly half of all global biofuel production. We combine econometric analyses, land use observations, and biophysical models to estimate the realized effects of the RFS in aggregate and down to the scale of individual agricultural fields across the United States. We find that the RFS expanded US corn cultivation by 2.8 Mha (8.7%) and total cropland by 2.1 Mha (2.4%) in the years following policy enactment (2008 to 2016). These changes caused enough domestic land use change emissions such that the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher.