Implementation of many policies intended to reduce fuels’ contribution to global warming require an estimate of the global warming intensity (GWI) of various fuels. Determining the climate effect of a direct substitution of fuels is not the same as determining the official value of each...

We find that plug-in hybrid electric vehicles (PHEVs) could significantly reduce automotive greenhouse gas (GHG) emissions and petroleum consumption, while improving energy security and urban air quality. Widespread PHEV adoption will depend upon technological and economic advances in batteries...

An increasingly common type of environmental policy instrument regulates the carbon intensity of transportation and electricity markets. In order to extend the policy's scope beyond point-of-use emissions, regulators assign each competing fuel an emission intensity rating for use in calculating...