Technology Status and Expected Greenhouse Gas Emissions of Battery, Plug‐In Hybrid, and Fuel Cell Electric Vehicles

Electric vehicles (EVs) of various types are experiencing a commercial renaissance but of uncertain ultimate success. Many new electric‐drive models are being introduced by different automakers with significant technical improvements from earlier models, particularly with regard to further refinement of drivetrain systems and important improvements in battery and fuel cell systems. The various types of hybrid and all‐electric vehicles can offer significant greenhouse gas (GHG) reductions when compared to conventional vehicles on a full fuel‐cycle basis. In fact, most EVs used under most condition are expected to significantly reduce lifecycle GHG emissions. This paper reviews the current technology status of EVs and compares various estimates of their potential to reduce GHGs on a fuel cycle basis. In general, various studies show that battery powered EVs reduce GHGs by a widely disparate amount depending on the type of powerplant used and the particular region involved, among other factors. Reductions typical of the United States would be on the order of 20‐50%, depending on the relative level of coal versus natural gas and renewables in the powerplant feedstock mix. However, much deeper reductions of over 90% are possible for battery EVs running on renewable or nuclear power sources. Plug‐in hybrid vehicles running on gasoline can reduce emissions by 20‐60%, and fuel cell EV reduce GHGs by 30‐50% when running on natural gas‐derived hydrogen and up to 95% or more when the hydrogen is made (and potentially compressed) using renewable feedstocks. These are all in comparison to what is usually assumed to be a more advanced gasoline vehicle “baseline” of comparison, with some incremental improvements by 2020 or 2030. Thus, the emissions from all of these EV types are highly variable depending on the details of how the electric fuel or hydrogen is produced.