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The generation and distribution of electricity comprises nearly 40% of U.S. CO2emissions, as well as large shares of SO2, NOx, small particulates, and other toxins. Thus, correctly accounting for these electricity-related environmental releases is of great importance in life cycle assessment of products and processes. Unfortunately, there is no agreed-upon protocol for accounting for the environmental emissions associated with electricity, as well as significant uncertainty in the estimates. Here, we explore the limits of current knowledge about grid electricity in LCA and carbon footprinting for the U.S. electrical grid, and show that differences in standards, protocols, and reporting organizations can lead to important differences in estimates of CO2, SO2, and NOxemissions factors. We find a considerable divergence in published values for grid emissions factor in the U.S. We discuss the implications of this divergence and list recommendations for a standardized approach to accounting for air pollution emissions in life cycle assessment and policy analyses in a world with incomplete and uncertain information.

Several cities are considering both photovoltaic (PV) generation and electric vehicles (EVs). A city evaluating a transition to an EV fleet has different decision criteria than private actors. This paper conducts a life cycle assessment and cost-benefit analysis for city vehicle fleet electrification decisions, using Pittsburgh, PA as a case study. The analysis includes several electric-grid scenarios and assesses the installation of distributed PV at city-owned parking facilities. Costs were included while comparing vehicle options, as were the emissions and externality costs of GHGs, SO2, and NOxfrom direct and upstream effects. For the vehicles under consideration for Pittsburgh’s fleet, BEVs were always found to have lower GHG emissions than Hybrids. Lowering external costs with fleet electrification, however, was found to be dependent on a rapid transition to a cleaner grid. A peak capacity of about 6000 kW of PV is possible on Pittsburgh city-owned parking facilities. This capacity would produce greater than 30 times the yearly energy needs of the city’s municipal vehicle fleet. However, the PV canopy structures over parking spaces potentially make systems costs prohibitive. This study provides a method for cities, counties, and other stakeholders to evaluate the potential benefits and costs of EVs and PV generation.