Well-to-wheel greenhouse gas emissions of electric versus combustion vehicles from 2018 to 2030 in the US.

CONCISE ABSTRACT: Electric vehicles (EVs) can reduce transportation-related greenhouse gas (GHG) emissions, given the planned electric grid decarbonization. Regulations can also reduce internal combustion engine vehicle's (ICEVs) emissions by mandating increased fuel economies or ethanol-gasoline mixes. Factors such as fuel economy, electricity grid mix, vehicle choice, and temperature affect EV GHG emissions relative to ICEVs, and successfully decarbonizing the transportation sector depends on understanding their combined effects. We use life-cycle assessment to compare the EV and ICEV well-to-wheel GHG emissions in the United States and four other states from 2018 to 2030. We found lower emissions for EVs than ICEVs in most conditions considered. In New York state, where natural gas power plants replace nuclear energy, GHG emissions of electricity generation increase over time after 2020. Future ICEVs can have comparable emissions to EVs due to fuel economy increase. Therefore, EV and ICEV can together lower transportation GHG emissions at a faster pace. EXTENDED ABSTRACT: Transportation-related greenhouse gas (GHG) emissions can be reduced by (a) increasing the share of electric vehicles (EVs) and (b) reducing GHG emissions of internal combustion engine vehicles (ICEVs) by mandating increased fuel economies or ethanol-gasoline mixes. Factors, such as fuel economy, electricity grid mix, vehicle choice, and temperature affect EVs' relative GHG emissions compared to ICEVs, and understanding their combined effect is necessary for a successful decarbonization of the transportation sector. We used life-cycle assessment to evaluate the simultaneous effect of the above-mentioned factors on the well-to-wheel GHG emissions of EVs and ICEVs from 2018 to 2030. The analysis was performed for the United States (US) average and state-level for Arizona, California, New York, and Oregon. Our results showed lower GHG emissions for EVs than ICEVs for most conditions considered. GHG emissions are expected to decrease in the US on average by 5% for EVs and 27% for ICEVs in 2030 compared to 2018. In 2030, the ICEV well-to-wheel GHG emissions were comparable to those of the EVs in the US average and Arizona. EVs perform best in California and Oregon throughout the considered period. In regions, such as New York, EVs driven 2021 and after will have higher GHG emissions than ICEVs, as natural gas power plants are replacing nuclear energy. While EV GHG emissions decrease over time due to grid decarbonization, future ICEVs can lower the GHG emissions, especially for larger vehicles, where EVs might not be the best option. Therefore, EV and ICEV can together lower transportation GHG emissions at a faster pace.

Evaluating the cost and carbon footprint of second-life electric vehicle batteries in residential and utility-level applications.

The volume of end-of-life automotive batteries is increasing rapidly as a result of growing electric vehicle adoption. Most automotive lithium-ion batteries (LIBs) are recycled but could be repurposed as second-life batteries (SLBs) since they have 70-80% residual capacity, which can be adequate for stationary applications. SLBs have been proposed as potential, inexpensive, low-carbon energy storage for residential and utility-level applications, with or without photovoltaics (PV). However, it is unknown whether SLBs will be better than new batteries and whether SLBs will provide similar cost and carbon emission reduction for the different stationary applications in all locations. This work compared the levelized cost of electricity and life-cycle carbon emissions associated with using SLBs and new LIBs in the US for three energy storage applications: (1) residential energy storage with rooftop PV, (2) utility-level PV firming, and (3) utility-level peak-shaving, leading to a total of 41 scenarios. SLBs reduced the levelized cost of electricity by 12-57% and carbon emissions by 7-31% compared to new LIBs in the considered applications, with higher reductions for utility-level applications. SLBs still provided benefits at the residential level when compared to rooftop PV alone by reducing the levelized cost by 15-25% and carbon emissions by 22-51%, making SLBs attractive to residential consumers as well. SLBs offer an opportunity to utilize an end-of-life product for energy storage applications, provided the uncertainty in SLB quality and availability is addressed.

Economic and Environmental Feasibility of Second-Life Lithium-Ion Batteries as Fast-Charging Energy Storage.

Energy storage can reduce peak power consumption from the electricity grid and therefore the cost for fast-charging electric vehicles (EVs). It can also enable EV charging in areas where grid limitations would otherwise preclude it. To address both the need for a fast-charging infrastructure as well as management of end-of-life EV batteries, second-life battery (SLB)-based energy storage is proposed for EV fast-charging systems. The electricity grid-based fast-charging configuration was compared to lithium-ion SLB-based configurations in terms of economic cost and life cycle environmental impact in five U.S. cities. Compared to using new batteries, SLB reduced the levelized cost of electricity (LCOE) by 12-41% and the global warming potential (GWP) by 7-77%. Photovoltaics along with SLB reduced the use of grid electricity and provided higher GWP and cumulative energy demand (CED) reduction compared to only using SLB. The LCOE of the SLB-based configurations was sensitive to SLB cost, lifetime, efficiency, and discount rate, whereas the GWP and CED were affected by SLB lifetime, efficiency, and the required enclosure materials. Solar insolation and electricity pricing structures were key in determining the configuration, which was economically and environmentally suitable for a location.