Plug-in electric vehicles (PEVs) bridge the gap between transportation and electric power—two sectors that until 5 years ago were effectively disparate. Overall, the potential future synergies between the two sectors seem promising. However, because these sectors are somewhat foreign to each other, some uncertainties are likely early on. One area of uncertainty is with regard to the U.S. Environmental Protection Agency’s (EPA’s) Clean Power Plan (CPP), released August 3, 2015.
The CPP is not designed to explicitly affect PEVs; rather, it is designed to decrease electric power sector CO2 emissions from existing fossil-fuel power plants. However, depending on the method by which each state implements the policy, PEVs may present a detrimental or beneficial component to state compliance strategies.
Because each state has a different electric power generation mix, each state will have individual goals and pursue varying strategies in order to comply with the CPP. The CPP CO2 reduction goals have been developed by the EPA using a rate-based approach, which places CO2 per megawatt-hour limits on power plants, but states may also use a mass-based approach (i.e., total metric tons of CO2 from the electric power sector).
PEVs Increase Demand
The mass-based approach will likely create complications for states with fast growing PEV markets. The complication arises on behalf of the fact that PEVs increase electricity demand, which increases the total emissions from power plants, while the overall CO2 reductions achieved on behalf of the PEV are not integrated in CPP calculations. This means that while a PEV would likely reduce net CO2 emissions, PEVs could make state compliance efforts for the CPP more difficult.
The rate-based approach may produce similar complications; however, this is entirely dependent on what grid resources are used to fuel PEVs. For instance, utilities may design incentives to coordinate PEV charging with peak solar or wind generation times, which would in effect increase utilization of renewable generation assets, decreasing the average rate of CO2 emitted per megawatt-hour produced in a state.
Vehicle Grid Integration
Programs and technologies to shift PEV charging to off-peak hours and integrate PEV charging into advanced grid services are being developed in large PEV markets. BMW’s iChargeForward program, which aggregates 100 BMW i3s in the San Francisco Bay Area for grid services, launched in July. Recently, charging station manufacturer eMotorWerks and non-profit software developer WattTime debuted a charging station that can automatically schedule PEV charging when the carbon emissions from the grid are lowest.
While the load represented by PEVs is still marginal compared to overall electric power sector demand, PEVs will become an ever increasing concern. Navigant Research estimates that the average PEV can increase the average U.S. household annual energy consumption by around a third and estimates that the median state PEV market share of 0.5% in 2014 will grow to over 2.5% by 2024. By the time the CPP takes effect in 2022, this equates to 4.4 million light duty PEVs in use, each consuming around 3,000–4,000 kWh annually.
PEV Market Share (% of New vehicle sales) by State, United States: 2014, 2024
(Source: Navigant Research)
As PEV adoption reduces overall emissions in most states and cases, state PEV adoption incentives should not run contrary to state CPP compliance efforts. Rather, states should encourage efforts to utilize PEVs as potential distributed generation/energy storage resources useful for CPP compliance.