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Plugging EVs into Utility IRPs

The electrification of transportation is posing a challenge and opportunity for utilities across the country, with significant implications for planning, load forecasting, and demand response. As the number of plug-in electric vehicles (EVs) in use continues to grow, the grid implications of these vehicles is an important planning consideration for energy utilities. In the short term, EVs will comprise a relatively small but growing proportion of the nation's vehicle fleet and research suggests that current grid infrastructure is sufficient to support EV charging needs. There is some concern around whether the grid's distribution infrastructure will have the capacity to accommodate the additional load of EV charging in the long term, especially if this charging adds to peak load. However, there is also an opportunity to use this demand-side resource to support integration of renewable energy and demand response activities. Tracking deployment of EVs and EV charging infrastructure and encouraging off-peak charging are thus important steps for utilities to consider.

The Vermont Energy Investment Corporation (VEIC), in partnership with the National Association of State Energy Officials (NASEO), conducted a review of Integrated Resource Plans from utilities across the U.S. to analyze how utility planners and regulators are accounting for the impacts of electric vehicles on the grid. The major findings from this study include:

  • - 19 of 31 utilities included in our review incorporated EVs into their plans.
    - Projected load due to EV charging, ranged from less than 1% to 5%.
    - While most plans from states predicted to have high levels of EV penetration included EVs, (e.g., WA, OR, VT) few conducted any additional modeling or analysis.
    - Time of use (TOU) rates were the most commonly referenced mechanism to mitigate grid impacts of EV deployment.

EV-specific time of use rates are already available in some areas, and data from the U.S. Department of Energy (DOE)-sponsored `EV Project' have already shown such rates to be a highly effective means of achieving off-peak EV charging.

EVs were commonly included in IRP discussions of emerging technology and uncertainty. Many of these plans acknowledged the potential load growth that may result from EV charging, but did not incorporate EVs into load forecasts. There was little to no discussion in most plans of any spatial considerations of EV energy demand, nor the robustness of distribution infrastructure.

As a result of these findings, we recommend that EVs be incorporated into future IRPs and utility planning processes through the following:

  • - Track EV and charging infrastructure deployment through coordination with local transportation partners (state Departments of Transportation, State Energy Offices, - Clean Cities Coalitions, and Electric Vehicle Supply Equipment installers).
    - Develop projections of EV penetration rates, additional energy demand, and peak load effects in the utility service area.
    - Determine spatially explicit infrastructure needs that may result from EV use.
    - Consider how utility efficiency programs can reduce projected demand resulting from EV charging.
    - Consider the services that EVs can provide as a grid resource through vehicle-to-grid technology and interoperability.

Utilities should partner with local transportation planning organizations and Clean Cities Coalitions to better understand travel patterns and integrate this information into the EV planning process. Planning for EVs, including how much additional energy they will require and where and when charging will occur, is a new challenge for the electric sector and may call for integration of travel behavior data.
Coordination with public agencies (mainly state Departments of Transportation, State Energy Offices, and State and Municipal Public Utilities Commissions) will facilitate optimal deployment of EVs, ensuring not only that electric infrastructure is adequate to handle the additional load in the necessary locations in coming years, but also that appropriate charging infrastructure is located so that travel demand can be met using EVs.

This work was a joint project between the Vermont Energy Investment Corporation and the National Association of State Energy Officials.

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