Plug-In Electric Vehicles Could Help the Grid: Prospects with Frequency Regulation

This is the third post in a three-part series that explores potential impacts of electric vehicles on the electrical grid. Part 1 and Part 2.

Previous posts in this series discussed how the demand for electricity from plug-in electric vehicles (PEVs) would affect the grid as well as a potential problem related to clustering. This final post describes an opportunity for these vehicles to help increase the stability of the grid and hold down utility rates for consumers.  As a reminder, a PEV is either an all-electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV).

A costly activity in managing power is controlling frequency. (Frequency is the number of times per second that alternating current (AC) is transmitted over the electrical grid.) The grid must operate at a constant 60 Hertz to ensure that devices operate as expected. To do this, utilities must balance electricity generation with load at all times. This balancing act on short time scales is known as frequency regulation. For a helpful explanation, see this website and video from Beacon Power.

Grid operators typically have to keep a portion of generating capacity (equal to about 1 percent of peak power) constantly ready to quickly ramp up or down generation to regulate frequency. Keeping this kind of capacity running (and mostly wasted) at all times is expensive and inefficient.

Enter PEVs. Utilities could use the batteries of these vehicles to assist in frequency regulation and keep the electricity providers’ costs down. The utility would not need to drain the battery of the vehicles, and instead would only charge and discharge the battery when they are not in use by small amounts to keep the grid running at the appropriate frequency. At the same time, the utility would be reimbursing consumers for the use of their batteries through a system known as vehicle to grid (V2G). In V2G, the utility is able to discharge the batteries slightly as needed to meet frequency regulation goals and pay the owner of those batteries for the privilege.

Utilities have a particular interest in fleet vehicles, such as the U.S. Postal Service fleet, because they run at set schedules and can thus provide predictable access to their battery power for frequency regulation. Large fleets from private companies could also partake in such an operation.

Two significant hurdles to using electric vehicles for frequency regulation are technical feasibility and utility regulations. Selling power back to the grid is simply not possible in many areas due to existing utility regulations. In addition, the feasibility of managing a large network of vehicles that will leave and enter the grid at unpredictable times is a significant technical challenge. This is less evident with fleet vehicles, but most electric vehicles will be operated by individuals. See our factsheet on the smart grid for more information on challenges related to electricity infrastructure.

On both issues, the University of Delaware partnered with several companies including PJM, a regional transmission organization (RTO) that coordinates the movement of wholesale electricity, to create the Mid-Atlantic Grid Interactive Cars Consortium (MAGICC) in order to develop and test systems that will work with today’s grid. MAGICC worked with Delaware’s state legislature to pass a law to codify interconnection standards and net metering. (Net metering and interconnection standards are the policy and technical standards that allow consumers to sell excess electricity they generate back to the utility.) The group has electric vehicles hooked up to the grid that are selling access to their vehicles’ batteries for frequency regulation today.

Frequency regulation is an opportunity for utilities to control operating costs and for PEV owners to earn a return on their idle vehicles. Throughout a typical day, most vehicles go unused in a place accessible to the electricity grid; Americans on average spend less than one hour per day commuting to work according to the U.S. Census Bureau. While the number of vehicles accessible to utilities is dependent on the adoption of PEVs by consumers, only 60,000 all-electric vehicles are needed to accommodate the frequency regulation required by PJM.

PJM is currently paying about $10 per day on average for access to the batteries of all-electric vehicles (EVs) in their market for 20 hours; these vehicles have twice the battery capacity of the typical plug-in hybrid electric vehicle (PHEV). A $150-300 monthly payment from the utility for the use of a customer’s batteries could substantially offset the additional upfront cost of these vehicles. Establishing such incentives on a larger scale is one potential policy option for promoting PEVs.

Nick Nigro is a Solutions Fellow