BMW and PG&E Prove Electric Vehicles Can Be a Valuable Grid Resource
- Jun 23, 2017-
Nearly 100 plug-in cars and a stack of second-life EV batteries successfully responded to dozens of demand response calls.
by Julia Pyper June 20, 2017
The concept of using electric vehicles as a grid resource is no longer just theory. A pilot program recently conducted by BMW and Pacific Gas & Electric successfully demonstrated that electric vehicles can serve as reliable and flexible grid assets, which could eventually save money for both utilities and EV owners.
The BMW i ChargeForward Project is one of the best examples to date of a utility and an automaker working together to develop new technologies and use cases for electric vehicles (EVs) and their batteries.
“One of the things that we really wanted to test here was, how can we work closely with an automaker?” said David Almeida, electric vehicle program manager at PG&E. “We are an old company, and we're a large company. Automakers are old companies, and they're large companies. We both have our own internal bureaucracies. And so, one of the challenges I wanted to understand when we were setting this up was, how do we make those two independent entities work well together?”
“By and large, we didn't have any of those institutional challenges that I was [worried about],” he said. “We ended up working very closely, I think partially because we've got this common shared goal of increasing electric transportation.”
With the i ChargeForward pilot, BMW was required to provide PG&E with 100 kilowatts of grid resources when called upon, through a combination of delaying charging for nearly 100 BMW i3 vehicles in the San Francisco Bay Area and drawing from a second-life stationary battery system built from reused EV batteries, for the duration of 1 hour. The grid services demonstrated in the pilot included day-ahead and real-time signals that were modeled after existing proxy demand resources from the California Independent System Operator (CAISO), in order to test whether these resources could eventually participate at the wholesale level.
Over the course of 18 months, from July 2015 to December 2016, the i ChargeForward project dispatched 209 demand response events, totaling 19,500 kilowatt-hours, according to a recently released program report.
The events were called using an OpenADR protocol, the agreed-upon pathway for demand response communications. Olivine, an approved scheduling coordinator with CAISO, acted as the interface between the utility and the automaker. Once triggered, BMW’s aggregation software determined how much of the 100-kilowatt load drop would be met by the stationary battery and how much would come from managed charging, and used the onboard vehicle telematics system for communicating grid messages to the cars.
All of the DR events included a mix between the second-life battery and the vehicles, with around 80 percent participation from the battery and 20 percent from the vehicles. However, when the utility called events at different times of the day, specifically when there was a high vehicle load, vehicle participation jumped up significantly, to around 50 percent.
The vehicle response rate was highly correlated with PG&E’s residential time-of-use rates, which offer lower electricity prices at night from 11 p.m. to 2 a.m. Almeida said that a high percentage of EV drivers plugged in their vehicles as soon as they got home, but delayed actual charging until later in the evening when rates declined. This showed that the vehicles have even more flexibility as a grid resource than initially thought, because they’re plugged in for longer periods of time and because customers are effectively responding to the rate structure.
“That gives us an indication that we have some ability to move vehicle charging throughout that window of [plug-in] time,” said Almeida, who will discuss EV infrastructure on a panel next week at Grid Edge World Forum.