The fleet of plug-in cars around the globe continues to grow each year — it surpassed 2 million in 2016, according to the International Energy Agency (IEA). Around 60% are battery electric vehicles (BEVs), which rely solely on electricity to function. With more drivers plugging in, the demand on our electricity grid is increasing in unison. BMW and Pacific Gas & Electric (PG&E) have been looking at ways to mitigate electricity demand, launching BMW i ChargeForward in 2015.
BMW i ChargeForward is a program designed to help reduce peak demand on the grid by advancing or delaying the charging of electric vehicles (EVs). Further, BMW can feed energy back into the grid from a cluster of stationary battery packs (which may one day be EVs themselves).
In general, the costs associated with supplying electricity increase with respect to peak demand, due to the utility supplier having to install more generation capacity. Also, “dirty” energy sources (e.g. coal) may be called upon during times of increased demand. Keeping peak demand in check can help lessen the sting of electricity price hikes, which in turn makes charging your EV as economical as possible.
BMW and PG&E have released the results of their ChargeForward pilot program, which ran from July 2015 to December 2016. It has been deemed a success in terms of both energy reduction and customer satisfaction.
BMW i ChargeForward — Goals
BMW Group is investigating vehicle to grid (V2G) managed charging and renewable energy integration in order to:
- Minimise upfront costs and total cost of EV ownership;
- Minimise the grid impact of plug-in EV charging;
- Support integration of renewable energy as part of the BMW commitment to sustainability;
- Identify and meet future grid requirements.
BMW i ChargeForward — Pilot Program
The ChargeForward pilot program intelligently managed the home charging of nearly 100 BMW i3 EVs in the San Francisco Bay Area, in order to offset peak demand on the electricity grid.
Further, a large chunk of energy was provided by a colony of “second life” lithium-ion batteries which were cannibalised from BMW MINI E Cooper demonstration vehicles. A total of eight stationary battery packs were built in parallel, housed in a 10 ft container at BMW’s Mountain View, CA campus. The system had a storage capacity of 225 kWh, and could supply the grid with up to 100 kW, if required. The batteries were charged with a mix of on-site renewable energy and grid energy.
In order to test the flexibility of the EV pool and stationary battery storage as a grid resource, events were tested in both “day ahead” (notifications sent 24+ hours before the event) and modeled “real time” (notifications sent 4 minutes prior to the event).
In summary, the BMW i ChargeForward pilot program involved three key steps (Figure 2):
- PG&E contacts the BMW server, requesting a load drop of up to 100 kW for one hour;
- BMW selects vehicles for charging delay (up to one hour per day, per vehicle), based on owner preferences and history. Owners are notified via their BMW smart phone app. Stationary batteries provide additional energy as required;
- Smart meters verify that the total requested load drop is achieved.
Participants received $1,000 initially, and earned further incentives of up to $540 at the conclusion of the program. This exact value was based on their level of participation in demand response events, which they could choose to opt-out of if they needed to charge their i3 immediately. Participation in BMW or PG&E sponsored surveys or questionnaires was also taken into account.
During the 18 month pilot program, BMW participated in 209 demand response events, totaling 19,500 kWh (Figure 3). This is equivalent to the annual power requirements of two average homes. BMW met the performance requirements for ~90% (189) of the events (a successful event is defined as BMW reaching 90% (90 kW) of the target 100 kW load offset). On average, 20% was contributed by the pool of BMW i3s, while 80% came from the 2nd life battery system. Overall, this percentage was the same for both “day ahead” and “real time” events.
The share of resources from the vehicle pool fluctuated depending on the time of day an event was called. Between 11 pm–2 am, the vehicle pool contributed up to 50% of the requested 100 kW. This large increase in vehicle participation was mostly due to PG&E incentivising charging during this time period by offering cheaper electricity to customers.
Since ChargeForward was designed to run primarily in the background, customer satisfaction proved to be high. Surveys revealed that 98% of participants were satisfied with the program and 93% felt that they are likely to participate in a similar program in the future.
“As EV adoption continues to grow, the potential for these clean vehicles as a grid resource becomes more significant,” said David Almeida, program manager for the PG&E and BMW i ChargeForward pilot program. “The success of this pilot program helps to demonstrate the future possibilities of scaling the smart charging capabilities of this growing resource to support the energy grid.”
BMW i ChargeForward — Phase 2
Based on the success of the ChargeForward pilot program, BMW received a grant from the California Energy Commission to conduct a second phase. Phase 2 will run from January 2017 to December 2018 and will again be supported by PG&E. It will explore the ability to optimise charging events wherever the vehicle is charging — both at home and on the go.
Late last year, BMW reached out to BMW i3, i8 and iPerformance owners in the Greater San Francisco Bay Area. This time around, they have secured more than 250 participants, with up to $900 in incentives available per driver. Once again, incentives will vary based on individual participation — the more flexible a participant is in terms of charging their vehicle, the better.
Phase 2 of ChargeForward will test the ability of EVs to function as a flexible grid resource by absorbing excess solar energy throughout the day. As shown in Figure 4, in California the the net energy load drops significantly throughout the day when the Sun is shining, thanks to the collection of solar energy. Once the Sun goes down, the net load ramps up. The resultant curve has been coined the “duck curve.” With solar power becoming ubiquitous, there is potential for EVs to absorb excess solar generation during the day, and reduce the ramp in the evening.
Other Ways to Reduce Peak Demand on the Grid
PG&E are not the only utility company incentivising plugging in during off-peak periods. Back in April, we reported on SmartCharge New York — a program devised by Con Edison & FleetCarma. In this case, rewards can be earned for charging during off-peak hours (12 midnight–8 am), and by not charging your EV on weekdays between 2 pm–6 pm in summer (June to September). These rewards can be redeemed in the form of e-gift cards and digital pre-paid cards from assorted retailers.
In a perfect world, EVs would always utilise sustainable energy, such as solar or wind, when charging at home or on the road. Stationary battery storage can make this a reality. Consumers can already do this at home, with roof-mounted solar panels coupled with battery storage. Future phases of BMW i ChargeForward will examine the integration of home solar and home energy storage in conjunction with EV charging management.
Tesla is taking an aggressive approach to EV charging at its Supercharger stations. CEO Elon Musk stated on Twitter earlier this month that “All Superchargers are being converted to solar/battery power. Over time, almost all will disconnect from the electricity grid.” With the roads soon to be inundated with the Tesla Model 3, transitioning to sustainable energy will be integral in reducing demand on the grid.
As the global uptake of EVs ramps up, it is essential that auto manufacturers and utilities begin planning and trialing ways of reducing their impact on the electricity grid. BMW and PG&E have already demonstrated how managing the timing of EV charging can improve grid efficiency through their ChargeForward pilot program.