As more and more people make the switch to plug-in cars, city planners and utility companies alike are facing new challenges to ensure that mass-electric car adoption doesn’t translate to an overloaded electrical grid as everyone tries to charge their car at the end of their work day.
Time of use tariffs — which encourage plug-in owners to delay electric vehicle charging until the early hours of the morning — is just one way to ensure that doesn’t happen. Cheaper than standard peak electricity, offering electric car owners special night-time rates to refuel their car encourages overnight charging, thus reducing peak demand on the electrical grid.
Given the fact that most modern electric cars come with programable charge timers, time of use metering is the first line of defence for a utility company seeking to encourage electric car owners to charge during off-peak periods — but now California’s Pacific Gas and Electric Company (PG&E) has partnered with BMW to take the next logical step: remote control of customers’ electric cars via a process called Demand Response
Announced at the end of July, BMW and PG&E will run a pilot project in the San Francisco bay area called the BMW i ChargeForward Program. Due to end at the end of 2016, the BMW i ChargeForward Program will give PG&E remote management capabilities of at-home charging of participating BMW i3 owners, delaying charging by up to 1 hour in order to reduce stress on the electrical grid during peak periods.
The idea is simple. By giving PG&E access to the charging cycles of customer’s BMW i3 electric cars, it can dynamically reduce grid demand by switching off customers’ cars when demand outstrips supply.
When grid demand drops, it can then restart charging as required.
To ensure that customer’s cars are charged on time for their next departure, the system will honour the chosen departure time in BMW’s i Remote app, using the vehicle’s current state of charge to calculate how much charge will be needed before the departure time to ensure a full battery.
It’s worth noting that PG&E doesn’t control vehicular charging directly. Instead, when it needs a load drop of up to 100 kilowatts in total, it contacts BMW to instruct it to initiate the delayed charging protocol. Then, based on vehicular state of charge and owners’ desired departure time, BMW chooses which vehicles should temporarily halt charging, notifying owners via the BMW i app to ensure that customers can opt out if necessary.
Smart meters, installed in the homes of participating customers, verify that the load drop has occurred, giving the utility company the desired headroom to cope with peak demand without switching on extra generators or causing a brownout.
The final piece of the puzzle comes in the form of a static battery pack connected to the electrical grid. Made form used BMW MINI E electric car battery packs, the static battery pack can feed power back into the electrical grid during peak demand periods, ensuring that PG&E can always gain 100 kilowatts of additional capacity when requested.
To encourage owners in San Francisco to sign up, BMW and PG&E are offering customers a gift card worth $1,000 at the launch of the program, along with a further $540 gift card at the conclusion of the program 18 months later.
Of course, such schemes aren’t exactly new. Despite being better known for its failed, highly-expensive battery swap program, Israeli firm Better Place used onboard vehicular telematics along with smart grid connectivity to remotely manage the charging cycles of each and every vehicle connected to the program. Since its battery swap stations were open and available in most major cities through the country, Better Place only had to ensure customers’ cars had enough power to reach the nearest battery swap station during periods of high demand, resulting in even more energy savings for the state’s utility company.
For those who don’t live in the San Francisco area and want to help their utility company reduce grid load, a new range of domestic charging stations such as the ChargePoint Home also make it possible to automatically delay or reschedule charging according to local utility demand, although incentives and utility participation vary from state to state.
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