Placement of electric vehicle chargers could minimise energy grid stress

Careful planning of electric vehicle (EV) charging stations could lessen or eliminate the need for new power plants during the broad shift away from ICE (internal combustion engine) vehicles, a new study shows.

Most national plans to combat climate change include increasing the electrification of vehicles and the percentage of electricity generated from renewable sources.

But some projections show that these trends might require costly new power plants to meet peak loads in the evening when cars are plugged in after the workday. This could also lead to overproduction of power from solar farms during the daytime which can waste valuable electricity-generation capacity.

MIT researchers have found that it’s possible to mitigate or eliminate both these problems without the need for advanced technological systems of connected devices and real-time communications, which could add to costs and energy consumption.

Instead, encouraging the placing of charging stations for EVs in strategic ways and setting up systems to initiate car charging at delayed times could make a significant difference.

The researchers used data gathered from anonymised records collected via onboard devices in vehicles in two sample cities: New York and Dallas.

They showed the times of day cars are used and for how long, and how much time the vehicles spend at different kinds of locations such as residential, workplace, shopping, entertainment and so on.

The findings suggest that better availability of charging stations at workplaces, for example, could help to soak up peak power being produced at midday from solar power installations, which might otherwise go to waste because it is not economical to build enough battery or other storage capacity to save all of it for later in the day.

Workplace chargers could therefore help to reduce the evening peak load from EV charging and also making use of the solar electricity output.

The study suggests that this could have a “considerable” effect on the local grid, especially if the system must meet charging demands for a fully electrified personal vehicle fleet alongside the peaks in other demand for electricity, for example on the hottest days of the year.

If unmitigated, the evening peaks in EV charging demand could require installing upwards of 20 per cent more power-generation capacity, the researchers say.

Alongside delayed home charging, each EV charger could be accompanied by an app to estimate the time to begin its charging cycle so that it charges just before it is needed the next day.

Unlike other proposals that require a centralised control of the charging cycle, such a system needs no interdevice communication of information and can be preprogrammed to accomplish “a major shift in the demand” on the grid caused a rise in the number of EVs, the researchers said.

The findings suggest that stress on the grid would be significantly reduced by combining workplace charging and delayed home charging to reduce peak electricity demand, store solar energy, and meet drivers’ charging needs on all days.

Professor Jessika Trancik, one of the lead researchers, said: “I think one of the fascinating things about these findings is that by being strategic you can avoid a lot of physical infrastructure that you would otherwise need.

“Your electric vehicles can displace some of the need for stationary energy storage, and you can also avoid the need to expand the capacity of power plants, by thinking about the location of chargers as a tool for managing demands – where they occur and when they occur.”

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