National and global plans to combat climate change include increasing the electrification of vehicles and the proportion of electricity generated from renewable sources. But some projections suggest that these trends may require costly new power plants to meet peak loads in the evening when cars are plugged in after the workday. Moreover, excessive power output from solar farms during the day can waste valuable electricity generation capacity.
In a new study, MIT researchers find that it is possible to mitigate or eliminate these two problems without the need for advanced technological systems for connected devices and real-time communications, which can lead to increased costs and energy consumption. Instead, encouraging the placement of charging stations for electric vehicles (EVs) in strategic ways, rather than letting them pop up out of nowhere, and creating systems to start charging the vehicle at later times could make a huge difference.
The study will be published in the journal Cell Physical Science Reportsby Zachary Needell PhD ’22, Postdoctoral Wei Wei, and Professor Jessika Trancik of MIT’s Data, Systems, and Society.
In their analysis, the researchers used data collected in two model cities: New York and Dallas. Data was collected from, among other sources, anonymized records collected via on-vehicle devices, and surveys that carefully sampled populations to cover changing travel behaviours. They showed daily vehicle use times, vehicle duration, and the amount of time vehicles spent in different types of locations—residential, workplace, shopping, entertainment, and so on.
The findings, says Trancic, “shift the picture around the question of where to strategically place chargers to support EV adoption and also support the power grid.”
Better availability of on-premises charging stations, for example, could help absorb peak energy produced at midday from solar installations, which would otherwise be wasted because it is not economical to build enough battery or other storage capacity to provide it all. . later in the day. Thus, workplace chargers can provide a dual benefit, helping to reduce the evening peak load from EV charging and also benefiting from solar electricity output.
These effects on the electric power system are significant, particularly if the system must meet the charging requirements of a fully electrified personal vehicle fleet along with peaks in other electricity demand, for example on the hottest day of the year. If not mitigated, the researchers say, the evening peak in demand for electric vehicle charging could require more than 20 percent of power generation capacity to be installed.
“Slow charging in the workplace can be better than faster charging technologies to enable higher utilization of solar energy resources in the middle of the day,” Wei says.
Meanwhile, with home charging delays, each EV charger can come with a simple app to estimate when to start its charging cycle so that it charges before it’s needed the next day. Unlike other proposals that require centralized control of the charging cycle, such a system does not require inter-device communication of information and can be pre-programmed – and could achieve a significant shift in grid demand due to the increasing penetration of EVs. The reason it works, says Trancic, is because of the natural variation in leadership behaviors among individuals in a population.
By “home charging,” researchers don’t just refer to charging equipment in individual garages or parking spaces. They say it is necessary to provide charging stations at street parking sites and in apartment building parking areas as well.
Trancic says the results highlight the value of combining the two measures — workplace charging and delayed home charging — to reduce peak electricity demand, store solar energy, and conveniently meet drivers’ charging needs on all days. As the team has shown in previous research, home freight can be a particularly effective component of a freight locations strategic package; They found that workplace charging is not a good alternative to home charging to meet the needs of drivers of all days.
“Given that there is a lot of public money going into expanding charging infrastructure, how can you incentivize the site so that this is efficiently and effectively integrated into the power grid without requiring a lot of additional capacity expansion?” Trancic says. This research provides some guidance for policymakers on Where to focus rules and incentives.
“I think one of the great things about these results is that by being strategic you can avoid a lot of the physical infrastructure that you might otherwise need,” she says. “Your electric car can replace some of the need for static energy storage, and you can also avoid the need to expand the capacity of power stations, by thinking of the location of chargers as a tool for managing demands – where and when they happen.”
The team found that shipping home late can make a surprising difference. “It basically incentivizes people to start charging later. This can be something that’s pre-programmed into your chargers. You incentivize people to delay starting charging a little bit, so that not everyone is charging at the same time, and that facilitates the top.”
Such a program requires some prior commitment on the part of the participants. “You’re going to need enough people committed to this program up front to avoid investing in physical infrastructure,” says Trancic. “So if you have enough people signing up, you basically don’t have to build these extra power plants.”
It is not a given that all of this will line up correctly, and putting in place the right mix of incentives will be crucial. “If you want electric vehicles to serve as an efficient solar energy storage technology, then… [EV] The market has to grow fast enough to be able to do that,” says Trancic.
In order to optimally use public funds to help make that happen, she says, “you can incentivize charging installations, which ideally would go through a competitive process — in the private sector, you would have companies bidding on different projects, but you could incentivize installation charging on the premises.” , for example, to take advantage of these two advantages. Transic adds that the chargers people have access to when they’re parked near their housing are also important, but for other reasons. Home charging is one way to meet your shipping needs while avoiding the annoying disruptions to people’s travel activities.
The study was supported by the European Regional Development Fund Operational Program for Competitiveness and Internationalization, the Lisbon Portugal Regional Operational Program, and the Portuguese Science and Technology Foundation.