EVs Put a Strain on the Grid
As electric cars become more common on our roads, some parts of the country are starting to see a strain on electric grids as increasing numbers of EV drivers plug in at home overnight. Like charging our phones when we get home at the end of the workday, it’s the most convenient way for most drivers to charge. But while many electric car owners schedule their charging for off-peak hours using their vehicle’s built-in functionality or a charging app – taking advantage of lower rates – a significant portion do not. And that means their EVs charge at the same time as peak energy use at home. In areas where EVs represent a high percentage of vehicles on the road, that’s becoming a problem.
A new study from MIT, published in the journal Cell Reports Physical Science, suggests that a shift in the way we think about charging could reduce the need to expand power generation, which can often come with its own carbon emissions. Instead of always charging at home in the early evening, the study says that increased implementation of charging at work for EV drivers could significantly reduce the strain on the power grid. And because workplace charging would typically take place during the day, the use of solar panels could essentially provide the additional electricity needed for free.
Workplace Charging Reduces the Strain
The authors of the study – Zachary Needell, Wei Wei, and Jessica Trancik – analyzed data from New York City and Dallas. They determined that access to workplace charging would increase the number of daily travel patterns that could be met by battery-electric cars, which still typically have a lower range than gasoline vehicles. The number of “always feasible” vehicle increased by a couple of percentage points when drivers were able to charge at work as well as at home.
When given access to workplace charging, driver preferences in terms of where and when they charge shifted the load on the electrical grid. The lowest strain on the electrical grid came from drivers who favored charging at work and “topped up” their electric vehicles at home, during off-peak hours between midnight and 6:00 am. This reduced charging demand in the early evening to near-zero.
In essence, access to workplace charging cased the peak in charging demand in the early evening to be lower in both study cities – staggered arrival times at home, and lower charging requirements would mean fewer vehicles are charging at once at any given time in the evening.
A Different Demand Profile
Charging at work and at home created a smoother demand profile – which could be easily met by the existing electrical grid, assuming that the workplace charging could be powered by solar. An alternative was for EV owners to still primarily charge at home – but during off-peak hours – while topping up at work. The net result still significantly reduced the strain on the grid during early evenings – and rewarded drivers with lower electricity rates.
The study’s conclusion aligns closely with what a Department of Energy study pointed out a couple of years ago: that focusing charging at homes and workplaces may be more important than just building chargers everywhere. While rapid public charging is important for long road trips, EVs can currently complete over 90 percent of everyday driving needs without ever needing public charging, so long as they have access to charging at home or work.
Of course, there’s a cost to implement charging at work for facility owners and employers that must be considered. Some companies, such as General Motors, have committed to having a large number of EV chargers onsite for their employees, but workplace charging must be financially attractive to those who use it in order to have the desired effect.