Smart Grid can help with prime-time charging of EVs
Norway leads the world in new car sales of electric vehicles, but how will charging all those EVs affect the Norwegian energy supply? Researchers at the Norwegian University of Science and Technology are helping to develop Smart Grid solutions that will ease the crunch caused by powering our transportation with electricity.
When people with EVs come home from work in the afternoon, they plug in their cars to charge them. That results in an extra peak in electricity consumption in the afternoon.
“We’re moving towards a different kind of power use,” said Professor Olav B. Fosso, professor and director of the Energy strategic research area at the Norwegian University of Science and Technology (NTNU).
This peak may eventually become a major challenge for the electrical grid.
“We could have big voltage problems, with limited transmission capacity within the distribution system,” says Fosso.
Capacity could also become a problem. Large variations in consumption throughout the day are challenging. Electrical power is perishable. That means it’s an advantage to have relatively stable power use over a 24-hour period. Renewable energy from the wind and sun has to be used immediately.
Fosso says Norway is lucky to be able to regulate its hydropower.
Water reservoirs allow adjustments in the power supply, but very few countries have that ability, and even in Norway high consumption at certain times of the day poses a challenge.
EV numbers on the rise
Afternoon charging of electric cars isn’t a problem—yet. But the orders for electric cars in Norway show that growth won’t stop with the almost 75,000 EVs already on the road, including hybrids.
“Nothing suggests that this development won’t continue,” says Fosso.
Cars have different charging power and storage capacities. Storage capacity is related to the car’s range. Mitsubishi’s capacity is around 16 kWh, while the Nissan Leaf has a capacity of around 20 kWh and Tesla, 85 kWh. Battery size determines the charging time for a given amperage, with typical charging efficiency ranging from 4-8 kW. Home chargers provide long charging times, but that may become problematic when a lot of people charge their cars at the same time in residential areas. Quick charger installations require a higher current feed and thus a stronger electrical grid.
