Grid congestion is the key obstacle to electric vehicle (EV) emissions reduction, a new study finds. This highlights a dilemma: Renewable energy is growing, but it is often remote from EV charging stations.
As things stand, without grid upgrades, EVs will still rely on fossil fuel-generated energy. To counter this, smart, targeted upgrades could solve grid congestion to unlock EVs’ potential.
Consequently, even if enough renewable energy is available, simply switching from gas-powered cars to electric vehicles (EVs) will be enough to fight climate change. According to Northwestern University this is unless the U.S. also upgrades its transmission grid.
If every gas-powered vehicle in the U.S. were replaced by an EV, transmission constraints would prevent the cleanest available electricity from reaching many charging locations. This “grid congestion” would force greater reliance on nearby fossil fuel power plants, undercutting the emissions benefits of electrification.
After identifying the issue, the study also recommends a modest set of targeted transmission grid upgrades to alleviate congestion and unlock the full emissions-reduction potential of EV adoption.
To analyse electricity’s journey through power lines, the researchers combined data on vehicle usage and power grid infrastructure. Using advanced computer models, the team simulated the flow of electricity across the U.S. under varying levels of vehicle electrification and renewable energy generation
In every scenario with high EV adoption and subsequent model, grid congestion emerged as a critical bottleneck.
According to chief scientist Adilson Motter: “Even if the U.S. fully adopts EVs and generates enough renewable electricity to charge them, it still won’t be enough. We found the limiting factor for cars to be powered by clean energy has less to do with the availability of renewable energy and more to do with the ability to transmit that energy from generation sites to where it’s needed. The power lines are congested, and that leads to congestion-induced carbon dioxide emissions.”
While clean energy is available, transmission capacity is often too limited to deliver it where it is needed, including EV charging stations. As a result, the grid draws electricity from closer — but more polluting — power plants that generate electricity by burning coal, oil and gas. Campaigning against this is popular with young people.
To address this bottleneck, the researchers calculated how much additional transmission capacity would be needed. The scientists found that increasing the existing grid’s transmission capacity by as little as 3 to 13% would significantly reduce congestion. This could, as an example, involve building new high-voltage lines or expanding existing ones — enabling more clean power from remote wind and solar farms to reach the cities and suburbs where EV charging demand is highest.
The researchers point out that the entire grid does not need to be rebuilt. Instead, they recommend targeted upgrades in areas where congestions are most likely to occur. The U.S. grid is divided into three largely independent regions — Eastern, Western and Texas — with limited ability to transfer power among them. Improved connections and coordination among regions would help clean energy reach the areas that need it most.
The study appears in the journal Nature Communications. The research paper is titled “Grid congestion stymies climate benefit from U.S. vehicle electrification.”
