Electric vehicles are coming, en masse. How can local utilities, energy managers and cities prepare? This is the key question examined by a new study conducted by researchers at PNNL, Pacific Northwest National Laboratory.
“While we don't know exactly when we'll reach the tipping point, fleets of fast-charging vehicles will change the way cities and utilities manage their energy grid and infrastructure.” He states it Michael Kintner-Meyer, an electrical systems engineer and lead author of the study. “It's not a question of if, but when.”
The study, published today, integrates and incorporates many factors never before evaluated together, such as electric trucks for long-haul delivery and transport, as well as smart charging strategies. Problems that still seem out of the reach of the decision makers, but that for the timing that is announced are dramatically close.
Electrification of transportation is coming.
Like any self-respecting revolution, even the electric one will end up rolling some heads. According to EV Hub, there are already many millions of electric vehicles, mainly cars and SUVs, on the roads around the planet. The researchers obviously kept the focus on the United States alone, evaluating the capacity of the electricity grid over the next decade.
Will our networks be able to manage the growing fleets of electric vehicles of all sizes, including trucks, that can be connected to charging stations for houses, businesses and short and long-distance roads?
PNNL's analysis revealed the maximum EV load the grid could handle without having to build new power plants and transmission lines.
Electrical revolution, good and bad news.
The good news is that through 2028 the entire power system, from generation to transmission, will hold up well to up to 24 million electric vehicles, about 9% of current vehicle traffic in the States. If we wanted to transpose it to Italy (I hope to find out more) the figure would correspond to around 4,5 million vehicles. The bad news, of course, comes next.
With around 30 million electric vehicles, things get risky. Locally, problems can arise. Many do not know, some do: a fast-charging electric vehicle can absorb the same load as 50 homes. If every house on a street had an electric vehicle, a power transformer would not be able to manage everyone's charging at the same time.
Smooth out the curve of the duck
As detailed in the report, current network planning does not adequately take into account a massive influx of electric vehicles. This omission aggravates an already stressful situation: the fearsome duck curve.
The duck curve is a 24-hour load profile on the power system and usually occurs in areas with many PV installations. The curve is based on a moderate load in the morning, a low load during the day when solar units feed electricity into the grid, and a high load at night when people come home from work and the sun goes down.
As demand increases, tension plummets. And with more electric vehicles plugging in to charge in the evening, the difference in elevation becomes even steeper and increases electricity costs.
Smart charging strategies
Avoiding charging during peak morning and early evening hours can smooth out peak demand and fill the duck curve, the study found. The approach has two positive aspects. In the first place, would benefit from relatively “clean” solar energy during the day. It would also reduce or eliminate the sharp evening peak, when solar energy fades and other sources come in to make up the difference.
The plausible scenarios underline the need to plan the energy grid.
The research team developed and modeled plausible scenarios for 2028. The scenarios include a mix of light (passenger), medium (trucks and vans) and heavy (freight) on-road vehicles - the first time that all three vehicle classes are included in this analysis. A road freight model was also developed with charging stations on motorways every 80 kilometers for all three vehicle classes.
The scenarios took into account the evolution of the energy grid and its capacity at the state and regional levels. The team focused on scenarios with the greatest potential for network impact.
Bottlenecks due to new EV charging have obviously appeared especially in areas… with more EVs.
In California, for example. Los Angeles plans to go fully electric with its city fleet by 2030. The peak has come from the growth of fast-charging cars and commercial fleets of electric trucks. These vehicles can draw 400 amps through a circuit for up to 45 minutes, instead of the 15-20 amps for 6-8 hours from most electric vehicles today.
Fast-charging vehicles are among the biggest challenges for today's planners
Lawmakers, planners, visionaries and decision makers have never really had to think about electric vehicles before. Now they will have to quickly change distribution systems and operations. The key is to understand now how to avoid large capital outlays in the future. And the challenge is not limited to big cities. The smaller ones, with limited resources, need help to build their own charging infrastructure and the ability to generate energy.
