When, where and how an electric vehicle is charged is very important. here’s why

The transportation sector accounted for approximately 29% of all greenhouse gas emissions in the United States in 2019, making it by far the largest source of emissions. And while other sectors and industries have seen their carbon footprint decline, emissions related to transport have actually increased in absolute terms between 1990 and 2019.

But that’s where the electric vehicle (EV) revolution is supposed to come in, isn’t it? While it’s true that electric vehicles are far better for the environment than gasoline or diesel-powered cars and trucks, they’re not exactly emissions-free. As we will see, it is a bit complicated.

Today’s electric vehicles and the high-density Li-ion batteries that accompany them involve energy-intensive manufacturing processes compared to their traditional vehicle counterparts. And when the electricity used to charge the batteries comes from fossil fuels, electric vehicles can indirectly contribute to emissions.

But after crunching the numbers, electric vehicles are still “greener”. For example, a 2020 study by researchers from Cambridge, Exeter and the University of Nijmegen found that in 95% of countries around the world, driving an electric car is better for the environment over its lifetime. of life compared to using a gasoline-powered car. Additionally, the emissions profile of electric vehicles can be significantly improved using certain strategies.

In a new study, researchers from the University of Michigan conducted comprehensive modeling, analyzing four different charging scenarios for a fleet of electric delivery vehicles. The researchers decided to focus on vehicle fleets because their collective impact on the environment can be more accurately predicted. More importantly, unified strategies can be directed downwards so that all vehicles in a fleet have a similar carbon footprint profile.

This is important in light of recent news such as Amazon announcing that it will buy 100,000 electric vehicles. Likewise, UPS has ordered 10,000 and FedEx has pledged to go all-electric by 2040.

Unlike previous life cycle assessment studies that primarily looked at regional and temporal data regarding charging emissions, researchers now also looked at the impact of charging on battery degradation. For many car owners, as well as people looking to buy a new car (and considering electric), the results can be significant. Battery resilience could be the difference between getting something like the Ford F or the new Ford F Lightning electric, or the gas-powered 2022 Kia Telluride versus its electric counterpart, the EV9.

The authors concluded that 50% to 80% of an electric delivery vehicle’s lifetime emissions occur during charging. Therefore, the most impactful thing to do is to charge the vehicle from a power grid that generates a lot of renewable energy. But emissions could be drastically reduced by up to 37% simply by optimizing charging strategies.

“Our evaluation strategy leads to two main recommendations for companies investing in electric vehicle fleets,” said Maxwell Woody of UM’s Center for Sustainable Systems, lead author of the study.

“The first is to consider battery degradation to determine when to charge and how much to charge. Certain charging strategies can extend battery life, which will both reduce greenhouse gas emissions greenhouse and protect the company’s investment.

In light of their findings, the researchers made some recommendations for managers of electric vehicle fleets. The first is rather obvious: do your best to source the electricity used to charge the batteries from renewable sources. Local grids can vary wildly in their mix of fossil/renewable energy sources, so companies might find it wise to focus the initial deployment of their EV fleet in regions that offer the greatest reduction benefits. of carbon.

Other guidelines were much more insightful. For example, loading a vehicle to 100% immediately after returning to the central depot results in the highest emissions. Instead, charging the battery just enough to complete the day’s route, what researchers call “sufficient charging,” doubled battery life and led to fewer emissions.

“Charging the vehicle upon return and charging it up to 100% results in a lot of time sitting at the depot/charging station with a full battery. This extra time spent at full charge will cause the battery to wear out more quickly – so quickly that the battery may need to be replaced over the life of the vehicle,” said study corresponding author Parth. Vaishnav, assistant professor at the UM School for Environment and Sustainability. .

“Creating this additional battery produces additional greenhouse gas emissions, as well as additional costs.”

The same strategies that minimize carbon emissions have also resulted in cost reductions, meaning companies have a strong incentive to properly manage their fleets. These same practices could then be applied to individual EV drivers and owners.

“The most important finding is that there’s a big opportunity here to reduce emissions,” said study co-author Greg Keoleian, a UM professor of environment and sustainability and director of the Center. for Sustainable Systems from UM.

“Electric delivery vehicles currently represent only a small proportion of delivery vehicles, but this number is expected to increase in the coming years. Establishing charging best practices now, as these vehicles begin to be deployed in greater numbers, is a crucial step towards reducing greenhouse gas emissions.

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