New University of Michigan Study: Electric Vehicle Charging Methods Can Impact Emissions

Courtesy of The The Responsible Battery Coalition

Research Finds that Optimizing EV Delivery Vehicles’ Charging Practices can Reduce Greenhouse Gas Emissions by as Much as 37%

WASHINGTON, D.C. — The Responsible Battery Coalition (RBC) today applauded the release of new research on improving electric delivery vehicle charging strategies from the Center for Sustainable Systems at the University of Michigan’s School for Environment and Sustainability. The study found that as much as 80 percent of emissions from electric delivery vehicles batteries occurs during charging phases. A link to the study can be found here.

“As electric vehicles become an even greater part of our nation’s supply and delivery systems, enhancing battery charging methods to reduce emissions and lengthen battery lifetime are critically important steps toward developing a true circular economy for vehicle batteries,” said RBC Executive Director Steve Christensen. “The Responsible Battery coalition is proud to support the work of the University of Michigan that will lead to more sustainable battery usage and recycling practices.”

Major transportation companies in the U.S. supply and delivery chains are making strides to develop electric delivery fleets. By 2040, RBC member FedEx plans to be fully electric and several other major companies have made significant investments in electric vehicles. RBC provided support for the University of Michigan study, which found that poor charging practices can shorten battery life, leading to faster replacement times and increasing the vehicle’s total greenhouse gas emissions.

The RBC is the premier coalition of major stakeholders in the battery manufacturing, use, sales and recycling sectors, and continues to deliver next step life cycle management for all vehicle and industrial batteries regardless of chemistry. By partnering with leading stakeholders in the battery supply chain, key thought leaders, and the nation’s top research institutions, the RBC develops scientifically validated and commercially viable solutions for the responsible management of today’s batteries and those yet to be imagined. The RBC, its prominent members, as well as research institutions, including Argonne Laboratories, the University of Michigan, and others, recently launched an EV initiative dedicated to applying the knowledge and best practices of the ‘circular economy’ that has been achieved for lead acid batteries to Lithium-ion batteries used in EVs.


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Hamburg, Germany – 30 August, 2018: Delivery vans Volkswagen e-Crafter parked on the parking. Today this model is one of the most popular electric LCV vehicles in Europe. Image courtesy of University of Michigan

Originally published by University of Michigan:

Electric delivery vehicles: When, where, how they’re charged has big impact on greenhouse gas emissions

The transportation sector is the largest contributor to greenhouse gas emissions in the United States, and a lot of attention has been devoted to electric passenger vehicles and their potential to help reduce those emissions.

But with the rise of online shopping and just-in-time shipping, electric delivery fleets have emerged as another opportunity to reduce the transportation sector’s environmental impact.

Though EVs represent a small fraction of delivery vehicles today, the number is growing. In 2019, Amazon announced plans to obtain 100,000 electric delivery vehicles. UPS has ordered 10,000 of them and FedEx plans to be fully electric by 2040.

Now, a study from University of Michigan researchers shows that when, where and how those fleet vehicles are charged can greatly impact their potential to reduce greenhouse gas emissions.

A key point of the study is that both the emissions directly tied to charging the vehicles and emissions that result from manufacturing the batteries must be considered. Charging practices that shorten a battery’s lifetime will lead to early battery replacement, adding to the total greenhouse gas emissions associated with that vehicle.

The U-M researchers found that 50% to 80% of the lifetime emissions associated with an electric delivery vehicle’s battery occur during charging. Therefore, charging from a cleaner energy source—such as an electrical grid with lots of renewables—is one of the most impactful ways to lower the emissions of an electric vehicle.

When both charging and battery degradation were considered, the researchers found that greenhouse gas emissions could be lowered by as much as 37% by optimizing charging strategies.

And, surprisingly, they also found that even in the most carbon-intensive regions of the United States, electric delivery vehicles resulted in fewer greenhouse gas emissions than their gasoline or diesel counterparts.

“Our evaluation strategy leads to two main recommendations for companies investing in fleets of electric vehicles,” said Maxwell Woody of U-M’s Center for Sustainable Systems, lead author of the study published online July 9 in the journal Environmental Science & Technology.

“The first is to consider battery degradation when determining when to charge and how much to charge. Some charging strategies can extend battery lifetime, and this will both lower greenhouse gas emissions and protect the company’s investment.”

The U-M team’s second recommendation to fleet owners is to consider where the energy charging the vehicle comes from. A vehicle charged from solar or wind energy and a vehicle charged from a coal- or natural gas-fired power plant will have very different environmental impacts.

“Considering the charging source can help companies determine the best places to charge, as local grids vary across the country. Companies should prioritize fleet electrification in regions that provide the greatest carbon-reduction benefits,” said Woody, a recent master’s graduate of U-M’s School for Environment and Sustainability who now works as a research area specialist at the Center for Sustainable Systems.

In their modeling study, the researchers analyzed four charging strategies and looked at their lifetime environmental impacts. The new U-M study goes beyond previous work by combining the regional and temporal variation in charging emissions with the impact of charging on battery degradation.

The researchers showed that a baseline charging scenario in which a vehicle is fully charged immediately upon returning to a central depot resulted in the highest emissions. Employing alternative charging methods led to emissions reductions of 8% to 37%.

“Charging the vehicle as soon as it returns and charging the vehicle up to 100% result in a lot of time spent sitting at the depot/charging station with a full battery. This extra time spent fully charged will cause the battery to wear out more quickly—so quickly that the battery may need to be replaced sometime in the vehicle’s lifetime,” said study corresponding author Parth Vaishnav, assistant professor at the U-M School for Environment and Sustainability.

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

Charging the battery only enough to complete the day’s route, a practice the researchers called sufficient charging, led to a large increase in battery lifetime—in some cases more than doubling it. As a result, emissions tied to battery production were reduced.

Overall, charging strategies that minimized greenhouse gas emissions typically lowered costs as well. In most cases, delaying charging until the vehicle was close to departure, combined with sufficient charging, was the optimal strategy for both cost and emissions.

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

“Electric delivery vehicles only make up a small proportion of delivery vehicles right now, but that number is expected to increase in the coming years. Establishing the best practices for charging now, as these vehicles are starting to be deployed in larger numbers, is a critical step toward lowering greenhouse gas emissions.”

The other authors of the study, “Charging Strategies to Minimize Greenhouse Gas Emissions of Electrified Delivery Vehicles,” are Michael Craig of the U-M School for Environment and Sustainability and Geoffrey Lewis of the U-M Center for Sustainable Systems. The work was supported by the Responsible Battery Coalition.


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