As electrification begins to spread across the transportation sector, the way in which battery systems are developed, manufactured, used, and recycled has a significant effect on the scale of their environmental impact. Growth from just a few percent today to more than 40% of the new vehicle market within the next 10-20 years means that there is a need for a “comprehensive set of recommendations to guide mobile battery deployment and technological development from an environmental perspective.” That was the rationale behind the creation of ten “Green Principles” that were developed by researchers at the University of Michigan’s School for Environment and Sustainability under sponsorship from the national nonprofit Responsible Battery Coalition (RBC).
“We’ve seen rapid growth in electric vehicles in the last few years, and recent projections that EV growth will increase exponentially in the next decade, so the publication of these guiding principles is both timely and highly relevant,” said Steve Christensen, executive director of RBC in a news release.
EVs require different battery considerations than do stationary grid applications. UM researchers have developed “Green Principles” for both applications. (Image source: University of Michigan)
Every Part of the Lifecycle
A team led by Dr. Gregory A. Keoleian, director of the University of Michigan Center for Sustainable Systems and a member of the RBC Scientific Advisory Board, developed the “Green Principles for Vehicle Energy Storage,” which define best practices for minimizing the environmental impact of EV batteries. Drs. Maryam Arbabzadeh and Geoffrey M. Lewis conducted the research with Dr. Keoleian.
“As we look at the full lifecycle of EV batteries – from initial raw materials extraction all the way through end-of-life – it is important to examine all aspects, including how and where charging will occur, maximizing overall performance and ensuring proper recycling,” Keoleian said. The principles were published in an article in the Journal of Energy Storage on May 25. The principles are similar to those previously established by the University of Michigan stationary grid battery applications and are valid for both emerging battery technologies such as lithium-ion, and also the stewardship of existing lead-acid batteries.
Through a close interaction with diverse stakeholders that included battery manufacturers, suppliers, OEMs, recyclers, and ANL and a careful review of existing literature on design, operation, and end-of-life of mobile battery systems, the research team was able to condense the information to the current ten principles. The team understood that the principles are not immutable and that there will often need to be tradeoffs between principles as electrification continues to develop. They have however produced a set of principles that can guide analysis and inform decisions on development and deployment of battery systems for mobile applications.
Key parameters, such as type of chemistry, influences battery cycle life and thermal stability, which ultimately sustainability. Degradation of battery capacity during charging and use can result in a reduction in round-trip efficiency and environmental performance. (Image source: Center for Sustainable Systems, adapted from Figure 1 in Arbabzadeh, Lewis, Keoleian J. Energy Storage (2019))
These are the 10 Principles
The ten principles, as stated in “Green principles for responsible battery management in mobile applications” in volume 24 of the Journal of Energy Storage (https://doi.org/10.1016/j.est.2019.100779) are as follows:
Principle #1: Choose battery chemistry to minimize life cycle environmental impact
Develop and select battery chemistry that enhances operational and broader life cycle performance, which ultimately drives sustainability.
Principle #2: Minimize production burden per energy service
Minimize the production burden per energy service provided by the battery system. Production burden includes material production, manufacturing, and associated infrastructure.
Principle #3: Minimize consumptive use of critical and scarce materials
Design and production of batteries should minimize the consumptive use of scarce and critical materials, since depletion of materials can constrain continued deployment of these systems.
Principle #4: Maximize battery round-trip efficiency
Maximize battery round-trip efficiency to minimize energy losses during vehicle charging and operation.
Principle #5: Maximize battery energy density to reduce vehicle operational energy
Design battery storage with maximum energy density to minimize mass-related fuel consumption.
Principle #6: Design and operate battery systems to maximize service life and limit degradation
Use charging patterns that minimize degradation by preserving battery capacity and round-trip efficiency. Temperature also impacts degradation.
Principle #7: Minimize hazardous material exposure, emissions and ensure safety
Exposure to, and emission of, hazardous materials should be minimized during production, use (operation and service), and end-of-life stages of the battery system in order to provide a safe environment for communities, workers, and users.
Principle #8: Market, deploy, and charge electric vehicles in cleaner grids
Charge EVs with cleaner electricity to lower life cycle emissions. Any grid-vehicle interaction should result in lower emissions, and cause minimum battery degradation.
Principle #9: Choose powertrain and vehicle types to maximize life cycle environmental benefits
Increasing degree of electrification from ICEV to PHEV to BEV should result in lower life cycle emissions, depending on the grid mix.
Principle #10: Design for end-of-life and material recovery
“Circular economy” end-of-life approaches (reuse, remanufacturing, and recycling) can significantly reduce environmental impacts and global demand for extracted materials.
How They Should Be Used
“These principles define and develop a solid approach to properly managing the next generation of mobile battery technologies,” RBC’s Steve Christensen told Design News. “Now we’ll continue our work with the university in 2019 to provide more specific guidance to limit battery degradation, including recommended consumer practices for optimizing battery life in electric vehicles and other consumer devices, such as mobile phones, laptop computers and cordless power tools.”
The findings behind the 10 green principles also lend themselves to educational campaigns associated with EV charging strategies to extend battery life and minimize emissions, Christensen told us. In addition, the focus on design for end-of-life and material recovery, battery round-trip efficiency, and comparisons of battery chemistries can be used by battery manufacturers and EV OEMs in minimizing the lifecycle environmental impacts.
Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.
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