As we move toward a cleaner transportation sector, a new $2 million project at the University of Michigan aims to develop easier and more cost-effective ways to make recyclable lightweight automotive sheet metals.
The project is a key effort as major car manufacturers look to lightweight light-duty trucks and shift away from internal combustion engines toward electric cars which require more lightweight components to increase vehicle range.
Dubbed “The Clean Sheet Project,” the effort seeks to develop new design tools and establish best practices for material producers and carmakers with a focus on recycling from start to finish in production. While the group’s initial focus will be on energy-intensive aluminum and advanced high-strength steel automotive sheet metals, it could eventually include guidelines for all manner of materials, including plastics, polymers and electric vehicle, or EV, batteries.
“We need to reduce the environmental impacts of vehicle production going forward, and one of the ways to do that is to boost the production of these lightweight sheet metals from recycled materials,” said Daniel Cooper, a U-M assistant professor of mechanical engineering and the project’s principal investigator. “Not only will that reduce emissions from the automotive production process, it will also help to limit destructive mining for raw materials.”
Moving beyond ‘downcycling’ scrap metal
“We already recycle many of the materials that are going into these new vehicles, but we don’t do it well,” Cooper said. “It requires putting the steel and aluminum into electric arc- or gas-fired furnaces, and then casting new metal.”
The recycled metal products aren’t high-quality because it’s difficult, if not impossible, today to obtain pure source material to melt down. And in the U.S., there is little demand for these contaminated scrap metals, so the materials are often shipped to other countries where low-paid workers sort them by hand.
At a vehicle’s end-of-life, recyclers use mechanical shears to try to break apart and pile up the different metals to send separately to furnaces. But vehicles contain many different metal alloys that are mixed together as they are broken up, and aluminum car panels often have steel rivets that are difficult to remove, even with magnets.
This task of separating the metals is only getting more difficult. Electric vehicles, for example, use even more copper wiring in their electronics and recycled steel can crack during manufacturing if it contains as little as 0.1% copper.
Typically, the recycled metal ends up being used in places with low performance requirements such as aluminum castings in engine blocks and steel reinforcing bars.
“We see tremendous opportunity for increased material reuse and recycling if vehicle designs include ease of disassembly, improved material separation and industry-wide commonization,” said George Luckey, manager of stamping and alloy development at Ford Research and Advances Engineering. Ford is among several private funding partners involved in the effort.
“The Clean Sheet Project will provide these insights and we are excited to join the University of Michigan and other partners in participating,” Luckey said. “This work strongly supports Ford’s commitments to reduced CO2 emissions, developing a circular economy and a carbon neutral future.”
An aluminum opportunity
Two powerful factors suggest that the time is now for establishing how to make more sustainable practices commonplace.
The first is that new commitments to electric vehicle manufacturing are coming regularly from major automakers in 2021, and that trend is likely to continue. Earlier this month UBS Investment Bank estimated that electric vehicles would account for 40% of all new car sales by the end of the decade. The second factor is that over the next few years, a wave of aluminum-sheet intensive vehicles will reach their end of life and make their way to scrap yards, Cooper’s previous research has shown.
Aluminum has become one of the most popular EV materials thanks, in part, to its low density, which helps keep vehicle weights down.
“This calls for a reinvention of how such high-value materials can be recycled or remade to produce new vehicles,” Cooper said. “Aluminum is known for being tricky to recycle without a loss of performance, and you can see why some people are getting nervous about where we’re heading. If we are switching to EVs, that probably means even greater demand for high-quality aluminum and a loss of the internal combustion engine market that currently uses a lot of the low-quality recycled metal.”
The Clean Sheet Project’s integrated approach
Previous efforts at making EV components more readily recyclable have seen some success, but the lack of an integrated approach across the industry from material producers and recyclers to carmakers and scrap processors has hurt the effort.
“Hopefully, our methodology could provide a breakthrough across the board,” Cooper said.
That methodology includes a computer modeling approach known as integrated computational materials engineering that will determine how well mixed metals can be recycled. These models can help researchers discover new materials that are more recycling-friendly and determine how more recycled materials can be used in high-quality components like aluminum car bodies. Additional modeling will assess vehicle design options, such as what and where materials are used.
Researchers will also analyze new technologies for disposing of old vehicles and separating the materials. The project will deliver a new suite of designs for recycling tools and technology roadmaps for the whole industry.
The Clean Sheet team is currently organizing a cross-sector workshop on automotive metal sheet design, production, manufacturing, and recycling in order to learn from industry experts on the opportunities to increase high-quality metal sheet recycling.
Roughly half of the project funding comes from the U.S. Department of Energy’s REMADE Institute—a public-private partnership that promotes sustainable technology adoption for industries. Along with Ford, additional funding partners include: Novelis, The Institute of Scrap Recycling Industries, The Aluminum Association, Light Metal Consultants and Argonne National Laboratories.