Study: US graphite sourcing for electric vehicle battery applications (DOI: 10.1111/jiec.70104)
New research from the University of Michigan and Ford Motor Co. shows that the United States could mine enough graphite to build batteries for electric vehicles and other applications, but economics and geopolitics make it a complex problem.
In August, the U.S. Department of Energy announced funding opportunities totaling nearly $1 billion to encourage the mining and processing of energy critical materials domestically to shore up their supply chains.
One of those critical materials is graphite, a mineral used in the electrodes of batteries used for electric vehicles and in stationary storage for the grid. Currently, all battery-grade graphite in the U.S. is sourced from abroad.
"Currently, China dominates the global supply of graphite and there are concerns about supply chain security," said Gregory Keoleian, professor at the U-M School for Environment and Sustainability.
Against that backdrop, Keoleian and colleagues from U-M and Ford sought to answer a straightforward question: Would the U.S. be able to mine enough graphite domestically to meet its anticipated demand between now and 2040?
The short answer is technically yes. The team projected that, over the next 15 years, demand for battery-grade graphite from mines will reach nearly 2 million metric tons in the U.S., while the country's supply of natural graphite amounts to more than 7 million metric tons. While that simple supply-is-greater-than-demand math works out in the country's favor, however, the full issue is far more nuanced.
The team's project was funded by Ford through a Ford-U-M Alliance Project award and its results are published in the Journal of Industrial Ecology.
"There's plenty of graphite, but it'll cost us a lot more to produce it than it would through Chinese mining," said Stephen Kesler, a study co-author and professor emeritus at the U-M Department of Earth and Environmental Sciences. "And that is not because they have lower wage levels and lower regulations. It is because our deposits are not of similar quality."
When he says quality, Kesler is referring to what those in the business would call the grade or concentration of graphite. In simple terms, it's the amount of graphite that mines can obtain per ton of rock they dig up, he said. A site called Graphite Creek in Alaska has the highest known grade of graphite in the United States, where roughly 5% of the extracted material would be graphite.
"That's at the lower end of the range that people are able to produce graphite economically," Kesler said. "Deposits in China and other places around the world are running 10% or better."
The researchers also considered the supply of and demand for synthetic graphite, which is made from needle coke, a byproduct of oil refining. Battery makers currently use more synthetic than natural graphite and demand for synthetic graphite is expected to outpace the U.S.'s ability to make it, according to the team's analysis.
Still, the study also showed that the combined demand for synthetic and natural graphite comes to just over 7 million metric tons, while the combined supply is projected to eclipse 9 million metric tons. If batteries shifted the usage ratio to include more natural graphite, that could benefit U.S. interests, the team pointed out. Furthermore, mining in the U.S. would also directly cut back on carbon emissions, Keoleian said.
"We also looked at the carbon footprint of graphite and it's likely that there would be a decrease in greenhouse gas emissions with production in the United States compared with China," Keoleian said. "So we should be producing it in the United States. We have a cleaner grid, and we generally have more strict standards with regard to operations from mining and manufacturing. Domestic production also alleviates the geopolitical risk associated with importing."
Mining graphite, however, isn't as simple as firing up more machinery at active mines in the U.S. because there are none. Although graphite was first mined in the U.S. in the 1600s, the country all but stopped production in the mid-1900s and never restarted as imports became so affordable. That said, a company called Graphite One is developing a mine at Alaska's Graphite Creek that's anticipated to be online before 2030.
Even once domestic production starts, though, there will be important questions to answer, the researchers said. A big one is whether the U.S. should try to depend solely on its domestic graphite or conserve at least some for the future. By instead continuing to import inexpensive graphite in the nearterm, the U.S. would also be buying time to better understand the mining potential of its own graphite deposits.
"We have lots of graphite occurrences around the country and only a few of them have been looked at in detail, so there's a huge amount of uncertainty about our total graphite resources. There are great big areas in this country that haven't been evaluated in any real way," Kesler said. "So I think in the case of graphite, we might want to continue to import while we pursue development of a domestic supply chain."
The research team also included two more members from U-M, both with the Center for Sustainable Systems: Christian Hitt, a research area specialist, and lead author Sarah Gorman, who earned her master's degree while working on the project. Hyung Chul Kim, Robert De Kleine and James Anderson from Ford also contributed to the study.
