Feds are trying to get the metal from plants through their roots


“Just as we do research with corn, wheat, soybeans to make these plants more efficient at taking up nutrients — nitrogen, phosphorus, potassium — there is a need for research that helps understand the mechanisms of metal overaccumulation. Is,” says McNear. “And then enhancing it, whether it's through gene editing or something else.”

ARPA-E is looking at a special type of dirt, known as ultramafic soil, which is high in iron, cobalt, chromium and nickel, to try to grow these plants. It is common where volcanic activity has occurred, for example in Northern California and Southern Oregon, but it is present throughout the US, from Wyoming to Pennsylvania and down south. The concentration of nickel in ultramafic soils is probably too low to open a proper mine, but too high to grow crops and other vegetation.

With this new funding, scientists can emphasize or breed existing plant species to improve the way they store nickel. Ideally, they'll land on a plant that grows rapidly, so you'll have a lot of nickel-rich biomass that will turn into metal-laden ash. “The problem historically has been that they're often not very productive plants,” says Brown. “And the challenge is that you have to have a high concentration of nickel And “Higher biomass to achieve meaningful, economically viable results.”

Provided scientists can land on the right hyperaccumulating plant for the US, it could theoretically provide more nickel for more batteries. It's not just growing fleets of electric vehicles that are demanding more batteries: The grid will also need larger batteries to store energy generated by renewables like wind and solar power. When the sun isn't shining and the wind isn't blowing, grid operators have to use batteries to meet demand. Utilities are also experimenting with ways to use EVs sitting in garages as distributed networks of battery backup power.

Of course, ARPA-E's overpopulated plants have to play well with the ecosystem – you certainly don't want them to become invasive and out-compete native species. But the idea is that over time, phytomining will actually improve the soil, releasing enough nickel for other non-hypomining plants to eventually grow. Hyperaccumulators can also clean up soil contaminated through traditional nickel mining, such as around smelting facilities, as McNear has experimented with. “Whatever goes out, the smoke settles around that facility,” he says. “Farmers can no longer use that land because it contained so much nickel, but they can grow nickel crops. And sell it back to the smelter – it's really a win-win.”

For now, ARPA-E is focusing on phytomining nickel, but says it could theoretically also explore ways to extract cobalt, copper or lithium from plants. This is green technology in true sense.