We all know that “money doesn’t grow on trees.” But what happens if it actually does… just not in the form we expect?
A team of scientists from the University of Melbourne are pushing the boundaries of that metaphor with a study of hyperaccumulators — plants that love minerals and thrive in particular contaminated soils; they draw those minerals up into their bodies and keep them until the sap can be harvested and “smelted” into metal. The process is called “phytomining”: Imagine crossing a mine with a sugar maple stand, making for a far more sustainable and less destructive way of extracting metals from the earth!
The New York Times has done a deep dive into the possible applications of these hyperaccumulators, of which there are over 700 known among this planet’s plant life. Dr. Alan Baker, botany professor, and his international team have rented a plot of land on the island of Borneo. There, they’ve collaborated with farmers to process the sap of the plants grown there into nickel citrate, a valuable mineral that can be used to manufacture batteries and stainless steel. This proof of concept has laid the foundation for a bigger, 50-acre trial, which the team hopes will grab the attention of the very industries they want to disrupt.
“Currently, the most common way to extract nickel for electronics requires intense energy — often derived from coal and diesel — and creates heaps of acidic waste. A typical smelter costs hundreds of millions of dollars and requires increasingly scarce ore that is at least 1.2 percent rich with nickel.
In contrast, plants on a small nickel farm could be harvested every six months on land where the nickel concentration is only 0.1 percent. After two decades, the roots would struggle to find enough nickel, but the land would have been sucked dry of its toxic metals, and fertile enough to support more common crops.’
The minerals are extracted from the plant matter itself by burning or compression, both processes easily scaled up or down. While phytomining can’t totally replace traditional mining, it can be used in places where traditional mining is untenable. Additionally, the plants used can draw minerals from soils polluted by traditional mining, stockpiling that much more material for the mining companies — thus incentivizing a cleanup that leaves the earth reinvigorated for other crops! And nickel is not the only “fruit” these plants can bear: different species slurp up other useful metals like cobalt and zinc.
I’m entranced by visions of “metal farms,” where (metaphorical) bushels of key minerals are brought in after a growing season that respects local climate and terrain. It seems so bucolic! And necessary: If we can’t wean ourselves off these industries entirely, it’s on us to find sustainable ways to get results. I’m looking forward to seeing the results of the bigger trial and watching companies get on board “harvesting” crops of pure minerals.