Nickel Farming

Nickel is in demand because it’s used in lithium ion batteries, common alloys such as stainless steel, and new super alloys for the aerospace and wind turbine industry. But mining and smelting nickel is energy intensive, using a great deal of diesel fuel and coal. And the after-products are environmentally dangerous. Luckily, we’ve found that nickel can grow on trees. Or more specifically, shrubs. Metals are toxic to most plants, which don’t grow in metal-rich soils. But some 700 species are hyperaccumulators—they actually pull metal from the ground and concentrate it in their tissues. It’s thought they do this to ward off pests or to help absorb potassium from poor soil. Of these species, over 400 accumulate nickel. Their blue-green sap can be up to 25% nickel—a concentration twenty times greater than the nickel ore mined for smelting. These shrubs can be farmed and the metal harvested in a technique called phytomining. Farmers cut back the shrubs once or twice a year and either squeeze sap from the foliage or burn it and gather the ash. The farms can be sited on nickel-rich soils that have been corrupted with mine tailings or are otherwise unfit for agriculture. After a couple decades, the plants will deplete the nickel in the soil through a process called bioremediation, and the land can grow food crops. Nickel farming will never replace large-scale mining, but it can help small farmers earn a living in areas with toxic soils.