Phytomining, using hyperaccumulator plants to extract metals like nickel, offers a sustainable alternative to traditional mining. This method could reduce environmental damage and provide a new source of nickel as demand for electric vehicle batteries rises. However, challenges remain in scaling production and ensuring economic viability.
In the wake of the Chernobyl disaster, scientists discovered a remarkable ability of certain plants to thrive in contaminated soils. These plants, known as hyperaccumulators, can absorb and store metals such as radioactive caesium, copper, zinc, and even gold. Fast forward to today, and the concept of using these plants for mining metals is gaining traction as a potential solution to the environmental issues associated with conventional mining.
Hyperaccumulators, like Indian mustard, have evolved to absorb metals from the soil, storing them in their shoots and leaves. This adaptation serves as a defense mechanism against predators and pathogens. In the 1980s, biologists began utilizing these plants in areas contaminated by mining activities, a process known as phytoremediation, which cleans up the soil.
Antony van der Ent, a leading researcher in this field, explains that if these plants can absorb valuable metals, we can extract them through a process called phytomining. Currently, around 700 hyperaccumulator species have been identified globally, with some plants capable of absorbing nickel, a metal in high demand due to its use in batteries.
One notable example of phytomining is taking place in Albania, where a start-up named Metalplant is cultivating nickel hyperaccumulators on a 10-hectare field. The soil in this region is too rich in nickel for traditional crops but not rich enough for conventional mining. The plants absorb nickel, and after harvesting, they are dried and processed to create nickel sulfate, suitable for electric vehicle batteries.
Metalplant reports a harvest of over three tons of nickel per season. However, this is a fraction of what a conventional mine can produce in just half an hour. Traditional nickel mining is notorious for its environmental destruction, including deforestation and toxic waste production, which can contaminate water sources and harm ecosystems.
Phytomining presents a lower environmental impact compared to traditional mining methods. It avoids toxic tailings and can potentially reduce greenhouse gas emissions by up to 90%. The process captures carbon dioxide during plant growth, balancing emissions when the plants are burned for metal extraction. Moreover, phytomining targets barren lands unsuitable for food crops, thus not competing with agricultural land use.
Rupali Datta, a researcher in this field, emphasizes that phytomining can help restore areas damaged by conventional mining, allowing for future forestry or recreational use.
Despite its potential, phytomining faces significant challenges. The yield is limited to one or two harvests per year, and the metal content in the soil can be depleted after about 20 years. To match the output of a conventional nickel mine, phytomining would require vast areas of land—up to 200,000 hectares, which is more than twice the size of New York City.
For decades, scientists have struggled to make phytomining a viable commercial process. However, in 2024, the US Department of Energy allocated $10 million to support research and development in this area, highlighting the urgency of diversifying nickel supply sources.
The global demand for nickel is projected to increase by nearly 70% by 2040, primarily driven by the electric vehicle market. Currently, over half of the world's nickel supply comes from Indonesia, often controlled by Chinese companies. This concentration poses risks to supply stability, making alternative sources like phytomining increasingly attractive.
Recent economic analyses have shown that the rising price of nickel could make phytomining more profitable. Metalplant aims to achieve price parity with conventional nickel production while promoting its environmental benefits as a "green advantage."
For phytomining to succeed, scaling up operations is crucial. Metalplant currently operates on a small scale but aims to expand to tens of thousands of hectares. Achieving a target of one ton of nickel per hectare is ambitious, as many researchers estimate lower yields.
The potential for phytomining exists in regions like Indonesia, the Philippines, Brazil, South Africa, and the US, where suitable land may be available. However, intensive farming practices could also pose environmental risks, necessitating careful management.
Phytomining is not poised to replace conventional mining but could serve as a complementary process, particularly in regions where traditional agriculture is unfeasible. It offers a promising avenue for communities in areas like the Balkans and Malaysia to generate income while rehabilitating contaminated land. As the demand for nickel continues to rise, phytomining could play a significant role in the future of sustainable metal production.
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