Critical Minerals? There’s a Plant for That – resilience.org

Phytomining: A Sustainable Approach to Critical Mineral Extraction

Introduction to Hyperaccumulation and Phytomining

Phytomining is an emerging industrial process that utilizes hyperaccumulator plants—a select group comprising approximately 0.2% of vascular plant species—to extract valuable metals from the soil. These plants have evolved the ability to absorb and store high concentrations of metals in their tissues, a process that would be toxic to most other species. This biological mechanism presents a novel opportunity to secure critical minerals required for the global transition to sustainable energy, thereby contributing to several United Nations Sustainable Development Goals (SDGs).

Researchers have identified hyperaccumulator species capable of extracting a range of elements, many of which are vital for green technologies. These include:

• Arsenic
• Cadmium
• Cerium
• Copper
• Cobalt
• Lanthanum
• Manganese
• Neodymium
• Nickel
• Selenium
• Thallium
• Zinc

Alignment with Sustainable Development Goals (SDGs)

SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action)

Phytomining directly supports the advancement of clean energy infrastructure. The critical minerals it extracts, such as nickel and cobalt, are essential components for manufacturing batteries, electric vehicles, wind turbines, and solar panels. By providing a more sustainable and potentially localized source for these materials, phytomining can help mitigate supply chain vulnerabilities that threaten to derail global decarbonization efforts, thus contributing to both SDG 7 and SDG 13.

SDG 8 (Decent Work and Economic Growth) and SDG 12 (Responsible Consumption and Production)

Conventional mining is frequently associated with severe environmental degradation and human rights abuses, including conditions compared to modern slavery in cobalt extraction. Phytomining offers an alternative production model that aligns with SDG 8 by creating safer, more ethical employment opportunities. Furthermore, it promotes SDG 12 by:

1. Utilizing low-grade ore, unprocessed mining waste, and metal-polluted soils that are not viable for traditional extraction methods.
2. Producing a higher-purity metal product that requires less energy-intensive refining.
3. Creating a circular system where residual organic biomass can be repurposed as fertilizer or for energy production (e.g., syngas), minimizing waste.

SDG 15 (Life on Land)

In contrast to the destructive nature of conventional pit and strip mining, phytomining is significantly gentler on terrestrial ecosystems. It can be employed to remediate contaminated land while simultaneously producing valuable metals. This dual-purpose function directly supports the objectives of SDG 15 by restoring degraded land and preventing further biodiversity loss associated with large-scale mining operations.

Current Applications and Technological Innovation

Focus on Nickel Extraction

To date, research and commercial efforts have concentrated primarily on nickel, a high-value metal essential for batteries and stainless steel. Over 500 of the 721 known hyperaccumulator species are nickel accumulators. Commercial operations are underway, including:

• Botanickel: Operating projects in Greece and Malaysia to produce partially plant-derived stainless steel.
• GenoMines: A French firm using genetically engineered plants and soil probiotics for nickel farming in South Africa.
• Metalplant: A U.S. company successfully mining nickel in Albania and developing genetically modified species for use in North America.

Research and Development Initiatives

Innovation in phytomining is being accelerated by targeted funding. In 2024, the U.S. Department of Energy’s ARPA-E program announced $9.9 million in grants to develop domestic nickel phytomining technology. These projects aim to genetically engineer fast-growing crops like Camelina sativa to accumulate 1-3% nickel by mass, potentially yielding up to 25,000 kilograms of metal per square kilometer annually.

Challenges and Environmental Considerations

Operational and Biological Hurdles

Despite its promise, the widespread implementation of phytomining faces significant challenges:

• Scalability: Developing the industrial infrastructure to process large volumes of plant biomass remains a primary obstacle.
• Biological Constraints: Many natural hyperaccumulators are small, slow-growing, or have specific geoclimatic requirements, making cultivation difficult.
• Invasive Species Risk: Non-native hyperaccumulators can escape cultivation and become invasive weeds, as demonstrated by a pilot project in Oregon.
• Limited Scope: Experts agree that phytomining cannot fully replace conventional mining due to the limited amount of metal accessible by plant roots.

Sustainability and Environmental Trade-offs

While phytomining is less destructive than traditional mining, it is not without environmental impact. In line with SDG 12 and SDG 15, a holistic assessment must consider potential burden-shifting. Large-scale cultivation of hyperaccumulators carries risks associated with industrial agriculture, including:

• Pesticide and fertilizer runoff.
• Water resource depletion.
• Loss of local biodiversity due to the establishment of monocultures.
• Disruption of fragile ecosystems that have evolved on naturally metal-rich soils.

Future Prospects and Conclusion

Potential for Rare Earth Element Extraction

A significant future application for phytomining is the extraction of rare earth elements (REEs). Current REE mining is environmentally destructive and dominated by a few nations, creating supply chain instability. Although commercial development is not yet realized, scientists have identified natural REE hyperaccumulators. Developing this capability would be a major step toward critical mineral security and more sustainable industrial practices (SDG 9: Industry, Innovation, and Infrastructure).

Conclusion: A Niche but Important Contribution to Sustainability

Phytomining is positioned to be a valuable, albeit niche, component of a more sustainable global economy. It offers a method to produce critical minerals while simultaneously remediating degraded land, sequestering carbon, and creating bio-based products. By addressing key objectives across multiple SDGs, from clean energy and responsible production to decent work and the protection of terrestrial ecosystems, phytomining exemplifies the type of innovative, multi-benefit solution required to build a more resilient and sustainable world.

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 7: Affordable and Clean Energy

  The article directly connects the extracted metals to the green energy transition. It states that minerals like nickel and cobalt are “needed to build batteries and other components for electric vehicles, wind turbines, solar panels, and other facets of the green energy transition.” This highlights the role of phytomining in securing materials for clean energy infrastructure.

• SDG 8: Decent Work and Economic Growth

  The article contrasts the emerging phytomining industry with conventional mining practices that involve severe human rights abuses, noting that cobalt mining “has been compared to modern slavery.” By offering an alternative extraction method, phytomining promotes safer and more ethical work. It also contributes to economic growth through innovation and the creation of new startups like Botanickel and GenoMines.

• SDG 9: Industry, Innovation, and Infrastructure

  Phytomining is presented as a significant innovation in the materials extraction industry. The article discusses it as an “emerging field” and a “developing industry” that uses scientific research, including genetic engineering, to create more sustainable industrial processes. The mention of “seven grants totaling US $9.9 million” from the U.S. Department of Energy underscores the investment in this new technology to build a resilient and sustainable domestic supply chain.

• SDG 12: Responsible Consumption and Production

  This is a central theme. The article describes phytomining as a method to “secure the vital metals we want without wrecking the planet in the process,” contrasting it with the “environmentally destructive” nature of conventional mining. It also addresses sustainable production by highlighting how phytomining can extract metals from “unprocessed mining waste” and “metal-polluted soils,” and how its byproducts (“leftover organic material”) can be repurposed into fertilizer, contributing to a circular economy.

• SDG 13: Climate Action

  By providing a more sustainable source of critical minerals for the “green energy transition,” phytomining indirectly supports global efforts to combat climate change. The article notes that a shortage of these minerals could “derail global decarbonization efforts.” Furthermore, it mentions that the process could contribute to “sequestering carbon.”

• SDG 15: Life on Land

  The article emphasizes that phytomining is “much gentler on the landscape than conventional mining,” which causes “environmental destruction across wide areas.” It highlights the technology’s potential for bioremediation, specifically in cleaning up “metal-polluted soils.” However, it also acknowledges potential negative impacts, such as the “loss of local biodiversity to a single-species operation,” which directly relates to protecting terrestrial ecosystems.

• SDG 16: Peace, Justice and Strong Institutions

  The article links the conventional mining of critical minerals to geopolitical instability, stating that it is “stoking geopolitical tensions, including contributing to Russia’s invasion of Ukraine.” It also points to severe injustices, such as the “modern slavery” conditions in cobalt mining. By developing domestic and more ethical supply chains, phytomining can contribute to reducing conflict and promoting justice.

2. What specific targets under those SDGs can be identified based on the article’s content?

1. Target 7.2: Increase the share of renewable energy

   The article supports this target by discussing a method to sustainably source critical minerals (nickel, cobalt, rare earth elements) that are essential for manufacturing renewable energy technologies like “wind turbines, solar panels,” and batteries for electric vehicles.

2. Target 8.7: Eradicate forced labour and modern slavery

   This target is directly addressed by the article’s reference to cobalt mining in the Democratic Republic of Congo, which “has been compared to modern slavery.” Phytomining is presented as a potential alternative that avoids such exploitative labor practices.

3. Target 9.4: Upgrade infrastructure and retrofit industries to make them sustainable

   Phytomining represents a technological upgrade for the mining industry. The article describes it as a way to extract valuable metals in a manner that is “much gentler on the landscape” and less reliant on “toxic chemicals” than conventional methods, thus making a critical industry more sustainable.

4. Target 9.5: Enhance scientific research and upgrade technological capabilities

   The article is replete with examples of this target in action, from university research at the University of York to government-funded projects like the “$9.9 million” in grants from ARPA-E. It also details technological advancements, such as developing “a genetically engineered version of Camelina sativa” to improve nickel accumulation.

5. Target 12.2: Achieve the sustainable management and efficient use of natural resources

   Phytomining is framed as a more sustainable and efficient method of natural resource management. It can extract metals from “lower-grade ore” and “unprocessed mining waste,” which are not easily accessible through traditional techniques, thereby making more efficient use of resources.

6. Target 12.5: Substantially reduce waste generation

   The article mentions that in the phytomining process, the “leftover organic material can even be repurposed into fertilizer,” biochar, or syngas. This turns a potential waste product into a valuable resource, aligning with the goal of waste reduction and reuse.

7. Target 15.3: Combat desertification, restore degraded land and soil

   The article highlights phytomining’s role in bioremediation, as it can be used to clean up “metal-polluted soils.” This directly contributes to the restoration of degraded land, a key component of this target.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Metal concentration in plant biomass

  The article states that hyperaccumulating plants can become “as much as 5 percent metal by weight” and that a target for genetically engineered plants is to “accumulate 1 to 3 percent nickel.” This percentage serves as a direct indicator of the technology’s efficiency (relevant to Targets 9.4 and 12.2).

• Metal yield per unit of land

  A specific metric is provided: “up to 25,000 kilograms of useful metal per square kilometer of soil each year.” This is a quantifiable indicator of the productivity and viability of phytomining operations (relevant to Targets 9.4 and 12.2).

• Investment in research and development

  The article mentions “seven grants totaling US $9.9 million” from ARPA-E. The amount of public and private funding dedicated to phytomining research can be used as an indicator to measure progress in innovation (relevant to Target 9.5).

• Area of land under remediation or sustainable mining

  The article identifies “more than 40,000 square kilometers (15,000 square miles) of serpentine soils” in the U.S. as potential sites for phytomining. The total area where phytomining is applied can serve as an indicator for land restoration and the adoption of sustainable practices (relevant to Target 15.3).

• Purity of extracted metals

  It is mentioned that the metal from phytomining is “often more concentrated and purer than that extracted by conventional mining” and may not need as much refining. The quality and purity of the final product is an indicator of the process’s efficiency and environmental benefit (less energy for refining) (relevant to Target 9.4).

• Reduction in human rights abuses in supply chains

  While not a quantitative metric from the article, a shift in sourcing critical minerals from conventional mines with documented abuses (like “modern slavery”) to phytomining operations would be a qualitative indicator of progress towards Target 8.7.

4. SDGs, Targets, and Indicators Table

Source: resilience.org