Farms Are Mines, Plants Are Metal
Phytomining and what it means for the world
Back in the days before I had this blog, an organization named CEARCH held a contest, asking anybody who was interested to submit a description of a cause (i.e. an area that people or a charity could focus on) that would be highly impactful in the world. Since they’re affiliated with effective altruism, their idea of impact was roughly what can give the greatest utility per unit of cost. I took a gander at it, and picked phytomining, the use of plants to “mine” metals, as my topic.1 This eventually developed into a rather long-winded post on the forum for effective altruism. Now I’ve decided to write up the main points of that post, plus some updates on recent developments, to get a broader audience interested in why phytomining could be important.
Phytomining starts with the fact that some plants, called hyperaccumulators, take in high concentrations of certain minerals as a feature of their biology. Take pokeweed, a common North Carolina plant distinguished by its poisonous purple berries.2 According to Colleen Doherty’s research, pokeweed stores high quantities of rare earth metals, a group of elements used in many electronics, when on soils with sufficiently high concentrations. Although pokeweed is one of the more common hyperaccumulators in my region, hundreds of other plant species are known to exhibit the same behavior. For example, as much as 25% of the latex of Pycnandra acuminata, a tree from New Caledonia, is nickel.
Phytomining is what happens when metals and minerals are extracted from those hyperaccumulator plants. If, instead of extracting the materials, the plant is just used to get them out of the soil, it’s the related activity of phytoremediation. Oftentimes, the metal in question is nickel, which has had the most interest and commercialization, but plenty of other metal-plant combinations are promising, including thallium.
There are various technical details to consider here, but the core of why phytomining is so promising is that this is more energy-efficient than traditional methods of smelting. The plants concentrate the ore, and can be harvested using the same techniques used by farmers. So it’s better for the climate, better for air pollution, and also better for soil pollution, especially if the phytomining is combined with phytoremediation.
Another major plus to using plants rather than traditional methods is that it doesn’t involve as much disturbance to the land and surrounding communities. This means it can more easily work with agricultural uses of land, and is also likely safer for workers in addition to the pollution-related benefits. And this is all in addition to the classic rationale of increasing possible metal supplies and, in some cases, spreading out their geographic distribution.
With all that being said, phytomining is still in its infancy. There’s clear evidence that it can work, with major successful results from scientific trials. But commercial projects are few and far between, with many being scarcely attested on the internet. The Albanian startup Metalplant and the French concern Econick seem to be two of the field leaders, from my outsider’s perspective. However, ARPA-E, part of the United States government, has been putting its money behind developing phytomining, signalling that the future seems rosy in this country, at least.
And there are tradeoffs to doing phytomining. It’s a new technology, so trying to switch to it too soon carries high risks of unproductive harvests. It can lead to the introduction of invasive species, with all the problems that brings. Plus, many of its benefits are in the future when it becomes better established, so helping along phytomining now isn’t that good a deal if some kind of large-scale societal event disrupts its progress.
Despite that, I reached a pretty positive conclusion in my original writing on whether phytomining is something that effective altruists should be at least following, if not outright supporting. And I don’t think this is particularly reliant on the philosophical peculiarities of that community. Rather, people who care about global development and many environmental issues more generally should be paying attention to the promises and pitfalls of phytomining.
The first argument in favor of phytomining is that people don’t want to live near mines, nickel mines in particular, given all the problems with air pollution and accompanying health issues. Phytomining offers them less pollution and good jobs, which seems like it should be a win-win for the developing world.3 Plus, it’s an intervention that can be scaled up, with many sources pointing towards phytomining making up a large proportion of global mining once it gets going. This could make a charity aiming to start phytomining enterprises in the Global South a good fit for major effective altruist funders, if it were willing and able to provide good evidence of cost-effectiveness.
The second argument appeals to climate and environmental concerns, which aren’t absent in effective altruism but is a bit of an awkward fit with certain elements of utilitarianism. Mining damages ecosystems, but phytomining can work with ecosystems, particularly if native plants are being used and the farming methods don’t involve pesticides or the like. This might fit better with a rights of nature approach than the dominant view in my initial audience, since its benefits include biodiversity.
Finally, something that fits well with effective altruist priorities, but that might sound a bit odd to others, is that phytomining could be useful if things go south. Whether because of nuclear war, AI catastrophe, or natural disaster, it’s possible the world could need to rebuild major technological institutions. In that case, it might be difficult to access large-scale mineral sources, but phytomining offers an easier way to get critical metals. While contemporary commercial phytomining is definitely useful for this, what might be even better is preserving hyperaccumulators in seed banks and researching small-scale operations suitable for poor circumstances. Even for people who share my view that a major civilizational setback is quite unlikely, it’s not so unlikely that this wouldn’t be a benefit.
Given all these advantages, I think there’s a strong case to be made for putting more resources into advancing phytomining. But I’m also aware of the limits of my own knowledge around the subject, and the limits of society’s knowledge. It’s important that there should be an emphasis on continued and interdisciplinary research in the rush to commercialization.
Still, there are some actions that seem clearly helpful, like spreading information about phytomining4, urging Congress to give more funding to ARPA-E for it, or conducting social-scientific research aimed at better understanding the dynamics of commercialization. While it’s too early to say anything yet, in the next decades we could be living in a world where plants do much of the hard work of gathering the raw materials for everything from computers to refrigerators.5
Side note: I tried using LLMs to edit this post. It didn’t go that well, and I have a follow-up post for probably some time next week going into more detail about why.
Also called agromining occasionally.
Its young leaves, when properly prepared as poke salad, can be eaten safely.
There still frankly isn’t enough detail for me to be certain how good the jobs are, but anything introducing additional crops to give farmers more possible sources of income should help, and minerals fetch a high enough price that many people are willing to work in mines despite the evident dangers.
Why I’m writing this article, as a matter of fact.
If you’re interested in learning more, check out this wonderful CSIS article, my original forum post for the effective altruism angle in particular, and van der Ent et al.’s dense but informative book Agromining: Farming for Metals.