To limit the global temperature increase to 1.5 degrees C or close to it, all countries must decarbonize—cut fossil fuel use, transition to zero-carbon renewable energy sources, and electrify as many sectors as possible. It will require huge numbers of wind turbines, solar panels, electric vehicles (EVs), and storage batteries — all of which are made with rare earth elements and critical metals.
The elements critical to the energy transition include the 17 rare earth elements, the 15 lanthanides plus scandium and yttrium. While many rare earth metals are actually common, they are called “rare” because they are seldom found in sufficient amounts to be extracted easily or economically.
Elements such as silicon, cobalt, lithium, and manganese are not rare earth elements, but are critical minerals that are also essential for the energy transition.
Supplying these vast quantities of minerals in a sustainable manner will be a significant challenge, but scientists are exploring a variety of ways to provide materials for the energy transition with less harm to people and the planet.
Demand is growing
The demand for rare earth elements is expected to grow 400-600 percent over the next few decades, and the need for minerals such as lithium and graphite used in EV batteries could increase as much as 4,000 percent. Most wind turbines use neodymium–iron–boron magnets, which contain the rare earth elements neodymium and praseodymium to strengthen them, and dysprosium and terbium to make them resistant to demagnetization. Global demand for neodymium is expected to grow 48 percent by 2050, exceeding the projected supply by 250 percent by 2030. The need for praseodymium could exceed supply by 175 percent. Terbium demand is also expected to exceed supply. And to meet the anticipated demand by 2035 for graphite, lithium, nickel, and cobalt, one analysis projected that 384 new mines would be needed.
China once supplied 97 percent of the world’s rare earth elements. Government support, cheap labor, lax environmental regulations, and low prices enabled it to monopolize rare earth metal production. Today China produces 60-70 percent of the world’s rare earth elements and is also securing mining rights in Africa. The U.S. produces a little over 14 percent and Australia produces six percent of rare earth elements.
In 2018, the U.S. was 100 percent dependent on other countries for 21 critical minerals. After China halted exports of rare earth elements to Japan in a dispute, many countries became concerned about the political and economic implications of depending on one market and began developing their own rare earth element production. The Biden administration has prioritized the development of a domestic supply chain for rare earth metals and critical minerals.
Mining’s environmental impacts
Mining often causes pollution of land, water, and air, spread of toxic wastes, water depletion, deforestation, biodiversity loss, and social disruption. Despite the fact that it is subject to federal and state environmental regulations, metal mining is the number one toxic polluter in the U.S.
It’s difficult to mine rare earth elements without causing environmental damage because of how they are extracted. One method involves removing topsoil, then creating a leaching pool where chemicals are used to separate out the rare earth elements from the ore. The toxic chemicals can seep into groundwater, cause erosion, and pollute the air. Another technique is to drill into the ground and use PVC pipes and hoses to pump chemicals into the earth. The resulting mix is then pumped into leaching ponds for separation, creating the same environmental problems.
In addition, because rare earth elements are often found near radioactive thorium and uranium, the waste left after rare earth elements are separated from the ore—tailings—contains chemicals, salts, and radioactive materials. Tailings are usually stored in ponds which can leak and contaminate water resources.
The Harvard International Review reported that mining to produce one ton of rare earth elements results in nearly 30 poundsof dust, 9,600-12,000 cubic meters of waste gas including substances such as hydrofluoric acid and sulfur dioxide, 75 cubic meters of wastewater, and one ton of radioactive residue—2,000 tons of toxic waste altogether.
The world’s largest rare earth element mine, Bayan-Obo in China, produced over 70,000 tons of radioactive thorium waste which is stored in a tailing pond that has leaked into groundwater.
The soil and water in Baotouin Inner Mongolia, China— considered the world’s rare earth capital—is polluted with arsenic and fluorite due to mining. This has caused skeletal fluorosis and chronic arsenic toxicity in the population. In Jiangxi Province, which was also polluted by rare earth element mining, experts say it could take 50 to 100 years to clean up the damage and restore the environment.
Mining for other minerals such as cobalt (needed for EV batteries) is polluting as well. The extraction process releases sulfides into the air and water, forming sulfuric acid. This acidic water can pollute streams or leach into groundwater. One mine in the Idaho Cobalt Belt that extracted cobalt, silver, and copper ore contaminated the area and a Salmon River tributary; it is now a Superfund site.
How can we supply the energy transition more sustainably?
With the growing demand for rare earth elements and critical minerals, mining practices that harm the environment will likely continue, if not increase.
“The pressure is such that that the first thing that might be disregarded and marginalized are the safeguards in order to fast track the process—environmental safeguards and social safeguards,” said Perrine Toledano, director of research and policy at the Columbia Center on Sustainable Investment, a joint center of the Columbia Climate School and Columbia Law School. “We know that there is a lot of pressure going on in some countries, in Africa and elsewhere, meaning that the governments may not have time to use due process. So that might set us back on sustainability.”
Fortunately, researchers are working on ways to make mining more sustainable or unnecessary. Here are some examples — most of which are still experimental and not yet ready for large-scale application.
A variety of labs around the world are looking at ways to put biology to use in mining. Cornell University scientists are developing “biomining,” programming microbes to produce organic acids that leach rare earth elements from ores or recycled e-waste. They are studying which genes are the best at bioleaching, then forcing mutations on those genes to make the microbes even more efficient. Researchers at Harvard are using bacteria from marine algae on a filter, then pouring a solution of several rare earth elements through it. The bacteria absorb all the elements. The filter is then washed with solutions of different pH balances, each of which enables different rare earth elements to detach. In Germany, researchers are using new species of cyanobacteria to absorb rare earth elements from mining wastewater or recycled e-waste. This method can be used even with low concentrations of rare earth elements.
Chinese researchers are using electrical currents to free heavy rare earth elements — those with high atomic numbers like dysprosium and terbium — from ores. The new electrokinetic method creates an electric field above and below the soil, which improves the efficiency of the leaching so that lower amounts of chemicals are needed. The method extracts more rare earth elements than traditional mining and pollutes less.
If soils are rich in nickel, chromium, and cobalt, and lack key nutrients, they may not be able to be used for food agriculture, but they can be mined. Agromining, or phytomining, cultivates “hyperaccumulative” plants that are able to absorb and store minerals and metals from the soil in their plant parts.
In France, scientists are cultivating hyperaccumulating plants to harvest nickel, a critical component of batteries and renewable energy technologies. After the plants are harvested, they are dried and burned. The resulting ash is richer in nickel than any ore. It is washed, then nickel is extracted by an acid at a high temperature; the solution is then filtered to remove the ash and recover the nickel. The overall process uses significantly less energy than traditional mining, and can also be used to decontaminate polluted soils, making them fertile enough to grow crops.
Over the years, researchers have discovered about 700 such plants around the world, and more are being discovered and bred to improve their metal-absorbing capacities. Most accumulate nickel, but others have been found to absorb thallium, zinc, copper, cobalt, and manganese.
“So far the technology has been available for small scale application,” said Toledano, adding that it’s a way for local communities to earn income and for artisanal miners to mine more sustainably. But some companies, like startup GenoMines, hope to scale up these methods.
One strategy to reduce the demand for rare earth elements is for manufacturers and product designers to engineer products that use less or no rare earth elements, or to replace rare earth elements with new or different materials. For example, BMW and Renault have made some of their EVs without rare earth elements. While this may make batteries less powerful, cars that are mainly driven in cities may not need as long a battery life. Recently Tesla announced that its next generation of electric motors would use no rare earth elements. Moreover, since 2017, the company has reduced its use of heavy rare earths in its Model 3s by 25 percent.
Scientists at Northeastern University are developing a substitute material for rare earth magnets called tetrataenite. Tetrataenite is only found in meteorites, but researchers are trying to recreate a process that took nature millions of years by rearranging the atomic structure of the material’s nickel and iron components in the lab.
The scientists have a $2.1 million grant from the Department of Energy to understand how magnetic materials made of “non-critical elements”are created in nature.
Researchers at the Critical Materials Institute of Ames Laboratory are also studying magnet substitutes. They have developed ways of predicting which materials have the potential to be made into magnets. They identify those with some attraction to a magnetic field, then add alloys to turn the materials into permanent magnets. The scientists found that this process could make forms of cerium cobalt (cerium is an abundant rare earth element) capable of substituting for neodymium and dysprosium used in the strongest rare earth magnets.
What about recycling e-waste?
The UN Environment Programme estimated that over 53 million tons of e-waste were generated in 2019, including $57 billion worth of raw materials laced with rare earth elements and precious metals such as platinum, gold, and silver. Recycling these valuable elements and metals could reduce the amount of mining that will be needed. For example, according to the Union of Concerned Scientists, recycling could help meet about 30 percent of the future demand for neodymium, praseodymium, and dysprosium.
However, a 2018 study found that only about one percent of rare earth elements are recycled from the products that incorporate them. Japan has been recycling its e-waste for rare materials since 2010. The U.S., second to China in producing e-waste, only recycled 15 percent of its e-waste in 2019; in contrast, Europe recycled 42.5 percent of its e-waste the same year.
Recycling is done either through acid leaching to separate out rare earth element oxides and salts, heating and melting the metals, or using electricity to separate the materials — hence, recycling has its own environmental impacts. Researchers are exploring new methods such as ultrasonic leaching and bio leaching.
But e-waste recycling remains hampered by insufficient infrastructure, and expensive and inefficient collection processes.
“For e-waste, first of all you need the collection infrastructure and it has not been properly developed, and you need incentives for the producer to be obliged and mandated to retrieve the electronic waste,” said Toledano. “If, at the beginning, the producer knows that there will be some obligation to recover the consumer goods then it will start designing the product in a way that is recyclable. In Europe, there is this related idea that you should be mandated to develop electronics that are not designed for obsolescence to limit the waste. The circular economy [where all resources are recycled and reused] is about avoiding waste in the first place before you go into recycling, because recycling is much more technology-intensive and expensive.”
The magnets in EVs and wind turbines could be recovered and recycled relatively easily, but because they are designed to last many years, it will be decades before there are enough recycled magnets to meet the growing demand. There are, however, companies preparing to recycle the batteries from the first generation of retiring EVs. For example, Canadian Li-Cycle Corps is building its third facility to recycle lithium-ion batteries, and there are dozens of new recycling battery projects starting up around the world.
Purdue University researchers have developed an innovative and inexpensive way to recycle coal ash to recover rare earth elements. Coal ash is as rich in rare earth elements as some ores, say the scientists. They have discovered a new method of separating out rare earth elements from other impurities, using materials that are inexpensive and efficient. If the technique can be scaled up, it could theoretically recover valuable materials from the 129 million tons of coal ash the U.S. produces annually.
Mining today and tomorrow
The MP Materials Mine in Mountain Pass, CA is currently the only rare earth producing mine in the U.S. MP Materials aims to create a complete supply chain for rare earth elements, but still sends its ore to China, which continues to dominate the world’s rare earth element processing.
Niobium, which has the potential to make batteries last longer, scandium, titanium, and other rare earth elements may soon be mined in Elk Creek, Nebraska. Many locals there feel it’s their patriotic duty to host the mine so the U.S. can develop its domestic supply of rare earth elements and minerals. Other mines in the works include a site in western Montana near the headwaters of the Bitterroot River, a renowned trout fishery.
The U.S. Critical Materials Corp, claims the area has the “highest-grade rare-earth deposit” in the U.S., holds seven square miles of mining claims in the Bitterroot National Forest, and has begun exploratory activities. In southeastern Wyoming, an Australian company, American Rare Earths, believes it has discovered the largest known rare earth element deposit in North America. This company’s goal is to eventually build a processing plant for the ore that will use new, less environmentally harmful methods.
The largest lithium deposit in the U.S. in Thacker Pass in Nevada has been mired in controversy. The deposit sits on sacred Indigenous land, and the tribes say they were not properly consulted. Nevertheless, after a federal court denied the Indigenous group’s requests for an injunction, construction on the mine has begun. Piedmont Lithium is mining lithium in North Carolina and has received a grant of $141.7 million from the Department of Energy to develop a second facility in Tennessee. When both facilities are operational, the company expects to quadruple current domestic lithium production.
Under the sea and in space
Deepsea mining could soon be given the go-ahead, as the International Seabed Authority is working on finalizing regulations for mining the ocean floor of the deep sea. Nauru Ocean Resources Inc., a subsidiary of a Canadian metals company, wants to mine polymetallic nodules from the ocean floor between Hawaii and Mexico. These nodules contain the cobalt, nickel, copper, and manganese essential for making batteries.
Collecting them would require large machines that scrape the ocean floor, generating clouds of sediment and potentially disrupting marine ecosystems. Some experts say this could jeopardize the ecosystem services provided by marine microbes, the basis of the food web and the ocean’s ability to store carbon, before scientists even understand the full extent of their benefits. A new report by Fauna & Flora International, a conservation organization, says that deep sea mining would cause extensive and irreversible damage.
But Toledano maintains that the science about deep sea mining is unclear.
“The science that could tell us that some part of it is not dangerous is not getting a lot of coverage, because everyone is really scared to go there,” she said. One expert who worked on a large ocean mineral survey that also assessed the environmental impacts of deep-sea mining told her that there is not a lot of life at that depth. Moreover, the nodules can be retrieved without digging, so the creatures that live in the sediments may not be greatly affected. Germany, France, Spain, Chile, New Zealand, Costa Rica, several Pacific Island nations, and others, however, have called for a ban on deepsea mining until the impacts on the marine environment can be fully assessed.
As the environmental impacts of mining land and the ocean floor grow, space mining could become a viable and more sustainable option. Greenhouse gas emissions would not matter in space, and there would be no ecosystems to damage, though mining would damage pristine environments. The Outer Space Treaty of 1967, signed by 113 countries, says that space is free for exploration and use by all countries, and that no nation can claim ownership to celestial bodies, but it’s not clear how this would apply to exploiting resources on the moon or asteroids. The UN has formed a group to develop principles for the exploration and exploitation of space resources.
Regolith, the soil on the moon’s surface, contains numerous valuable elements, including silicon needed for solar panels and computer chips, iron, magnesium, aluminum, manganese, titanium, neodymium, and platinum group elements. Earth has a greater abundance of rare earth elements, but the moon could also hold rare earth elements in low concentrations.
A number of companies are exploring lunar mining, and AstroForge, an asteroid mining startup, is planning to launch two missions this year to explore mining asteroids that are thought to have abundant platinum group elements.
Space mining would still have some environmental impacts on Earth’s atmosphere, but much less than mining on Earth itself. In 2018, researchers at University of Paris-Saclay in France calculated the greenhouse gas emissions from rocket launches, the combustion of rocket fuel, and reentry into the atmosphere. To mine a kilogram of platinum from an asteroid would result in 150 kilograms of CO2 being released into Earth’s atmosphere, while producing a kilogram of platinum on Earth would generate 40,000 kilograms of CO2.
Getting needed resources more sustainably
Both political parties agree that the U.S. must increase its domestic supply of rare earth elements and critical minerals. The mining industry is capitalizing on this by lobbying for easing environmental reviews and regulations. But in fact, this is exactly when policymakers, mining companies, and all green technology makers need to be developing ways to make sourcing materials for the energy transition more sustainable.
Because mining is local, it has big impacts on local climate resilience and quality of life, and mining has often taken place where people have less power to object. More sustainable mining means that local stakeholders should be able to weigh in on potential mining projects. The communities that will be affected must have free prior and informed consent, a principle protected by international human rights standards.
Governments should support research and development into products that use lower amounts of rare earth elements or that can substitute scarce resources with abundant ones. In addition, policymakers should create incentives to encourage the development of more sustainable techniques for extraction and processing, and the recycling of e-waste. Imposing a tax on mine waste would also provide an incentive to develop ways to reduce pollution.
Toledano believes the key to making mining more sustainable is developing the circular economy—an economy that aims for zero waste and pollution by keeping materials, products, and services in circulation for as long possible.
“The circular economy has a long way to go to properly function in the value chain of minerals and materials, but it is going to be a common environmental solution in the sense that ultimately, you’ll be relying less on virgin extraction,” said Toledano. “We will never cover all our needs with the circular economy, but we can still make a lot of progress.”
Source: Columbia Climate School