Tellurium: secret clean energy ingredient
Rare metalloid used in American-made solar, batteries are next Critical Minerals Alliances 2023 - September 12, 2023
Last updated 9/13/2023 at 4:44pm
From promising solid-state battery technology that could eliminate range anxiety for electric vehicle owners to solar panels and thermoelectric devices that transform sunshine and heat into low-carbon energy, tellurium is emerging as a secret ingredient of the clean energy future.
"It has flown largely under the radar, even though it's essential for cadmium-telluride solar panels and new lithium-tellurium batteries that could revolutionize energy storage," said Tyrone Docherty, president and CEO of First Tellurium Corp., a company advancing tellurium exploration projects in the United States and Canada.
One of the reasons tellurium has gone largely unnoticed is that cadmium-telluride (CdTe) solar technology has not gained international acclaim, only accounting for around 5% of the photovoltaic (PV) solar panels installed globally. In the U.S., however, these thin-film panels are much more popular, making up around 55% of new installations, according to the U.S. Department of Energy's 2023 Critical Materials Assessment.
This outsized popularity in the U.S. is due to the success of Ohio-based First Solar Inc., the world's largest manufacturer of CdTe solar panels.
Seeking to bolster this homegrown technology, the U.S. Department of Energy is investing $20 million into the cadmium telluride Accelerator Consortium, an initiative seeking to increase the efficiency of CdTe cells and lower the cost of these thin-film panels and the materials that go into them.
DOE foresees shortages of the tellurium as the popularity of this solar technology rises.
"Without significant expansion of the tellurium supply capacity, shortages of Te could occur in the short term (2025) and are likely in the medium term (2025-2035)," the Energy Department penned in its 2023 Critical Minerals Assessment.
To help fill shortfalls of tellurium needed for solar panels and other clean energy technologies, First Tellurium is exploring two North American mineral exploration projects – Klondike in Colorado and Deer Horn in British Columbia – that could offer North American supplies of this critical metalloid.
Heavy First Solar investments
The demand for tellurium is growing alongside First Solar, which has already invested heavily into its manufacturing capacity in the U.S., plans to invest roughly another $1.2 billion to expand its capacity to produce American-made solar modules above 10 gigawatts by 2025.
"This investment is an important step towards achieving self-sufficiency in solar technology, which, in turn, supports America's energy security ambitions, its deployment of solar at scale, and its ability to lead with innovation," said First Solar CEO Mark Widmar.
Toward achieving these lofty ambitions, First Solar announced in August that it will build a $1.1 billion plant in Louisiana capable of producing 3.5 GW of CdTe solar panels per year.
Additionally, the company is investing $185 million to upgrade and expand its three CdTe solar panel plants in Ohio, the largest vertically-integrated complex of its kind in the Western Hemisphere. First Solar anticipates that its American plants will have the capacity to produce 14 GW of solar panels per year by the end of 2026.
By the time the Louisiana plant comes online, First Solar will have spent more than $4 billion in U.S. solar manufacturing and research and will employ more than 3,000 people in four states.
"We are investing in America's future," said Widmar.
First Solar is also working alongside DOE as a private sector partner in the cadmium telluride Accelerator Consortium, a three-year collaboration to lower the cost, increase the efficiency, and expand American production of CdTe solar technology.
"While already enjoying great success in the marketplace, recent scientific developments make it clear that CdTe PV has significantly more potential for dramatically higher module efficiency, lower cost, increased lifetime energy, and more rapid production," said Martin Keller, director at DOE's National Renewable Energy Laboratory, which is heading the consortium.
DOE hopes this consortium will ensure that America remains the leader in CdTe thin film solar cells that will bolster the economy while achieving the Biden administration's clean energy goals.
"As solar continues its reign as one of the cheapest forms of energy powering our homes and businesses, we are committed to a solar future that is built by American workers," said Energy Secretary Jennifer Granholm.
Green energy symbiosis
DOE's vision of more homes and businesses being powered by American-made CdTe solar panels will require significant new tellurium sources over the next decade.
Tellurium, however, is an extremely rare metalloid that falls in a grey area of the periodic table between metals such as aluminum and tin and non-metals like carbon and phosphorus.
"Most rocks contain an average of about 3 parts per billion tellurium, making it rarer than the rare earth elements and eight times less abundant than gold," the U.S. Geological Survey penned in a report on the critical metalloid.
While tellurium may be one of the scarcest of the elements, a little bit goes a long way. Out of the 600 metric tons produced globally during 2022, about 40% (240 metric tons) went into CdTe solar cells, 30% (180 metric tons) went into thermoelectric devices capable of transforming waste industrial heat into clean electricity, and the balance (180 metric tons) was primarily used in alloys and the production of rubber.
Most of the tellurium produced was recovered as a byproduct of refining copper.
This is creating a green energy symbiosis where the same climate goals that are increasing the need for tellurium are also powering the demand for the copper that goes into the electrical cables that link CdTe solar panels together and then to the grid.
China and Russia, however, account for roughly two-thirds of the global tellurium production.
"Tellurium supply risk is expected in the short and medium terms largely due to its strong codependence with copper production markets, low producer diversity with the majority of the refined Te coming from China, and potential for demand to exceed supply unless tellurium production increases," according to DOE.
Delivering domestic tellurium
To help alleviate some of the tellurium supply risks to America's rapidly expanding CdTe solar sector, global metals and mining company Rio Tinto invested approximately $2.9 million to build a plant capable of recovering roughly 20 metric tons of this semiconductive metalloid at a Utah refinery that processes copper concentrates produced at its Kennecott Mine.
"We are proud to deliver a new domestic supply of tellurium to support the manufacturing of solar panels and other critical equipment here in the United States," Rio Tinto Copper CEO Clayton Walker said upon the mid-2022 start-up of this facility.
The tellurium recovered from Kennecott is being refined by 5N Plus, a leading global producer of specialty semiconductors and performance materials.
Most of the tellurium recovered by Rio Tinto and refined by 5N Plus is going into CdTe cells being manufactured by First Solar.
"Rio Tinto's decision to invest in tellurium is a win for responsibly-produced, American solar," said First Solar Chief Manufacturing Operations Officer Mike Koralewski. "We're thrilled that tellurium from Kennecott will play a role in powering our country's transition to a sustainable energy future."
With byproduct copper production of tellurium "nearing saturation in every country other than China," DOE says that the U.S. may need to look for alternative supplies of this critical semi-metal.
First Tellurium hunt
First Tellurium is exploring some of North America's most promising tellurium supply alternatives on its properties in Colorado and Canada's British Columbia.
"It's clear that North America is going to need a lot more tellurium," said Docherty. "This is why we're on the hunt for new tellurium projects in addition to Deer Horn and Klondike."
First Tellurium's Klondike property in Colorado was previously owned by First Solar, which was looking for a secure domestic supply of the thin-film solar panel ingredient as it was ramping up manufacturing in the U.S.
When the solar manufacturing company decided to forego its mining venture, First Tellurium picked up this property where samples with as much as 3.3% tellurium, along with 33.7 grams per metric ton gold and 364.8 g/t silver, were collected.
"The Klondike property has by far the highest tellurium grades in rock samples of the hundreds of prospects and mines we examined in the U.S. and Canada from 2006 to 2011," said John Keller, the previous mineral exploration manager for First Solar and a current consultant to First Tellurium. "Some samples at Klondike were an order of magnitude higher in tellurium grade than any others we collected in the U.S. or in Canada."
The most advanced project in First Tellurium's portfolio, however, is Deer Horn.
Located in western BC, Deer Horn hosts 93,000 kilograms of tellurium, along with 100,000 ounces of gold and 3.3 million oz of silver, in the combined indicated and inferred resource categories, making it the only gold-silver project in North America with an industry-compliant NI 43-101 tellurium resource.
This property hosts a number of other targets enriched with bismuth, copper, molybdenum, tungsten, and zinc. Metals that have been deemed critical in Canada and the U.S.
"Canadian and U.S. governments are really pushing new strategies and funding initiatives to address the problem of critical mineral supplies," said Docherty. "North America is just too dependent on foreign sources for the critical metals required for clean energy, defense and other essential needs."
Solid-state tellurium batteries
In addition to exploring for new North American tellurium sources, First Tellurium is investigating new green energy uses for this critical metalloid.
This includes what is considered to be a key technology to the widespread adoption of e-mobility, a battery that lasts longer, charges faster, and is safer than the lithium-ion batteries currently being installed in EVs.
Earlier this year, a research team at the University of British Columbia Okanagan published a study that shows adding a dash of tellurium enhanced the lifespan, charging time, safety, and capacity of existing lithium battery technologies.
"All-solid-state, lithium-tellurium batteries enable higher energy output with an improved safety rating inside a smaller form-factor, thereby expanding its possible applications," said Jian Liu, principal's research chair in energy storage technologies at UBC Okanagan.
Fenix Advanced Materials, a BC-based company that specializes in ultra-high purity metals for the clean energy sector, is supplying the UBC research team with high-quality tellurium derived from Deer Horn.
"The high purity of the tellurium along with the mineral's overall attributes makes it ideal as a rechargeable battery material," said Liu.
Using this material, the team developed a quasi-solid-state lithium-tellurium test battery with a flexible gel polymer electrolyte that allows lithium ions to move between the lithium anode and the tellurium cathode.
"It's possible that tellurium could have the largest single impact on future battery technology over any other critical mineral," said Docherty. "Its properties are unique, the demand is increasing, and America's mandate is to source tellurium at home and become less reliant on China is changing the landscape."