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2024 Climate Tech Companies to Watch: First Solar and its advanced solar panels

First Solar is expanding production of its thin-film solar cells and opening new factories to meet a surge of demand. Meanwhile, it’s investing in perovskites—tiny crystalline materials that many view as a key solar technology of the future. 

The world needs more electricity than ever, as the AI boom puts intense demand on data centers and more heat waves increase the use of air-conditioning. To reduce emissions and keep global warming in check, a larger share of that electricity must come from renewables. 

Much of the growth in renewables comes from solar. And First Solar is one of the largest manufacturers of solar panels in the US, which is the world’s second-largest solar market after China. The company is benefiting from US tariffs on foreign-made solar panels and tax credits made available through the Inflation Reduction Act. 

Today, Chinese firms produce the vast majority of the world’s solar panels. Most build cells that incorporate a layer of silicon to absorb the sun’s light and awaken electrons within, which then flow out as current. Instead of silicon, First Solar’s cells rely on a thin film made from two other elements: cadmium and tellurium. These cells can be produced more quickly than silicon cells, using less energy and water. 

But there’s still room for improvement in the cells’ performance. Today’s best silicon solar panels convert roughly 25% of the sun’s energy into electricity, and cadmium telluride tends to lag behind that. To boost efficiency, First Solar is now looking to incorporate a new class of materials called perovskites into its cells. These tiny crystals absorb different wavelengths of light from those absorbed by silicon or cadmium telluride. Cells that add perovskites to the mix—known as perovskite tandem solar cells—could potentially convert even more of the sun’s energy into electricity. 

First Solar is among a handful of companies exploring how to layer these crystals into commercial solar cells to improve performance. Last year it acquired a firm called Evolar, a leader in thin-film and perovskite research, to further this aim. 

Key indicators

• Industry: Renewable energy 
• Founded: 1999
• Headquarters: Tempe, Arizona, USA
• Notable fact: First Solar’s backlog of orders totals 76 gigawatts and stretches out to 2030.

Potential for impact

Globally, solar energy accounted for more than three times as much new capacity for electricity generation as wind in 2023, according to the International Energy Agency. There are a few reasons why—the price of panels has dropped dramatically in the past 20 years as production ramped up, and they’re relatively easy to install and maintain. 

Solar’s future looks just as bright—global solar capacity is expected to reach nearly 2,000 terawatt-hours this year, and the IEA says we could see it quadruple by the end of the decade. In the US, First Solar’s expanding production and its recent investments into perovskites will shape the solar market for years to come. 

Caveats 

One of the biggest obstacles to bringing more utility-scale solar plants online in the US is hooking these projects up to the grid once they’re built. The federal agency that approves grid interconnections has a backlog of requests. Right now it takes about five years, on average, for a new solar plant to open. Recent reforms aim to make this process faster, but their impact is still unclear. 

Compounding this problem is a shortage of transformers, which step the voltage of electricity up or down; these are crucial to managing the flow of clean energy across the grid. And there are siting challenges, since developers must obtain permits and some community groups oppose large installations. First Solar’s customers are overwhelmingly based in the US and include developers of new solar projects that face all these issues, which could limit the company’s growth.

The fate of the US solar industry is strongly influenced by domestic policy, and the US presidential election could affect First Solar’s expansion plans in a few ways (even if tax credits to US manufacturers have enjoyed broad bipartisan support). Though it seems unlikely that the IRA would be repealed, it’s possible that a new administration could amend parts of it. 

The new president could impose higher tariffs and place more restrictions on imports. First Solar has publicly supported such tariffs—which critics blame for the high price of US panels. Or the president could lower tariffs and decrease import restrictions. Uncertainty on policy matters could make developers less willing to place new orders until a new administration is in place. 

And there’s no guarantee that the company can make tandem cells work. Perovskites are notoriously unstable and break down in the sun—rather inconvenient for a solar material. First Solar will need to find new ways to produce and package them at scale, and prove to customers that these panels will work reliably for years once installed. 

Finally, though First Solar’s panels avoid concerns about forced labor in the supply chain for silicon produced in China, such problems have also occurred in the company’s own supply chain. 

Next steps

Later this year, First Solar will begin producing miniature versions of tandem solar panels at a factory in Ohio. If these panels perform well in tests, the company will manufacture full-size prototypes at its new R&D center nearby.  

Meanwhile, First Solar is building new manufacturing facilities to expand production of its cadmium telluride panels. The company opened its first factory in India earlier this year and now manufactures in four countries—India, the US, Malaysia, and Vietnam. 

In the US, First Solar just opened a new plant in Alabama, with another to follow in Louisiana in 2025. By 2027, the company expects to have more than 25 gigawatts of annual manufacturing capacity—more than the total capacity of new utility-scale US solar installed last year. 

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: Electric Hydrogen and its push to mass-produce a carbon-free fuel

Large swaths of the global economy are nearly impossible to electrify but could run on low-emissions hydrogen, helping the world transition away from fossil fuels. Electric Hydrogen is working toward more efficient, affordable production of green hydrogen.

Electric Hydrogen is striving to develop production methods that make it easier and more affordable to generate huge amounts of green hydrogen.
Hydrogen has emerged as a promising alternative to fossil fuels for the transportation sector and as a feedstock in the production of steel, fertilizer, methanol, and other products. 

But hydrogen production to date has been pretty dirty. The vast majority of hydrogen is produced from natural gas, emitting significant levels of planet-warming greenhouse gasses. It can also be generated by an electrolyzer, a device that uses electricity to split water molecules into hydrogen and oxygen. But most electrolyzers are small and expensive, and they consume lots of energy and water. Moreover, they typically rely on electrical grids that aren’t powered by predominantly clean energy.

Electric Hydrogen wants to address these issues by developing electrolyzers that have about 10 times the capacity of today’s standard devices while also being more affordable and efficient.

The company is already operating a pair of electrolyzer plants in California, including a one-megawatt facility in San Carlos and a 10-megawatt project in San Jose. In April, Electric Hydrogen opened an electrolyzer factory in Devens, Massachusetts, which will crank out its first line of 100-megawatt electrolyzers. The company also raised $380 million in funding in 2023 from backers including BP, United Airlines, and Microsoft, making it the first electrolyzer company to be valued at over $1 billion. 

Key indicators

• Industry: Hydrogen
• Founded: 2020
• Headquarters: Natick, Massachusetts, USA
• Notable fact: Two of the company’s three cofounders came from First Solar, a solar panel manufacturer that is also featured on this year’s list.

Potential for impact

To slow the pace of climate change, we need to drastically reduce our use of fossil fuels. Heavily polluting industries like fertilizer and chemical manufacturing are notoriously difficult to clean up. Fertilizer alone accounted for 2% of global emissions in 2022, according to a study published in Scientific Reports. It’s also tricky to eliminate emissions from certain types of transportation, including shipping and aviation, mainly because fuels can simply store more energy for a given weight than today’s batteries. 

It’s these sectors where hydrogen shows the most promise, because it can be made into fuel that produces only water vapor as a by-product. But it’s hard to make clean hydrogen cost-competitive with fossil fuels. 

Caveats

Electric Hydrogen will need to prove that its 100-megawatt electrolyzer systems can operate reliably at a low cost. To make low-emission hydrogen, the electrolyzers will need to use a lot of renewable energy, which may not always be available. In addition, Electric Hydrogen doesn’t share many details publicly about how its technology works, which makes it difficult to gauge the company’s claims and progress. 

Next steps

The good news is that the Inflation Reduction Act, signed into law by the Biden administration in 2022, provided generous subsidies aimed at accelerating  US-based hydrogen production. Though the details of how exactly these tax credits will be awarded are still being worked out, Electric Hydrogen is poised to benefit greatly from them in the coming years, either directly or through cost reductions for its customers.

Meanwhile, Electric Hydrogen plans to send the Natick facility’s first electrolyzer systems to OCI, a clean methanol manufacturer in Beaumont, Texas, later this year. Full commercial operation of these systems is expected in 2025, and the methanol will likely be used for maritime shipping around Europe. The company is also hoping to build out its business in Europe and Australia within the next few years. 

If these electrolyzers work as efficiently and affordably as hoped, it will mark a huge step toward the company’s goal of producing clean, affordable hydrogen.

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: Pivot Bio and its nitrogen-delivering microbes

Pivot Bio is using genetically edited microbes to deliver just the right amount of nitrogen to crops, cutting climate emissions without reducing agricultural yields.

The development of synthetic fertilizer was one of the great achievements of the last century, providing an abundant source of nitrogen that boosted crop yields and helped feed a growing global population. 

But the product is also a climate and environmental disaster. The production process releases huge amounts of carbon dioxide, and after it’s applied to fields it releases nitrous oxide, a far more powerful greenhouse gas. Synthetic fertilizer contributes about 5% of worldwide climate emissions and pollutes groundwater, lakes, and rivers.

Pivot Bio, a biotechnology company based in Berkeley, California, is harnessing microbes to deliver a usable form of nitrogen directly to the roots of crops, reducing the amount of synthetic fertilizer farmers need to use and the pollution that comes with it.

Nitrogen is an essential ingredient for photosynthesis, but most plants can’t directly absorb it from the air. Fertilizer manufacturers help them along by breaking down the strong triple bonds between nitrogen molecules and combining those molecules with hydrogen to form ammonia. After it’s applied in fields, much of the fertilizer turns into ammonium and nitrate, nitrogen-rich compounds that plants can take up and use to grow.

Certain bacteria and other microorganisms in soil pull off a similar trick naturally, if not as consistently. Pivot is putting a modern twist on this natural process, genetically engineering select microbes to increase the amount of nitrogen they deliver to the roots of plants over the growing season.

More and more farmers are putting it to use in their fields. The company’s products were applied to 5 million acres last year, up from 1 million two years earlier. 

Key indicators

• Industry: Food and agriculture 
• Founded: 2011
• Headquarters: Berkeley, California, USA
• Notable fact: Pivot Bio says its products can replace 40 pounds of synthetic fertilizer per acre. US corn farmers generally apply about 150 to 220 pounds of fertilizer per acre every year, depending on the variety and hoped-for yield.

Potential for impact

Pivot sells the microbes as a seed coating or as a liquid that farmers can apply in furrows at the time of planting. 

The company says the current version of its main product, designed for corn, can replace about 25% of the synthetic fertilizer normally used, without reducing crop output. The company has also developed nitrogen-delivering microbes tailored for wheat, sorghum, and other small grains, all selling for around or below the price of traditional fertilizer. Pivot adds that farmers have applied its products to more than 10 million acres (if you count repeated uses), nearly all in the US so far.

Pivot says that while generating a million tons of ammonia as fertilizer produces 2.6 million metric tons of carbon dioxide, manufacturing the microbes needed to deliver a million tons of nitrogen in the field produces only about 35,000 tons of emissions. The company estimates that its customers have cut emissions by the equivalent of more than 900,000 tons since the start of 2022. About 78% of that reduction occurred just last year, though the company says some of that increase was due to improved data collection.

A handful of academic studies have backed up the company’s claims that its products can reduce fertilizer use and emissions without lowering crop yields.

Caveats

Some farmers have reported mixed results in their fields, and Pivot’s products don’t necessarily increase yields over what’s possible with standard fertilizer use. That isn’t necessary for the company to make the case that it can help the climate—but it would make Pivot an easier sell to farmers.

Many are loath to cut down their use of synthetic fertilizer, a tried-and-true product, unless new policies require them to do so or pollution-cutting products promise to boost productivity as well.

The other obvious challenge with Pivot’s approach is that it’s not a complete solution to synthetic fertilizer pollution, since it can replace only a fraction of that fertilizer.

Next steps

But it’s a big fraction in an industry that’s notoriously challenging to clean up, and one that’s set to grow.

Chris Abbott, the company’s CEO, stresses that Pivot can save farmers money, since its products are cost competitive with synthetic fertilizer but will more reliably deliver nitrogen that actually translates to plant growth.

The company expects that its next generation of microbes, scheduled to be ready for the 2026 US planting season, will be 25% more effective at generating nitrogen at the roots of crops. With future improvements, Abbott believes, the products will eventually be capable of replacing as much as half the synthetic fertilizer in fields, with crop yields the same or better. 

If Pivot nears that goal and continues to win over farmers, it could begin to meaningfully reduce one of agriculture’s biggest sources of climate pollution.

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: Sun King connects low-income households to clean energy

Sun King is helping poor households across Asia and Africa access reliable, clean power and healthier ways of cooking. 

Accessing clean sources of energy has always been a challenge for low-income communities worldwide, given the high up-front costs. At least hundreds of millions of people around the world have unreliable or no access to the electricity grid, forcing many of them to spend as much as 10% of their incomes on dirty fuels—like kerosene and diesel—that harm both their health and the environment.

One work-around for this challenge is to allow households to pay for clean energy in small, affordable amounts as they use it. 

This is what Sun King has been able to deliver. By providing solar panels, handheld solar-powered lamps, batteries, and home systems that power lights and devices to communities in sub-Saharan Africa and Asia, it says, it offers reliable renewable electricity to some 40 million people. Its pay-as-you-go business model allows households to spend as little as $0.15 per day.

Now, having acquired PayGo Energy in 2023, Sun King is expanding its product portfolio into clean cooking. 

PayGo’s stoves run on liquefied petroleum gas, which produces less of the health-damaging and climate-warming pollution generated by charcoal, biomass, and similar fuels used to heat basic stoves in many homes. The household costs for the stoves and fuel are subsidized by carbon credits that the company earns for reducing greenhouse-gas emissions, through a voluntary carbon offsets program. 

Crucially, PayGo has earned high marks from academic experts for developing household cookstoves that reliably reduce indoor air pollution and climate emissions. Sun King says it’s also developing other cooking appliances, like pressure cookers, that could run on the renewable electricity it provides. 

Key indicators

• Industry: Renewable energy 
• Founded: 2008
• Headquarters: Nairobi, Kenya
• Notable fact: Sun King supplies solar products to more than 40 million people in 10 African and two Asian countries.

Potential for impact

Sun King’s whole range of product lines helps cut the emissions driving climate change. 

For instance, it has already sold 23 million solar products to previous users of kerosene lamps, each of which can pump out around a ton of carbon dioxide a decade. 

And by reducing the need to collect biomass to produce household light, heat, or fuel for cooking, the company can help reduce deforestation as well as the emissions that occur from burning plant matter.

Cooking with wood and charcoal is a major contributor to global warming, responsible for approximately 2% of worldwide carbon emissions. The particulate pollution it releases also kills millions of people annually.

Voluntary carbon markets for clean cookstoves will only work if the programs are conducted in a transparent and credible manner; such programs have come under severe criticism for inflating the climate benefits of the appliances, in part by overestimating how much they’re actually used. But PayGo was among a few cookstove projects that researchers at the University of California, Berkeley, found did meet stringent quality criteria, in part by “metering” actual usage of cleaner replacement stoves. The stoves also use a fuel that meets World Health Organization health standards for indoor air pollution.

By operating in more rigorous ways, the company could help drive more investment in cookstove projects that actually make a difference for both public health and climate change.

Indeed, quality carbon credits—like those Sun King plans to release—have begun to fetch higher prices, in a market that has started to discriminate against inflated credits.

Caveats 

Even though Sun King and PayGo Energy adhere to very high standards in monitoring emissions, these approaches are not foolproof and may be flawed by inaccurate or overly generous assumptions.

And it may remain difficult to persuade many households to shift to cleaner stoves, depending on their specific needs, cultural practices, habits, and incomes. 

Meanwhile, though providing off-grid solar power at a low up-front cost is a boon to low-income households in regions with spotty or overpriced electricity, these homes and communities will ideally be connected to large, clean, stable electricity grids in the future. That would ultimately provide the lower-cost, around-the-clock electricity needed to power businesses and create local jobs. 

Next steps 

Sun King is now conducting a pilot initiative with a thousand households across Kenya, to introduce its next-generation clean cookstoves. The company also launched its first dedicated cookstove shop in the same country, known as EasyCook, in July. 

Meanwhile, Sun King continues to improve its solar products and market reach. It has begun rolling out a new home system that delivers increased energy output at a lower retail price, and it launched operations in South Africa and Cameroon this year.

As the cost of solar panels and batteries continue to fall, Sun King’s products are becoming increasingly competitive with traditional grid electricity, offering consumers across growing parts of Africa and Asia cleaner, cheaper, and often more reliable energy.

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: Ceibo and its copper mining tech

Ceibo seeks to eliminate a major potential speed bump for the clean-energy transition: the looming global copper shortage. The firm’s low-impact extraction technology targets ores that aren’t economical to mine today but could help meet the copper demands of an electrified world.

Copper wires form the backbone of the clean-energy economy, connecting cars, buildings, and factories to the grid. Copper is also essential to solar panels, wind turbines, and EVs. Demand for the metal in these and other cleantech applications is expected to nearly triple by 2040. But much of the copper that remains in the ground is locked up in low-grade ores that aren’t economical to mine. The mining technology company Ceibo hopes to change that.

Today, about 20% of the world’s copper is produced from copper oxide ores. Copper is extracted by crushing the rock, placing it in a giant pile, and spraying it with dilute acid. As acid percolates through the rock, the copper dissolves and leaches out. 

The remaining 80% of the world’s copper comes from copper sulfide ores, which don’t dissolve well in acid. To extract that copper, the industry uses a more energy- and water-intensive process that involves concentrating the metal in vats of chemicals before smelting it at high temperatures.

Ceibo is tweaking the lower-impact leaching process so that it works on copper sulfides. The company’s chemistry-based approach mimics the way naturally occurring microbial communities liberate copper from sulfide ores, but at an accelerated pace. By altering conditions within the rock pile, including pH and oxidation state, Ceibo’s tech makes it possible to recover more than 70% of the copper. Companies that are already mining copper oxides can plug the firm’s tech into their existing infrastructure without costly retrofits.

Ceibo is in the process of testing its technology in partnership with key players in the mining industry. The firm has also raised $36 million from clean-energy and mining financiers, part of a growing trend of investment in startups seeking to process copper sulfides with leaching. Among those startups, Ceibo stands out for being headquartered in Chile, the world’s largest copper producer. This could give the firm a home field advantage as it seeks to build partnerships with major industry players and rapidly scale its technology. 

Key indicators

• Industry: Mining 
• Founded: 2021
• Headquarters: Santiago, Chile
• Notable fact: Ceibo got its start offering dust suppression services to copper miners under a different name, Aguamarina. Dust pollution is a major challenge for the copper industry.

Potential for impact

While the cleantech sector’s appetite for copper is expected to surge, the mining sector isn’t keeping pace. With many of the best-quality ore deposits already exhausted, analysts predict a potential copper shortfall of more than 10 millions tons a year by 2040. 

Liberating the potentially vast quantities of copper tied up in sulfide ores that aren’t economical to mine today may be key to closing the copper supply gap. Ceibo is aiming to produce a million tons of copper annually within the next 10 years, with further expansion in the future. At such scales, Ceibo’s relatively low-impact approach to copper processing could help clean up the industry.

Caveats

The idea of using acid to leach sulfide ores isn’t new; researchers have been trying to develop a scalable, cost-effective way to do so for decades. The problem is so well known that industry insiders sometimes refer to it as the Holy Grail of copper mining. 

Environmental variability is a key challenge. A company might develop a method that works well for one particular ore type but fails when applied elsewhere. Ceibo is developing a process that the company says is flexible by design, using a mix of proprietary chemical reagents and geochemical modeling to adjust to conditions on the ground. But the firm still has to demonstrate that its technology can help miners extract copper efficiently at commercial scales in a broad spectrum of geologic and environmental conditions. 

Next steps

So far, Ceibo has focused on proving its process in laboratory settings. To date, in partnership with mining companies, it has tested the performance of its technology on more than 20 ores. Later this year, Ceibo aims to begin running its first on-site pilot tests.

While much of Ceibo’s initial work has taken place in Chile, the firm recently opened a US office to gain a greater foothold in the North American market, which is being buoyed by the Biden administration’s efforts to expand domestic supply chains for critical minerals.

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: LanzaJet and its next-generation jet fuel

LanzaJet is making next-generation aviation fuel without fossil fuels. The company recently opened the world’s first commercial-scale production facility that turns alcohol into jet fuel and plans to produce up to 9 million gallons each year.

LanzaJet wants to cut aviation’s climate impact by rethinking where jet fuel comes from. 

Today, hopping on a plane means burning huge amounts of fossil fuels—the aviation industry accounts for about 3% of global greenhouse-gas emissions. 

LanzaJet’s technology makes jet fuel using alcohol, which can be sourced from a variety of materials, including corn and sugarcane. The company’s process starts with ethanol and then uses a series of steps that pull out water, string molecules together into longer chains, and add hydrogen. The result is a chemical mixture, which the company then processes further to separate out the components that can be burned as jet fuel. 

The company is a leader in this alcohol-to-jet-fuel pathway. Currently, nearly all commercially available alternative jet fuels use waste fats, oils, and greases as their starting material, but as the industry scales, there’s a growing concern about their limited supply. 

This new option for alternative fuels could drastically expand supply and help the industry scale more quickly, which will be crucial to meeting climate targets. LanzaJet opened the first commercial alcohol-to-jet-fuel factory in Georgia in January 2024 and has buyers secured for all the fuel produced at that facility through 2034. British Airways, one of LanzaJet’s investors, will be a customer. 

Key indicators

• Industry: Aviation fuels 
• Founded: 2020
• Headquarters: Deerfield, Illinois, USA
• Notable fact: LanzaJet spun out of LanzaTech, a company whose main technology uses microbes to convert waste materials into chemicals and fuels.

Potential for impact

Alternative fuels still produce carbon dioxide and other greenhouse gases when they’re burned in a plane’s engine. The difference is that they typically remove some carbon from the atmosphere first. In this case the corn or sugarcane used to make the ethanol soaks up carbon dioxide as it grows. The result is that at least some of the emissions from flying can be considered offset by the process of making the fuel.

LanzaJet’s fuels could cut the climate impacts from burning fuel roughly in half, though the exact amount will depend on the source of alcohol used. The company’s sugarcane-derived ethanol could cut emissions by between 54% and 66%, according to the US Environmental Protection Agency, which certifies low-emissions fuels under the country’s Renewable Fuel Standard program.

The company plans to test out its new Georgia factory using corn-based fuels, though it’s only certified to sell sugarcane-based fuels in the US so far. LanzaJet is also partnering with its former owner, LanzaTech, to take materials like municipal solid waste and industrial waste gas and transform them into ethanol, which LanzaJet will then make into jet fuel. This pathway could result in jet fuel that’s 85% less polluting than fossil fuels, the company claims.

Caveats 

Scaling could present a major challenge for LanzaJet, as it does for the industry as a whole. Alternative jet fuels made up just 0.17% of all global aviation fuel used in 2023. LanzaJet’s goal is to produce a billion gallons of alternative jet fuels annually by 2030, significantly more than the roughly 160 million gallons produced by the entire alternative fuels industry last year. To achieve that, the company will need to build many large facilities, and do it quickly.  

Cost is another major challenge for new fuels—on average, alternative jet fuels cost 2.8 times more than their fossil-fuel counterparts in 2023. Prices could come down as facilities scale, but fuel is a significant cost for airlines, making this a crucial consideration for future customers.

Experts also caution that fuels from biological sources still have environmental impacts. Those effects depend largely on the specific agricultural practices used to produce them. Clearing natural ecosystems to plant massive fields of single crops, for example, can on balance release more greenhouse gases into the atmosphere than those crops will ever capture. In the worst-case scenarios, some crop-based biofuels produce more emissions than fossil fuels. LanzaJet and other fuel makers will need to choose their source materials carefully and be transparent with regulators and the public about the effects of producing their products.

Next steps 

LanzaJet is working to validate and ramp up its first commercial facility, which the company hopes to have operating at full capacity by the end of 2024. Next, the company will begin building even larger facilities, including a 27-million-gallon-per-year facility in the UK in partnership with British Airways that should be operating by 2027.

Explore the 2024 list of 15 Climate Tech Companies to Watch.

2024 Climate Tech Companies to Watch: Rondo Energy and its hot bricks

Rondo Energy is supplying cheap, zero-emissions heat to factories to replace fossil-fuel-powered boilers, furnaces, and kilns. Its approach of using bricks and iron wire to provide a steady supply of hot air or steam stands out for its simplicity and potential to scale.

Finding a clean way to produce the large amounts of heat required for industrial processes is one of the biggest unsolved climate challenges. Widely discussed solutions, like carbon capture and green hydrogen, still struggle to compete economically with burning coal or gas.

Rondo offers an alternative approach: stacks of bricks, heated by electricity generated from the wind and sun. Inside Rondo’s heat batteries, cheap renewable electricity heats iron wires similar to those in a toaster oven, which warms hundreds of tons of bricks to temperatures of up to 1,500 °C. With four to six hours of charging a day, those bricks can turn intermittent renewable power into a 24-7 heat source for industrial facilities.

Among startups trying to commercialize zero-emissions heat batteries, Rondo stands out for its simple approach. Competitors’ heat batteries often involve some kind of new technique or engineered material that’s a few steps away from any current industrial technology. But the heat-resistant bricks inside a Rondo heat battery are similar to those that have been used in high-temperature steelmaking for over a century, meaning they are already produced cheaply and at industrial scales. That sales pitch is resonating with investors, who have poured $85 million into the startup over the past two years.

Key indicators

• Industry: Energy storage 
• Founded: 2020
• Headquarters: Alameda, California, USA
• Notable fact: The company’s name pays homage to the musical term for a type of composition with a recurring theme. Cofounders John O’Donnell and Pete von Behrens previously worked in concentrating solar thermal power; Rondo is their second venture into thermal storage.

Potential for impact

Industrial production of stuff, from clothing and food to cement and fertilizer, is responsible for about a third of global greenhouse-gas emissions. Most of those emissions come from burning fossil fuels to generate heat in factories. If Rondo’s heat batteries prove cost-competitive at scale, they could help eliminate billions of tons of carbon emissions that would otherwise enter the atmosphere each year.

Caveats 

While heat-resistant bricks are a proven industrial technology, using them as zero-emissions heat batteries will require building more wind and solar plants to generate huge amounts of cheap renewable energy. Electricity reforms would also be needed in many parts of the US to make heat batteries cost-competitive with other forms of industrial heat. These might include allowing heat battery users to purchase cheap wholesale power from the grid during times of the day when renewable energy is abundant—something that isn’t possible today in jurisdictions that only sell power to industries at a fixed daily rate. 

Next steps 

Rondo has a 2-megawatt-hour battery operating commercially at an ethanol plant in California. Its scale-up plans are ambitious: In partnership with Siam Cement Group, the company is already producing enough heat-resistant brick to store 2.4 gigawatt-hours of energy a year, which could power more than 200 American homes. It plans to boost production to 90 gigawatt-hours a year in the future. Between 2025 and 2027, recently announced customers in the food and beverage and chemical industries are expected to start using versions of Rondo’s commercial heat batteries in industrial facilities. 

Experts are looking forward to seeing how Rondo’s batteries perform over time, both in bigger installations and in very high-temperature applications like steel and cement making, which are considered among the most difficult processes to decarbonize.

Explore the 2024 list of 15 Climate Tech Companies to Watch.