Breakthrough, DCVC invested $55 million in Brimstone


Hugo Leandri (left) and Cody Finke, co-founders of Brimstone Energy.

Photo courtesy of Brimstone Energy

Cars and electricity are getting a lot of attention in decarbonization conversations, and they should be. But building materials like cement and steel also need to be scrutinized.

Cement production is responsible for approximately 8% of global carbon dioxide emissions and 5.5% of total global greenhouse gas emissions.

On Thursday, Breakthrough Energy Ventures, Bill Gates’ climate finance firm, and DCVC, a Silicon Valley venture capital firm, announced they had completed a $55 million funding round in Brimstone Energy, a start-up aimed at marketing negative carbon cement.

“We have to recognize that cement is a huge climate problem and no one has figured out how to solve it at scale without dramatically increasing costs or moving away from the regulated materials the construction industry knows and loves” , said Breakthrough partner Carmichael Roberts. CNBC.

Brimstone was founded by two scientists who grew up halfway around the world, bonded in Beijing where they traveled to talk about toilets and are now aiming to solve this huge cement problem.

Toilets don’t measure

Co-founders Cody Finke and Hugo Leandri overlapped while in grad school at the California Institute of Technology in 2017, where they both worked on wastewater treatment. But the couple really bonded when they both attended the Reinvented Toilet Expo in Beijing in 2018.

“We had a lot of fun eating cockroaches in the tourist market and running around Beijing and talking about environmental issues like sanitation and greenhouse gas emissions,” Finke told CNBC. They also tried to eat snakes, as shown in this photo:

Code Finke (L) and Hugo Leandri bond after eating snakes on sticks in Beijing in 2018.

Photo courtesy Hugo Leandri

Finke, a Seattle native, had previously worked on developing solar-powered toilets that could also generate hydrogen and electricity, and his CalTech team won $100,000 from the Bill & Melinda Gates Foundation for winning the first place in the philanthropic organization Reinvent the Toilet Challenge in 2012.

He was excited about the idea, but it was expensive to scale.

“I felt like wastewater technology was doing a great job of treating wastewater, but to really save lives, it would have to be deployed. Even with optimistic assumptions, I couldn’t understand how this technology could be deployed because it was just too expensive,” Finke told CNBC. “So the chances of impact were low.”

Coming out of toilet research, Finke began looking for other places to focus his energies. Around this time, David Danielson of Breakthrough Energy Ventures gave a talk at CalTech about high-carbon sectors that weren’t yet getting much attention from innovators. Finke recalls Danielson mentioning steel, cement, and fertilizers, to name a few.

Finke used his knowledge of chemistry to develop ideas for co-generating clean hydrogen and other commodities, such as sulfuric acid or cement. In 2019, the two decided to be co-founders to develop and commercialize their laboratory science.

Leandri, who grew up in the French territory of Reunion Island near Madagascar, knew a little about the world of cement as he completed an internship in his father’s concrete company.

In 2020, they secured $500,000 in funding from the Department of Energy under the federal government’s ARPA-E, or Advanced Research Projects Agency-Energy, program to continue developing their ideas in chemistry.

Although neither of them are currently working on solar-powered toilets, a core belief of Brimstone comes from their days in the toilet: any solution they create cannot simply be good for the world; it must make financial sense for clients in order to have a big impact.

“One of our key criteria at Brimstone is that we believe that to be adopted globally, the technology we develop must fundamentally save people money,” Finke said.

“We don’t know of an example in history where global adoption has gone from lower cost to higher cost. It always goes from higher cost to lower cost.”

A new process for making ordinary cement

Normally, creating cement involves heating limestone, which releases carbon dioxide. Even if the energy used to heat the limestone is 100% clean, 60% of the carbon emissions would remain because of what’s inherent in the limestone rock, Finke said.

Some companies are trying to make climate-friendly cement by capturing carbon dioxide and storing it underground or using it. Other companies that are innovating in the field are manufacturing an alternative product that performs the same functions as cement but is not cement.

The Brimstone process creates what is called Ordinary Portland Cement (OPC), but instead of using limestone, it involves grinding calcium silicate rock and using a leaching agent to extract the calcium. Calcium silicate makes up about 50% of the earth’s crust, according to Finke, and is so common that it’s often ground up and used to make gravel. The process is the subject of four patents.

Incidentally, the company’s name comes from an archaic term for sulfur, which was used in an earlier version of its process. “We no longer use sulfur, but we still use stones, and we have a burning passion for decarbonization,” says Finke.

Investors appreciate the company’s focus on creating standard cement at a similar or cheaper price, instead of an alternative that might be more expensive and have to overcome new regulatory hurdles.

“Brimstone is the first company we’ve seen that can make the exact same material we use to build our buildings and bridges today – ordinary Portland cement – but with no carbon emissions and with the potential to cost the same or less than, traditional cement,” Roberts told CNBC.

This is also the key for DCVC.

“Brimstone’s ability to manufacture real OPC is critical as over 95% of all cement produced is OPC,” Rachel Slaybaugh, director of DCVC, told CNBC in a statement. “Ergo, no new regulations, material specs or standards are required. This is a key differentiator from other companies working in space, who are all producing a new type of material that is not well known. or understood by the construction industry.”

The Brimstone Energy team in the lab in Oakland, California.

Photo courtesy of Brimstone Energy

Super valuable by-products

After the cement is produced, it is mixed with other ingredients – known in the industry as “supplementary cementitious material” – in order to make concrete. The chemical process that Brimstone has developed to make cement also produces these materials, which “are becoming increasingly rare around the world and increasing in monetary value accordingly,” Slaybaugh told CNBC.

In older cement production techniques, these materials are usually either fly ash, a byproduct of coal combustion, or slag, a byproduct of steel production. Burning coal is falling out of favor due to its contribution to climate change, and it has become cheaper and more common to recycle steel, which means there is less slag.

As a by-product, Brimstone’s chemical process also produces some forms of magnesium that will react with carbon dioxide and turn it into a solid form, removing it from the atmosphere.

“Sitting on the ground doing nothing, they will react with the carbon dioxide and turn that carbon dioxide into rock,” Finke told CNBC.

Altogether, Brimstone’s cement can be carbon negative even if industrial processes are powered by heat produced from fossil fuels, the company claims.

Brimstone would rather avoid fossil fuels for generation and use clean heat from companies like Antora Energy, but only when that technology is available at scale and at low cost.

“My view is that, unfortunately, only cheaper things are built and not more expensive things, so today a clean energy plant would not be funded or built,” Finke told CNBC.

Next steps for Brimstone

Brimstone has its primary lab facilities in Oakland, CA, and secondary lab space in Ketchum, Idaho. The 14-person startup has yet to generate revenue, and the $55 million funding round will go toward building a pilot plant, which it aims to make operational in 2023.

The road is long for Finke and Leandri.

But they are motivated. Growing up in Seattle, Finke remembers watching Al Gore’s “An Inconvenient Truth” and being “devastated” by the thought that Mount Rainier might melt.

“Climate change is something that’s really close to my heart,” Finke said, and working on one spoke about the network of solutions needed to decarbonize makes sense of it.


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