Literally unearthing a climate solution with Cody Finke of Brimstone

Episode Summary

Executive Summary: The episode traces Cody Finke’s path from climate-tech projects at Caltech to co-founding Brimstone, a company reinventing cement production to cut emissions. After learning that most cement emissions come from limestone chemistry—not just fuel—Finke identified calcium silicate rock as a lower-carbon input that can still make ordinary Portland cement, with a waste byproduct that can sequester CO2. The interview explores the science, market barriers, IP strategy, scale-up plans, and climate significance of decarbonizing cement.

Main Topics: Why cement is a major climate problem (Priority: 5/5): Guy Raz frames cement as an underappreciated source of emissions, explaining that global cement production emits nearly as much CO2 as cars and that most of the problem comes from the chemistry of limestone. Finke’s search for a tractable climate solution (Priority: 5/5): Cody describes early projects at Caltech, including solar-powered toilets and water electrolysis, and why he abandoned them: both lacked a compelling economic path to scale and impact. The chemistry of cement emissions (Priority: 5/5): The conversation breaks down how cement production creates emissions from both fuel use and limestone calcination, with limestone releasing stored carbon when heated. Brimstone’s alternative feedstock and carbon-negative pathway (Priority: 5/5): Finke explains Brimstone’s use of calcium silicate rock instead of limestone, enabling ordinary Portland cement production while avoiding embedded CO2 and creating a magnesium byproduct that can passively absorb carbon. Commercialization strategy and market adoption (Priority: 4/5): The episode examines why novel cement materials face adoption barriers, why Brimstone chose to make standard Portland cement, and how regulation and developer demand may drive initial uptake. Scaling, patents, and the capital challenge (Priority: 4/5): Finke discusses patents, third-party certification, pilot and commercial plant plans, and the large capital needs required to prove and deploy the technology at industrial scale.

Key Arguments: Cement is a massive emissions source, but it is often overlooked because it is a less visible part of the carbon problem than fossil fuels or transportation. A climate solution must also be an economically viable business; otherwise it will not scale and therefore will not meaningfully reduce emissions. Most cement emissions come from the chemistry of limestone, not just the heat used in production, so changing the feedstock can dramatically reduce CO2. Novel cement products are hard to adopt because builders and engineers prioritize reliability, insurance, and avoiding delays; standard Portland cement is far more likely to be accepted. Calcium silicate rock can be used to make ordinary Portland cement, allowing a drop-in product rather than a risky new material. Brimstone’s process can be low-carbon or even carbon-negative because its feedstock contains no CO2 and its magnesium-rich byproduct can sequester atmospheric carbon. Scale and cost parity are essential: Brimstone aims to be cheaper or at least not more expensive than incumbent cement in order to drive widespread adoption. Patents and licensing give Brimstone a path to partner with incumbent cement firms once its process is proven at scale. Initial customers are likely to be climate-motivated real estate developers, since they sit higher in the value chain and can demand lower-carbon materials. The long-term market is enormous, so even a capital-intensive rollout could be attractive if the process works and can be replicated globally.

Data Points: Global cement emissions share: about 8% of global CO2 emissions - Guy Raz explains that cement and concrete together account for roughly the same emissions as the world’s cars. Concrete vs. cement emissions: about 90% of emissions come from cement - Cody clarifies that concrete is the final product, while cement is the main emissions source. Fuel-related cement emissions: about 40% - Finke says roughly 40% of cement emissions come from burning fuel to heat the kiln. Limestone-related emissions: about 60% - He states that the majority of cement emissions come from releasing CO2 from limestone during calcination. Hydrogen emissions share: 70% of greenhouse gas emissions - Finke refers to the scale of emissions that hydrogen could theoretically help decarbonize. Early project duration: 3 or 4 years - He spent several years on the solar-powered toilet project before concluding it lacked a scalable business model. Climate project recognition: Bill and Melinda Gates Foundation award - The solar-powered toilet/wastewater project won recognition despite not becoming a scalable business. Funding raised: over $60 million - Guy Raz notes Brimstone has raised substantial venture funding to date. Certification milestone: third-party certification in July - Brimstone’s cement passed existing ordinary Portland cement standards, confirming chemical and physical equivalence. Commercial plant build time: 2 or 3 years - Finke says a modern cement plant typically takes this long to build. Plant cost: around $1 billion - He estimates the cost of a modern cement plant. Existing plants: 3,000 today - Finke estimates the current global number of cement plants. Future plant count: 5,000 by the end of the century - He projects growth in cement plant demand as the world develops and decarbonizes. Long-term market size: $5 trillion - Using $1 billion per plant and 5,000 plants, Finke frames the eventual market opportunity. California cement target: 40% below baseline by 2035 - Guy Raz cites California policy as a near-term driver of demand for lower-carbon cement. California net-zero target: 2045 - Guy Raz notes the state’s requirement for net-zero cement emissions by 2045.

Pivotal Quotes: "There needs to be a compelling economic case." — Cody Finke: Explaining why his solar-powered toilet project could not scale despite working technically and winning recognition. "The chemistry problem was most of the CO2 emissions have nothing to do with energy. They have to do with the chemistry of making cement." — Cody Finke: Describing the key insight that led him to Brimstone’s approach. "We basically make synthetic baby powder passively." — Cody Finke: A memorable explanation of the magnesium carbonate byproduct that can sequester CO2.

Implications: If Brimstone scales, cement could become a drop-in, lower-carbon construction material with major climate impact. The episode suggests industrial decarbonization depends on chemistry, economics, regulation, and incumbent partnerships—not just innovation.