breakthrough-energy-ventures
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Barclay Rogers
Barclay Rogers is the co-founder and CEO of Graphyte, a carbon removal company that turns waste biomass into dense, dehydrated carbon blocks and buries them to keep CO2 out of the atmosphere for over a thousand years. A former environmental lawyer and mechanical engineer turned multi-time agtech and climate founder, he built Graphyte's 'Carbon Casting' process to deliver durable carbon removal at under $100 a ton, an order of magnitude cheaper than direct air capture. The company is backed by Bill Gates' Breakthrough Energy Ventures and runs its first commercial plant in Pine Bluff, Arkansas. Rogers also teaches a climate change solutions course as an adjunct professor of law at Tulane University.
Colin South
Colin South is a New Zealand-born biotechnology executive and the founding leader of ArkeaBio, a Boston climate-tech company building the world's first vaccine to cut methane emissions from cattle. He grew up on a 1,000-head sheep farm, earned a PhD in bioprocess engineering from Dartmouth, and spent 25-plus years turning microbes into commercial products across the food, fuel, and energy industries. He launched ArkeaBio in 2021, ran it as CEO from January 2022, and in September 2025 stepped into the Chief Business Officer seat as the company brought in a new CEO and pushed toward field trials.
Josh Browne
Josh Browne is the co-founder and CEO of M2X Energy, a Rockledge, Florida climate-tech company that converts wasted methane from flares and landfills into low-carbon methanol using modular, truck-transportable gas-to-liquids systems built around repurposed internal-combustion engines. M2X grew out of his Columbia PhD dissertation, was founded in 2020 by Breakthrough Energy Ventures, and raised a $40 million Series B in 2024 (about $62.5 million total). Before M2X, Browne founded a data-science firm, Rho AI, that was acquired by General Motors. He started as the company's CTO and now runs it as CEO.
Tim Heidel
Tim Heidel is the co-founder and CEO of VEIR, a Massachusetts startup building overhead superconducting transmission lines that can carry five to ten times the power of conventional lines on roughly the same footprint. An MIT-trained electrical engineer who ran the research behind MIT's Future of the Electric Grid study, then steered a portfolio of grid projects at ARPA-E and vetted climate bets at Bill Gates' Breakthrough Energy Ventures, Heidel concluded that the grid's biggest bottleneck was transmission itself - too slow, too costly, too ugly to permit. VEIR is his answer: black pipes carrying superconducting tape bathed in liquid nitrogen at -321F, aimed squarely at AI data centers, utilities and renewable developers.
Turner Caldwell
Turner Caldwell is the Co-Founder and CEO of Mariana Minerals, a San Francisco-based startup rewriting the rulebook on how critical minerals are found, dug up, and refined. After nearly a decade ascending Tesla's battery supply chain from factory design to heading the metals and minerals team, Caldwell left to build Mariana in 2024. The company now operates Copper One in southeastern Utah - the world's first mine running autonomous haul trucks, robotic drills, and AI-driven refining under a single proprietary operating system called MarianaOS. Backed by a16z, Breakthrough Energy Ventures, and Khosla Ventures with $85M in Series A funding, Mariana targets 10 mineral projects in 10 years, compressing a timeline that traditionally stretches 15+ years for a single mine.