Josh Posamentier, co-founder and managing partner at Congruent Ventures, will join Venture Houston as a speaker this year. Photo via congruentvc.com

It's been a challenging year for venture capital, but how are climatetech startups doing specifically? One Bay Area investor shares his point of view on this this topic ahead of Venture Houston next week.

Joshua Posamentier, co-founder and managing partner of Congruent Ventures, a San Francisco-based firm that invests in early-stage sustainable companies, is taking the stage at Venture Houston on September 7. Among others, Posamentier will be in conversation with the founder of one of his firm's portfolio companies, Fervo Energy, discussing seed and early-stage funding for sustainability-focused startups.

Venture Houston is presented by HX Venture Fund, a fund of funds that deploys capital into non-Houston firms to encourage investment in local startups. This year's theme is "Spotlighting the path for decarbonization in a digital world."

Posamentier, who has worked over a decade in this space, shares some of his thoughts on Houston as an energy transition leader, the challenges climate-tech startups face, and more in an interview with EnergyCapital.

EnergyCapital: How do you see Houston and its role in this energy transition, its challenges, its opportunities, etc.?

Josh Posamentier: I actually tend to disagree with the people that say Houston is too far down the oil and gas path. I mean, it's it's capitalism at the end of the day. There's money to be made in in climate mitigation technologies. People are going to go chase it, and I think Houston, of all places, is a pretty capitalistic city. And people are definitely not shy about chasing the next big opportunity. I mean, it was oil and natural gas before, and now it's now it's alternative energy. And so I think from that perspective, it's fine. There's a lot of money.

I think the biggest challenge is honestly, especially on a perception basis, a lot of the policy and social stuff that's endemic to Texas, which is a bummer. I mean, especially for younger talent. Austin had a shine, but I think that's largely gone and Houston never had it. So, I think it's something that needs to be overcome and needs to be thought about at a state level basis, especially if you're going to want to attract young entrepreneurial talent.

EC: What are some of the challenges energy transition startups are facing these days? How is your fund kind of supporting your portfolio companies through these challenges?

JP: There's some normalization that's had to happen over the last 9 to 12 months. As you know, corrections have come down the pipe in the venture ecosystem. By all accounts, it has been really frothy for the last few years, especially so in parts of climate. Some of that's due to the the proliferation of investment from non climate-specific firms. And it's, in many ways, decoupled from the ups and downs of different parts of the venture ecosystem, but it also has different timelines. I think not everyone always appreciates what that means and what that implies for for startups. So there's a lot of frustration and a lot of missed expectations in the early stage part of the ecosystem that are slowly getting fixed. I think getting expectations more in line with reality is going to help immensely.

The other thing is just figuring out how to talk more in a language that venture investors understand. I think that's a little bit of a challenge. There's there's actually a pretty big gap between if you're an oil and gas developer and thinking about how you fund that kind of a business versus how you fund a technology-enabling business. Fervo Energy is an interesting example. It's a tech company, but now it's really a tech enabled developer because they have no choice but to do that full stack. They went to school out here. They understand the ecosystem. They've really taken the effort to really understand all the capital players. And so we're waiting to see how that ultimately plays out.

But there's just different capital. I think it is a little challenging. And this is a good thing. There does need to be a way, I think, to just get people more exposure to to the market there — in the Houston market specifically. If you're spinning at Stanford, there are hundreds of VCs within walking distance. In Houston, the ones I know I can count on one hand.

EC: Has that pace of commercialization changed over the years or have founders found ways to survive that valley of death?

JP: I don't think anything's really changed fundamentally. I think people have gotten a little more clever about understanding how the adoption occurs, and figuring out how to phase into those processes that that comes with experience. But there's only so much acceleration you can do when you're dealing with critical infrastructure. You know, people are not going to want to just jump right in, rip out, and replace things that keep the lights on. And so you just have to figure out how to how to capitalize a business in such a way that you can you can live with those kinds of timelines. Venture capital is a fantastic tool, and it is far from the right tool for every problem. And so there are plenty of opportunities to deploy other tools that are more appropriate to different kinds of different kinds of challenges.

EC: What attracted you to investing in Fervo Energy?

JP: So, it's how we think about portfolio construction. Fervo has an amazing team, which we will bend a lot of rules for, and we saw this opportunity as something they could build a ton of value by validating the tech, establishing a huge land position, and then raising different kinds of capital for the out years and for the project development. A bunch of our companies took venture capital to develop a technology, and then they know that venture is not the right class of capital to then scale that throughout the world and whatever. So they would basically raise other forms of capital in the out years to deploy the technologies.

EC: And one of those options is government funding. How do your portfolio companies utilize that?

JP: A big chunk of our portfolio has some government money, even if it's very early stage research grants or something like that. I see government money being the most effective in a couple of ways. One way obviously is to get the core research out of it versus just spin it into something more commercial that we can all then look at.

The other place that is really exciting is in is getting technologies to scale where they're then cost effective without further subsidies. When we underwrite companies, we are very explicitly underwriting them in the absence of subsidies at scale. The assumption is those are just there to basically bridge the gap between "this is totally uneconomic because it's a tiny, tiny little factory or something" versus "it would be plenty economic if it were a big factory." So, if they can just bridge that gap with a little bit of government money.

We've been through this this cycle a couple of times, and we can't in good faith underwrite anything assuming that government subsidies are going to continue. We very much believe it's a bridge — it's got to be a bridge to something. It can't be a bridge to nowhere. And I think there are a lot of companies out there today that are almost designed to just pump the government incentives, and that's not a recipe for a business that can grow on its own over time.

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This conversation has been edited for brevity and clarity.

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Houston geothermal company raises $97M Series B

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Houston-based geothermal energy startup Sage Geosystems has closed its Series B fundraising round and plans to use the money to launch its first commercial next-generation geothermal power generation facility.

Ormat Technologies and Carbon Direct Capital co-led the $97 million round, according to a press release from Sage. Existing investors Exa, Nabors, alfa8, Arch Meredith, Abilene Partners, Cubit Capital and Ignis H2 Energy also participated, as well as new investors SiteGround Capital and The UC Berkeley Foundation’s Climate Solutions Fund.

The new geothermal power generation facility will be located at one of Ormat Technologies' existing power plants. The Nevada-based company has geothermal power projects in the U.S. and numerous other countries around the world. The facility will use Sage’s proprietary pressure geothermal technology, which extracts geothermal heat energy from hot dry rock, an abundant geothermal resource.

“Pressure geothermal is designed to be commercial, scalable and deployable almost anywhere,” Cindy Taff, CEO of Sage Geosystems, said in the news release. “This Series B allows us to prove that at commercial scale, reflecting strong conviction from partners who understand both the urgency of energy demand and the criticality of firm power.”

Sage reports that partnering with the Ormat facility will allow it to market and scale up its pressure geothermal technology at a faster rate.

“This investment builds on the strong foundation we’ve established through our commercial agreement and reinforces Ormat’s commitment to accelerating geothermal development,” Doron Blachar, CEO of Ormat Technologies, added in the release. “Sage’s technical expertise and innovative approach are well aligned with Ormat’s strategy to move faster from concept to commercialization. We’re pleased to take this natural next step in a partnership we believe strongly in.”

In 2024, Sage agreed to deliver up to 150 megawatts of new geothermal baseload power to Meta, the parent company of Facebook. At the time, the companies reported that the project's first phase would aim to be operating in 2027.

The company also raised a $17 million Series A, led by Chesapeake Energy Corp., in 2024.

Houston expert discusses the clean energy founder's paradox

Guest Column

Everyone tells you to move fast and break things. In clean energy, moving fast without structural integrity means breaking the only planet we’ve got. This is the founder's paradox: you are building a company in an industry where the stakes are existential, the timelines are glacial, and the capital requires patience.

The myth of the lone genius in a garage doesn’t really apply here. Clean energy startups aren’t just fighting competitors. They are fighting physics, policy, and decades of existing infrastructure. This isn’t an app. You’re building something physical that has to work in the real world. It has to be cheaper, more reliable, and clearly better than fossil fuels. Being “green” alone isn’t enough. Scale is what matters.

Your biggest risks aren’t competitors. They’re interconnection delays, permitting timelines, supply chain fragility, and whether your first customer is willing to underwrite something that hasn’t been done before.

That reality creates a brutal filter. Successful founders in this space need deep technical knowledge and the ability to execute. You need to understand engineering, navigate regulation, and think in terms of markets and risk. You’re not just selling a product. You’re selling a future where your solution becomes the obvious choice. That means connecting short-term financial returns with long-term system change.

The capital is there, but it’s smarter and more demanding. Investors today have PhDs in electrochemistry and grid dynamics. They’ve been burned by promises of miracle materials that never left the lab. They don't fund visions; they fund pathways to impact that can scale and make financial sense. Your roadmap must show not just a brilliant invention, but a clear, believable plan to drive costs down over time.

Capital in this sector isn’t impressed by ambition alone. It wants evidence that risk is being retired in the right order — even if that means slower growth early.

Here’s the upside. The difficulty of clean energy is also its strength. If you succeed, your advantage isn’t just in software or branding. It’s in hardware, supply chains, approvals, and years of hard work that others can’t easily copy. Your real competitors aren’t other startups. They’re inertia and the existing system. Winning here isn’t zero-sum. When one solution scales, it helps the entire market grow.

So, to the founder in the lab, or running field tests at a remote site: your pace will feel slow. The validation cycles are long. But you are building in the physical world. When you succeed, you don’t have an exit. You have a foundation. You don't just have customers; you have converts. And the product you ship doesn't just generate revenue; it creates a legacy.

If your timelines feel uncomfortable compared to software, that’s because you’re operating inside a system designed to resist change. And let’s not forget you are building actual physical products that interact with a complex world. Times are tough. Don’t give up. We need you.

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Nada Ahmed is the founding partner at Houston-based Energy Tech Nexus.

Houston maritime startup raises $43M to electrify cargo vessels

A Houston-based maritime technology company that is working to reduce emissions in the cargo and shipping industry has raised VC funding and opened a new Houston headquarters.

Fleetzero announced that it closed a $43 million Series A financing round this month led by Obvious Ventures with participation from Maersk Growth, Breakthrough Energy Ventures, 8090 Industries, Y Combinator, Shorewind, Benson Capital and others. The funding will go toward expanding manufacturing of its Leviathan hybrid and electric marine propulsion system, according to a news release.

The technology is optimized for high-energy and zero-emission operation of large vessels. It uses EV technology but is built for maritime environments and can be used on new or existing ships with hybrid or all-electric functions, according to Fleetzero's website. The propulsion system was retrofitted and tested on Fleetzero’s test ship, the Pacific Joule, and has been deployed globally on commercial vessels.

Fleetzero is also developing unmanned cargo vessel technology.

"Fleetzero is making robotic ships a reality today. The team is moving us from dirty, dangerous, and expensive to clean, safe, and cost-effective. It's like watching the future today," Andrew Beebe, managing director at Obvious Ventures, said in the news release. "We backed the team because they are mariners and engineers, know the industry deeply, and are scaling with real ships and customers, not just renderings."

Fleetzero also announced that it has opened a new manufacturing and research and development facility, which will serve as the company's new headquarters. The facility features a marine robotics and autonomy lab, a marine propulsion R&D center and a production line with a capacity of 300 megawatt-hours per year. The company reports that it plans to increase production to three gigawatt-hours per year over the next five years.

"Houston has the people who know how to build and operate big hardware–ships, rigs, refineries and power systems," Mike Carter, co-founder and COO of Fleetzero, added in the release. "We're pairing that industrial DNA with modern batteries, autonomy, and software to bring back shipbuilding to the U.S."