Houston-based Caliche Development Partners begins doubling natural gas storage capacity and building the world’s largest helium cavern, fueled by a key Texas deal completion. Photo courtesy of Caliche

With the acquisition of its Texas business now complete, Houston-based Caliche Development Partners is moving ahead with expansion of a natural gas storage project in Beaumont.

This milestone comes after a previously announced majority investment in Caliche by New York City-based investment firm Sixth Street, which has offices in Houston, Austin, and Dallas. Sixth Street recently closed on the Texas portion of the deal, and it expects to wrap up the California portion of the deal in mid-2025.

The amount of Sixth Street’s investment in Caliche wasn’t disclosed.

Completion of the deal’s Texas component gave Caliche the go-ahead to start spending Sixth Street’s money on the Beaumont project.

Caliche already has started construction on the 14 billion-cubic-feet expansion of its Golden Triangle Storage natural gas storage facilities. Two new caverns, expected to come online in 2026 and 2027, will double total storage capacity to 28 billion cubic feet (Bcf).

The Golden Triangle Storage system connects to seven major pipelines in the Beaumont-Port Arthur area.

Meanwhile, Caliche has started construction on what’s billed as the world’s largest helium storage cavern, also located at the Golden Triangle site. This cavern is slated to begin operating in 2025, while Caliche expects its planned carbon sequestration project located just four miles west of Golden Triangle to enter the next phase of the Class VI permitting process by May 2026.

Caliche is an acquisition and development company that specializes in underground storage of natural gas, industrial gasses like hydrogen and helium, and carbon emissions. Caliche’s projects are in the Texas Gulf Coast’s Jefferson County and Northern California’s Colusa County.

Caliche says Sixth Street’s backing will enable it to expand its Golden Storage Triangle complex. Photo via calichestorage.com

Investor acquires majority stake in Houston energy storage, CCS co.

here's the deal

Investment firm Sixth Street has purchased a majority stake in Houston-based Caliche Development Partners, which focuses on buying, developing, and operating natural gas and gas storage facilities along with carbon sequestration projects.

Financial terms weren’t disclosed.

The deal includes Caliche’s Golden Triangle Storage facilities and carbon sequestration project in Beaumont, and its Central Valley Gas Storage facilities in Princeton, California.

Caliche says Sixth Street’s backing will enable it to expand its Golden Storage Triangle complex, including the addition of two natural gas caverns.

Caliche’s leadership will continue to oversee day-to-day operations and remain investors in the company. All employees in Caliche’s Texas and California offices and at its facilities are staying aboard.

“We continue to meet the growing demand for the storage of natural gas and industrial gasses, including helium and hydrogen, and provide the infrastructure for lower environmental impact forms of energy through our commitment to safety, deliverability, [and] asset integrity,” Dave Marchese, CEO of Caliche, says in a news release.

Richard Sberlati, a partner at Sixth Street, which has an office in Houston, says Caliche’s success “comes from a combined 65 years of collective storage experience, and we look forward to partnering with the company’s management as they further grow the business.”

Sixth Street’s acquisition of Caliche’s Texas business operations is expected to close in late 2024, and its acquisition of the California business operations is set to close in mid-2025.

Founded in 2016, Caliche announced in 2020 that it had arranged a $150 million debt facility with Houston-based investment firm Orion Infrastructure Capital. Two years later, Caliche gained $268 million in funding from Orion and Chicago-based asset management firm GCM Grosvenor.

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CultureMap Emails are Awesome

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."

Shell partners with UK-based co. for hydrogen electrolyzer pilot

ultra-efficient electrolyzer

Shell Global Solutions International, a subsidiary of Shell, which maintains its U.S. headquarters in Houston, has signed a collaboration agreement with London-based Supercritical Solutions to advance Supercritical’s ultra-efficient hydrogen electrolyzer technology toward a field pilot demonstration.

In the deal, the companies will collaborate on a paid technology feasibility study that will support the evaluation and planning of the pilot demonstration, according to a news release. Supercritical Solutions’ technology aims to deliver high-efficiency renewable hydrogen at a lower cost for the industrial hydrogen market.

"Signing this collaboration agreement with Shell is a major milestone for Supercritical Solutions and an important step on our commercialisation journey,” Luke Tan, co-founder of Supercritical, said in the news release. “We are directly addressing the cost and complexity barriers facing the renewable hydrogen market. We are excited to move forward with a company like Shell, whose global leadership has been proven to accelerate innovative technologies to market.”

Supercritical’s hydrogen electrolyser technology can operate at high temperatures and pressures of up to 220 bar without the need for an external hydrogen compressor, rare-earth materials or easily degradable membranes. The technology removes the typical compression step in the process while delivering hydrogen at industry standards. It requires significantly less energy than many traditional electrolyzers and is more cost-efficient.

This recent investment builds on an ongoing relationship between Shell and Supercritical. Supercritical was founded in 2020 and was runner-up in Shell’s New Energy Challenge, which helps startups and scaleups develop sustainable technologies, in 2021. Shell Ventures then invested in Supercritical’s Series A funding round in 2024 with Toyota Ventures.