Plum Acquisition Corp. IV and Controlled Thermal Resources Outline a Large-Scale Geothermal and Critical Minerals Platform Plum Acquisition Corp. IV (“Plum IV”) and Controlled Thermal Resources Holdings Inc. (“CTR”) are moving toward a proposed business combination that would create a public company focused on one of the most ambitious geothermal and critical minerals developments in the United States. The combined entity is expected to trade on Nasdaq under the pro forma ticker CTRH, reflecting a platform built around clean baseload power, lithium recovery, and broader critical minerals production. The investor presentation dated August 2026 frames the transaction around CTR’s Hell’s Kitchen project in Imperial County, California, which is presented as a strategically positioned resource opportunity with energy, minerals, infrastructure, and permitting advantages. At the center of the presentation is a clear message: this is not just a power project, and it is not j...
The 10 Hottest Geothermal Startups to Watch
By :Robert Buluma
In the second quarter of 2026 alone, a geothermal startup raised nearly $1.9 billion in an IPO, another announced plans for the world’s first commercial pressure geothermal facility, and a third began powering Amazon data centers with AI-discovered wells. After decades as a niche power source confined to volcanic hotspots, geothermal energy is having its breakout moment—and a new generation of startups is leading the charge.
Driven by surging electricity demand from AI data centers, manufacturing reshoring, and electrification, investors are pouring billions into companies that can harness the Earth’s heat anywhere, not just in Iceland or California. The US Department of Energy estimates that next-generation geothermal could supply 100 gigawatts or more domestically—enough to power 75 million homes.
What makes today’s geothermal startups different from their predecessors is technological convergence: fracking techniques from the oil and gas industry, artificial intelligence for exploration, closed-loop systems that eliminate water contamination risks, and even electric pulses that “destroy rock with lightning.”
Here are the ten companies rewriting the rules of clean, firm power.
1. Fervo Energy: The Public Market Bellwether
When Fervo Energy went public on the Nasdaq in May 2026, it wasn’t just a milestone for the company—it was a referendum on next-generation geothermal itself. The Houston-based startup raised $1.89 billion in its IPO, pricing 70 million shares at $27 each, giving it an initial valuation of roughly $7.7 billion. Trading opened at $36, a 33 percent premium, and closed even higher. This was a real signal of confidence for the industry.
Fervo’s technology adapts advanced drilling and hydraulic fracturing techniques from the oil and gas industry to create enhanced geothermal systems (EGS). Unlike traditional geothermal, which requires naturally occurring pockets of hot water, EGS injects water into hot, dry rock formations to create artificial reservoirs. This approach dramatically expands where geothermal can be deployed.
The company’s flagship project, Cape Station in Utah, is under construction with 500 MW of capacity, and first power is expected in late 2026. Fervo has already secured a 15-year power purchase agreement (PPA) with Shell Energy and counts Google among its strategic investors. In a sign of mainstream validation, the company was named one of TIME’s 100 Most Influential Companies of 2025.
Why it matters: Fervo’s public offering proves that Wall Street now sees next-generation geothermal as a scalable, investable asset class—not a science experiment.
2. Eavor Technologies: The Closed-Loop Pioneer
While many geothermal startups focus on fracturing rock, Calgary-based Eavor took a fundamentally different path: a closed-loop system that circulates water through sealed underground pipes, never contacting the surrounding rock. In December 2025, Eavor achieved what no company had done before—delivering commercial electricity to the German grid from its Geretsried facility using its patented Eavor-Loop™ technology.
With Geretsried now on-stream, the company expressed confidence that its closed-loop geothermal system will secure its place as the leading solution for commercial geothermal applications.
The engineering behind Eavor-Loop is ambitious: two vertical wells reaching nearly 2.8 miles below the surface, connected by a dozen horizontal laterals, each 1.8 miles long, resembling the tines of a fork. Once sealed, water circulates through this underground radiator, collecting heat from surrounding rocks without ever needing to be replenished or treated.
The Geretsried facility will supply 8.2 MW of electricity to the grid and 64 MW of district heating to nearby towns. Eavor has secured roughly C$138 million from the Canada Growth Fund and a €91.6 million grant from the EU Innovation Fund to accelerate deployment.
Why it matters: Eavor proved that geothermal can work without the environmental risks associated with hydraulic fracturing, potentially smoothing regulatory pathways in water-scarce or seismically sensitive regions.
3. Quaise Energy: Drilling Beyond Limits
Deep geothermal has always faced a fundamental constraint: existing drill bits soften and fail at extreme depths and temperatures, where the most energy-dense heat resides. Quaise Energy’s solution sounds like science fiction—millimeter-wave drilling, a technology originally developed for nuclear fusion research.
Instead of grinding through rock, Quaise uses high-power gyrotrons to vaporize rock from a distance, creating clean, lined boreholes that remain stable at depths exceeding six miles. In April 2026, the company announced it was on track to build the world’s first power plant using superhot geothermal energy—rock hotter than 300°C—in Oregon. Project Obsidian is expected to deliver at least 50 MW of 24/7 renewable power from only a handful of wells, with commercial operation targeted for 2030.
The goal is to build out to a gigawatt in the area. An analysis presented at the 2026 Stanford Geothermal Workshop validated the company’s projections, confirming that higher subsurface temperatures yield substantial improvements in power density.
The implications are staggering: tapping just 1 percent of the world’s superhot rock resources could supply 63 terawatts of firm, carbon-free power—more than eight times current global electricity generation.
Why it matters: If Quaise succeeds, geothermal could rival the output density of fossil fuel and nuclear plants, potentially unlocking gigawatt-scale clean energy anywhere on the planet.
Most geothermal systems either rely on naturally occurring hot water or create artificial reservoirs through fracturing. Sage Geosystems has pioneered a third approach: Pressure Geothermal™, which taps into the Earth’s natural pressure to create a fully engineered underground reservoir that expands and contracts like a mechanical spring.
In January 2026, Sage closed a $97 million Series B round led by Ormat Technologies and Carbon Direct Capital to deploy the world’s first commercial Pressure Geothermal facility. The facility will be built at an existing Ormat power plant, dramatically accelerating the path to market.
The technology works by injecting water into hot, dry rock formations. The water heats up and pressurizes, and when released, drives turbines to generate electricity. Because the system leverages the Earth’s natural elasticity, it also functions as a long-duration energy storage solution—a crucial capability for grids integrating intermittent solar and wind.
Pressure Geothermal is designed to be commercial, scalable, and deployable almost anywhere. It unlocks over 130 times more geothermal resource potential in the US alone compared to conventional methods.
Why it matters: Sage pairs power generation with energy storage in a single system, addressing two of the biggest challenges in renewable energy simultaneously.
5. Mazama Energy: Chasing Superhot
At Newberry Volcano in Oregon, one startup is pursuing what might be the most aggressive temperature target in the geothermal industry. Mazama Energy, incubated by Khosla Ventures and backed by Gates Frontier, announced in October 2025 that it had created the world’s hottest Enhanced Geothermal System at a bottomhole temperature of 331°C. The company expects to reach 400°C in 2026.
Why does temperature matter? Every 100°C increase roughly doubles power output per well. Harnessing superhot resources—300–450°C—allows Mazama to extract up to 10 times more power density, use 75 percent less water, and drill 80 percent fewer wells than current approaches.
The company has already completed and stimulated a 10,200-foot deviated producer well, achieving optimal alignment with its injector well within six feet of the planned trajectory. Initial circulation tests confirm excellent connectivity between the wells.
Mazama is targeting a 15 MW commercial pilot in 2026, scaling to a 200 MW development at Newberry, with long-term aspirations to reach 400°C and beyond. The economics are compelling: the company aims to deliver electricity at less than 5 cents per kilowatt-hour, competitive with natural gas.
Why it matters: Mazama is pushing the thermal limits of what geothermal can achieve. If superhot EGS proves commercially viable, it could transform the economics of clean firm power overnight.
6. Zanskar: AI That Sees What Geologists Miss
Exploration has always been geothermal’s Achilles’ heel. Conventional methods rely on surface clues—hot springs, geysers, fumaroles—that reveal only a fraction of viable resources. The vast majority of geothermal potential lies hidden beneath the surface, invisible to traditional prospecting. Zanskar is solving this problem with AI.
The Utah-based startup has built a machine learning platform that analyzes publicly available geologic data, satellite imagery, and seismic surveys to identify “blind” geothermal resources—sites with no surface expression. In the past year, Zanskar has made multiple discoveries across the Western United States, validating its AI-native approach.
The results have been staggering. In January 2026, Zanskar raised a $115 million Series C round led by Spring Lane Capital, followed by an additional $40 million development capital facility designed to scale to $100 million. Then, in May 2026, the company signed a 20-year PPA to supply 100 MW of geothermal power to NV Energy, which will power Amazon data centers in the Reno area—the tech giant’s first geothermal-powered data center.
Zanskar is also leveraging California’s GEODE program to locate new resources in partnership with community aggregators. The company now controls a multi-gigawatt pipeline of discovered sites.
Geothermal is one of the few energy sources uniquely positioned to deliver affordable, around-the-clock power.
Why it matters: Zanskar is systematically de-risking geothermal exploration, transforming a historically speculative process into a data-driven discipline. This could be the key to unlocking gigawatt-scale development.
7. GA Drilling: Reinventing the Drill Bit
Before any geothermal plant can generate power, someone has to drill a hole—and deep drilling is punishingly expensive, accounting for up to 70 percent of project costs. Traditional rotary drilling struggles in hard, abrasive rock, with drill bits that wear out quickly and replacement trips that consume weeks of rig time.
GA Drilling has developed NexTitan, a downhole anchoring and drive system that delivers up to 30,000 lbf of axial thrust directly at the drill bit while supporting continuous circulation. Unlike conventional drilling, where torque is transmitted from the surface through a long string of pipe, NexTitan places the power source at the bottom of the hole, enabling deeper, more efficient penetration through formations that historically made deep drilling uneconomical.
In March 2026, GA Drilling secured a $44.1 million investment led by TomEnterprise, the platform of former EQT CEO Thomas von Koch, with participation from a major global drilling contractor. The funding followed a successful field deployment at the NORCE Research facility in Norway, where NexTitan delivered a validated output of 32,000 lbf under real downhole conditions.
This investment gives the company the capital and momentum to accelerate commercial deployment at scale. NexTitan is designed to significantly reduce drilling costs, and these funds allow GA Drilling to prove that with real-world customer data across multiple geographies.
Why it matters: GA Drilling isn’t reinventing geothermal—it’s reinventing the fundamental economics of reaching deep heat. Lower drilling costs could unlock projects that were previously financially impossible.
8. Telura: Destroying Rock With Lightning
In Munich, a startup that exited stealth in March 2026 is pursuing an even more radical approach to drilling. Telura has developed electric impulse drilling (EID), which applies high-voltage electrical pulses to break rock from within—essentially, destroying rock with lightning.
Traditional mechanical drilling grinds through rock with rotating bits, generating enormous heat, wear, and downtime. EID creates plasma channels inside the rock, causing it to fracture along natural grain boundaries with minimal mechanical contact. The result: drilling up to 10 times faster, with dramatically reduced wear and energy consumption.
Telura emerged from stealth with a $5 million pre-seed round from Nucleus Capital, Possible Ventures, and First Momentum, following over two decades of foundational research at Germany’s top technical universities. The technology integrates with existing drilling systems, which sets the company up to move fast, with the first market entry in 2026.
The company is now validating the technology under real-world conditions in partnership with SPRIND, the German federal agency for leap innovations. Given that drilling accounts for up to 70 percent of geothermal project costs, a 10x improvement in speed and cost could fundamentally reshape the industry’s economics.
Why it matters: Telura’s approach eliminates the mechanical limitations that constrain conventional drilling. If successful, deep geothermal could become economically viable almost anywhere on Earth.
What if geothermal didn’t require water at all? That’s the question Rodatherm set out to answer. Operating in stealth since 2022, the Calgary and Salt Lake City-based startup has developed a closed-loop system that uses refrigerants instead of water as the working fluid. The result is a system that requires five times less fluid volume than conventional water-based binary-cycle plants while achieving 50 percent higher thermal efficiency.
In September 2025, Rodatherm closed an oversubscribed $38 million Series A round—the largest first venture raise for a geothermal startup in history—led by Evok Innovations and including TDK Ventures, Toyota Ventures, and the Grantham Foundation.
Rodatherm’s system is fully cased, pressurized, and optimized for hot sedimentary basins. The refrigerant-based fluid circulates through a closed loop, absorbing heat from the surrounding rock and directly driving a power-generating turbine. Because the system is sealed, there is no risk of fluid loss or groundwater contamination, and the operating life spans decades with minimal maintenance.
The company is now building a pilot system in Utah that will validate the design at commercial scale before expanding to a full 100 MW facility at the same site. Rodatherm expects to achieve levelized costs of energy competitive with fossil fuels at early project scale.
Why it matters: By eliminating water consumption entirely, Rodatherm could deploy geothermal in arid regions where traditional plants are infeasible—including vast areas of the American Southwest, the Middle East, and Australia.
10. Bedrock Energy: Geothermal for Buildings
While most geothermal startups target utility-scale power generation, Bedrock Energy is focused on a different market: heating and cooling buildings. Space heating and cooling account for roughly 39 percent of building-related carbon emissions, and traditional ground-source heat pumps remain too expensive and disruptive for widespread adoption. Bedrock’s proprietary drilling technology and subsurface simulation software aim to change that.
The Austin-based startup has developed a sensor package and two-way communication system that allows for drilling up to eight times faster in difficult conditions, dramatically reducing installation costs. Bedrock has raised over $25 million in capital from investors including Cantos Ventures and Energy Impact Partners.
The company’s technology integrates with existing drilling systems, which allows for fast deployment. Bedrock’s space-efficient borehole fields are designed to make geothermal heating and cooling accessible to homeowners, businesses, and infrastructure developers in any city.
Rather than chasing deep, high-temperature resources, Bedrock targets shallow geothermal—depths of a few hundred feet—where the Earth maintains a stable year-round temperature. By making ground-source heat pumps faster and cheaper to install, the company could accelerate the electrification of heating and cooling in residential and commercial buildings.
Why it matters: Bedrock addresses the overlooked “other half” of energy consumption: thermal loads. If geothermal heating and cooling become cost-competitive with natural gas, the impact on building emissions could be transformative.
The Bottom Line
Taken together, these ten companies represent a fundamental rethinking of what geothermal energy can be. Fervo has proven the financial markets are ready. Eavor delivered the first commercial closed-loop electrons. Zanskar showed that AI can find hidden resources. Telura and GA Drilling are attacking drilling costs from opposite angles—one with electricity, one with mechanical innovation. Quaise and Mazama are chasing the superhot frontier where power densities rival fossil fuels. Sage is pairing generation with storage. Rodatherm is eliminating water constraints. And Bedrock is bringing geothermal to the built environment.
The common thread is technological convergence. Oil and gas drilling techniques, AI, advanced materials, and plasma physics are being applied to geothermal in ways that were impossible a decade ago. The result is an industry transitioning from niche to mainstream—and these ten startups are leading the way.
Source: This article was written by Robert Buluma with insights from Alphaxioms
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