Space-Based Geothermal: Lunar and Martian Thermal Energy Systems By: Robert Buluma Space-based geothermal is one of the most compelling ideas in the future of space exploration. It does not mean building a traditional Earth-style geothermal plant on the Moon or Mars. Instead, it refers to using subsurface materials, thermal storage, and planetary heat-management systems to keep off-world bases alive, warm, and operational in extreme environments . On the Moon, the problem is surviving the long lunar night. On Mars, the problem is keeping habitats and equipment warm enough to function in a constant deep-cold environment . The topic sounds futuristic, but the engineering logic is real. NASA and other researchers have already studied lunar regolith as a thermal storage medium, and recent research continues to frame thermal energy architecture as a major part of sustainable lunar habitation [5][2]. For Mars, habitat studies emphasize thermal management as a core requirement, not a side det...
Eavor at the Crossroads: What Geretsried Really Tells Us About the Future of Closed-Loop Geothermal
By Alphaxioms Geothermal Insights | May 13, 2026
For years, Eavor Technologies was the geothermal sector's most talked-about enigma. The company raised hundreds of millions of dollars, attracted backing from heavyweights including BP, Chevron, Helmerich & Payne, and Temasek, and made bold promises about a proprietary closed-loop technology that would quietly revolutionise how humanity extracts heat from the earth. But it rarely said much in public. The secrecy was, to many observers in the geothermal community, a feature rather than a bug — protecting intellectual property, managing competitive intelligence, buying time.
Now, Eavor is talking. And what it is saying is worth listening to very carefully.
In an exclusive interview published on May 13, 2026, by GeoExpro editor Henk Kombrink, Eavor's new president and CEO Mark Fitzgerald — who took the role in October 2025 — acknowledged the key developments surrounding the company's flagship demonstration project in Geretsried, Bavaria. He confirmed that Eavor is stepping away from the operator role at the site, that the project is currently delivering between 0.5 and 1 MWe gross — which means effectively zero net power to the grid — and that the company has pivoted its identity from operator to technology provider. The interview is a landmark moment in the Eavor story, and its implications extend well beyond one drill site in southern Germany.
This article offers a deeper reading of what the Geretsried experience means — for Eavor as a company, for closed-loop geothermal as a technology class, and for the broader geothermal sector's credibility with the financiers and policymakers it needs to survive.
What Actually Happened in Geretsried
To understand the significance of the current situation, it helps to revisit what Geretsried was supposed to be. The project, conceived as a large-scale demonstration of Eavor's proprietary Eavor technology, involved drilling deep injector-producer well pairs and connecting them with horizontal closed loops through which a working fluid would circulate, absorbing heat from surrounding rock and delivering it to the surface — entirely passively, without the need for natural permeability, no hydraulic fracturing, no aquifer interference. The original plan called for four injector-producer pairs, each connected by twelve loops, representing a full commercial-scale deployment.
What was completed was one injector-producer pair with six horizontal loops — half the planned number. Of those six, only three to four are actually contributing meaningfully to flow. Two loops experienced clogging by rock fragments so severe that cleaning operations could not restore them. A third contributes only partially. The plant's current energy output of 0.5 to 1 MWe is gross output. The plant's own operational power demand sits at approximately 0.5 MWe, meaning the project is delivering little to nothing to the grid under most operating conditions.
The plant's thermodynamic efficiency in this configuration is, by Fitzgerald's own admission, around 2%. He projects that efficiency would rise to 14% with a full complement of operational loops — but that full complement does not exist, and there is no confirmed plan or budget to complete it under the current project structure.
The project spent approximately EUR 350 million to reach this point. There is no budget remaining to drill the additional three injector-producer pairs that were part of the original concept. Two drilling rigs remain on site, which Fitzgerald identified as a reason the company is moving urgently to find a new operator — keeping rigs idle is expensive, and the clock is ticking.
This is the operational reality of Geretsried as of May 2026.
The Pivot: From Operator to Technology Provider
Eavor's decision to reframe itself as a technology provider rather than an operator is significant, and deserves analysis beyond the corporate language used to describe it.
The shift is not merely strategic repositioning. It reflects a substantive recognition that building, operating, and owning large geothermal infrastructure at the frontier of a new technology type is a different business from developing the technology itself. The former requires patient capital, operational expertise, regulatory stamina, and community relations management over decades. The latter requires a concentrated focus on IP development, licensing, and partner ecosystems. These are distinct organisational competencies, and Eavor has concluded — after Geretsried — that it is better suited to the second.
Fitzgerald framed this with the line: "We see ourselves as a technology provider, as we believe that other parties may be more capable of the operational side of things." That is a measured way of saying something that the Geretsried experience has made plain: drilling and operating deep closed-loop geothermal wells at scale involves a level of subsurface complexity, operational problem-solving, and site-specific uncertainty that demands a different kind of institutional capability than the one Eavor built during its fundraising and technology development years.
The headcount reduction — from 147 employees to 80 — is consistent with this repositioning. A technology licensing and advisory company does not need the same field operations infrastructure as a project developer and operator. The leaner organisation is presumably being structured around the capabilities needed to support partners who take on operator roles: subsurface modelling, drilling engineering consultation, technology transfer, and project economics support.
The open question is whether there are credible operators willing to take on Geretsried in its current, incomplete state, and on what terms. An operator inheriting a half-built project with two clogged loops, no remaining project budget, and rigs accumulating day rates is inheriting a difficult situation. The commercial terms of any such arrangement will tell us a great deal about the market's actual confidence in the technology.
On the Question of Proof of Concept
Fitzgerald stated — more than once during the interview, according to Kombrink — that Eavor believes it has "proven the concept" and now needs to "prove commerciality." This framing deserves scrutiny.
Kombrink himself pushes back on this reading in his article, and he is right to do so. A proof of concept, in the engineering and investment sense, typically means demonstrating that a system can perform its intended function under real-world conditions at a scale that supports extrapolation to commercial deployment. By that standard, Geretsried has demonstrated several things: that deep closed-loop wells can be drilled in a hard-rock Bavarian subsurface environment, that circulation through the loops can be maintained without external pumping energy, and that drilling efficiency improved with each successive loop — a meaningful learning curve result.
What it has not demonstrated is the ability to deliver meaningful net energy output from a closed-loop geothermal system at any scale relevant to commercial power generation. A plant operating at 2% thermodynamic efficiency and delivering effectively zero net power to the grid, after EUR 350 million in expenditure, has not proven commercial viability. It has proven that the concept is physically real. That is different, and the distinction matters enormously to the DFIs, commercial banks, export credit agencies, and infrastructure investors who would need to finance future projects.
The 14% efficiency figure Fitzgerald cites for a fully operational loop configuration is, for now, a projection based on modelling. It has not been demonstrated. Whether a future project — presumably deeper, in different geology, with a different operator — will validate that projection is the central uncertainty that the market is now evaluating.
Implications for Closed-Loop Geothermal as a Technology Class
Eavor is not alone in the closed-loop geothermal space. Several other technology developers — including Sage Geosystems, which Alphaxioms has covered previously — are pursuing variations on the theme of accessing geothermal heat without relying on naturally permeable hydrothermal reservoirs. The interest in closed-loop and advanced geothermal systems (AGS) reflects a genuine strategic logic: the world's geothermal resources are vastly larger than the subset that is accessible through conventional hydrothermal extraction, and unlocking non-conventional resources would transform geothermal from a niche technology into a mainstream baseload option.
But Geretsried is now the most data-rich real-world test of closed-loop AGS that the industry has, and its results will inevitably shape how the broader category is perceived by investors and project developers. This creates a dual risk. The first is that Geretsried's difficulties lead to an overcorrection — a dismissal of closed-loop approaches based on the performance of one demonstration project in one geological setting. The second is the opposite: that the technology community downplays Geretsried's challenges too quickly, preserving enthusiasm but delaying the hard engineering work needed to actually solve the problems the project exposed.
The clogging of two loops by rock fragments is an instructive failure mode. It points to the difficulty of maintaining open, unobstructed flow pathways through kilometres of horizontal wellbore in fractured crystalline rock — a problem that is not obviously solvable by simply going deeper or drilling more loops. It is the kind of subsurface complexity that only real-world drilling can reveal, and the industry needs to sit with what it reveals rather than move on prematurely.
What Eavor Needs to Do Next
Fitzgerald's stated priorities are clear: find a new Geretsried operator quickly, identify follow-up project sites — potentially in Germany, though not necessarily Hanover given that area's subsurface complexity — and go deeper than the 4.5 km wells at Geretsried to access higher-temperature rock.
Each of these steps involves material execution risk. Finding an operator for Geretsried is a near-term test of whether the market believes in the project's remaining potential. Identifying viable deeper sites requires subsurface characterisation work that takes time and capital. And going deeper introduces a new set of drilling engineering challenges — higher temperatures, greater pressures, longer reach — that the Geretsried experience does not fully de-risk.
The transparency pivot Fitzgerald has initiated is, however, genuinely important and should be sustained. Geothermal is a sector that has historically suffered from a credibility deficit with mainstream capital markets, partly because project data is treated as proprietary and results are difficult to independently verify. Eavor's secrecy in its early years was understandable but ultimately counterproductive — it fuelled scepticism and made it harder for the broader market to form an informed view of the technology. A more open communication posture, including honest discussion of what Geretsried has and has not demonstrated, is the right approach if Eavor genuinely wants to build a durable technology licensing business.
The interview with Kombrink is a start. The test will be whether this openness extends to technical data — actual loop flow rates, temperature profiles, efficiency measurements, and drilling cost breakdowns — that would allow independent engineers and investors to form their own judgements.
The East African Perspective
From Alphaxioms' vantage point, anchored in the geothermal development landscape of the East African Rift Valley, the Eavor story carries specific lessons.
The Rift Valley is endowed with one of the world's most commercially accessible geothermal resources — high-temperature, shallow, proven hydrothermal systems at Olkaria, Menengai, Longonot, and dozens of other prospects across Kenya, Ethiopia, Tanzania, Djibouti, and beyond. These are not closed-loop opportunities. They are conventional hydrothermal resources where the primary barriers to development are not technology but capital access, grid infrastructure, regulatory capacity, and bankability frameworks.
The temptation — which occasionally surfaces in regional geothermal discourse — to leapfrog conventional hydrothermal development in favour of newer, less proven technology types should be resisted. The East African geothermal sector does not need to wait for closed-loop AGS to mature before it can deliver gigawatts of clean baseload power. It needs the financing architecture, institutional capacity, and policy environment to develop the resources it already knows are there.
That said, the Eavor story is instructive for East Africa in a different way. It illustrates the difference between a compelling technology narrative and demonstrated commercial performance — and the importance of insisting on the latter before committing large amounts of capital or institutional credibility to a project. The EUR 350 million spent at Geretsried is a reminder that geothermal development, at any technology frontier, demands rigorous pre-feasibility work, phased investment structures, and honest milestones.
Conclusion: Cautious, But Watching
Eavor's Geretsried experience is neither a vindication nor a death knell for closed-loop geothermal. It is something more useful: a detailed, expensive, and honest lesson in the gap between technological possibility and commercial reality.
Fitzgerald's candour in the Kombrink interview is a sign that the company understands the gravity of the moment. The pivot to technology provider is a rational response to what Geretsried has revealed about Eavor's comparative strengths and limitations. The transparency commitment, if sustained, will serve the company and the sector better than continued opacity.
But the proof of concept claim should be held lightly. What has been proven is that closed-loop circulation in deep hard-rock wells is physically achievable. What has not been proven is that it can be achieved at a cost, scale, and reliability sufficient to compete with other low-carbon baseload options. That proof — if it comes — will require more projects, more data, deeper wells, and the kind of sober, iterative engineering process that the geothermal sector excels at when it is at its best.
Source:GeoExpro
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