Germany Geothermal Joint Venture: Badenova and Herrenknecht Launch Deep Geothermal District Heating Project in Hartheim, Upper Rhine Graben

Next Geration for the Energy Transition: Badenova and Herrenknecht Launch a Geothermal Joint Venture in Hartheim

Deep geothermal is moving from niche to necessity in Europe, and the new joint venture between Badenova and Herrenknecht in Hartheim, Germany, is a powerful signal of where the heat transition is heading.For utilities, industrials, and investors tracking the geothermal decade, this project is a live example of how capital, drilling technology, and policy can align to turn subsurface heat into bankable infrastructure.

Alphaxioms: Why Hartheim Matters for the Geothermal Decade

At Alphaxioms, we focus on geothermal projects that change the trajectory of markets, not just add another asset to the map.Hartheim stands out because it combines a regional utility with a global drilling technology champion in one joint venture, in one of Europe’s most promising geothermal corridors – the southern Upper Rhine Graben.

This region already hosts active exploration campaigns and permits, including badenovaWÄRMEPLUS’ 207 km² exploration license in Lahr and Ortenau‑Süd, where medium‑depth reservoirs around 1,200–1,400 m and 50–60°C have been identified. That geological context shifts Hartheim from risky frontier exploration to a targeted expansion of a developing “heat basin” where data, experience, and infrastructure can compound over time.

The expected investment of roughly EUR 60 million for drilling, surface facilities, and grid integration places Hartheim squarely in the mid‑scale heat infrastructure category: large enough to attract institutional capital, accessible enough for municipal and regional partners. In Alphaxioms terms, Hartheim is a testbed for replicable geothermal heat portfolios rather than a one‑off demonstration.

Badenova’s Geothermal Strategy: From Permits to Heat Portfolios

Badenova has been quietly building a geothermal strategy for years through its subsidiary badenovaWÄRMEPLUS, which holds exploration permits in Lahr and across the Ortenau‑Süd area.[6] These permits authorize systematic geoscientific work – seismic surveys, temperature profiling, and reservoir analysis – across multiple municipalities, laying the foundation for a regional heat portfolio instead of isolated wells.

For a regional utility, that is a strategic pivot. Geothermal is not just a diversification line; it can become a backbone of district heating, municipal building supply, and industrial process heat. With medium‑depth resources suited to direct‑use heating rather than power generation, Badenova is targeting exactly the segment of the energy system that has been hardest to decarbonize: heat.

Projects like Hartheim align closely with Germany’s emerging policy frameworks, including risk‑sharing and low‑interest loan structures now being deployed to unlock deep geothermal for district heating.[3] As Alphaxioms has highlighted for other German sites, once a utility builds confidence with one successful project, subsequent wells and networks can be rolled out faster, creating a cluster effect and a pipeline of investable assets.

Herrenknecht’s Evolution: From Drilling Supplier to Geothermal Partner

Herrenknecht is best known for tunnel boring machines, but the company has spent over two decades developing specialist rigs and systems for deep drilling via Herrenknecht Vertical.In recent years, it has clearly shifted from “equipment provider” to “strategic geothermal player.”

A key milestone was Herrenknecht’s majority acquisition of H. Anger’s Söhne, a drilling contractor with a strong track record in demanding deep geothermal wells. This move effectively integrated hardware and field operations, giving Herrenknecht control over both the rigs and the crews that deliver projects in complex geology.

Herrenknecht has also partnered with other geothermal innovators, such as Arverne Group in France, to launch DrillDeep – a business focused on deep geothermal services across Europe with hydro‑electric, low‑impact drilling concepts. Combined with the European Geothermal Innovation Award in 2026, these steps mark Herrenknecht as a technology leader and innovation driver in Europe’s deep geothermal sector.

The Hartheim joint venture is therefore a natural extension of this strategy: Herrenknecht is stepping into the role of co‑developer and long‑term project partner, not just a supplier.For investors reading Alphaxioms, that matters – industrial partners taking equity alongside utilities are a strong signal of confidence in the underlying asset class.

Subsurface Risk and Technical Execution: Why Hartheim Is Bankable

Every geothermal project lives under the shadow of subsurface risk. In Hartheim, Badenova and Herrenknecht are not starting from zero; they are leveraging years of data and experience gathered in the wider Upper Rhine Graben.Exploration around Lahr and Ortenau‑Süd has already identified favorable temperature profiles and reservoir conditions for medium‑depth heat projects, narrowing uncertainty around achievable flows and temperatures.

Herrenknecht Vertical’s rigs are designed for automated, high‑precision deep drilling, with advanced casing, circulation, and safety systems tailored to geothermal wells. Through H. Anger’s Söhne, Herrenknecht has direct access to operational teams that have drilled and completed challenging geothermal wells at depths up to 7,000 m, including projects that required careful handling of pressure, chemistry, and seismicity concerns.

In parallel, European experience in the Upper Rhine and nearby regions – including French‑German joint ventures drilling deep wells for district heating – provides valuable analogues. Those projects have shown that, with robust seismic imaging, careful stimulation design, and transparent community engagement, deep geothermal can be deployed in populated regions with controlled risk.

Image: Proven geothermal potential in the Upper Rhine Graben. The trench structure characterized by fault zones (black lines) is characteristic here. ©

This combination – favorable geology, proven rigs, experienced crews, and a growing body of comparable projects – is why Hartheim is more likely to be seen by banks and infrastructure funds as a bankable geothermal heat asset rather than an experimental attempt.

Heat Infrastructure, Not Just Energy: The Hartheim Investment Case

Alphaxioms looks at geothermal through an infrastructure lens, and Hartheim fits that profile. The EUR 60 million budget is expected to cover drilling and completion of production and injection wells, surface heat‑exchange and pumping systems, and integration into district and local heat networks.

Revenue is primarily heat‑based: long‑term offtake agreements with municipalities, public buildings, and industrial clients looking for reliable, price‑stable, low‑carbon heat.With geothermal, once the wells are drilled and reservoirs are confirmed, operating costs are low and largely independent of fuel markets, making cash flows more predictable than those tied to volatile gas or biomass supply.

The joint venture structure enhances this investment case. Badenova brings local customer relationships, regulatory navigation, and network planning expertise. Herrenknecht contributes drilling technology, operational excellence, and innovation capacity.Together, they create a vertically integrated development stack: from subsurface imaging and drilling to surface systems and heat offtake.

For investors, this looks like a classic baseload infrastructure asset with strong industrial backing, clear alignment to national and EU decarbonization policies, and a credible pathway to replication across multiple sites.

Policy, Finance, and the European Heat Transition

Hartheim lands in a policy environment that is increasingly favorable to geothermal, particularly for district heating. Germany has launched financing instruments that blend low‑interest loans with drilling risk coverage, explicitly designed to unlock deep geothermal projects for municipalities and utilities.This sort of framework is exactly what developers and financiers have been asking for: shared risk on the most uncertain phase (drilling) and stable long‑term conditions once heat production is established.

At the European level, awards and recognition for drilling innovation, such as the European Geothermal Innovation Award, signal that policymakers and industry bodies see technology as the key to scaling geothermal.Innovations in compact rigs, advanced drilling methods, and real‑time subsurface monitoring make projects like Hartheim safer, cheaper, and more suitable in urban or semi‑urban settings.

Badenova’s broader explorations in Ortenau‑Süd and Lahr fit neatly into this landscape, positioning the utility to link multiple geothermal sites into a regional heat strategy.When paired with risk‑sharing finance structures, a supportive regulatory environment, and strong industrial partnerships, such strategies can shift geothermal from “interesting pilot” to “mainstream heat backbone” for whole regions.

What Hartheim Signals for the Geothermal Market

From Alphaxioms’ vantage point, Hartheim sends three clear signals to the geothermal market.

First, industrial champions like Herrenknecht are no longer content to sit on the sidelines; they are stepping into co‑development and JV roles, putting their balance sheets and reputations behind projects. That’s a major confidence boost for investors worried about execution risk.

Second, regional utilities can and will treat geothermal as infrastructure, not just an optional pilot. Badenova’s portfolio of permits and its willingness to engage in JVs shows a pathway for other Stadtwerke and regional utilities across Germany and Europe.

Third, the Upper Rhine Graben is steadily emerging as one of Europe’s key geothermal corridors, with projects ranging from district heating tests in Graben‑Neudorf to deep demonstration wells and now Hartheim’s JV.At Alphaxioms, we see this as a classic basin play: once a few anchor projects succeed, investment and expertise cluster, and the pipeline of projects grows rapidly.

Looking Ahead: Replication, Portfolios, and the Geothermal Decade

If Hartheim delivers technically and commercially, it will likely be the first in a chain of geothermal heat projects that Badenova and Herrenknecht can replicate across the Upper Rhine Graben. The existing permits around Lahr and Ortenau‑Süd provide a natural pipeline of potential sites, each with evolving data sets and community relationships.

Future business models could extend beyond simple heat sales. As more cities commit to net‑zero, geothermal hubs may be combined with seasonal storage, low‑temperature networks (“thermonets”), and hybrid systems that integrate waste heat, solar thermal, or CHP.Herrenknecht’s ongoing work on advanced drilling and monitoring systems suggests that costs and risks can be steadily reduced, unlocking more sites and expanding the geography where geothermal is bankable.

From an investor’s perspective, the most interesting opportunity is portfolio creation. A cluster of successfully developed geothermal heat assets in the Upper Rhine Graben could be bundled, refinanced, and potentially securitized, creating a new category of green infrastructure products.Hartheim, in that sense, is not just a project; it is a potential cornerstone in a future geothermal portfolio.

At Alphaxioms, we see the Badenova–Herrenknecht joint venture in Hartheim as a pivotal proof point for Europe’s geothermal decade: a real‑world partnership that turns deep subsurface heat into long‑term, low‑carbon infrastructure. For energy professionals, utilities, and investors, this is a story worth following from the first seismic trucks to the moment the first households and industries in Hartheim switch to geothermal heat.

 Source: Schwarzwaeld