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Green Therma Secured Funding for Geothermal Expansion

The startup aims to scale its heat extraction technology with a new capital raise planned through 2027.

Updated on Oct. 4, 2026 in Energy

Bold vector editorial illustration showing a vertical steel pipe extending into layered earth, representing deep-well geothermal energy extraction.
Green Therma has secured Series A funding to expand its deep-well geothermal energy technology, with plans for a major capital raise by 2027. AI Illustration. Upload story photo >

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Green Therma has closed a Series A funding round to advance its geothermal energy technology. The startup plans to launch a capital increase of at least EUR 25 million between fall 2026 and spring 2027.

Why it matters

This fundraising effort supports the scale-up of deep-well geothermal extraction designed to provide long-term heat supplies. The company is currently moving from pilot demonstrations to a full-scale operational project in Denmark.

The system utilizes oil industry piping to circulate water in a closed loop, reaching depths of over three kilometers. This approach was tested in 2024 at the Ullrigg facility.

The players

Green Therma

A geothermal energy startup focused on scaling deep-well heat extraction using oil-industry infrastructure.

Aalborg Varme A/S

A district heating utility that has signed a 30-year supply agreement with Green Therma.

The details

Green Therma uses Heat4Ever technology, a method that adapts oil-field extraction hardware to tap into geothermal heat at significant depths. By circulating water through a closed-loop pipe system, the company draws thermal energy from depths exceeding three kilometers. This process has been tested at pilot sites in Groß Schönebeck, Germany, and Stavanger, Norway, to refine production and installation efficiency.

Timeline

  1. 2023: Green Therma was founded.

  2. 2024: DualVac technology test conducted in Stavanger.

  3. April 2026: Shareholders provided a convertible loan.

  4. Fall 2026 - Spring 2027: Planned capital increase of at least EUR 25 million.

  5. First half 2027: Completion of Aalborg demonstration project.

The Tech Race

Green Therma is shifting from the experimental validation stage conducted at the GFZ Helmholtz Centre for Geosciences to a commercialized delivery model. This transition mirrors efforts across the energy sector to adapt legacy hydrocarbon infrastructure for renewable geothermal output.

The 30-year heat supply agreement signed with Aalborg Varme A/S indicates the long-term utility-scale potential of this technology. Residents in the region are expected to benefit from the operational heat output beginning in 2027.

The takeaway

Green Therma is attempting to prove that oil-industry hardware can reliably sustain large-scale geothermal heat production. Watch the Aalborg project completion in mid-2027 as a key indicator of the technology's readiness for commercial district heating.

What happens next

The company expects to conclude its Aalborg demonstration project in the first half of 2027, with the system reaching full operational status later that year.

Further reading

Learn more about the latest developments in Energy.

Source note: This article includes information reported by Energywatch.

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