Green Therma

What Green Therma does

Green Therma ApS is a Danish clean energy company founded in 2023 that has developed the Heat4Ever™ closed-loop deep geothermal heat extraction system based on its patented DualVac™ vacuum-insulated pipe-in-pipe technology. The system circulates water through a single sealed deep horizontal well at 3-4 km depth, absorbing heat from surrounding rock at 90-150°C and delivering it to the surface with minimal heat loss via continuous vacuum insulation. Each well produces 2-4 MW of thermal energy — enough to heat approximately 1,500 households — with a designed operational lifespan of 50+ years and minimal maintenance, since the oxygen-free closed-loop architecture prevents corrosion and avoids contact with groundwater.

The company serves district heating utilities and industrial heat consumers (80-120°C applications including greenhouses, breweries, hospitals, universities, and industrial parks) seeking baseload renewable heat that is independent of weather, seasonal variation, and specific geological reservoir conditions. Its primary commercial anchor is the Aalborg Forsyning demonstration project — a 100+ MDKK investment structured under a 30-year heat supply agreement that is expected to deliver approximately 2 MW to roughly 1,000 households from 2027. Additional pipeline activity includes signed Letters of Intent with Stadtwerke Wismar GmbH (Germany, May 2026) and Geothermie Rupertiwinkel GmbH (Bavaria, March 2026), and a technical demonstration with GFZ Helmholtz-Zentrum für Geoforschung at Gross Schönebeck (Germany) to validate DualVac performance at depths exceeding 3 km.

Commercialization is executed through enterprise direct sales to utilities, supported by a strategic business network of six major oilfield services and energy equipment partners — SLB, Baker Hughes, Halliburton, KCA Deutag (now part of Helmerich & Payne), Nabors, and Tenaris — which collectively provide global drilling rigs, well construction, directional drilling expertise, digital drilling technology, and tubular manufacturing for Heat4Ever deployments. Revenue streams include long-term heat supply agreements, technology licensing and project development, and recurring monitoring and optimization services over multi-decade asset lives. The company is privately held, headquartered in Copenhagen, with subsidiary Green Therma GmbH in Hamburg and additional offices in Stavanger (Norway) and Frisco, Texas (USA). Revenue is not publicly disclosed and the company is pre-revenue with first commercial heat delivery scheduled for 2027.

Name

Green Therma

Legal name

Green Therma ApS

Website

https://greentherma.com

Company type

Private

Founded year

2023

Operating status

Operating

Headcount range

11–50 employees

Short description

Green Therma ApS (Denmark, founded 2023) developed the Heat4Ever™ closed-loop geothermal system and patented DualVac™ vacuum-insulated pipe technology to extract renewable heat from 3-4 km depth for district heating utilities and industrial consumers, with first commercial delivery scheduled for 2027.

Ownership category

akta.pro rank

Product category

Geothermal Heat Services

NAICS

Geothermal Electric Power Generation (221116), Power Boiler and Heat Exchanger Manufacturing (33241), Heating Equipment (except Warm Air Furnaces) Manufacturing (333414), Steam and Air-Conditioning Supply (221330)

SIC

Oil & Gas Field Services, Nec (1389), Cogeneration Services & Small Power Producers (4991), Heating Equipment, Except Electric & Warm Air Furnaces (3433)

akta.pro primary industry

Closed-Loop Geothermal Power Generation (Advanced Geothermal Systems) (EUACAHAE)

akta.pro secondary industries

Geothermal Equipment & Component Manufacturing (Turbines, Heat Exchangers, Pumps, ORC Units) (EUAMAEAI), Geothermal Power Plant Development & IPP (Permitting, Financing, Project Development) (EUAMAEAD), Geothermal Drilling & Well Construction (Production/Injection, Directional, Well Services) (EUAMAEAB), Geothermal Grid Integration & Power Offtake (Interconnection, PPAs, Ancillary Services) (EUAMAEAK)

Keywords

• Closed-loop geothermal
• District heating solutions
• Renewable heat supply
• Deep geothermal wells
• Vacuum pipe technology

Headquarters

HQ city

Copenhagen

HQ country

Denmark

HQ region

Europe

Offices4 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Technology or R&D, Infrastructure, Operations, Personnel, Marketing or Sales

Revenue model

1. Heat Supply Agreements: Long-term heat supply contracts (e.g., 30-year agreement with Aalborg Forsyning) providing stable, predictable cash flows from renewable heat delivery to district heating networks
2. Technology Licensing and Project Development: Providing Heat4Ever technology, DualVac systems, and integrated project delivery to utility companies, industrial customers, and project developers globally through strategic partnerships
3. Geothermal Monitoring and Optimization Services: Ongoing monitoring and optimization services helping operators maximize yield and ensure efficient, stable operation over decades

Go-to-market motion1 record

Distribution channels6 records

Marketing channels5 records

Core offering

Green Therma develops and deploys the Heat4Ever™ closed-loop geothermal solution, which uses a patented single deep horizontal well and DualVac™ vacuum-insulated pipe technology to extract renewable heat from 3-4 km depth at 90-150°C without requiring permeable geological reservoirs. The company delivers full-scale geothermal projects to district heating utilities and industrial heat consumers through strategic oilfield services partnerships, and provides ongoing monitoring and optimization services plus long-term heat supply agreements (such as the 30-year contract with Aalborg Forsyning).

Product overview

Green Therma offers a unified product portfolio centered on the Heat4Ever™ closed-loop geothermal solution, which combines the proprietary DualVac™ vacuum pipe technology with topside facilities and digital systems. The Heat4Ever solution uses a single deep horizontal well (approximately 4 km vertical, 2-3 km horizontal sections) to extract geothermal heat from 90-150°C rock formations without geological reservoir dependencies. The DualVac technology provides continuous vacuum insulation to minimize heat loss during transport. Green Therma also provides ongoing monitoring and optimization services to ensure efficient long-term operation. The solution is designed for district heating networks and industrial applications requiring 80-120°C temperatures, producing 2-4 MW per well (equivalent to approximately 1,500 households).

Differentiator

Problem solved

Functional benefit

Products and services

• Heat4Ever™ Closed-Loop Geothermal Solution Patented closed-loop geothermal solution that uses a single deep horizontal well (~4 km vertical and 2-3 km horizontal sections) to extract renewable heat from 90-150°C rock formations at 3-4 km depth. The system circulates water in a completely closed pipe without contacting the subsurface, delivering 2-4 MW per well — enough to heat approximately 1,500 households — for district heating networks and industrial consumers.
• DualVac™ Vacuum Pipe-in-Pipe Technology Patented single-well dual pipe technology providing continuous vacuum insulation along the entire pipe system, separating cold and hot fluid like a thermos flask to minimize heat loss and maximize energy production during transport from >3 km depth. Integral to Heat4Ever and available for technology licensing and integration into customer projects.
• Geothermal Monitoring and Optimization Services Ongoing data-driven monitoring and optimization services that help operators maximize geothermal yield and ensure efficient, stable operation over decades. Combines digital systems with operational expertise across the asset lifecycle.

Quantifiable outcome

• 2-4 MW heat output per single well, enough for approximately 1,500 households
• +3 more outcomes

Named customers3 records

Segments3 records

Ideal customer profiles3 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature3 records

Partnerships

13 partnerships are on record, tiered minor and core.

• Stadtwerke Wismar GmbHminorStrategic or Co-development Partner · 12 May 2026Letter of Intent signed May 2026 to jointly assess potential for deploying geothermal heating solution in Wismar, Germany. Project will begin with pre-feasibility study including geological screening and technical evaluation before considering full feasibility study.
• TenariscoreStrategic or Co-development Partner · 11 May 2026Strategic partnership announced May 2026 combining Green Therma's Heat4Ever solution with Tenaris's global expertise in tubular manufacturing, TenarisHydril premium connections, and well services. Collaboration aims to advance next-generation closed-loop geothermal systems across Europe with a full European supply chain to reduce reliance on imported energy and strengthen Europe's energy independence.
• Geothermie Rupertiwinkel GmbHminorStrategic or Co-development Partner · 24 March 2026Letter of Intent signed March 2026 to explore feasibility of deploying Heat4Ever closed-loop technology in Rupertiwinkel geothermal area, Bavaria, Germany. Initial phase focuses on feasibility assessment including geological analysis and heat demand evaluation.
• Aalborg ForsyningcoreStrategic or Co-development Partner · 29 January 2025First Heat4Ever demonstration project partnership. Aalborg Forsyning provides site at Industrivej 12G in Storvorde and purchases heat through 30-year agreement. Green Therma invests, establishes, and operates the ~2 MW plant. Project cost 100+ MDKK with completion expected 2027.
• KCA Deutag (now Helmerich & Payne)coreStrategic or Co-development Partner · 20 March 2024Strategic collaboration with KCA Deutag and SLB to deliver Heat4Ever wells to public and private clients. KCA Deutag delivers drilling rig and associated services, supported by Kenera business unit for rig technologies and digital services. First project is full-scale demonstration with horizontal well at ~3.5 km depth.
• SLBcoreStrategic or Co-development Partner · 30 August 2023Strategic alliance to develop and provide Heat4Ever closed-loop geothermal well solution worldwide. SLB provides well design, drilling expertise, digital drilling solutions, well construction services and monitoring equipment for pilot and commercial wells. First milestone was drilling a complete pilot well in Denmark in 2024.
• NaborscoreStrategic or Co-development Partner · 2 March 2023Collaboration for drilling deep horizontal wells enabling geothermal production with Heat4Ever. Nabors provides advisory planning, drilling expertise and operational experience. Valuable experience from extensive horizontal well drilling in USA and Middle East ensures safe and efficient completion of future Heat4Ever wells.
• Baker HughescoreStrategic or Co-development PartnerStrategic collaboration agreement for access to Heat4Ever solution with DualVac technology and joint development of relevant geothermal projects globally. Leverages Baker Hughes expertise in energy technology development.
• HalliburtoncoreStrategic or Co-development PartnerAgreement for Heat4Ever solution access with DualVac technology and collaboration on geothermal project development globally. Halliburton's 70 years of geothermal experience helps reduce risks, increase efficiency, and maximize asset value throughout the geothermal well lifecycle.
• GFZ Helmholtz-Zentrum für GeoforschungcoreStrategic or Co-development PartnerCollaboration on DualVac technology demonstration project at Gross Schönebeck research facility in Germany. GFZ provides geothermal expertise and advanced test facilities. Project tests vacuum insulation at >3 km depth and validates system performance under various operating conditions over one year.
• Aarhus UniversityminorStrategic or Co-development PartnerProject partner conducting geological studies supporting development, implementation, and commercialization of new geothermal solution for Aalborg demonstration project.
• GEUS (Geological Survey of Denmark and Greenland)minorStrategic or Co-development PartnerProject partner conducting seismic surveys and developing geological models providing crucial knowledge for drilling operations at Aalborg demonstration site.
• Energy Cluster DenmarkminorStrategic or Co-development PartnerProject partner managing funding compliance, reporting, networking, and dissemination for Aalborg demonstration project.

Scale indicators7 records

Recent moves6 records

Expansion highlights9 records

Emerging players

• Fervo Energy: US-based enhanced geothermal systems (EGS) company using horizontal drilling and fracking techniques adapted from oil & gas. Targets both geothermal power and direct-use heat; comparable in addressing scalable deep geothermal but uses a different (reservoir-based) technical approach.
• Sage Geosystems: US-based deep geothermal developer focused on closed-loop and near-closed-loop systems for baseload power and heat. Directly comparable in targeting dispatchable geothermal heat/power independent of geological conditions.
• Vulcan Energy Resources: Germany/Australia-based developer of deep geothermal heat and lithium extraction projects in the Upper Rhine Valley, supplying low-carbon heat to industrial customers. Comparable as a European deep geothermal heat provider targeting decarbonization of industrial and district heating demand.
• AltaRock Energy: US-based enhanced geothermal systems developer pursuing commercial-scale EGS for baseload renewable power. Comparable in targeting scalable deep geothermal independent of natural hydrothermal resources, though US-focused.

Broad incumbents

• Enefit: Estonian state-owned energy company developing oil shale-to-heat and deep geothermal projects for district heating in the Baltics. Comparable in district heating decarbonization focus and Northern European operating geography.
• Ormat Technologies: Established global leader in conventional geothermal power generation with manufacturing of binary and flash power plants. Comparable as a public-market reference for geothermal project economics and scale, but operates in conventional hydrothermal rather than closed-loop systems.

Direct peers

• Eavor Technologies: Canadian closed-loop geothermal developer using a multilateral well design (Eavor-Loop) to extract heat from deep rock without requiring hydraulic fracturing or permeable reservoirs. Most directly comparable to Green Therma's Heat4Ever in technology approach and target market of district heating.
• Baseload Capital: Swedish investment firm dedicated to financing and developing deep geothermal projects globally, with portfolio companies using both EGS and closed-loop designs. Comparable as a capital and project development partner active in the same European district heating segment.

Regional players

• Reykjavik Geothermal: Iceland-based developer of high-temperature geothermal power and direct-use heat projects in East Africa, Asia, and Central America. Comparable as a project developer in deep geothermal, though primarily focused on conventional high-resource areas.

Others

• Seequent (Bentley Subsurface): Subsurface software and modeling provider widely used in geothermal and oil & gas projects. Comparable as an enabling technology supplier supporting geothermal reservoir engineering, drilling, and wellfield design — adjacent ecosystem player.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks7 records

Key highlights7 records

Customer concentration

• YouTubeyoutube.com/playlist?list=PL_wJ6Y6DlzkJ-mUphbHSklhzgprH4FAVT
• LinkedInlinkedin.com/company/green-therma-well-company

Revenue estimate

Valuation estimate

Number of profiles

Profiles8 records

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Green Therma