The Largest Green Energy Source in the World


mirrors 30 years of research and innovation in the field of geothermal energy

We are project partners for a self-sufficient, truly decentral, scalable and environmentally friendly geothermal energy supply, with experience from over 400 realized Open Downhole Heat Exchangers (ODHE). The spectrum of our customers ranges from energy suppliers and municipalities to industrial and commercial enterprises or real estate companies.


sets new standards in geothermal energy

In contrast to conventional petrothermal or closed loop systems, we generate energy by using the natural water saturation of the earth’s crust (pore water). This is achieved by using a unique, semi-permeable piping system. And unlike hydrothermal geothermal energy, we do not need aquifers, which eliminates the need for expensive up-front seismic exploration. No exploration risk and thus no risk of failure.

The ODHE system

New standards in geothermal energy

HI ENERGY‘s well-design is made up of Open Downhole Heat Exchanger (ODHE) single wells, into which several outer pipes and a center returnpipe are inserted. Cold water is fed into the outer pipes where it flows downwards, absorbing heat by conduction in the process.

The innovation: the downward pipes are furnished with a smart array of tiny openings and the space between the pipes is filled with a substrate for flow resistance. This allows a gentle molecular flow of water (and exchange of heat) between the circulating water in the pipes and the porewater in the surrounding rock where consequently convective heat transport is being activated. Differences in temperature and pressure between the water circulating in the well and the pore water contained in the rock are the triggers for the activation of this gentle movement surrounding the well. A circulation speed of the pore water in the range of 1-2 millimeter per day is sufficient to transport the increased amounts of energy. We call this the PCF effect (Petro Calor Fluxus).

Important: There is no exchange of water between the water in the pipes and the surrounding porewater and no additional pressure is applied.

The combined effect of convection + conduction multiplies the energy density in the system. At the bottom of the system, the heated water is being fed into the insulated centerpipe where it is transported back to the surface and run through heat exchangers for heating and cooling applications and/or feed turbines to generate electricity.

The ODHE’s PCF effect thus ensures that heat is transferred from large to small areas or volumes without any reduction in the amount of heat. This compression of the heat flow by means of conduction and convection significantly increases the energy density.

This thermodynamic influence on the pore water has been proven in over 30 years of measurements on numerous wells in operation. Our own measurements on existing plants have been confirmed by independent scientific measurements and expert opinions dating back to 2005. Results from scientific long-term simulation calculations by professors at the University of Heidelberg form the basis for accurately calculating any planned well in any rock formation at practically any location in the world with regards to continuous energy output.

The potential of the ODHE Concept

A study on the potential of hydrothermal geothermal energy for power generation in Germany, by the Geothermal Alliance of Bavaria from 2017 concludes:

“On the theoretical potential, major changes occur. Paschen et al. (2003) put the hydrothermal share of the total theoretical potential at only 5%. This means that 95 % of the heat that can be used for power generation in Germany cannot be tapped with hydrothermal geothermal energy, but with an approach which utilizes the saturation of the crust. This would result in a 20-fold higher technical potential, assuming constant boundary conditions.1

1 Potential of hydrothermal geothermal energy for electricity generation in Germany by the Geothermal Alliance Bavaria, 2017 Authors: Eerer, Sebastian ; Schifflechner, Christopher ; Hofbauer, Sebastian ; Wieland, Christoph ; Zosseder, Kai ; Bauer, Wolfgang ; Baumann, Thomas ; Heberle, Florian ; Hackl, Christoph ; Irl, Matthäus ; Spliethoff, Hartmut.

The above conclusions confirm our PCF concept: to provide reliable heat, power and green hydrogen and securing scalability without risk at any location in the world for generations to come. All this with a process that is not only Co2-neutral, but Co2-free.

The advantages

Reliable and risk free

ODHE systems are extremely stable, reliable and without loss of performance over decades. Only pure water is used as a medium, so no chemicals or other additives are used as with closed loop systems. Heat pumps specifically designed for this technology and particular application deliver an annual performance factor (COP) of 5, with no performance losses during operation. ODHE systems deliver performance in a more reliable manner than any comparable geothermal system on the market.

Revolutionizing deep geothermal energy – forever!

If we were to harness just a fraction of the Earth’s interior heat, our global energy problems would be solved forever. This is because the continental crust, typically about 35 km thick, consists largely of solid, hot, water-saturated rock. A gigantic, natural and inexhaustible energy source right at our feet!

Electricity, district heating, green hydrogen

Conventional geothermal technology requires fractures in the rock, or it pressurizes underground water deposits to extract thermal energy. The disadvantages: Often too little thermal water, or undesirable earthquakes caused by artificially creating fractures in the rock. Closed-loop systems need to reach the bedrock or apply chemicals at lesser depths.

We, on the other hand, can apply ODHE with PCF effect almost anywhere on the planet: To drive turbines to generate electricity, to provide district heating, or to produce green hydrogen.

Changing the landscape

ODHE-Powerplants need little space and due to their construction can be gently integrated into the area where energy is required. Especially for district heating of local heating grids, the powerplant can be elegantly integrated in urban developments, saving space and protection nature as well as making energy an experience for all.

Some attributes surrounding the PCF-Effect of our ODHE Concept

In deep drilling, the rock formations in question play the decisive role in terms of permeability and thermal conductivity. They determine how deep a well must be drilled based on the specified power requirements (thermal and/or electrical). The thermal conductivity of the rock around the borehole and the temperature difference between rock temperature and circulation temperature in the borehole determine the strength of the PCF effect. The well-known physical principle of communicating tubes ensures a uniform circulation of water (cold falls, heat rises) that is largely self-sustaining. The hot water rises from the lowest point of the borehole in an inner tube, releases its energy at the surface to heat exchangers for district heating or turbines for power generation, and is then returned. Unlike conventional methods, our system is minimally invasive, meaning geological faults are eliminated, and with them negative effects such as earthquakes or subsidence.

Possible locations: Anywhere!

Aside from areas around active volcanic zones, rock heat can be extracted for heat and power at virtually any point on earth. Decentralized energy supply becomes standard with the ODHE System.

Running times for generations

Thanks to the closed cycle, the system is hardly subject to wear and tear. A scientific report confirms a useful life of well over 100 years.

Minimally invasive in every respect

The well itself is virtually invisible. In the case of larger systems in the megawatt range, the system for generating energy is about the size of a tennis court. No CO2 is emitted during operation, nor are any other pollutants produced. The use of resources to produce the well is minimal compared to the long-term yield.

Finally independent!

We have calculated it: Approximately 70.000 deep boreholes would be enough to make Germany completely energy independent. That would be the green future with secure, inexhaustible and environmentally friendly energy that we all want.


A small minimum distance between our boreholes, as well as a choice of drilling depth depending on the energy demand, allow power plants with capacities in the megawatt range to be built and operated without any problems, even on a small area.

Pilot project in the Alps

In the municipality of Vahrn near Bressanone/Brixen (South Tyrol), the construction of the world’s first ODHE-Powerplant with a single-hole deep drilling is planned on the basis of completed approval procedure for the drilling. Essential preliminary work has already been carried out. This plant will supply the city of Bressanone and parts of the surrounding area with district heating, and is also designed to generate up to 20 million kilowatt hours of electricity.

Contact us

We will gladly inform you about the advantages and solutions of our highly efficient geothermal technology.


Gartenstrasse 2
6302 Zug ZG

Tel.: +41 (0) 41 728 7865
E-Mail: officeAThi-energyDOTch


Jens Bernecker, Kai Sachsenberg, Dirk Ueberfeld, Marcus Heider, Hans Augschöll


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