Return on investment

Enopsol has designed, planned and implemented more than 30 large-scale ATES and groundwater cooling systems in Denmark and abroad. The capacity of the systems – measured in terms of effect – range from 350 kW to 5,000 kW.

The typical ROI is 4-10 years, depending of the type of system (construction/industry/district heating/hospital) and the conditions at the installation site, including the physical conditions for underground heat and cold storage.

The system’s annual service time also has a significant influence on cost-effectiveness – the longer the service time, the better your financing options. Primary cooling systems will have the shortest ROIs, because groundwater cooling can replace traditional compressor cooling, making it possible to achieve energy savings in excess of 90%.

Primary heating systems, e.g. district heating, will have the longest ROIs, as the energy savings in relation to natural gas heating are approx. 50% at current energy prices.

The following table shows a selection of Enopsol’s solutions distributed according to capacity and ROI rate.






Grundfos- Bjerringbro

1,5 MW cooling

1,8 MW heating

Less than 5 years

Cooling system alone

Turnkey contractor

Widex A/S

2,3 MW cooling

1MW heating

Less than 4 years


Widex is self-sufficient in energy by means of a wind turbine and an ATES-system.

Turnkey contractor

Rambøll HQ

1 MW cooling

500 kW

Less than 4 years


Turnkey contractor

SDU, Kolding

450 kW cooling

500kW heating

Less than 4 years


Turnkey contractor

CPH Lufthavn

5 MW cooling

Less than 6 years

Cooling system alone

Turnkey contractor

Landsbyvarme, ELFORSK

2 MW heating

Less than 10 years

Gl. Annisse og Sdr. Stenderup are model towns.

Turnkey contractor

Gentofte Hospital

650 kW

Ongoing pre-project study


Jægerspris Kraftvarme

1 MW heating

Less than 10 years

Stage 1

Pre-project study

Ejby Fjernvarme

2 MW heating

Less than 10 years

Stage 1

Pre-project study

See calculation examples under Know-how.


An ATES system can be financed by self-financing or by taking out a loan. Financing can also be carried out in stages, see Economics. Further, there are various funding options and special subsidy schemes (read more about subsidies under Funding and subsidies).

Scalable investment

An ATES solution is scalable, which makes it possible to spread out the investment in a system over time. A system can be built in stages that will be fully functional until the system is 100% complete. The initial costs for groundwater surveys, planning, licences etc. typically represent 10-20% of the total investment.

CPH Airport is one of many clients who have opted for the benefits of investment over an extended number of years.

Funding and subsidies

The goal of making Denmark fossil-free within a relatively short timeframe is placing pressure on many businesses and utilities to find alternative solutions that contribute to Denmark’s green profile. These solutions need to be cost-effective – and in the case of utilities, it must be possible to establish them in densely built-up areas or areas where there is no access to a supply network like district heating (greenfield land).

The European Union and national governments have launched various initiatives for financial funding for R&D in green solutions. For more information in Denmark, visit the website of the Danish Energy Agency:

Current funding and subsidy initiatives include:

Energy Technology Development and Demonstration programme (EUDP): (in Danish only).

Other subsidy schemes, see: (in Danish only).

Investment subsidies are available for energy-efficient projects in which existing fossil-based energy systems are converted to renewable energy sources or district heating. This can include conversion of an existing energy system as well as investment in a new boiler system or district heating unit.

Conversion to renewable energy: (in Danish only).

VE til proces (renewable energy subsidy scheme for manufacturing companies): (in Danish only).

Subsidy scheme for energy-intensive companies: (in Danish only).

Click and see cases

CPH Airport installs one of the world’s largest groundwater systems, achieving annual energy savings of DKK 7m.

Rambøll saves 85% on cooling with year-round renewable energy consumption.

Widex A/S: Self-sufficient and 100% CO2 neutral.

Healthclinic in Horsens converted to sustainable energy with effecient groundwaterplant

Hjortebjerg Plant Nursery gets 96% of its heat in winter from underground, saving 60% on its heating bill.

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