Lake water utilisation for heat pump technology

The employers' centre "Centre Patronal" is a Swiss employers' organisation based in Lausanne. The city is located on Lake Geneva in the French-speaking Swiss canton of Vaud. In order to come a step closer to CO2 neutrality, they invested in a promising environmental technology. By using the deep water from Lake Geneva, it is now possible to heat and cool in an environmentally friendly way. AGRU Kunststofftechnik supplied suitable pipelines made of the high-performance plastic PE 100-RC for the use of lake water. Professional divers from the Swiss company Hydrokarst Swiss installed the pipeline and lowered it to the lake bed.

AGRU supplied sweep bends for the seawater intake pipe.
AGRU supplied sweep bends for the seawater intake pipe. Picture: Hydrokarst Swiss

Vers le haut

The principle of using seawater is easy to explain: a heat pump is used to extract energy from the water, which is raised to a higher, usable temperature level through compression. In the process, a multiple of the electrical power used for the heat pump is generated as heat and the energy required for heating is reduced by up to 50 %. Lakes and large rivers provide gigantic heat reservoirs that have hardly been used to date. Even a frozen lake can provide environmentally friendly heating energy in the depths of winter. The principle of the heat pump can also be used for cooling, thus completely eliminating the need for power-hungry air-conditioning systems.

Lake Geneva is located on the border between Switzerland and France. It is the largest lake in both countries. Its deepest point, 310 m, is in front of the city of Lausanne. The Centre Patronal employer centre is located here. It is investing in a new facility that uses the water of Lake Geneva to cool and heat the building. For this purpose, deep water is drawn in, heated or cooled with heat pump technology and returned to the lake after use. AGRU supplied a total of 800 running metres of AGRULINE piping systems with external diameters of 500 mm in SDR 11 for the construction work, which was completed in March 2021.

The company Hydrokarst Swiss, which was commissioned with the installation, welded the pipes supplied by AGRU into inlet and outlet pipes in the delta of the Rhone, France's most water-rich river. AGRU supplied impressive special parts, such as 6 m high sweep bends, which are characterised by very low flow resistance. The ready-assembled pipeline was provided with concrete ballast and pulled over a distance of 20 km to the site on the water surface. In order to avoid kinks, the special divers lowered the pipelines in an S-shaped curve down to a depth of 80 m. There, the temperature is almost constant between 4° and 8° Celsius all year round, which is ideal for operating a heat pump.

Markus Ebster, Head of BU XXL Piping Systems tells: "The competition for this exciting project was great, AGRU scored with quality, engineering and technical support during planning and realisation. Even before the start, we were able to convince the planner of the advantages of our solid-wall extruded plastic pipe solution compared to the originally planned GRP pipes. The end of fossil fuels is foreseeable, AGRU supplies the technology made of engineering plastic for a climate-neutral energy supply."

The pre-assembled pipeline was towed 20 km across Lake Geneva to the site.
The pre-assembled pipeline was towed 20 km across Lake Geneva to the site. Picture: Hydrokarst Swiss
The pipeline was carefully flooded and lowered to a depth of 80 m in an S-shaped curve.
The pipeline was carefully flooded and lowered to a depth of 80 m in an S-shaped curve. Picture: Hydrokarst Swiss

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