Use of lake water for heat pump technology

The employer center "Centre Patronal" is a Swiss employer organization based in Lausanne. The city is located on Lake Geneva in the French-speaking Swiss canton of Vaud. To take a step closer to CO₂-neutrality, they invested in a promising environmental technology. By using the deep water of Lake Geneva, it is now possible to heat and cool in an environmentally friendly way. AGRU Kunststofftechnik supplied suitable pipelines made of the high-quality 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 bottom of the lake. 

The operating principle of using lake water is easy to explain: using a heat pump, energy is extracted 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, reducing the energy required for heating by up to 50%. Lakes and large rivers constitute gigantic heat reservoirs that have hardly been utilized to date. Even a frozen lake can provide environmentally friendly heating energy in the middle of winter. The principle of the heat pump can also be used for cooling, making energy-hungry air-conditioning systems completely unnecessary.

Lake Geneva is located on the border between Switzerland and France. It is the largest lake in both countries. Its deepest point, 310 meters, is in front of the city of Lausanne. The Patron Employment Center is located here. It is investing in a new facility that uses Lake Geneva water to cool and heat the building. To this end, 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 linear meters of AGRULINE pipes with an outer diameter of 500 mm in SDR 11 for the construction work, which will run from September 2020 to March 2021. 

The company Hydrokarst Swiss, tasked with the installation, welded AGRU-supplied pipe bars into inlet and outlet pipes in the Rhône delta, France's most water-rich river. AGRU supplied impressive special components, such as 6-meter-high pressed bends, characterized by very low flow resistance. The ready-made pipeline was fitted with concrete ballast and pulled to the site over a distance of 20 km on the water surface. To avoid kinking, special divers lowered the pipelines in an S-shaped arc to a depth of 80 m. There, the water temperature is very low all year round, almost constantly between 4° and 8° Celsius, which is ideal for heat pump operation. 

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