Heating neighborhood buildings with car parks or tunnels – rts.ch

Surface geothermal energy allows the Earth’s heat to be recovered without drilling. With her team, an EPFL researcher developed panels capable of capturing energy in parking lots or tunnels to redistribute it to buildings in the neighborhood.

No need to dig to recover heat from the earth! The principle of drill-free surface geothermal energy is to capture heat from underground parking lots or subway entrances to heat surrounding buildings.

Unlike a heat pump that recovers energy from the ground, this system uses existing galleries to bring heat to the surface. Concretely, it is a question of installing panels applied against the walls of the cellars to bring out this energy that is constantly renewed. Thus, the use of fossil fuels is reduced thanks to taking advantage of the untapped heating potential of cities.

>> The system heat sensor panels:

The panels absorb geothermal heat from the surrounding ground as well as waste heat present in the surrounding air. [enerdrape.com]

The start-up Enerdrape, founded at EPFL, has developed very light panels that work on the same principle as a geothermal probe: extracting heat from concrete or air, the water is heated inside a closed circuit of tubes. Then a heat pump is supplied to heat the buildings in the district.

The surface of car parks in Europe represents fifty million square meters: this type of solution is therefore far from anecdotal.

An EPFL spin-off

Margaux Peltier completed her studies at the EPFL and carried out academic research with conclusive results, in collaboration with doctor of mechanics Alessandro Rotta Loria and professor Lyesse Laloui. A series of awards led the researcher to turn her studies into an entrepreneurial adventure to prevent “another good university solution from ending up in the drawers”. She is the co-founder and general manager of the company Enedrape which will soon commercialize this invention.

>> Watch “How a parking lot can become a source of energy”:

How a parking lot can become an energy source [RTS]

How a parking lot can become an energy source / Video news / 5 min. / October 20, 2022

The principle may seem simple, but in reality it took nearly eighteen years of fundamental research in the Laboratory of soil mechanics from EPFL behind the development of the prototypes: light panels two centimeters thick, with a complex network of sandwich tubes to heat the water.

What takes time is in fact research, confides Margaux Peltier to the CQFD microphone: “How to obtain this heat without influencing the soil, the concrete. I had to make sure it worked well, especially over time.”

He mentions that it was also necessary to develop tools, namely calculation: “It is a certain knowledge that is learned over the years. Part of the research was done in the laboratory; then, a large part is done between the laboratories and the start-up to develop the product and materialize this technology”. These panels, so light, had to be cost-effective and had to be able to be industrialized.

These very light panels work on the same principle as a geothermal probe: they extract heat from concrete or from the air, which heats water inside a closed circuit of tubes to power a heat pump. [capture d'écran - RTS]These very light panels work on the same principle as a geothermal probe: they extract heat from concrete or from the air, which heats water inside a closed circuit of tubes to power a heat pump. [capture d’écran – RTS]With this type of installation it is possible to gain between 4 and 5 degrees: “It doesn’t seem like much on its own”, acknowledges the scientist, “but normally it is the temperature differential that you gain with a heat pump. heat in the classic probe”.

Provide up to 60% of a building with heating

Pilot projects were developed in other countries: in London, in particular, in the corridors of the Northern Line metro, and in Paris in the 4and rounding with line 1. But it is the old technology that is used: “It was also developed in the laboratory: we were working on this technology by placing the tubes directly in the concrete during construction. The disadvantage is that we can only use it in new constructions”.

What the start-up does can be applied to existing buildings. And it is above all car parks that are at the center of the research team’s attention for the time being, before launching into a specific solution for subway tunnels or even motorways: “The important thing is to be close to consumers”, says Margaux Peltier .

Up to 60% of a building’s heating could come from using this heat from the basement, an energy available all year round, free of charge: “We have this potential under our feet that is not being used, whether due to lack of will or lack of technology . Now, we are increasingly trying to use everything we can, especially at the local level.”

The installation depends on a pump for circulating water, supplied with electricity. But there is no loss, as it produces four to five times more energy than the electricity consumed, according to company analyses.

>> Also listen to “Science qui peut! – Geothermal energy, an underexplored field”:

Science that can! – Geothermal energy, an unexplored field / La Matinale / 2 min. / November 18, 2022

Radio subject: Sophie Iselin

Web Article: Stephanie Jaquet

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