Ten blue and white striped posters appear to serve as billboards in a parking lot in Sébeillon, Lausanne. They make no noise and give a little color to the concrete. If we look more closely, we see that they are attached to metal plates connected by pipes and sensors. The message they convey relates to the heat from underground parking garages that can be recovered in a sustainable way to heat a building. And for good reason: they are basically a state-of-the-art example of surface geothermal energy without drilling, provided by an EPFL spin-off, Enerdrape.
In the energy transition, these panels are the prototypes of a “new tool in the toolbox” of the energy mix, according to Margaux Peltier, the director of Enerdrape met on site. They can contribute up to 60% to heating a home, or to cool it in the summer, and are used in basements, by installing solar panels underground, for a marginal extra cost that is almost free, depending on the company.
A solution that enhances energy autonomy
Their potential and their explosive simplicity earned Enerdrape the Prix SUD, organized by Weather and transferred on May 5, and should make it possible to raise 2 million francs this year to enter a marketing phase, the company hopes. The increase in the price of hydrocarbons and the lack of security of supply in this area make this renewable solution, which enhances energy autonomy, all the more interesting.
“Our panels work on the same principle as a geothermal probe: they extract heat from the concrete or the air, which heats the water in a closed circuit of pipes that pass through them and feed a heat pump, but without drilling because we do not get energy from the depths,” explains the director. The water thus gains an average of 5 degrees, enough to get a good return from the heat pump.
It all started in the EPFL Soil Mechanics Laboratory, with academic research with convincing results, led by Margaux Peltier, the doctor of mechanics Alessandro Rotta Loria and professor Lyesse Laloui. A series of awards prompted the former to turn these studies into an entrepreneurial adventure to prevent “another good university solution from ending up in the drawer”, she says. The Frenchwoman took entrepreneurship courses, developed a prototype, fell behind due to the pandemic. Enerdrape Sàrl – an Anglicism that mingles energy and curtains (curtain) – was nevertheless registered in the Vaud Trade Register in the spring of 2021, took on the first employees in the summer and benefits from a patent license from EPFL.
“Our solution complements intermittent energy sources,” says Margaux Peltier. It does not compete with solar panels, because they are not placed on the roofs, and produces the same amount of energy day and night, because in the cellars the heat is constant. It competes with gas, which is more powerful but more polluting and costs more in the long run.”
The efficiency of the system depends on the building benefiting from it: 1 m2 of panel will be less than 2 m . to heat2 surface area if old and poorly insulated, but 5 m2 if it meets the latest standards. The installation depends on a pump for the circulation of the water, which, however, produces 4 to 5 times more energy than the electricity consumed.
“I really like the idea of exploiting the energy potential of underground buildings,” says Eric Plan, secretary general of the organization CleantechAlps and member of the Prix SUD jury. “Geothermal energy is today the bad relationship of the energy transition and Enerdrape’s technology makes it possible to put it back into the debate,” he notes.
The start-up has found a subcontractor in Italy who can produce its slates in large quantities. They are lighter than their photovoltaic cousins, free of rare metals and easy to install. Enerdrape wants to expand its sales team, is looking for installers to use its panels and is consulting with the first customers at home and abroad. The market is huge, according to Enerdrape, who estimates the surface area of underground car parks in Europe at 50 million m².
“Enerdrape has an innovative approach and great potential. Every start-up remains at risk for the first few years because there are many limits such as time, human and financial resources. But Enerdrape has a good alignment between project teams and the market, which is important to continue to consolidate to realize its potential,” says Caroline Coquerel, an Innosuisse accredited coach, who guides Enerdrape.
Enerdrape is now working on lighter panels, 8 kg compared to more than 15 for those of Sébeillon, while optimizing the yields of the installations and the connections to the heat pumps, in particular by placing the panels closer together.
“The challenges of mitigating climate change are huge, but seeing the solutions emerge encourages me to be confident,” says Margaux Peltier. “Nevertheless, we need to accelerate their deployment, and fast,” she concludes.