Tapping into the energy stored beneath our cities

Switzerland’s 2050 energy strategy, outlined by the Federal Office of Energy (OFEN), makes one thing clear: urgent action is needed to switch to clean, innovative energy systems. And with the combination of soaring electricity prices, increasingly unreliable domestic power sources, and the federal government’s target of becoming carbon neutral by 2050, Switzerland must take concrete steps to secure its energy supply.

Over 45% of the energy used in Switzerland is for heating and cooling systems in buildings, and more than 60% of this energy comes from fossil fuels (roughly 30% from fuel oil and 25% from natural gas, according to the OFEN). These figures underscore just how important it is to transition to renewable alternatives.

The government has already introduced incentives for incorporating renewable energy into newly constructed buildings, but the real challenge lies in existing ones – and especially those in dense urban areas. That’s where power needs are the highest and the concentration of built surfaces is the greatest. Cities are also where the task is the most complicated for planners, building owners and building operators. The key will be to find add-on systems that can shrink existing structures’ carbon footprint – an objective that’s now more important than ever.

Untapped potential

There’s one clean energy resource that’s abundantly available right under our cities: geothermal energy. But until now the potential of this versatile form of power has been largely untapped. In recent decades, geothermal energy has proven to be both promising and effective when sourced at medium depths, such as with geothermal probes. But other forms of underground energy could also be better exploited.

Researchers at EPFL’s Laboratory of Soil Mechanics have been studying novel ways of accessing underground energy for nearly 20 years, including systems for supplying existing buildings with geothermal power. This research has resulted in technology now marketed by Enerdrape, an EPFL spin-off.

Geothermal panels

The researchers have developed the world’s first geothermal panels, which transform underground heat into power for heating and cooling buildings. The panels can be installed in existing underground structures like tunnels and parking garages to collect geothermal energy. In short, Enerdrape’s technology provides a simple way to bring geothermal energy to the surface without drilling.

Rolled out in 2023

The firm has been testing its panels for the past year in a pilot project in Lausanne. The data show that its system works well. Enerdrape’s founders are now in the final steps of bringing their technology to market and are preparing for an initial funding round, with a view to a large-scale roll out of the panels in 2023. Given the dual energy and climate crisis we’re now facing, it’s high time we started taking advantage of this oft-forgotten energy resource right under our feet.

Margaux Peltier, EPFL civil engineer, CEO of Enerdrape and research assistant at EPFL’s Laboratory of Soil Mechanics

• This article was published late October 2022 in three local dailies – La Côte (Vaud Canton), Le Nouvelliste (Valais Canton) and Arcinfo (Neuchâtel Canton) – under a joint initiative between EPFL and ESH Médias to showcase the R&D being carried out at EPFL on advanced construction techniques.