Geothermal probes in the ETH Zurich anergy grid
Geothermal probes, which extend up to 200 meters into the ground, absorb heat in the summer and release it again in the winter. Six geothermal probe fields are part of ETH Zurich’s anergy grid on the Hönggerberg campus. Intelligent networking of heat sources and sinks, in combination with seasonal shifting, significantly reduce the need for fossil fuels and the associated carbon dioxide emissions.
ETH Zurich’s Hönggerberg campus is a proper city district with over 12,000 students and employees. They study, work and live in more than 30 buildings and use almost 77 gigawatt hours of energy (electricity and heat) per year, of which around 22 gigawatt hours are used for heating alone. Until 10 years ago, natural gas was used almost exclusively for heating. In 2006 ETH Zurich set the goal to reduce its CO2 emissions by at least 80% by 2040, or 8,000 tons of CO2 per year.
The anergy grid, which is in operation since 2013, is a dynamic underground storage system with intelligent networking of heat sources and sinks in combination with a seasonal shifting. It will help lower fossil energy demand and thus CO2 emissions. In 2018, the anergy grid already covered 81% of useful heating demand and 87% of useful cooling demand. In the final expansion stage, the anergy grid will provide a large part of the heating and cooling of Hönggerberg campus. Possible external consumers (e.g. residential building) and sources of waste heat (e.g. a new data center) can be integrated into the energy concept after prior inspection. With the planned expansions, the total cooling demand will most likely exceed 25 gigawatt hours in the year 2024 and will further approximate the absolute heating demand. Such a starting point is ideal for dynamically operated networks or areas and confirms the selected and pursued strategy.