Cornelia Steiner, 21 October 2020
The project MUSE deals with managing urban shallow geothermal energy in urban areas. It investigates resources of shallow geothermal energy in 14 pilot area cities in Europe. Knowledge about the temperature regime of the underground is essential to calculate the energy content, that is available for heating and cooling with for example groundwater heat exchangers. These systems mainly use shallow groundwater bodies.
The temperature in shallow depths down to around 20 m strongly depends on the surface temperatures (see figure 1). In urban areas they are generally higher than in rural areas due to human activities. Surface sealing, little vegetation and waste heat cause this widely known urban heat island (UHI) effect, which causes also increasing underground temperatures. Underground installations such as sewage systems, district heating pipes, basements, tunnels and geothermal energy systems are additional heat sources (see figure 2), that amplify this underground UHI effect. A quantification of these heat fluxes into the underground is unfortunately rather complex and until now afflicted with many uncertainties. But it is possible to measure the resulting groundwater temperatures, which are higher in urban areas compared to the sourrounding rural areas. Mean annual groundwater temperatures of above more than 20 °C are not uncommon anymore in European cities.
Groundwater heat exchangers are a mixed blessing in areas with already strongly increased groundwater temperatures. If used predominatley for cooling they further heat up the groundwater. However, if cooling dominates, the system withdraws heat from the groundwater and therefore helps to reduce the underground UHI. A dense monitoring network for groundwater temperatures in cities is important to detect underground UHIs and to take counteractive measures in advance.
The underground UHI is an integral part of MUSE. By elaborating groundwater temperature maps based on field measurements, we identify areas with elevated groundwater temperatures. Furthermore, we suggest management strategies for a sustainable and efficient use of shallow geothermal energy in urban areas.
Other MUSE Posts:
- MUSE – Open-loop systems requirements & advantages
- MUSE – Web-based information systems for shallow geothermal energy
- MUSE – Closed-loop systems requirements & advantages
- MUSE results published in Energy Policy
- MUSE – Differences between deep and shallow geothermal energy
- Legal framework, procedures and policies of shallow geothermal energy use in the EU and MUSE partner countries
- BBC article about MUSE activities in Cardiff
- Pilot area activities – #14 Assessment of shallow geothermal energy resources in Warsaw agglomeration, Poland
- Pilot area activities – #13 Geophysical survey and groundwater monitoring in Brussels, Belgium
- MUSE at “EGU2020: Sharing Geoscience Online” – Free online geoscience conference
- Pilot area activities – #12 Thermal groundwater use in the urbanized area of Zagreb, Croatia