The heat given off by car engines warms up underground car parks in such a way that the heat passes through the ground into the groundwater. In Berlin alone, enough energy is transferred to the groundwater to supply 14,660 households with heat. This finding was made by a team from Martin Luther University Halle-Wittenberg (MLU), the Karlsruhe Institute of Technology, and the University of Basel. According to the researchers, this warming could have long-term effects on groundwater quality. In their study, published in the journal "Science of The Total Environment", they also propose a solution. Using geothermal energy and heat pumps, the heat could be extracted from the ground and utilised.
The researchers examined temperatures in 31 underground car parks in various cities throughout Germany, Austria and Switzerland. In six of them, they were also able to measure the temperature of the groundwater in the immediate vicinity. This allowed a heat profile to be created for all locations. Their investigations showed that underground car parks heat up the groundwater throughout the year. The volume of traffic in the underground car parks, their proximity to the groundwater and ambient groundwater temperatures were the biggest influencing factors. "Public underground car parks heat up the groundwater more than private facilities as they are often deeper and the cars park there for shorter periods of time," explains Maximilian Noethen, a geoscientist from MLU.
Read more at Martin-Luther-Universität Halle-Wittenberg
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