The German port city of Hamburg has concluded the trial phase of a massive subterranean aquifer heat storage system, which is supposed to replace a coal plant and which can provide heat to 8,000 households in winter, Julia Witte writes in Die Welt. “Hamburg’s largest thermos flask”, as the aquifer is dubbed jokingly, can absorb about 160 million kilowatt hours of heat in water that has been heated to 80 degrees Celsius and then pumped back into the ground to preserve the temperature, she writes. With investment costs of about six million euros, “a subterranean storage is much cheaper than insulated tanks above the ground”. Storing heat is one of the Energiewende’s greatest challenges, Witte explains, adding that the moderate heat loss of about twelve percent on average provides grounds for optimism that aquifers can indeed offer a solution.
Find more information in the CLEW dossier Cities, municipalities and the Energiewende.