In Innsbruck, the dream of using the excess heat produced by the city’s power transformer became reality in early 2017. For several years, the local energy services provider, IKB (Innsbrucker Kommunalbetriebe), had identified the power transformer as an attractive opportunity to provide heat with zero additional CO2 emissions.
In its quest towards waste heat recovery, IKB has thus started looking for innovative and efficient solutions to make this project happen in the framework of the SINFONIA Smart City Initiative. No solution had been implemented so far in Innsbruck to capture the excess of heat produced by the transformer, but IKB experts conducted a series of simulation studies to identify and select the most secure and efficient option.
Which solutions did partners use to capture the excess heat?
“At the beginning, we were considering to use the heat released by the oil circuit cooling the transformer,” explains Marco Casotti, Innovation Manager at IKB, “but in practice, this solution would have been difficult to implement”. The next idea of the IKB team was to extract the transformer’s convection heat from the indoor air and use it as a heating system through air-to-water heat pumps.
After the successful implementation of this system and to multiply its efficiency, project partners decided to use the ambient heat from the external air as an additional source of thermal energy. To achieve this objective, a smart monitoring system for the multi-leaf dampers controlling the airstreams between external air and waste heat from the transformer was installed and connected to the heating system of the IKB offices located nearby.
Of course, such a solution is only suitable if a heat consumer is located in the same area as the transformer. If this is the case, the potential for energy savings is significant.
Caveats and results
But there is an important caveat. “As a primary condition to replicate this innovative heating system, engineers and specialists have to make sure that this will not lead to overheating and efficiency losses in the transformer operation, mainly for safety reasons,” advises Bernhard Hupfauf, head of department at IKB. In Innsbruck, this has been secured thanks to an active collaboration with actors from the electricity sector and through preliminary tests on the transformer.
After two months of monitoring, the results have already exceeded expectations: the new heat recovery system met 80% of IKB Headquarters’ heating demand, rather than the predicted 50%.
Encouraged by this success, the IKB is now working on the deployment of a Smart District in the Rossau area, where all buildings’ heating and electricity systems will be connected together in a smart way.