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International Conference on Innovative Applied Energy    

E-Proceedings ISBN: 978-1-912532-05-6

St Cross College, University of Oxford, United Kingdom



Swimming baths as “shiftable load”?



Gunther Gehlert, Reiner Schütt and Christian Buchmüller

Westcoast University of Applied Science, Germany


Paper Abstract

Swimming baths often use combined heat and power (CHP) units for heating and electricity generation. If a bath is situated in a region with a high fraction of wind turbines, a CHP would be counterproductive (from a grid point of view) in times of high wind power generation. In Germany therefore, a special law has come into effect in 2017 (§13 6a EnWG*, Germany). This law gives a guaranty that operating an electrical heater (Power-to-heat unit, PtH) instead of the CHP in windy periods will have no negative economic effect to the CHP operator. The grid operator has to refund the cost for the additional installation and the higher operating cost for both the PtH unit and the additional cost for operating the electrical consumers without CHP generation. In this study, the effects of an additional PtH unit for pool heating during high wind periods have been evaluated for a swimming bath in northern Germany. The feasibility in terms of heating constraints, electrical grid integration, economics and law has been evaluated. From a building heating point of view, it has to be made sure that the operation time periods of a PtH fit to grid overload times where load management measures (i.e. shut downs of wind turbines) take place. Consequently, a PtH should be able to being operated for typical overload time periods without “overheating” the swimming pool. From an electrical point of view, the geographical position and the grid infrastructure are a major issues. Moreover, the local load management measures have to be evaluated. Finally, the legal and economical evaluation has to clarify the business potential for both the swimming bath and the grid operator.

It has been found that the thermal integration is relatively simple and a positive effect on the electrical grid is very probable because heat demand of the bath and windy periods are mostly parallel, especially during winter. From a legal point of view (§13 6a EnWG, Germany), only large CHP plants (>500kW) are allowed to participate. Moreover, the same law prohibits a direct profit when operating the PtH unit, i.e. operation of the PtH unit is cost-neutral at best. This leads to the conclusion that this concept has the technical potential to really reduce the number of wind turbine shutdowns on the one hand. But on the other hand, the broad participation of bath operators is questionable due to the legal constraints.


Paper Keywords
Shiftable load, grid load, pool heating, combined heat and power, power to heat, energy revolution, energy transition.
Corresponding author Biography


The International Conference on Innovative Applied Energy (IAPE’18)