The town of Lichtenau near Paderborn has set ambitious goals for climate protection. The core is the climate campus at Lichtenau High school with a comprehensive energy renovation. With the transition to renewable energy supply the renewal of the outer shell, the annual CO2 emissions are to be reduced by around 250 tonnes.
With the installation of the large ice storage tank in October 2021, the town has moved one step closer to this goal. The installation was carried out by the company caldoa GmbH and wassupported by Paderborn-based H. Beckmann GmbH, a regional specialist for regenerative heating and energy technology. Beckmann, in turn, commissioned goodmen energy GmbH to plan the heating and cooling system, including its control.
Latent heat storage system uses the thermal energy during the phase transition from liquid to solid, i.e. when the water freezes into ice. During this process, the so-called heat of crystallization is released and this is considerable in the case of water.It is about the same as cooling water from 80 degrees to 0 degrees and ensuring comparatively smaller storage volumes. A heat pump use this energy for heating and hot water production.
Thus, the ice storage can be considered as a (cold) energy source storage that absorbs excess thermal energy from the building or the environment and returns it to the building when needed - either for heating or cooling.
The system consists of a combination of active and passive components. This ensures that sufficient heat generator or regeneration power is available at all times.
The system components in detail:
- Ice storage: 531 m³ air volume/451 m³ useful volume.
- Recooler for free regeneration, 300 kW
- Air/water heat pump(s), 116 kW total output
- Brine/water heat pump, WQ: ice storage, 188 kW
- System buffer tank 3,000 liters (temperature level 45/35°C)
- System buffer storage tank 3,000 liters (temperature level 35/28°C)
- System control incl. heat sources, regeneration, and consumer management
The system concept enables different operating states such as heating, cooling, and operation for regeneration of the system. The purpose of these different hydraulic circuits is to operate the system efficiently and to maintain system operation without problems even at peak times or during extremely cold periods.
The operating states in detail:
- Heating mode
- Regeneration mode
- Cooling mode
- Natural cooling
- Free cooling
- Active cooling incl. night cooling