Giant heat battery takesrachtens hospital off gas

Heat batteries are known on a small and medium scale, in residential homes, community centers and at sports clubs. But the Nij Smellinghe hospital in Drachten shows that they can be applied on a much larger scale. In 2027 they want to be completely off gas and CO2-neutral on energy, thanks to a gigantic heat battery.

The hospital is going to install a PowerStove. That battery converts renewable energy into heat, up to 360 °C, and that energy can be stored for several days or even weeks. As a result, the energy is available when needed. The heat is then used to make steam, which in turn is used for sterilization, pharmacy, kitchen, humidification and peak demands for heat and tap water, among other things. Ultimately, this should lead to savings of 285,000 m3 of gas per year.

Completely off the gas

It is the latest step in making the hospital more sustainable. There are already solar panels on the roofs and solar carports that generate 3 million kWh of energy annually. In addition, the hospital has two Thermal Storage Systems (CHP), insulated facades, a lithium battery and a smart Energy Management System (EMS) that automatically adjusts the use of systems such as charging stations and batteries. The PowerStove is now replacing gas-fired boilers.

"This heat battery supplies steam to our existing infrastructure via a steam generator," says Arno Vredevoort, manager of Technical Management and Maintenance at Nij Smellinghe. "As a result, the gas-fired steam boilers will soon no longer be needed. Only for emergencies will they still be on standby, running on biodiesel. This offers many advantages and is the final step for Nij Smellinghe to go completely off gas."

Nij Smellinghe is going to install two PowerStoves. Each is 8 meters long, 3.5 meters high and 3 meters wide. Preparations for the installation will begin before next summer and by spring 2027 the PowerStoves should be up and running.

How the PowerStove works

The PowerStove is a heat battery that converts locally and sustainably generated energy into heat and then stores it for long periods of time. Green electricity is used to heat thermal oil, which is transferred viaheat exchangers transfer heat to magnetite (iron ore) in a well-insulated container. This allows the battery to retain heat up to 360 degrees Celsius for several days to weeks.

At the Nij Smellinghe, heat will be retained for an average of about three days. When the hospital needs steam, for example for sterilization, pharmacy, kitchen or humidification, this heat will be used to make steam and distributed through the existing infrastructure.

Steam in the hospital

Hospitals use steam for processes that require temperatures above 100 °C. Such as the sterilization departments, the kitchen, the laboratory and in air humidification. Steam kills bacteria and germs on medical instruments and rids them of harmful microorganisms. This is a safe alternative to chemical agents. Steam is also indispensable in the kitchen for preparing meals and cleaning dishes. Furthermore, good humidity in the hospital is important for a healthy working environment and steam is used for that.