The wood chip heating system has been running at almost double capacity since the beginning of January. In addition to the residential and industrial buildings already connected, BWB now also obtains sustainable thermal energy from regional Nidwalden wood. The energy obtained is used both for heating buildings and for energy-intensive production processes, which means that the use of fossil fuels can be largely reduced.
"The combustion capacity of the woodchip heating system is a decisive factor," explains René Niederberger, project manager in the BWB maintenance team, who is also part of the Dallenwil Uertekorporation.
"The BWB's high-temperature baths require a flow temperature of at least 105 degrees. The permissible temperature range is very narrow, which is why the exact coordination of the heat supply is a key technical challenge," says René, explaining the energy requirements of the anodizing plant.
Technical highlights and challenges
The return heat from the first energy transfer is efficiently reused. It supplies additional bathing facilities and is used to heat the entire building complex at a lower temperature level. Excess heat is temporarily stored in a stratified storage tank on the north side of the BWB. The energy from the photovoltaic system and the waste heat from the compressed air systems is also integrated into the overall system there.
A key advantage of the heating network is the staggered use of energy. BWB's production facilities are preheated from midnight onwards, which means that peak loads can be used in a targeted manner and energy requirements can be continuously reduced throughout the day. The company's own oil heating system remains available as a redundant backup system and can be used both for internal operations and for the entire heating network if required.
As the link between the two organizations, René Niederberger is supporting the project from a technical and operational perspective: "For Uerte, the expansion means optimal utilization of the energy infrastructure. For BWB, the integration into the heating network represents another important milestone on the way to the gradual decarbonization of its production processes."
Internal exchange of expertise
Verantwortliche für Unterhalt und Energiemanagement aller BWB-Standorte verschaffen sich ein Bild des Wärmeverbunds.
Those responsible for maintenance and energy management at the BWB sites were able to gain an impression of the heating network at the open day. René Niederberger gave a guided tour of the facilities, and the exchange stimulated exciting discussions on energy efficiency and decarbonization.
Questions and answers for René Niederberger
Nur wenige Grad Spielraum: Die präzise Abstimmung der Wärmeeinstellungen sichert einen reibungslosen Produktionsablauf.
What is "decarbonization"? Have our goals now been achieved?
René: For us, decarbonization means gradually reducing CO₂ emissions by replacing fossil fuels in our production and building systems. With the connection to the heat network, we normally achieve completely fossil-free operation of the anodizing plant and heating of the building.
Our goals in this area have therefore largely been achieved. In other areas, particularly in logistics and upstream processes, we are still dependent on fossil fuels. Decarbonization is therefore an ongoing process for us and is not yet complete.
Where does the wood for the heating network come from?
René: The wood comes from Nidwalden's protected forests, which are maintained by the regional corporations and, among other things, protect the slopes that are prone to landslides. The wood is stored at regional collection points, processed into woodchippings on site and delivered directly to the heating networks. This results in short transportation routes, renewable raw materials and a closed regional energy cycle.
How does the stratified storage system work at BWB and what is crucial?
René: The stratified storage tank serves as a thermal energy store in which heat is stored temporarily at different temperature levels. The decisive factor here is the stable temperature stratification: hot water collects in the upper area, cooler water remains in the lower area.
The slim, vertical design of the storage tank supports this clear separation of the temperature layers. At the same time, it is important to avoid flow turbulence, as this would destroy the stratification and reduce the usable energy quality.
A continuous and even energy input - both from the wood chip heating system, the photovoltaic system and the waste heat from the compressed air systems - ensures that the temperature zones remain stable and that the heat can be supplied to the various consumers in the system as required.
What was the biggest challenge during implementation?
René: One of the challenges was the upstream needs analysis. We had to critically scrutinize our existing operational framework and, in some cases, consciously change it.
The switch to an external heating network requires technical adjustments on both the supply and demand side, for example in terms of control technology, temperature windows and operating and start-up times. At the same time, it means a paradigm shift: away from a purely internal energy supply towards a networked system based on coordination, flexibility and joint optimization.
And what happens next?
René: In the next step, the system will run through a complete seasonal cycle for the first time under the new framework conditions. As woodchip heating requires more lead time than oil heating, the focus is on the forward-looking coordination of heat supply and demand.
Especially in the transitional periods between winter and summer operation, the control and temperature ranges are further fine-tuned to ensure stable and efficient operation over the long term.
