Preparing district heating for year-round reliability

1st September 2023
News District heating

During the summer, when the need for heat is at its lowest, we prepare the district heating plants for the peak season. We do this so that our customers have access to secure and reliable heat, all year round. This not only secures our energy supply to residents, but also contributes to the robustness of industries and communities in the places where we operate.

– The work is significant in ensuring that we can deliver heat and hot water, which entire communities rely on, says Alessandro Canu, Production Manager, Sweden.

Every year, we carry out extensive audit work to repair boilers and improve our operational reliability. The work is carefully planned, and the implementation is often intensive, yet the work is something that often goes unnoticed by customers. During an audit work, the heat supply to industries and residents is rarely affected, even if the plant has meanwhile been both equipped and secured for future challenges.

The boilers are turned off for a short period

A revision stop is usually a stop in the operation of a boiler in order to repair parts that cannot be done while it is in operation. This usually occurs during a short period, where several planned repairs are carried out in parallel. Throughout the year, components of the district heating boiler wear out, some of which are critical for the boiler to function.

– We need our boilers around the clock, all year round. Therefore, our audit shutdowns are carefully planned to have as short stops as possible, says Canu.

Backup boilers temporarily support to secure heat

Most of our plants have a backup boiler that remains inactive for the majority of the year, but which can be used as a backup when the main boiler is not in operation or in need of extra capacity. During the few weeks when the maintenance work is ongoing, the backup boiler operates at full capacity to continue supplying heat and hot water to the extent needed.

In Hudiksvall, however, a more unusual technique is used. There we have an underground storage facility, which can be used to provide the community with heat while we have audit stops. This underground storage function as a large battery where energy is stored and can be used when it is needed most. When the storage is full, it is enough to cover Hudiksvall’s heating needs for an entire month. The underground storage facility replaces peak and reserve boilers, and both increases electricity production in Hudiksvall and reduces production costs.





Inside the 25-meter-high underground storage facility in Hudiksvall, Sweden, energy is stored for year-round use. Photo: Lars Sundin





The underground storage extends the time margin for both maintenance work and operational disturbances, as the main boiler shutdowns become less critical. Through carefully executed maintenance work of our facilities, we can not only secure the supply of heat but also reduce the number of interruptions in the district heating supply.

Continuous improvements to shorten stops

Maintenance work mainly takes place during the summer. The reason for this is that the heat demand is less in the summer, and therefore, the shutdowns have less impact on both the operations and customers less. An audit shutdown rarely lasts more than 2-3 weeks, but during this time our staff work intensively.

– After the audit work is completed, we immediately plan for next year’s work. We aim to improve and get faster every time, while ensuring that we don’t need to have more disturbances later in the year, Canu concludes.


Read more:

District heating for housing and premises

Robust and sustainable heating in Säffle

Why Renewable & Recycled energy sources?