Surplus heat from sponge iron to heat Gällivare

One of Sweden's most keenly anticipated industrial projects is being built in Gällivare – Hybrit. The company is building its first demonstration plant for sponge iron production employing a newly developed technology, which should be ready in 2026. Initially, 1.3 million tons of sponge iron will be produced per year. The production will be integrated into the manufacture of iron pellets, the most important element for the production of steel. The main investors are LKAB, Vattenfall and SSAB. The aim is for SSAB's steel production to be fossil-free.

Inhabitants to be relocated
Parallel to one of the country's biggest industrial projects being built in Gällivare, a major change is about to take place in the municipality. To allow LKAB to continue mining, the village of Malmberget with about 1,000 inhabitants is to be relocated to Gällivare, a process that has been gradually taking place in recent years.

"The surplus heat we can get from Hybrit presents us with an enormous opportunity to transform our business. We don't know yet how much surplus heat there will be, but if everything goes as planned it could cover our entire current production," says Erik Karlsson, the CEO of Gällivare Energi.

"If so, we can transform our current production based on biofuels to become a 100% circular district heating system based on fossil-free surplus heat," he adds.

Gällivare Energi has been granted SEK 10 million by Region Norrbotten (the European Regional Development Fund, ERDF) and the Swedish Agency for Economic and Regional Growth to establish what's needed to switch from the current production method by buying industrial surplus heat. The grant will be used to fund studies which will include simulations and tests for the adaptations needed to be able to use surplus heat in the existing district heating system.

Maximum effect
The energy company has also conducted several feasibility studies concerning the surplus heat, involving FVB running network calculations on how the heat can be fed into the district heating network.

"This is an important element to see how they can best handle the surplus heat and the effect can be considerable," says Ulrika Sagebrand at FVB, who was responsible for the study.

"We ran network calculations for a couple of likely scenarios, but in reality, the available output can be higher or lower," she adds.

FVB looked at how the surplus heat can replace a significant amount of current district heating production.

"We don't know how hot the surplus heat will be yet, so we used two scenarios. One with the same supply pipe temperature as now, i.e. max. 110 degrees, and the second with a temperature of max. 90 degrees.
I calculated with 12 MW and 35 MW surplus heat respectively for both scenarios. 35 MW of available surplus heat should cover the entire heat requirement for the network at outdoor temperatures over -5°C and around 70% of the maximum output requirement," says Sagebrand.

The network model, which is for the entire network, i.e. the demonstration plant, all production plant and all customers in Gällivare, was modified to represent the district heating network 10–15 years into the future.

"Regardless of whether we used 12 or 35 MW, 90 to 110 degrees, we could see that a thicker pipe (preliminarily DN 400) will be needed from the demonstration plant at LKAB to the town centre, a stretch of around 5 km. Pressure levels and operational strategy for the distribution pumps will also have an effect."

Important decision-making data
"The results from the calculations will provide important decision-making data for Gällivare Energi when it comes to making strategic investments in its distribution network, and will be a help for budgeting the investments needed for the surplus heat to be piped to district heating customers," says Sagebrand, with support from Erik Karlsson:

"This is a very important feasibility study with the first realistic indications of what will need to be done in our existing district heating system, and it shows that a lot of adaptation will be required," he says.

Gällivare Energi is now going ahead with more in-depth studies on using the surplus heat and how the company can contribute to a sustainable Gällivare. The vision is to show the way for other towns looking to use new sources of energy as a result of the green transition, particularly those towns in the Arctic climate zone.