FVB - Experts & Thought Leaders

In Västerås, Mälarenergi is building Europe’s largest hot water reservoir in a rock cavern. The reservoir will hold 300,000 cubic meters of water, which can cover the district heating requirements in the city for up to two weeks. FVB has been commissioned by Energiforsk to conduct a technical follow-up of the reservoir.  Clean-up The rock cavern was formerly an emergency reservoir for fuel oil but was shut down in 1985. It is being turned into a huge hot water reservoir. However, first, all the old oil must be cleaned up. As there was more oil left than expected, the clean-up has been difficult, and the work has taken longer than expected.  rock cavern The rock cavern consists of three spaces that can be controlled individually" “The rock cavern consists of three spaces that are similar to three huge accumulator tanks that can be controlled individually,” explains Ulrika Sagebrand at FVB, who is leading the research project.  “We will perform measurements in one of the rock caverns because we expect the other rock caverns to behave in a similar way,” she continues. temperature gauge An important part of the project involves investigating how the temperature stratification of the water behaves. They will therefore install a temperature gauge at each meter and since the rock cavern is 25 meters deep, there will be a total of 25 temperature gauges. There is a service tunnel above the rock caverns where personnel from Mälarenergi can access equipment and the hot water is fed in and out. There is also an instrument in the service tunnel that measures how much water there is in the rock cavern, its temperature, and more. multiple sensors “We do not have any such service tunnel over our measuring site, and this will be a challenge for us, so we will attach multiple sensors to a line with a sinker, which will keep them anchored to the bottom of the rock cavern and floating buoys that will hold the sensors up." "It’s a practical challenge to get this in place and we are working on it right now." Mälarenergi’s measurement data We will measure the temperature ten meters into the actual rock itself in five different places" "We will also use Mälarenergi’s measurement data for our analysis. In addition, we will find out how quickly the cavern is heated by the hot water." "We will measure the temperature ten meters into the actual rock itself in five different places,” says Ulrika Sagebrand.  Goals of the project In the project, FVB will also summarize the current knowledge situation and describe how Mälarenergi has gone about the work of converting the rock cavern for oil into a hot water reservoir. Another goal of the project was to report results from the initial operation, but there will be changes due to delays in the clean-up work. Delayed clean-up challenges Mälarenergi had hoped that the rock cavern would be cleaned up and ready to be filled in the summer of 2023, but since the clean-up work took so long, they will not be able to start filling the reservoirs with hot water until May. They then have to wait another year, because the energy company has to fill hot water when they have access to cheap energy, which is during the summer months. Follow-up The study will be finalized in autumn 2024, and hopefully, we can do that part in a follow-up" “It’s unfortunate for our research project, as we were going to follow up on how the project went from a technical standpoint with the storage and layering of the water." "The study will be finalized in autumn 2024, and hopefully we can do that part in a follow-up.” Ulrika Sagebrand still sees major benefits in the project. Future benefits  “Even though we don’t have time to get all the values during the planned research period, we will have all the sensors in place, which is important since the caverns will be off-limits in the future." "These sensors will also be able to be used for other follow-up projects in the future.” Why is this research project so important? “There is a renewed interest in large-scale thermal storage in the district heating industry for environmental and economic reasons. Our study can provide important information for other seasonal storage solutions. New knowledge is needed because few studies have been done recently." “A big difference from older studies is that there is now a greater interest in using existing rock caverns. Previously, new rock caverns were built for storage, but using an existing rock cavern involves some other challenges, and we’re looking at those in more detail in our research project.”

Per Skoglund takes over as the new CEO of FVB Sverige AB on January 1, 2023. He has been the Deputy CEO since 2017 and is succeeding Leif Breitholtz. Per Skoglund is taking over the position of CEO during a turbulent time in the world, particularly in the energy sector. ”This is the right time for our services. I feel strongly about the company and want to continue to develop our current business offerings,” says Per Skoglund. FVB From the beginning, FVB has been very strong in district heating and was the company that introduced district cooling in Sweden. FVB also works with energy issues relating to Industry, Buildings and Properties, Electricity and Automation, and Water and Sewage. The company currently has 150 employees with offices in ten locations in Sweden. “We are continuing our strategy of organic growth within our current business offerings. We also want to expand within water and sewage, which will require major investments in the future,” continues Per Skoglund. Extensive experience Per has worked at FVB since 2003, mainly as head of the Stockholm office Per Skoglund is the fourth CEO in FVB’s 50-year history. He has a Master of Science in Mechanical Engineering from the KTH Royal Institute of Technology and has many years of experience in the energy sector. Per has worked at FVB since 2003, mainly as head of the Stockholm office. As CEO, he will work at the head office in Västerås. “We are very pleased with this recruitment. FVB is an employee-owned company and so we wanted an internal recruitment for the position of CEO. Per Skoglund has extensive experience in the energy sector and knows the company. He is also well-known by our customers and is very professional in his role,” says Lars Andersson, Chair of the Board at FVB Sverige AB. Per Skoglund is succeeding Leif Breitholtz, who has been CEO for 17 years. Leif Breitholtz will stay with FVB as Senior Advisor with responsibility for foreign operations.

“Steam usually maintains a high pressure and temperature in our assignments, but in the beautiful church of Kättilstad in Östergötland Sweden, the pressure is no higher than under the lid of a kettle on the stove when everything is as it should be. That was the challenge,” says Johan Söderberg at FVB, who has worked on a somewhat unusual project. “For some reason, air collected in the cooler parts of the system and built up a counter pressure back there. The problem had grown slowly over a long time without anyone thinking about it, until the day the system could no longer run,” says Johan Söderberg. How do you best heat a church that is almost three hundred years old so that the interior, paintings, and pipe organs are not harmed? The solution has been for the church to be heated briefly, only when needed, which makes the visitors feel like the church is warm and cozy. Wooden barrel vault The painted wooden barrel vault is the key to it working so well. During the renovation in 1932, the church was equipped with a heating duct, but with beautiful cast iron radiators along the walls instead of elements under the pews. When the wooden radiator covers are heated up, moisture is added to the church room. When the heating system is at rest, the radiator covers instead absorb the same amount of moisture. The short-term increases in temperature with indirect heat is very gentle on the interior. Low-pressure steam With the choice of low-pressure steam, there is no risk of anything freezing “With the choice of low-pressure steam, there is no risk of anything freezing, and at the same time the effect is as high as possible once the system is in operation.” “The necessary controls can be limited to ensure that the system is running for different lengths of time depending on how cold it is, which is something that has been handled by the booking system for a few years now,” Johan Söderberg explains. He continues: “The result is that the Kättilstad church is one of the churches with the most sustainable heating in Sweden, even though the boiler is fired with oil. Only 5-30 liters of oil are burned before each church service, and soon it will be converted to bio-oil.”