Heating and sanitation technician – VVS no 3/2020 Text: Robert Wilkund
Helistorage in Kokkola
The start-up company Heliostorage in Kokkola, in collaboration with St1, has designed a facility where the solar energy of the summer half-year is utilized with solar collectors on the roof and stores the thermal energy in the ground or runs it through heat exchangers to the property’s radiator system. The facility is also served by a ground source heat pump with separate energy wells. Kaustisen Evankelinen Opisto operates in the building.
Since the 1980s, there has been a lot of research at universities into how best to store thermal energy in the ground for use during the winter. Kokkola-based Helistorage is the first company in the world to commercialize this technology and sell working solutions to customers. During the summer months, there is sometimes a large surplus of thermal energy and the constant problem is how to store it for the winter at a reasonable cost. Timo Sivula, Heliostorage’s Head of Development, says that underground energy storage is very suitable for facilities that consume more than 200 MWh per year and have access to large roof space where solar collectors can be built. Ideally, the property should have oil heating to be phased out and an imminent roof repair in the future plans. In addition, there should be access to land on the plot where the energy storage will be built.
Underground energy storage
An underground energy storage facility consists of a number of boreholes in the ground. The drilling area looks like a series of large concentric circles from above. Within the outermost circle there is a smaller circular formation of boreholes and in the center is the core where the temperature is highest.
Different soil types show large differences in their suitability for energy storage. Research shows that clay soils mixed with sand provide the best conditions for energy storage in the ground. Bedrock also does not work well as energy storage due to too high thermal conductivity. The energy storage in Kaustby consists of 36 boreholes with a depth of about twenty meters. At the start of operation, the temperature of the terrestrial energy storage is about 8 degrees. According to calculations, the energy storage will eventually contain an amount of energy of 25 MWh. The power that can be extracted is estimated to be around 10 kW.
Solar collectors on the roof
The roof of the property in Kaustby is a pitched roof with an eastern and western part. The solar collectors cover the entire roof surface and are made of aluminum profiles with built-in fluid pipes and a collector. The solar collector modules are covered by a corrugated but transparent polycarbonate sheet that prevents the wind from sweeping away the collected heat. The combined area of the solar collectors on the east and west sides amounts to 600 m2 and is estimated to have a peak power of 250 -300 kW. During commissioning in August 2020, a peak power of over 175 kW was measured from the western part alone.
The system perceives the roof as two separate collectors where the control system measures the temperature of the outlet flow of each collector and determines where the liquid flow goes. Sometimes the outlet from the east side is routed to the inlet on the west side to drive up the temperature to a usable level. What is the useful level is determined by the algorithms that regulate the liquid flow in the plant. One of the parameters is the temperature of the terrestrial energy storage, which is expected to reach 65-70 degrees in the core by the end of the summer.
The plant is designed so that the algorithms will control when energy is taken from the charged energy storage and when it is taken from the solar collector. The temperatures of the different circuits are continuously measured and the data is sent via the IOTA protocol to Heliostorage’s cloud service, while ingenious algorithms optimize where to feed heat into the building. Heliostorage’s approach aims to primarily supply the heat exchanger to the radiator network and the domestic hot water with energy. Only the surplus will be fed into the underground energy storage.
Advanced technology
Mats Manderbacka, who can be considered a serial entrepreneur, is the entrepreneur behind Heliostorage. He manufactures the solar collectors at his own company in Kokkola. Manderbacka explained that behind Heliostorage’s terrestrial energy storage are advanced algorithms and modern control technology. The company employed a talented mathematician who worked for two years on the algorithms that optimize and control the flow of liquid. The intelligence of the plant itself is located on the server as a cloud service and the control runs via a fixed internet connection in the building.
The Kaustby project is a purely commercial project where the customer pays for the energy consumed. Heliostorage’s partner KS Geoenergi from Kronoby supplies the geothermal heat pump and drills the energy wells, while St1 handles the financing. Manderbacka believes that after a couple of years the geothermal heat pump in Kaustby will have to take a break while the solar collector supplies the property with heat.
The next project is already in the pipeline. An agreement has been signed with Guangzhou Power Supply Ltd. Helistorage will supply system design and materials for a major project in China. It is clear that there is significant interest in the market for low-emission heating systems. China is known to have enormous carbon dioxide emissions from the energy sector and wants to reduce emissions in various ways.
Upcoming projects
When the master plan is approved, an eco-village will be designed and built in Masaby, Kyrkslätt (see article on page 18). Heliostorage is involved with the supply of solar collectors and system design of a 4 GWh ground-based energy storage. Heliostorage has signed a pre-contract with Arctic Village for the delivery of 6 eco villages around Finland.
Implemented projects
Funded by the European Regional Development Fund ERDF, Heliostorage, together with Centria University of Applied Sciences and Geological Survey of Finland GTK, delivered a 500 MWh pilot system for Finn Springs soft drink factory in Toholampi. The project utilizes and stores the waste heat from, among other things, the compressors in the manufacturing process. The stored heat is used to heat the office during the winter months.
