Profitable combination of geothermal energy and photovoltaic cells

- The first full month with the plant's new system started, we could note that the heat consumption, when normalized year-adjusted, decreased by as much as 78% compared with the previous year. Smarter energy solutions with new technology generates profit for both us and our tenants, but above all it is a sustainability benefit for environment, says Rickard Wahlberg, Energy and Technology Developer at Catena.

Several of Catena’s properties offer the possibility of replacing district heating with different geothermal solutions. In properties with refrigeration and freezer plants, a combination including photovoltaic cells can further improve profitability in projects while also reducing greenhouse gas emissions. In 2018, we invested in a combined facility of this kind at the Dikartorp 3:12 property, located in Jakobsberg, outside Stockholm. The property houses a terminal for refrigerated and frozen goods, meaning it has considerable cooling needs, while other parts of the property have premises that require heating. The surplus energy generated by the cooling units is recycled and used in other parts of the property. Combined with the geothermal heating facility, this allows the property’s heating needs to be covered very efficiently.

Since the refrigerated terminal has particularly high energy needs during the summer months, photovoltaic plants are also well-suited this type of property. The photovoltaic cells generate most electricity in the summer months – the part of the year when the refrigeration plant needs most electricity to power the cooling units.

During the warmer half of the year, the property needs less heating, meaning that the excess heat generated by the cooling units can instead be used to recharge the energy stored by the geothermal plant. The recharging of heat in the boreholes prepares the
geothermal plant for the colder part of the year, engendering better opportunities to efficiently cover the demand for heat throughout the year.

Brief facts about the facility
The geothermal plant consists of 20 energy wells to a bore depth of 225 metres each and three heat pumps with an output of 264 kW. The photovoltaic plant consists of 943 photovoltaic modules of 270 W and is expected to provide 248,000 kWh/year.

SEK 8.3 million project expense

13.1% direct return

7.6 years repayment period