Homes in Helsinki may be cooled and heated using seawater starting in 2029, with Helen, the energy utility of the Finnish capital, moving forward with a project to build a 400-million-euro seawater tunnel to its combined heat and power plant in Salmisaari. (Antti Aimo-Koivisto – Lehtikuva)


HELEN, the energy utility of the City of Helsinki, has taken a step forward in its project to build a 400-million-euro tunnel system that enables the utilisation of seawater in district heat production.

Helen on Wednesday announced Finland’s YIT and Spain’s Acciona as its alliance partners for the project, saying the trio will over the next two years devise a plan for transferring heat from seawater to heat pumps to be installed at its plant in Salmisaari, a sector of the quarter of Ruoholahti.

The pumps, the price of which is not included in the 400-million-euro cost estimate, will be able to generate district heat from seawater as cold as 2°C.

The actual construction phase is projected to take roughly five years, meaning the plant could start utilising heat from seawater in district hear production at the earliest in 2029.

“Helen believes seawater heat pumps will have an important role in the shift toward a dispersed energy system, where energy is produced at several sites. The energy platform, meaning the heating and cooling network, offers an opportunity to combine innovative technologies and production methods,” said Timo Aaltonen, the director of energy platform at Helen.

Helsingin Sanomat on Wednesday wrote that, if completed, the tunnel would be the first constructed using tunnel-boring machines (TBMs), which were used to, for example, to build the Channel Tunnel linking Great Britain to France. Acciona will contribute its expertise in tunnel boring to the project, having used the machines bore a tunnel for high-speed rail traffic between Oslo and Ski in Norway.

The seawater tunnel is to terminate some 17 kilometres off the coast of the Finnish capital.

Helen has announced that the combined heat and power plant will stop using coal in 2024. Its Hanasaari plant, in turn, will stop using the fossil fuel in April 2023. The energy utility is presently conducting a feasibility study into utilising waste heat collected at the Kilpilahti industrial site in Porvoo.

Aleksi Teivainen – HT