Porvoo Cathedral

Porvoo cathedral is kept warm with heat transferred by Altia Naturet geothermal fluids

Dec 31, 2020

A sizable investment was made last autumn when Porvoo cathedral received a geothermal heating system. Talman Energiaporaus carried out the drilling and selected Altia Naturet as the geothermal fluid that will circulate in the pipelines. Talman Energiaporaus and Altia have nearly 10 years of successful cooperation behind them.

Porvoo cathedral, which was built at the turn of the 14th century and received its current shape in the 15th century, has lived through many trials and tribulations. It suffered damage in the bombing during the Second World War and has survived several arson attacks, the latest in 2006.

The church has, however, always been maintained well. Thorough renovations and repairs have been carried out on several occasions, most recently in 2018.

Production of Naturet at Altia’s Rajamäki plant

In year 2018, the Porvoo cathedral received a major heating system renovation: the previous oil heating was replaced by a geothermal system. Talman Energiaporaus has drilled eight 340-metre wells for the pipelines into the bedrock under the church courtyard. The ground heats up the fluid that circulates in the pipes and the system transfers the thermal energy up to the church.

The geothermal energy is distributed into the church buildings using an underfloor water circulation system. Hot tap water is also heated using geothermal energy. The fluid that flows in the ground pipes is Naturet geothermal fluid, manufactured by Altia Industrial. Naturet products are ethanol-based fluids designed for heat transfer and cooling in geothermal heating systems. The products are manufactured in Rajamäki at Altia’s plant for technical ethanol products. Some of the ethanol raw material is received from Altia’s Koskenkorva distillery where domestic barley is turned not only into beverage-class grain spirit, but also into technical ethanol for industrial needs.

Benefits of Naturet products: high quality, domestic labour and reliable deliveries

Altia has manufactured and developed Naturet products for more than 25 years. During that time, the company has cemented its position as the Finnish market leader in ethanol-based heat transfer fluids. The demand for Naturet products has grown over the years as geothermal systems and heat pumps have become increasingly common energy sources. The biggest customers are drilling companies such as Talman Energiaporaus. Next year, Talman Energiaporaus celebrates its 10 years of operation. Altia’s Naturet has been their only geothermal fluid from the start. According to the company’s owner Kaisa Eskelin, cooperation with Altia has been very successful. “Above all, we value Naturet products for their high quality and for the fact that they are manufactured in Finland. Reliable deliveries are also important for us. If we don’t get the products in time, our work stops right there. With Naturet products, we know that the fluids will always be delivered in time”, Eskelin says.

GeoSafe products chosen for the church standing on groundwater area

The Naturet products are available in three ethanol content categories. The ethanol must be denatured, or made unfit for drinking, using methods required by the law. In addition to the denatured ethanol, the products contain water and a corrosion inhibition mixture. “The product family also includes alternative GeoSafe products that do not have a corrosion inhibitor. This makes them well suited for important groundwater areas. The Porvoo cathedral is located very close to a groundwater area that is an important source of drinking water, which is why GeoSafe geothermal fluids were used for this particular system”, said sales manager Katja Raatikainen, who is responsible for Altia’s Naturet products.

The Porvoo cathedral was a fairly demanding drilling location. Not only was the groundwater area close by, but the limited space, the location in the middle of an old town centre, and the tourist season that partly overlapped the project period also required careful planning.

Environmental and economic benefits of geothermal energy

Planning for the adoption of geothermal energy began approximately two years ago, and the work on site started at the beginning of September. The project went smoothly and was completed in schedule by the middle of December. The church invested EUR 340,000 in the new system. The investment is estimated to pay itself back in 10 years. Before the investment, a total of 30,000 litres of oil were used annually to heat the cathedral. According to technical facility manager Timo Kraufvelin from the joint parishes of Porvoo, motivations for the investment included both economic and environmental concerns.

“Environmental values are very important for the church, and the transfer from oil to ecologically sound geothermal heat constitutes a major action for the environment. Cost savings are also achieved at the same time. The transfer required a large investment, but will pay itself back.”

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