Information meeting on modeling heat load Februrary 20, 2024

The public event regarding Flexens’ project continued on Tuesday, 20.2, at an event organized at the Ykspihlaja guest house. Modelling of the heat load in cooling water was presented. The project is currently undergoing the EIA report phase.

The NTM center has assessed that the heating of the seawater is the biggest environmental burden of the facility, and the goal was to provide additional information and the public an opportunity to hold a dialogue and ask questions. The event gathered a large audience, about 20 people in total, some of whom were members of the Ykspihlaja residents' association next to the factory area and some of whom were members of the nearby cottage association.

The event started with a presentation by the project manager Jim Häggblom and then a presentation by the project's environmental advisor Envineer on heat load modeling. Mikko Jantunen from Flexens and Sanna Suvanto and Aada Elshof from Envineer were also present.

The plant's operations do not actually generate process wastewater, but only clean cooling water. At the event, Envineer presented a summary of the cooling water heat load modelling:

The outlet point for cooling water is in a fairly open place in front of the harbour at the tip of the present breakwater, and the object's depth is about 10 meters.

According to the modelling, the temperature effects are limited to Karleby harbour, which is no more than 2–3 kilometers from the unloading site, and to Ykspihlajaviken. The size of the load's temperature impact is greatly influenced by the fact that the heating load varies monthly depending on how much of the waste heat from the production facilities is led to the sea.

The area of ​​influence is also generally larger during the ice cap period than during the open water season. The effect of the heat load is greatest in the spring before the ice melts and during the warmest time in midsummer. During the open water season, however, the currents in front of the harbour greatly intensify the mixing and dispersion of cooling water and the attenuation of the heat load.

The cooling water to be discharged can be deeply mixed with a fairly large volume of water, especially in winter. In open water, on the other hand, the flow direction and strength in front of the outlet point varies due to changes in wind speed and direction, and the more permanently observable area of ​​influence of the heat load around the outlet point is quite small. During the summer months, however, warm cooling water can intensify the temperature stratification in front of the harbour. According to the modelling, the average seawater temperature may rise by 0.1-0.5 °C in mid-summer in an area of ​​2-3 km2 in front of the harbour and by 0.5-2 °C near the outlet.

Under the ice cover, the seawater temperature in front of the harbour and in Ykspihlajavik rises by an average of a few tenths of a degree and possibly by more than 0.5 degrees just in front of the outlet. During the ice cap period, the exchange of water from Ykspihlajaviken to the open sea is relatively low, and the effect of the heat load thus spreads to a larger area than the open water season.

The effect of the heat load on the ice cover and its thickness is also essentially limited to a couple of kilometres from the outlet point in the direction of Ykspihlajaviken and its front, and mainly during the pre-winter when the temperature of the cooling water to be released starts to rise. However, a permanent melted area of ​​a few hectares will form around the outlet pipe.