Turning waste water into eco-energy
Helsingin Energia Katri Vala heat pump plant utilises energy in a sensible way by producing both district heating and cooling.The heating plant which is situated at depth of 25 metres from the ground level uses a single process for producing district heating and cooling from purified waste water and sea water.
– Various parts of a similar type of production are used elsewhere in the world, but so far have not been combined in this way. What is unique about this project is its whole idea and scale, says the Director of Helsingin Energia Marko Riipinen.
– The heat pump plant is extremely efficient. It utilises energy which would otherwise be lost and produces renewable energy while improving the eco-efficiency of the district heating system even more. The carbon dioxide emissions of the Katri Vala heating and cooling plant are 80 per cent smaller than those of alternative production solutions, and there are no noise disturbances to the environment.
The plant’s location near to the city centre is ideal due to the fact that an outfall tunnel for purified wastewater and a multi-utility tunnel, through which the heat and cooling energy produced at the plant is transmitted to customers, intersect under the Katri Vala park.
Re-claiming lost energy
The average amount of waste water produced on an ordinary day is 260 000 cubic metres, which runs through sewers to Viikki waste water treatment plant. The purified waste water is rather warm even after it has gone through the handling process. Depending on the time of the year this temperature varies between 10-17 degrees Celsius.
– Previously this lost energy was not utilized in any way. The heat pump plant functions bril-liantly, producing eco-efficient energy while cooling down the purified waste water by seven degrees before it is discharged into the sea, says Riipinen.
The waste water which is purified during the winter season is used only for district heating, since the necessary district cooling can be produced directly from sea water.
– Cooling is needed also in the winter, even if the outside temperature drops to - 25 degrees, notes Riipinen.
The unmanned plant is remote controlled, and it is monitored from the Sähkötalo heat control room. The production output of the plant is 90 Megawatts of district heat output and 60 Megawatts of cooling output. The heat pump plant produces three per cent of annual production of district heat-ing.
- The annual heat energy produced by the heat pump plant is enough to keep a small town, or 12 000 detached houses, warm for a year. In district cooling the plant is the biggest of all of our district cooling centres. Its power output is equivalent to the combined cooling output of 60 large office building.
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