Waste heat to heat almost 2,000 private homes with only one investment

Vaasan Sähkö is building a waste heat recovery unit at the Påtti wastewater treatment plant. The new waste heat recovery unit  will utilise the heat from treated wastewater. This heat will be used in the district heating network to cover the needs of almost 2,000 detached houses. In other words, this is enough thermal energy to supply all the detached houses in Vaasan Sähkö’s district heating network.

The use of waste heat in the district heating network is a good example of how the circular economy works. This solution utilises the thermal energy of water flowing from households to the wastewater treatment plant as a heat source. The waste heat recovery unit is scheduled for completion by the end of 2023 and will support the goals of both Vaasan Sähkö and the City of Vaasa in terms of becoming carbon neutral during this decade.

The solution also has a balancing effect on the cost pressure of district heating.

– The waste heat recovery unit guarantees that the price of our district heating remains competitive. When district heating is produced cleanly, the pricing, for example, is not affected by emission fees, says Vaasan Sähkö’s district heating manager, Markus Tuomala.

The waste heat recovery unit will be equipped with two heat pumps that will recover 50 to 60 gigawatt hours of heat per year, which will then be used for heating homes and domestic water.

The solution will not affect water or wastewater fees.

– The heat from treated wastewater is discharged into the sea if it is not utilised, says Vaasan Vesi’s  instrument technician Timo Auranen, speaking from the Påtti wastewater treatment plant.

– With the new heat recovery solution, most of the wastewater heat will be used as district heating.

“The fastest way to move to a zero-emission era”

Making investments directly in district heating production is an effective way of reducing the carbon footprint of residents. Nearly 2,000 homes will switch to green thermal energy in one go.

– It’s better to invest in one efficient waste heat recovery unit than to have almost two thousand homeowners invest in new heating solutions in order to gain access to emission-free heat, says Tuomala.

– In cities, district heating is the fastest way to move into an emission-free era. The existing network can always effectively implement the best technology available, without individual properties having to make their own investments based on future needs.

The future solution is also an important part of the Vaasa region’s self-sufficiency energy policy.

About the project

  • What: Recovery of waste heat from treated wastewater
  • Cost: Approx. EUR 11 million
  • Support: EUR 1.9 million of investment support from the Ministry of Economic Affairs and Employment
  • Energy production: 50-60 gigawatt hours (GWh) of heat / year
  • Planned commissioning: Year 2024

The Påtti wastewater treatment plant treats the entire wastewater of the City of Vaasa and part of the wastewater from the neighbouring municipalities of Mustasaari and Maalahti.