A white tanker truck arrives at Varkauden Aluelämpö's Hasintie heating plant in Varkaus, and the driver connects a large delivery hose to the tank. With a low rumbling sound, the Stora Enso's truck starts emptying the contents of its tank through the hose into the new pellet silos of the heating plant.
Varkauden Aluelämpö was one of the first heating plants in Finland to modernise an existing oil boiler for using pellets as fuel. “The modernisation was a more profitable option financially than completely replacing the old equipment,” says District Heating Engineer Jyrki Väänänen of Varkauden Aluelämpö.
Because the pellets incineration takes place in the existing oil boilers, the pellets are first ground into dust. “The furnace has no fire grate, so burning pellet dust is the most efficient solution. Since the pellets are pure wood and contain no binding agents, grinding is easy,” says Mikko Onkalo, Managing Director of Varkauden Aluelämpö.
"A consistent quality also prevents emission peaks, which is very important to us since we participate in the emissions trading system."
The clean wood pellets and the consistent quality were important criteria when Varkauden Aluelämpö selected the pellet provider. “A consistent quality also prevents emission peaks, which is very important to us since we participate in the emissions trading system,” Onkalo continues. In the emissions trading system, the traceability of raw materials is also important. “The transparency and extensive certification of Stora Enso's production chain were significant factors.”
Breaking new ground with a familiar partner
Varkauden Aluelämpö's plans for the future include using energy produced by the waste incineration plant being built in Riikinneva in Leppävirta, as well as the surplus energy from Stora Enso's plant in Varkaus as the primary sources of energy. The pellet power plant will even out peaks in consumption in the wintertime, for example.
“Among the renewable forms of energy, pellets suit our purposes best due to their long storage life and easy start-up of the plant,” Väänänen says.
The conversion of the Varkauden Aluelämpö power plant from heavy fuel oil to pellets is a pilot project, which other players in the sector have been monitoring closely. “Fluctuations in the price of oil, the world situation and environmental values were our motivators for embarking on this change. Pellets are a price-competitive alternative,” Onkalo says.
“The pellet production in Kitee was launched a year ago, and the use of pellets has also grown this year,” says Mauno Väyrynen, Pellet Production and Sales Manager at Stora Enso. “The increased volumes of use are a very positive factor for the development of the sector.”
“We have worked with Stora Enso for decades, since we have been purchasing heat from the Varkaus plant for a long time. We value the consistent quality and local deliveries,” Onkalo continues.
Getting ready for the cold season
The pellet plant has only been in operation for a few weeks, but the test runs have produced good results. Pellets are now incinerated in one boiler only, but the plan is to convert a second boiler for pellet incineration in the autumn. “Burning pellets is also considerably quiet. Previously, you could always hear the hum of the oil boiler as soon as you were at the plant gate, but now there is a silence,” Mikko Onkalo says.
The tanker truck lowers its tank and the driver disconnects the hose. This will be a common sight in Varkaus if the coming winter is cold. “At full capacity, the plant generates approximately 10 MW of energy for the customers of Varkauden Aluelämpö,” Väänänen calculates. This will also mean more pellet deliveries per week.