The statistics reveal that Oulun Energia produces increasingly lower carbon emissions in its operations each year, both in terms of total emissions and per unit of energy produced. In the past ten years, the number has almost halved. In 2011, energy production generated over 800,000 tonnes of carbon emissions as defined in the EU Emissions Trading Scheme. In 2020, that number was 425,000 tonnes. In 2021, emissions were estimated to be 390,000 tonnes. The difference from the previous year is due to the fact that, in 2020, the Laanila biopower plant started its operations and the old unit one of the Toppila power plant was closed down.

- Carbon emissions as defined in the EU Emissions Trading Scheme will decrease as the use of peat as a fuel decreases,” says Lauri Heilala, Director of Fuel Sourcing at Oulun Energia.
- Efforts have been made to reduce the use of peat. In the short term, the substitute fuel is wood.

In 2011, peat accounted for 70 per cent of Oulun Energia’s fuel use. That number was 45 per cent in 2020. Of the existing power plants, unit two of the Toppila power plant uses peat and wood as fuel. The Laanila ecopower plant burns household mixed waste, and the Laanila biopower plant primarily burns wood and SRF (Solid Recovered Fuel). SRF refers to sorted waste from the retail sector and industry, for example.

Wood fuel includes sawdust, bark and recycled wood, which are industrial by-products. According to Lauri Heilala, the aim is to obtain it from the nearest possible sources. As the use of peat decreases, so will carbon emissions. Peat is counted as a fossil fuel and wood as a fully renewable fuel. 60% of SRF waste is considered carbon-free and 40% CO2-emitting.

Recovering waste heat

By producing energy with improved efficiency and by reducing waste, emissions will be reduced in proportion to the unit of energy produced. Operations Manager Mikko Vesterinen says that, in the new Laanila biopower plant, the recovery of waste heat from flue gas increases the overall efficiency of the power plant considerably: the tank’s fuel capacity is 215 megawatts, and more than 50 megawatts of waste heat can be recovered. Treatment of flue gas also reduces airborne pollutants. In Oulu, nitrogen oxide, sulphur and particulate emissions, which affect air quality locally, have decreased over the years. The new Laanila biopower plant has the most modern filtration process.

The electrostatic precipitator purchased for the Toppila power plant in 2015 also showed results in the form reduced particulate emissions. But it is not just the filtration that cleans the air.
- The reduction in nitrogen oxide and sulphur emissions is mainly due to increase in the use of wood and the decrease in the use of peat and fuels, says Vesterinen.

Targeting carbon neutrality by 2030

Oulun Energia aims to be carbon-neutral by 2030 in its own energy production by increasing the use of renewable energy sources, such as wind and solar, improving energy efficiency and investing in carbon sequestration. Carbon sequestration is carried out using the granulated ash created in the burning process to fertilise forests, which accelerates their growth. Production Director Tommi Kantola says that moving to carbon neutrality in heat production requires the implementation of multiple different solutions.

Nowadays, 90% of district heat production is concentrated in the Laanila and Toppila power plants. Kantola believes that energy production will diversify in the future. The completed district heating network is a good platform for distributing carbon-neutrally generated heat to users, and new sources of heat are constantly being investigated. One possibility is in retail cold storage, which simultaneously solves retail cold storage cooling and apartment heating by heating apartments with the waste heat from the refrigeration equipment. The utilisation of geothermal heat from deep underground is another possibility. Oulun Energia is involved in a research project involving several energy companies that is investigating geothermal drilling near Tampere.

Unit two of the Toppila power plant will continue operations for years to come, but in time it will be replaced by something else. According to Tommi Kantola, the big challenge is in what will take its place.
- When Toppila 2 reaches the end of its service life, maybe it won’t be replaced by a combustion power plant. Instead, decentralised production could be an option. Combustion will also be carried out in a more sustainable manner and with lower emissions, perhaps even carbon-neutrally.

This article was originally published in Oulun Energia’s customer magazine 3/2021. Text by Pirkko Koivu, illustrations by Erika Neitola.