Refining of ash accelerates climate goal achievement

03 May 2022, 10:23 EEST

Fortum and Westenergy cooperation - Westenergy plant

Fortum and circular economy company Westenergy are developing waste-to-energy solutions to be even better for the environment. Fortum's new ash refining method significantly reduces the carbon dioxide emissions from Westenergy’s operations.


Material recycling is essential, but globally there will always be materials that cannot be recycled effectively. Non-recyclable materials are also waste that needs to be treated, and converting waste into energy is in fact a key part of the current waste management system in Finland and around the world. Waste incineration is getting better for the environment through continuous development. The partnership between Westenergy and Fortum in the treatment of ashes is a fine example of this.

“Westenergy further processes waste into usable electricity, heat and recycled materials. When energy is recovered from waste, the waste does not completely disappear, but ash and other non-combustible materials remain. These residues must be dealt with responsibly,” says Westenergy’s Head of Business Intelligence Juha Ripatti. “Fortum has been an excellent partner for us in this. Westenergy has a waste-to-energy plant in the Mustasaari area of Vaasa, and Fortum has handled ash treatment for the plant since 2012.”

Previously, ash that could not be recovered was used as binder in cement mixtures and taken to the landfill to prevent the impurities it contains from leaching into the environment. Known as cement stabilisation, this has been an effective final disposal method for a challenging product, however, relatively substantial amounts of carbon dioxide emissions and landfill waste are generated in the process. Also, by using this method, the salt contained in the ash and the materials it binds end up in the landfill and cannot be recovered for further use.

The new ash refining method significantly reduces the carbon footprint

“Westenergy aims for carbon-neutral energy production by the end of the 2020s, and to make the transition to carbon-negative production at the beginning of the next decade. We want to offer a service in which greenhouse gas emission reduction and carbon capture are thrown into the bargain,” says Ripatti. “Among other things, this means that we evaluate climate and environmental aspects also when we select our partners. Fortum’s new ash refining method meets all our criteria related to the climate and environment, so it can help us achieve our climate goals.”

“The treatment of Westenergy’s ashes in our ash refinery in Pori includes the removal of salt from the ash and the binding of heavy metals to the ash. Once this has been done, the ashes are ready for final disposal without cement. The salt is disposed of to the sea in purified and analysed discharge water; however, our objective is to also recycle the salt in the future, and we are continuously working on finding ways to reuse the salt from the ashes,” says Matti Vaajamo, Commercial Director, Ash and Slag Business Line at Fortum. “Emissions are significantly reduced with this method, and not least through the omission of cement. The carbon footprint calculations we have made with Westenergy show that the carbon dioxide emissions from ash refining are up to 84 % lower compared to the emissions from cement stabilisation.”

“In the future, we will also consider and explore other possible ways of dealing with the remaining ash after the refining process rather than taking it to the landfill,” says Ripatti. “The results will help us achieve the goals we have set for logistics. We would like to use carbon-neutral fuels and power in our logistics.”

Long-term collaboration benefits all

The collaboration between Fortum and Westenergy is a fine example of how strong partnerships promote climate and circular economy work.

“Fortum has set partnerships as one of its strategic priorities, and it has been great to form one with Westenergy,” says Eeva Saarinen, Product Manager at Fortum Waste Solutions. “As a result of our long-term partnership, we know each other's strengths and needs, and we can have an open and constructive dialogue about any areas of development. It is important for us to provide solutions that genuinely help our customers achieve their climate and environmental goals.”

“We greatly appreciate our long-term collaboration with Fortum,” says Ripatti. “We have all learned something new, and together we have set our visions further into the future. It is truly a partnership.”


Westenergy operates within the circular economy. The company owns a modern Waste-to-Energy plant where combustible waste is refined into electricity, heat and recovered materials. The energy produced in the plant has a significant impact on reducing the need for fossil fuels in energy production, and Westenergy produces about 50 % of the district heating needed in the Vaasa region. By producing material for earthwork and recycled metals and by participating actively in developing a circular economy in the operation area, Westenergy is creating a cleaner and more sustainable future.

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