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Helen fast-tracking coal phase-out with Vuosaari C and other investments

As a step towards a carbon-neutral future, Helsinki municipal energy utility Helen Oy is building a biomass-fired heat plant at its Vuosaari energy site. Vuosaari C will utilise unique energy efficiency and reuse the waste heat from flue gases in an unprecedented way. Bringing forward the commissioning of the bioheat plant by a year enables a partial coal-phase out sooner than planned while the estimated EUR 260 million investment is not expected to impact the price of district heating.

Currently consisting of two gas-fired combined-cycle units, Helen’s Vuosaari combined heat and power (CHP) plant (580 MWth, 630 MWe) provide a major part of electricity and district heat in Helsinki. As part of the replacement of the soon to be closed Hanasaari coal-fired CHP, Helen is planning for a 250 MWth biomass-fired unit (shown in white above) at the Vuosaari energy site along with other investments in heat recovery and storage (image courtesy Helen).

The Finnish energy major’s target is carbon neutrality by 2035, with coal being phased out even sooner. The Hanasaari power plant in downtown Helsinki will close by the end of 2024, and its heat production will be replaced with heat recycling with heat pumps, energy storage, and the biomass-fired heating plant to be built at the Vuosaar energy site, on which the investment decision has already been made.

Hanasaari may be assigned for reserve use before then, depending on the commissioning schedule of the Vuosaari C bioheat plant.

Bioenergy needed to secure winter heat demand

The bioheat plant will be necessary to secure Helsinki’s heat requirement also in the cold winter months. At Salmisaari, the final coal will be replaced by 2029. The primary target is to substitute coal with solutions that are not based on combustion, though the investment decisions have not yet been finalised.

The planned capacity of the Vuosaari bioenergy plant is 260 MW and its share of Helen’s fuel consumption is estimated at about 15 percent. Construction of the Vuosaari bioenergy heating plant will start this spring with the earthworks, the actual building work getting underway in autumn 2020.

The aim is to have the heating plant in production use for the heating season 2022–2023, about a year sooner than anticipated.

Bringing forward the commissioning of the bioenergy heating plant permits the deployment of the Hanasaari cogeneration plant for reserve use before the planned closure, as early as during 2023. Replacement of the Hanasaari heat production will still require biofuels, in order to secure availability of heat also in the cold winter season. We are seeking other solutions for Salmisaari, said Pekka Manninen, CEO of Helen.

Waste heat recovery twice over

The new EUR 260 million bioenergy heating plant will be built for maximum flexibility, with a view to solutions of the future. The design and capacity of the plant take account in a number of ways of options like using different fuel fractions.

Sumitomo SHI FW (SFW), a subsidiary of Japan-headed Sumitomo Heavy Industries Ltd (SHI) has been selected by Helen for the supply of a circulating fluidized-bed (CFB) boiler for the bioheat plant.

The further development of the Vuosaari energy production area is also taken into account in the heat distribution connections.

The principal fuel to be used at Vuosaari C is forest chips created as a forestry by-product, which has no other uses. The procured fuel is certified for sustainability or source controlled by other means. The bioheat plant achieves its energy efficiency by utilising flue gas heat recovery and absorption heat pumps.

Valmet has been selected to supply the flue gas condensing plant and condensate treatment equipment, including a boiler make-up water production system

After the combustion process, the flue gases are piped to the heat recovery plant and then on to separate absorption heat pumps. This way, we are able to utilise the fuel as effectively as possible, and the double heat recovery ensures that the flue gas entering the chimney is only 10-20 degrees, explained Antti Saikkonen, Project Director at Helen.

Deployment of the bioheat plant in district heat production is not expected to affect the price of district heating.

Other investments

Helen continues to invest in large-scale energy recycling using heat pumps, as well as planning projects on heat storage. Replacement production already been completed or is under construction include new heating and cooling plant that was commissioned beneath the Esplanade Park in the summer of 2018, the Katri Vala heating and cooling plant is being extended, and a new heat pump utilising heat from seawater is also under construction in Vuosaari.

Investments are also being made in heat storage: the old oil storage caverns in Mustikkamaa are currently being converted into an underground heat store. Other areas under investigation include utilising geothermal heat and, in slightly longer-term, ideas like modular small-scale nuclear reactors.

The 420 MWth/220MWe Hanasaari coal-fired combined heat and power (CHP) plant in downtown Helsinki power plant started to co-fire wood pellets at the end of 2015. Commissioned in 1974, the plant will be closed by the end of 2024 and the site repurposed as a residential/recreational area.

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