Biomass conversion & lifetime extension of Avedøre Unit 1

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In 2016, DONG Energy’s Avedøre Power Plant Unit 1 will deliver green heat and power to the citizens of Copenhagen. Besides a bio-conversion the project also comprises a lifetime extension which is planned for 2018. Ramboll advises on the project that constitutes a major and highly efficient biomass conversion scheme.

Supplying heat and power for Copenhagen citizens

Avedøre Power Plant is situated less than 10 km from the centre of Copenhagen, and is one of the most energy efficient combined Heat and Power Plants in the world. Avedøre Unit 1 (AVV1) was commissioned in 1990 as a 250MW coal and oil fuelled unit, and now, a bio-conversion of the plant is to be completed by the autumn of 2016. To maintain fuel flexibility, the plant will still be able to burn coal, but wood pellets will be its primary fuel.

Once completed, AVV1 will provide heat for an additional 65,000 households. Thereby, AVV1 and AVV2 will generate heat for more than 215,000 households in the Greater Copenhagen area and enough power to supply over 600,000 household’s annual electricity consumption. In addition, the bio-conversion will reduce the plant’s CO2 emissions by approx. one million tonnes per year.

"In Denmark we have a head start on using biomass as a resource to produce energy at our plants. We must continue to develop that experience so that our solutions become attractive to other countries in the process of transition to a greener energy,” says Thomas Dalsgaard, director at Dong Energy, the owner of Avedøreværket.

Preserving efficiency while changing fuel types

The combination of producing combined heat and power is widely used in Denmark. By utilising the excess heat from the power production for district heating, AVV1 attains an energy conversion efficiency of up to 91 pct. High energy efficiency results in better fuel economy and a reduction in CO2 emission per produced kWh.

"It takes more to retrieve the same amount of energy from wood pellets than from coal. However, following the completion of the bio-conversion, AVV1 will still be able to reach the same energy capacity on pellets as it did before on coal. Preserving high efficiency is central, and by utilizing the reserve capacity we won’t have to downgrade the plant in any way. Also, we’re able to change fuel types, e.g. from coal to pellets, without shutting down operation. That's unique", says Jacob Thysgaard, Chief Project Manager at Ramboll’s power division.

Extending the plant’s lifetime

AVV1 dates back to 1990, and has gradually depleted its lifespan. Therefore, when making a bio-conversion you also need to make a lifetime extension, in this case making the plant run until 2033. Among others, Ramboll has assessed the building structure, boiler, electric installations and flue gas cleaner, and developed a feasibility study of the life extension.

Furthermore, Ramboll has undertaken a maturation project for the bio-conversion of AVV1 including fuel transport, fuel storage and combustion systems with the purpose of preparing the project for the subsequent implementation phase. This included mapping of demands from authorities and determining the scope and choice of solutions. Additionally, Ramboll has developed a full bio-conversion concept report and will assist with procurement as well.

"At Ramboll we possess wide and unique experience within the design and conversion of power plants. We offer the necessary knowledge of technologies for logistics and combustion of coal and pellets. In combination with our broad experience with smaller plants for straw and wood chips, this forms a broad knowledgebase for advising our clients", says Jacob Thysgaard.

A major biomass conversion scheme

Avedøre Power Plant Unit 2 has already been converted into a multi-fuel plant that runs on wood pellets and natural gas. The unit is able to reach efficiency levels that are rarely seen at other power plants around the world.

Together with Studstrup Power Plant, which is undergoing the same process, AVV1 and AVV2 are one of the world's larger biomass conversion schemes, and Ramboll is advising on all projects. The silo installations themselves will hold 100,000 tonnes of biomass. When the conversion of both Studstrup Power Plant and Avedøre Power Plant are completed, DONG Energy will have an annual wood pellet consumption of 1.8 million tonnes of which 1.2 million tonnes will be used at Avedøre and 600,000 tons at Studstrup.

Avedøre Power Plant produces about 30 pct. of the total electricity use in Zealand, which is about 1.3 million households’ yearly electricity consumption.


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