During the period 2022-2023, Umeå Energi carried out a pilot study on Bio-CCS with support from the Swedish Energy Agency. Sigholm was entrusted with the roles of main project manager and sub-project manager for four out of five sub-projects (technology, permits, logistics and financing).
The pilot study focused on Umeå's Dåva 1 CHP plant, which burns waste and residues from the forest industry, and Dåva 2, which is fuelled by biofuels. The potential is about 300 000 tonnes/year of carbon dioxide captured from Dåva 1 and 2, with a mix of biogenic and fossil carbon dioxide depending on the fuel mix. The aim of the project was to investigate the possibility of capturing and transporting the carbon dioxide to geological storage with a focus on understanding the system and how the existing CHP plants are affected technically and commercially.
Technology
Dåva 1 and 2 are located next to each other and the assignment included investigating which was most advantageous: to build a separation for the common flow or two separate carbon dioxide separations optimised for each boiler. For this, analyses of flue gas composition, operating seasons and different separations based on different absorption solutions were carried out. For a common plant, the analyses showed large variations in the flow between the operating seasons, which would make it difficult to run the plant efficiently during both maximum flow and low load periods. As part of the assignment, it was also investigated how the waste heat from the separation and liquefaction could be utilised for the district heating network and how it affected the Dåva area and the entire district heating system.
Logistics
The logistics chain was planned on the basis that the carbon dioxide is transported by ship from the port of Umeå to geological storage. The project investigated the best way to transport the carbon dioxide from Dåva to the harbour by pipeline, truck or train as alternatives. A major advantage of Dåva's location is its proximity to the newly built Bottniabanan railway and nearby freight terminal, enabling rail transport without major infrastructure investments. This led to trains quickly becoming the main mode of transport. The logistics chain was dimensioned for different size options on the separation from the engineering project. A traffic analysis of the railway was then carried out to ensure that there is room for the additional traffic.
Permits and regulatory issues
For Umeå Energi, it was important to get an early picture of how existing environmental permits need to be changed or completely reapplied for due to the plans for carbon capture. Sigholm worked closely with the client to compile the current situation, develop proposals for which steps should be prioritised going forward and identify the most important challenges. To put the work in context, the investigation was linked to an environmental analysis of relevant legislation at both national and European level.
Financing and business model
All CCS projects involve large investments and also have large overheads in the operational phase. For them to be realised, solid and continuous work is required to build a stable business. Like many other Swedish energy producers, Umeå Energi has a mix of fossil and biogenic carbon dioxide, which adds an extra complexity to how the project is financed. Sigholm led the sub-project tasked with laying a foundation for a profitable business model.
Photo: Johan Gunséus for Umeå Energi
The article was published 10/09 - 2023
