The technology behind BECCS

From Hjorthagen to bedrock – how it works

Bio-CCS captures and stores carbon dioxide from flue gases produced when forest residues are used for energy production. This is one of several methods for removing carbon from the atmosphere – also known as negative emissions or carbon sinks.

At Stockholm Exergi, bio-CCS works like this:

1. Sustainably sourced forest residues – such as wood chips, branches and tree tops – are delivered by ship or rail to Värtahamnen.
2. At our bio-CHP plant in Hjorthagen, the biomass is used to generate electricity and district heating. The heat is distributed to Stockholmers via our 3,000 km long district heating network.
3. Instead of releasing the carbon dioxide into the atmosphere, it is captured inside the chimney.
4. The flue gases, which contain around 19% CO₂, are led into a new facility where a large compressor captures and compresses them.
5. A chemical process is then used to separate the carbon dioxide from the other gases.
6. The captured carbon dioxide is converted into liquid form.
7. Finally, the liquid CO₂ is transported to a permanent storage site, where it mineralises and becomes part of the surrounding bedrock.

A research facility to optimise and validate the process

With support from the Swedish Energy Agency, Stockholm Exergi has been operating its bio-CCS research facility since 2019. While carbon capture is an established method, this facility allows us to evaluate and adapt the technology to the specific conditions at Värtan’s bio-CHP plant.

Read more about the research facility

A Site with Historic Significance

Electricity and heat have been produced in Värtan since the early 1900s. Nearly 120 years after the original Värtaverket was inaugurated, we now want this site to host the next major milestone in our journey: enabling a more sustainable future by continuing to deliver energy while actively reducing climate impact.

The original power plant was designed by Ferdinand Boberg and commissioned in 1903. In 1969, the first Värtan facility was connected to the city’s district heating network. Since then, the network has expanded and now supplies heat to large parts of central Stockholm. In 2016, we inaugurated our new bio-CHP plant at the site. It is fully powered by renewable energy from forestry and sawmill residues. Now we are preparing to add bio-CCS technology, which requires a new facility adjacent to the existing bio-CHP plant.

Why Värtan is the ideal location

For bio-CCS to work, the carbon capture facility must be directly connected to the bio-CHP plant – and the CO₂ must be transported by ship for permanent storage. That’s why Värtahamnen in Hjorthagen is the ideal location. It combines access to our modern bio-CHP plant with proximity to our existing port infrastructure in Energihamnen.

Disclaimer
Co-funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible for them.