Power reserve – Karlshamnsverket

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Quick-start and reliable electricity production

Karlshamn Power Plant acts as a lifeline in the power system and is ready to start at the request of Svenska kraftnät, Sweden’s Transmission System Operator (TSO), which has procured 330 megawatts from the plant. This corresponds to the majority of Sweden's strategic reserve, a total of 350 megawatts. The contract period runs from 15 January to 15 March 2026.

Karlshamnsverket is located in southern Sweden, where the capacity requirement is higher than in other parts of the country. Normally, hydropower, nuclear power, wind and solar power meet Sweden's electricity demands. When normal power production is interrupted, or when the need for electricity is unusually high, Karlshamnsverket can be started at short notice to deliver electricity. The plant can go from standby to production in two hours.

Karlshamnsverket is fueled by oil and has a total capacity of 662 MW. It’s been a reserve power plant since the beginning of the 1980s. This is a task that we take very seriously and that we have done quite well at. You could say that the power plant functions as insurance for the entire electricity system.

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This is how Karlshamns power station works

Listen to Henrik Pagels, operations manager at Karlshamns power station, when he shows us how Karlshamns power station works.

Ready to deliver power when Sweden needs it most

Over a longer period, for example an entire year, Swedish has a surplus of energy and we export large amounts of fossil-free electricity to other countries. However, this doesn’t meant that there is enough electricity at any given moment. Karlshamnsverket is there for those moments – when the system suddenly needs extra capacity. This is mostly during the winter, when we use a lot of electricity in Sweden.

The power plant is always staffed, regardless of the season or time of day, since interruptions to our electricity system can occur at any time. In addition to the power reserve, the power station can deliver several other supporting services, such as helping maintain a stable frequency in the electricity grid. The need for these services varies during the year – they’re not limited to the winter months.

It’s essential for a reserve power plant to be able to start up quickly when needed. That is why maintenance and improvement projects are so important at Karlshamnsverket, and what we spend the most of our time on when we’re not in operation. Many employees have expertise both in maintenance and in operations. Operational staff work with preventative maintenance, and we start up our maintenance technicians jump in as reserve power technicians and operate the power plant together with their operational colleagues.

The power reserve is the life line of the Swedish electricity system

With the environment in focus

The environment is very important to us. When you see smoke coming out of our chimneys or a large oil tanker in our port, remember that we work deliberately and systematically with all kinds of environmental issues that are relevant for our operations. We are ISO 14001 certified, which is an international standard that establishes what a company needs to do to have a structured environmental agenda. Certification means that we meet the high standards that certified companies adhere to in terms of environmental expertise and procedures. If you have questions about our environmental policy or goals, you are welcome to contact us at [email protected].

In the 1990s, we made major investments to reduce the power plant’s emissions. We installed an NO₂ catalytic converter in blocks 2 and 3. In block 3, there is also an electric filter and a desulfurization facility, with a proprietary technology and removal rate of more than 98%. That also makes it possible to use higher sulfur oil in block 3, and still keep emissions well below the given maximum levels.

Burning oil also creates carbon dioxide. Karlshamnsverket is part of the EU’s Emissions Trading System, which is an important tool for reducing carbon dioxide emissions.

Solljus genom fönster på Karlshamnsverket | Uniper

Flue gas cleaning at Karlshamnsverket

Effective flue gas cleaning in three steps

When oil is burned, carbon dioxide is also produced. Karlshamnsverket is part of the EU Emissions Trading System, which is an important tool for reducing CO₂ emissions.

Flue gases pass through the catalytic converter after being injected with vaporized ammonia through narrow ceramic channels. The ceramics are doped with vanadium pentoxide, which is the active component in the catalytic reaction. The subsequent chemical reaction creates water and nitrogen gas, which are both natural components in the air we breathe. The catalytic converter removes over 85% of the nitrogen oxide.

In the electric filter, flue gases pass through an electrically charged field where dust particles are trapped in large sheets. The removal rate is over 90%. The dust is sent to reprocessing, where its valuable contents of the metals vanadium and nickel are collected.

In the desulfurization facility, sulfur is removed from the flue gas to become usable gypsum. The desulfurization technology used is based on an idea developed at the power plant. The desulfurization facility has a removal rate of over 98%.

The first step in the desulfurization facility is a scrubber. Here, any particles that passed through the electric filter are removed and the flue gases cooled and injected with liquid. This high level of dust removal means that the flue gases are almost entirely free from dust and heavy metals when they go to the absorber for desulfurization. This guarantees that the final product from the facility, gypsum, is extremely clean.

In the absorber, sulfur dioxide in the flue gases reacts with finely ground limestone to produce gypsum. The gypsum produced in the absorber is removed using hydrocyclones and vacuum band filters. Gypsum is primarily used as raw material in gypsum boards.