About us

Söderenergi produces district heating for approximately 300,000 residents, as well as for offices and industries in the southern Stockholm region, along with enough electricity to supply around 100,000 homes.

Each year, we convert around 1 million tonnes of waste into energy. About half of this is delivered by ship to our port in Södertälje. Our main production takes place at the Igelsta facilities in Södertälje. This is also where electricity is generated at the CHP plant, Sweden’s second-largest biomass-fired combined heat and power plant. In addition, we operate a district heating plant in Fittja and a smaller facility in Skogås.

The majority of our heat production is sold and distributed to our owner municipalities by Telge Nät in Södertälje and Nykvarn, and by Södertörns Fjärrvärme in Huddinge, Botkyrka, and Salem. We also have production partnership agreements with Stockholm Exergi and Norrenergi. This collaboration strengthens heat production and sales while enabling more efficient use of the shared production system.

Watch our film: Söderenergi – Eco-smart energy (with English subtitles)

Short facts about Söderenergi

Fourth largest district heating producer in Sweden
Produces approximately 2,500 GWh of district heating in a normal year.
Produces approximately 500 GWh of electricity in a normal year.
Sells electricity certificates.
Produces steam and hot water for industry in Södertälje.
Certified in environmental and occupational health and safety management.
Was established in 1990. Watch our film Söderenergi the story – being part of the ecocycle

Our business idea

We create sustainable and innovative solutions together with recycling and energy clients in the circular society.

Our vision

A sustainable society and improved quality of life for future generations.

Values

Collaboration, Commitment, Honesty, Openness and Respect are the values that guide everything we do at Söderenergi.

Sustainability

Our contribution to society

We create long-term value for our owner municipalities and customers by delivering reliable, competitive energy with low environmental and climate impact. Through efficient resource use and continuous innovation, we contribute to a more circular and resource-efficient society.

Through our environmental services, we support efficient waste management by recovering energy from residual waste that cannot be reused or recycled. This reduces landfill dependency and enables the production of district heating and electricity.

Söderenergi integrates environmental, social and economic considerations across its operations and business relationships. As an employer, neighbour and local partner, we aim to create positive impacts for employees, communities and future generations.

Our sustainability policy is based on three areas

Climate and environment
We prioritize recycled and renewable fuels, improve energy efficiency, and work to reduce emissions and other environmental impacts. We promote reuse and recycling of residual materials and deliver reliable, competitive energy with low environmental and climate impact.
Occupational health and safety and social sustainability
A safe and well-functioning work environment is essential for well-being and performance. We focus on safety, health and prevention across physical, organizational and social aspects, and act in line with our values to promote a sustainable working life and society.
Economic Sustainability
We uphold high standards of business ethics with zero tolerance for bribery and corruption. We ensure transparency in operations and procurement and require suppliers to comply with our Code of Conduct and sustainability requirements.

Read our latest Sustainability Policy

Our Environmental service – a business model for district heating

Our district heating system is part of the waste hierarchy, reducing the need for landfill. After recyclable materials have been sorted, we recover energy from remaining waste.

This process produces district heating and electricity while keeping emissions to air and water controlled. Residual materials such as ash are safely managed and prepared for future recycling where possible.

Our environmental service supports resource efficiency across value chains for waste producers, recyclers, property owners and energy users.

Business ethics

We promote strong business ethics, long-term relationships and procurement in line with the principle of public access. We require suppliers to comply with our Code of Conduct and ensure adherence throughout their own supply chains.

Söderenergi’s Supplier Code of Conduct

Our plants

When Söderenergi was established, several energy production facilities already existed. A few of these are still used today as backup production during very cold days, when energy demand is high. Over the years, the facilities at Igelsta have been upgraded and expanded to support a modern district heating system.

The Igelsta combined heat and power plant was built in 2009 and is currently Sweden’s second-largest biomass-based facility that produces both heat and electricity.

Igelsta combined heat and power plant

This combined heat and power production facility is the largest environmental investment to date for the municipalities of Södertälje, Botkyrka, and Huddinge. It is an investment that contributes to improved climate performance locally, nationally, and globally. Carbon dioxide emissions are reduced by approximately 75,000 tonnes of CO₂ per year, equivalent to the emissions from around 25,000 petrol-powered cars driven 15,000 kilometres annually.

The scale of the facility is considerable. The main boiler is 50 metres high, and its total weight of 3,000 tonnes is suspended from the roof structure to allow for expansion during temperature changes. The turbine and generator together weigh 373 tonnes and are among the supplier’s largest units for electricity production using biofuel. Annual fuel consumption exceeds 600,000 tonnes of biofuel, equivalent to approximately 100 tonnes per hour.

All benefits of the facility come from the efficient use of recycled wood waste and forest residues to produce both electricity and district heating. The facility uses a circulating fluidised bed (CFB) combustion system. The bed consists of fine-grained sand which, together with combustion air from below and fuel input, forms a fluidised hot bed at approximately 850°C. This process creates high thermal inertia, which rapidly evaporates moisture in the fuel.

A common misconception is that fuel must be dry. In reality, many recycled fuels contain high moisture content. This technology enables efficient combustion of such fuels and also allows energy recovery from moisture through flue gas condensation. As a result, the facility is well suited for fuels with high moisture content.

Electricity is produced in a steam turbine and generator that convert thermal and kinetic energy in steam into electricity. The steam conditions are 540°C and 90 bar, known as superheated steam, meaning it is approximately 240°C above the boiling point. The turbine rotor weighs over 30 tonnes and rotates at 50 revolutions per second. This requires highly precise monitoring to ensure safe operation and efficient resource use.

The combined heat and power plant has a capacity of 210 MW of heat and 85 MW of electricity and is a key asset for Söderenergi. It operates for approximately 6,200 hours per year and produces around 1,400 GWh of heat and 500 GWh of electricity annually.

Igelsta CHP Plant

Igelsta heating plant

The heating production facility includes three hot water boilers as well as a steam generator for delivering high-quality steam to local industry. The facility was originally built with three identical boilers for pulverised coal combustion. Today, all boilers have been converted to use biofuels and solid recovered fuel (SRF).

Boiler 1 is primarily fuelled by solid recovered fuel (SRF). It was converted in 1997 from pulverised fuel combustion to grate combustion. In this system, combustion air is supplied from below while fuel is fed from above via a moving grate (“travelling grate”). The maximum output is approximately 80 MW. The boiler is one of Söderenergi’s key production units, with an operating time of over 6,000 hours per year, corresponding to approximately 430 GWh.

Boiler 2 is fuelled by bio-oil (tall oil pitch). It is a peak-load boiler, meaning it is mainly used during the autumn and winter seasons. The maximum output is approximately 95 MW.

Boiler 3 is primarily fuelled by recycled wood waste (RWW). It uses a bubbling fluidised bed (BFB) combustion system. The bed consists of fine-grained sand which, together with combustion air from below and fuel input, forms a fluidised bed at approximately 850°C. This creates high thermal inertia, allowing rapid evaporation of moisture in the fuel. The design makes the boiler well suited for fuels with high moisture content, and it is equipped with flue gas condensation to recover additional energy from the flue gases. The maximum output is approximately 95 MW, and the boiler operates as one of Söderenergi’s base-load units. It runs for approximately 3,500 hours per year, corresponding to around 300 GWh.

Fittja plant

The Fittja production facility is located in Botkyrka. It includes two hot water boilers with a total heat output of 380 MW. The facility is primarily fuelled by wood pellets that are ground into powder. It is generally in operation during the winter season.

Söderenergi’s subsidiary SFAB has its headquarters located at the Fittja production facility.

Skogås heating plant

The facility is located in Huddinge municipality. The district heating system is hydraulically interconnected with Stockholm Exergi’s network. Heat demand in the area is approximately 120 GWh in a normal year, of which Skogås supplies around 20 GWh.

The heating production facility has four smaller boilers, fuelled by bio-oil.

In addition to our production facilities, we also operate a port and a fuel terminal.

Igelsta port

Approximately half of the total volume of solid fuel arrives by sea, primarily from Northern Europe. The port has capacity for two vessels at a time and handles around 150 ship calls per year.

The port includes a small unloading area, a sampling station, a fuel processing facility, and a conveyor system. From a safety perspective, applicable maritime and port safety regulations are followed.

Nykvarn train terminal

The train terminal is located on an area of eight hectares next to the Svealand Railway in Nykvarn. Here, we receive forest residues in containers transported from different parts of Sweden.

The facility also functions as a solid fuel depot and serves as our central logistics hub. A heat-sensing camera system, combined with fire detection and intrusion monitoring, is used to monitor each individual fuel pile and analyse temperature trends.

All heavy equipment and vehicles on site run on 100% biofuel. Fuel is transported from the terminal to Söderenergi’s main production facility by a fully electric shuttle truck.

BECCS

Söderenergi initiated a BECCS (Bioenergy Carbon Capture and Storage) project with the ambition of contributing to both national and international climate targets through the capture and permanent storage of approximately 500,000 tonnes of biogenic carbon dioxide annually. The project was paused in 2026 but remains an important opportunity for future negative emissions.

The Igelsta Plant in Södertälje offers highly favourable conditions for BECCS implementation. The combined heat and power plant operates on biomass fuel, providing a suitable biogenic CO₂ stream for capture. The site also offers sufficient space and energy capacity for the capture process, while its own port with direct access to the Baltic Sea provides a significant logistical advantage for future CO₂ transport and storage.

Utilising the captured biogenic CO₂ (BECCUS) alongside storage is also an option, as it can be reused in products such as fuels, chemicals, or building materials, providing additional environmental benefits by reducing the need for fossil-based inputs.

Efficient energy recycling

Söderenergi’s R1 factor is 1.19 (average for 2025).

Energy recovery efficiency is measured using the R1 energy efficiency factor. The higher the R1 value, the more efficient the energy recovery. The minimum required value is 0.65. A value of 1.19 is high in a European context and reflects the fact that we produce both electricity and district heating, enabling more complete energy recovery.

Waste that cannot be reused in new products has its energy recovered in our boilers instead of being sent to landfill. This energy recovery takes place after material recycling and is a natural step in the EU waste hierarchy.

Only waste incineration with efficient energy recovery is considered recovery. This is defined in the EU Waste Framework Directive as well as in Swedish waste management regulations.

Fuels

Waste as fuel

When choosing fuels, we aim to balance three key environmental objectives: reduced climate impact, improved resource management, and a non-toxic environment. By using waste as fuel, the need for virgin renewable and fossil fuels can be reduced. According to the EU waste hierarchy, waste should first be prevented and, as a last resort, disposed of in landfill.

We primarily use recovered and renewable biofuels.

The benefit of district heating is already reflected in the waste hierarchy model. Once materials that can be recycled or reused have been sorted out, we manage the remaining fraction and recover its energy. We do not compete with material recycling; instead, we use waste as a source of energy that would otherwise be lost.

For wood-based fuels, we require sourcing in line with the UN Global Compact’s Ten Principles, ensuring that fuel does not originate from illegal logging or protected forests.

Renewable biofuels

Forest residues
Wood pellets
Bio-oil

Recovered fuels

Recycled wood waste (RWW)
Solid recovered fuel (SRF)

Based on 2025 data

Based on 2025 data.

Waste customers

The Environmental Service for our waste customers – a verification tool

Climate impact and requirements for circularity are becoming increasingly important, particularly in energy recovery. To demonstrate the benefits of our collaboration, we offer an Environmental Service for waste customers.

Based on this service, we have developed a verification tool that increases transparency and traceability of waste flows. The tool documents and quantifies the climate and environmental benefits for our waste customers. In practical terms, it enables the calculation of benefits associated with a specific amount of waste, including the resulting production of heat and electricity, recovered metals, and quantities of heavy metals such as lead.

This verification improves transparency and strengthens traceability across the waste value chain.

Verification that increases transparency and traceability of waste.

Contact person: Jan Steinle, Fuel Manager.

Work at site

At Söderenergi, the working environment, safety, and environmental considerations are always top priorities. Work at our facilities involves risks, and we prioritise the safety of both visitors and personnel. Failure to comply with safety and security rules may result in immediate removal from the site.

For visitors

Visits to Söderenergi’s facilities must be arranged in advance with a responsible contact person on site. If you have not completed SSG training, you must be accompanied by an employee during your visit to the area or facilities.

Contractors working on site

Contractors working within Söderenergi’s facilities must have a valid SSG Access card and completed SSG safety training with passing results. SSG is responsible for administration and training.

All contractors must bring their own helmet and high-visibility vest. For questions regarding SSG requirements at Söderenergi, please contact the work environment coordinator.

Site Huts at Igelstaverket

Site huts must be ordered no later than four weeks before arrival at the Igelsta plant.

Safety rules for Drivers

At Söderenergi, safety, working environment, and environmental responsibility are prioritised. Work at our facilities involves several risks, and we expect all visitors and drivers to follow our safety rules.

Upon arrival, all drivers must register with the gate for access.

Passengers are not allowed within the facility.
Additional drivers for training or long-distance transport must be registered with the gate.
Pets are not allowed outside vehicles and remain the responsibility of the driver.
Traffic rules, signs, and instructions must be followed at all times.
You may only be in or near your vehicle; a helmet and high-visibility vest must be worn when outside the vehicle.
Safety goggles and respiratory protection must be used where required. Fuel drivers must use P3 filters.
Fall protection is required when working at heights above two metres.
Cargo must be uncovered within the facility and littering must be avoided.
Fuel deliveries requiring sampling or weighing must be unloaded in the designated area.
Remaining deliveries must be uncovered after weighing (outside the scale).
Do not obstruct other traffic; plan parking carefully.
Vehicles must be cleaned before leaving the site to protect the surrounding environment.
Cargo areas must be covered before exiting the facility.
Vehicles must leave the site as soon as possible after delivery.
Failure to comply with safety rules may result in immediate removal from the site.