In Sweden, municipal utility company Göteborg Energi AB has begun commissioning of its largest climate investment ever – a new biomass-fired steam boiler unit – that replaces fossil gas previously used in its Rya combined heat and power plant.
Being integrated with the existing Rya CHP plant enables Göteborg Energi to provide, under normal operating conditions, 100 percent renewable and recovered district heat to the city – a core target of the city’s Environment and Climate Program.
I am both proud and happy that we are now fulfilling our promise to the people of Gothenburg. The district heating will be completely recycled and renewable, and we will no longer be dependent on fossil natural gas. This will both provide greater security in our deliveries and strengthen the city’s energy preparedness, said Per-Anders Gustafsson, CEO of Göteborg Energi.
With a price tag of SEK 2.53 billion (≈ EUR 231 million), the new steam boiler is Göteborg Energi’s single largest climate investment to date.
We now have momentum in the climate transition in Gothenburg. I am very pleased that Göteborg Energi’s largest climate investment ever has been completed. District heating in Gothenburg will now be completely free of fossil gas, resulting in significant emission reductions for the city. At the same time, we will receive locally produced renewable energy that increases security of supply, said Karin Pleijel (MP), municipal councilor and ultimately responsible for the city’s climate work.
On time and under budget
According to Göteborg Energi, the project was completed on time and within budget. Groundbreaking was held on November 29, 2023, and two years later, the plant was up and running.
On November 17, 2025, we had the first fire, and the unit has been part of our regular district heating production ever since. The project schedule has been extremely tight, but we managed it on time and well under budget, said Per-Anders Gustafsson.
The new unit utilises bubbling fluidised bed (BFB) technology, which allows for the use of a wide range of fuels.
Supplied by Valmet, which also delivered the boiler building, flue gas cleaning and flue gas condensing systems, and piping to connect the new boiler to the existing steam turbine, the new unit provides 156 MW of heat and 39 MW of electricity to the local energy system.
Raumaster supplied the external fuel reception, storage, and handling system while civil works were conducted by Veidekke Entreprenad.
Rya energy hub
The basis for Göteborg Energi’s district heating is recovered heat from the port’s oil refineries and a waste-to-energy (WtE) facility.
When it gets colder, and recovered heat is not enough, additional biomass-fired production units are started up.
The Rya site is a central hub in Göteborg Energi’s district heating production. In addition to the Rya CHP plant, there is also a large hot water buffer tank that functions as an energy storage facility, and heat pumps at Rya VP help optimise operation in the system.
The new biomass-fired steam boiler is a baseload plant, the first to be started in the system. This means continuous production of both heat and electricity from the end of September to mid-May, approximately 4,000 hours annually.
Increased flexibility and security with reduced environmental impact
With the integration of the new steam boiler with the existing Rya CHP plant, the entire area becomes an energy “Swiss Army knife”.
Depending on the circumstances, the Rya units can be run on a variety of fuels and optimised based on prevailing circumstances.
This means that the Rya CHP plant and the entire site become a key player in the city’s energy preparedness and the development of civil defence. The existing gas turbines will remain in place and can be quickly deployed to deliver power to the Swedish electricity system should a shortage situation arise. If we were to maximise production, it would be about an electricity production output of 260 MW and a heat production of 465 MW, which in a state of emergency would be very valuable for Gothenburg’s energy supply, remarked Per-Anders Gustafsson.
By using regionally sourced recycled wood and logging residues as fuel instead of imported fossil gas, the new steam boiler reduces fossil carbon dioxide (CO2) emissions by approximately 30,000–150,000 tonnes annually, compared to historical levels.
We will get significantly better environmental values for our district heating. We will go from just under 50 g CO2eq/kWh in 2024 to around 25 g/kWh in 2026, said Per-Anders Gustafsson.
Being no longer dependent on fossil gas to heat homes and business premises in Gothenburg also helps stabilise heat prices by reducing exposure to volatile gas prices.
With the new biomass-steam boiler in place, we are not exposed to gas prices. Historically, not least during the recent energy crisis, we saw that gas prices could skyrocket in a short time frame, and that gas shortages can occur. Now we have the boiler in place, it will be the basis for continued low and stable district heating prices, concluded Per-Anders Gustafsson.
