Sandvik CHP Station in Växjö, Sweden delivers heat and electricity to the Municipality of Växjö.
Växjö, a 80,000 citizen city in southern Sweden, is striving to become one of the greenest cities in Europe. At the combined heat and power plant, Sandvik, the conversion to biomass has been pivotal in the attempt to meet future energy demand in sustainable fashion.
In 1996, Växjö Municipality decided to become fossil-free. The city engineered a partnership with local firms, industries and transport companies. Together, they signed the policy commitment “Fossil Fuel Free Växjö” to stop using fossil fuels and reduce CO2 emissions within heating, energy, transport, businesses and private homes.
Since then, long-term planning, heavy investments and close monitoring of all carbon emissions have been key enablers of the ambitious vision that has become particularly successful in using biomass for district heating. Today, Växjö is a green, vibrant city at the heart of Kronoberg, Sweden. But population challenges are mounting.
Fossil-free electricity and heat
In a few years, the number of inhabitants is expected to reach 90,000. To meet the ever-growing demand for district heating, district cooling and electricity, the Sandvik plant needed to be expanded with a Unit 3 that will replace the old oil-fired unit, Sandvik 1.
- The new Unit 3 ensures energy security for the Municipality of Växjö. It uses sustainable local fuels such as wood chips, bark, saw dust and branches, ultimately making Växjö’s heat and power production fossil-free, says Project Manager Nils F. Forsberg.
The CHP plant comprises external fuel handling, steam boiler, steam turbine, generator and flue gas cleaning, and the 105 MW of thermal power is distributed on approximately 40 MW of electricity and 65 MW of district heating. And it boasts an energy utilisation factor of 92%.
Ramboll was chosen to be responsible for the biomass boiler, flue gas treatment, balance of plant, and steam turbine. The project encompasses all phases from procurement of the major components, monitoring of manufacturing, erection and commissioning to commercial operation and guarantee test.
The expansion represents the largest investment in renewable energy in Växjö’s history. And an investment project of this size does not come without a challenge or two.
- The erection phase lasts several seasons, and heavy weather conditions could close down the construction activities for periods. Planning the time schedule requires a certain margin for these external risks and stresses. Also, expanding a power station that is in full operation takes some extra care to avoid disturbance during tie-in and future operation, explains Nils F. Forsberg.
The Project Manager adds that a project of this scale also takes strict coordination between different disciplines and cultures to keep the time schedule and meet quality demands.
The plant is scheduled for commissioning in 2014/2015.