The facility burns around 130,000 tonnes of residual waste annually, producing electricity and feeding a district heating network. But it generally delivers more heat to the network than required, particularly during the summer.
In response to this inefficiency, waste management firm Returkraft AS is piloting three custom-made CraftEngine devices that convert this wasted heat into electricity. These have been produced by Viking Heat Engines (VHE), a firm also based in Kristiansand. Installation was completed in November.
VHE’s devices are a form of external heat engine, using the organic Rankine cycle. Such engines can operate at much lower temperatures than steam turbine or combustion engine-based generators.
The small-scale installation will produce at least 150 kilowatt hours of electricity each year and will pay for itself within two or three years.
If all goes to plan, the firm could buy fifty or sixty of the engines, said Returkraft's managing director John Bernander. They will start being made on a production line in early 2015, so will come at a fraction of the current cost, he added.
The firm has already received inquiries from other waste-to-energy operators that are interested in implementing the technology.
Enova, the Norwegian government organisation dedicated to improving energy efficiency, provided 3.3 million kroner (€390,000) for the project, covering about half its cost.
