Company timeline
SkyClean was established to develop slow pyrolysis into an industrial solution for carbon removal and renewable energy production. From early development at DTU Risø to the world’s largest pyrolysis plant in Vrå, the timeline below traces the key milestones in scaling the technology from research to commercial operation.
Pre-2019
Technology development at DTU Risø
The foundation of the SkyClean technology was developed through research at The Technical University of Denmark (DTU) Risø, focusing on controlled slow pyrolysis and biochar production.
Photo: Energy Cluster Denmark
Photo: Energy Cluster Denmark
July 2019
Stiesdal SkyClean incorporated
The SkyClean business unit was established to commercialise pyrolysis technology for carbon removal and energy production.
Building on research into slow pyrolysis at DTU Risø, Henrik Stiesdal identified that existing solutions lacked the robustness and scalability required for industrial deployment. Stiesdal SkyClean A/S was created to develop a fully integrated, industrial system, bringing control, efficiency and scale to biochar production and carbon removal.
Building on research into slow pyrolysis at DTU Risø, Henrik Stiesdal identified that existing solutions lacked the robustness and scalability required for industrial deployment. Stiesdal SkyClean A/S was created to develop a fully integrated, industrial system, bringing control, efficiency and scale to biochar production and carbon removal.
August 2021
200 kW SkyClean test plant inaugurated
The 200 kW test plant in Brædstrup was built by a local blacksmith using the technology developed at DTU Risø. The plant had a capacity of 200 kW and could treat 500 tons of agricultural waste annually, resulting in a total CO₂ reduction of approximately 600 tons.
Operation of the 200 kW test plant provided key insights into feedstock handling, process stability and biochar quality, forming the basis for scaling to pilot level.
Operation of the 200 kW test plant provided key insights into feedstock handling, process stability and biochar quality, forming the basis for scaling to pilot level.
March 2022
2 MW fully automated SkyClean pilot plant inaugurated
In 2022, a ten times bigger pyrolysis plant (2MW) was built in Skive as a part of an energy cluster called GreenLab. This plant was designed to use straw pellets as feedstock.
The 2 MW pilot plant enabled continuous operation, process optimisation and validation of system performance, supporting the design of industrial-scale plants.
The 2 MW pilot plant enabled continuous operation, process optimisation and validation of system performance, supporting the design of industrial-scale plants.
June 2022
SkyClean Scale-up project receives €16.5 million
Together with 4 universities and several industrial partners, the SkyClean Scale-up project received funds to further develop pyrolysis as a technology and scale up SkyClean’s pyrolysis plant to industrial and commercial size.
October 2024
20 MW full scale SkyClean plant inaugurated in Vraa
The world’s largest pyrolysis plant enters operation in Vrå, Denmark. Integrated with an Agri Energy biogas facility, the plant converts digestate fibres into biochar while supplying surplus heat to the co-located biogas upgrading process.
The 20 MW SkyClean plant in Vrå can capture 0.8 tons CO₂e per hour and produce 8.5 MW of heat.
The 20 MW SkyClean plant in Vrå can capture 0.8 tons CO₂e per hour and produce 8.5 MW of heat.