Stiesdal

Stiesdal A/S is a Danish climate technology company founded in 2016 by Henrik Stiesdal, a pivotal figure in the modern wind power industry. Stiesdal's journey began long before the company's inception; he designed and built one of his first wind turbines in 1976 and licensed a commercial design to Vestas in 1979, a move that helped catalyze the global wind industry. His extensive career includes roles as CTO for Bonus Energy (later Siemens Wind Power), where he was instrumental in developing the world's first offshore wind farm in 1991. After retiring from Siemens in 2014, he established Stiesdal A/S to develop and commercialize high-impact climate change mitigation technologies.

The company operates on a business-to-business model, focusing on the industrialization of green technologies to reduce costs and accelerate adoption. Stiesdal is structured into three primary subsidiaries, each tackling a different segment of the green transition. **Stiesdal Offshore** focuses on industrialized foundations for floating offshore wind turbines. Its flagship product, the Tetra foundation, uses a modular, tetrahedral steel structure that allows for lean, factory-based manufacturing and rapid, port-side assembly, significantly lowering costs compared to traditional methods. A full-scale demonstrator, the TetraSpar, was deployed off the coast of Norway in 2021 in partnership with Shell, RWE, and TEPCO.

**Stiesdal Hydrogen** aims to make green hydrogen production more affordable. The subsidiary has developed the HydroGen Electrolyzer, a modular alkaline electrolysis unit designed for mass production and seamless integration with fluctuating renewable energy sources. These systems are engineered for a plug-and-play installation, removing the need for complex on-site construction and enabling rapid deployment for Power-to-X applications, such as upgrading biogas or creating clean fuels.

**Stiesdal SkyClean** provides a carbon-negative technology that combines biofuel production with carbon capture. The SkyClean system uses pyrolysis to convert agricultural and forestry waste into biochar, renewable gas, and oil. The process captures atmospheric carbon in the stable biochar, which can be sequestered in soil for centuries while also acting as a soil enhancer. The generated biofuels offer a carbon-neutral alternative for sectors like transportation. A 20MW demonstration plant in Vrå, Denmark, validates the technology at an industrial scale.

Keywords: Henrik Stiesdal, climate technology, floating offshore wind, green hydrogen, carbon capture, Power-to-X, TetraSpar, industrialized foundations, pyrolysis, biochar, SkyClean, HydroGen electrolyzer, renewable energy, energy storage, climate change mitigation, sustainable fuels, wind turbine technology, carbon sequestration, modular design, green transition