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Innovation and Service for a World with Clean Power

About us


The history of Thomassen goes back to 1886 when Geurt Thomassen started a workshop in Arnhem, The Netherlands, specialized in the production of grinding tools for windmills and dressing machines for millstones. In 1896 we built our first own designed gas engine, starting a long series of engines that over the years gained great fame for their reliability and performance. In the sixties, as an OEM, we started to manufacture aircraft derivative and heavy-duty gas turbines. In total we have manufactured more than 300 heavy-duty gas turbines.

In the course of time, we pursued and acquired worldwide acknowledgement of our customizing capabilities. In the process of accommodating the customer’s needs, impressive history of innovative designs was built up, amongst others:

  • The world’s first model PG6551B gas turbine
  • The world’s first single shaft combined cycle
  • The world’s first DLN system for the LM6000PB high performance gas turbine

In 1997 Thomassen International split up in three different companies and Thomassen Turbine Systems (TTS) was born. We continued the manufacturing of GE-type gas turbines until license termination in the year 1999. With all engineering knowledge gained while being original equipment manufacturer, we shifted our activities to the aftermarket service business.

In 2006 TTS was taken over by original equipment manufacturer Ansaldo Energia further enhancing fast, innovative and reliable service solutions for third party technologies. Additionally in 2010, a new workshop for heavy-duty gas turbine repairs was opened in Abu Dhabi under the name of Ansaldo Thomassen Gulf but in the meantime Ansaldo ESG left the group.

In 2016 the American company Power Systems Manufacturing (PSM) joined the Ansaldo Energia Group. PSM is a full service provider to gas turbine equipped power plants worldwide, offering field services and flexible Long Term Service Agreements, technologically advanced aftermarket turbine components & performance upgrades, and parts reconditioning & repair for Frame 6B, 7B/E/EA, 9E, 9FA, 7F and 501F/701F.

In 2021 Ansaldo Thomassen was acquired by the Korean company Hanwha General Chemical which led to our new company name Thomassen Energy BV. Together with PSM we are now part of the Hanwha Gas Turbine Services group offering a complete product and service portfolio for multiple technologies.