Wärtsilä Tests 100% Hydrogen Engine Connected to Spain's National Grid

Technology group Wärtsilä has begun validating its latest 100% hydrogen engine, which is directly connected to Spain’s national electricity grid in Bermeo, in the north of the country. The trial is the world’s first demonstration of a large-scale pure hydrogen engine supplying power to a national grid. The step is considered a significant milestone in the development of power generation technology based on sustainable fuels. Through this test, Wärtsilä seeks to prove that generating engines can operate using 100% hydrogen whilst supporting energy systems increasingly dominated by renewable sources. The test is being conducted using the Wärtsilä 31H2 engine, part of the Wärtsilä 31 platform, one of the world’s most efficient four-stroke multi-fuel engines. The engine is described as the world’s largest pure hydrogen engine currently undergoing performance verification in Bermeo. Rasmus Teir, Director of Strategy, Technology & Decarbonisation at Wärtsilä, said hydrogen technology development is a vital part of addressing the global energy transition challenge. “This is a test for the future of renewable energy. As countries rapidly scale up wind and solar power, one of the biggest challenges facing the energy transition is how to maintain a reliable and sustainable electricity supply during periods of low renewable generation or demand spikes. Currently, our Wärtsilä 31H2 hydrogen engine is operating on 100% hydrogen and supplying power to Spain’s national grid, demonstrating that large-scale hydrogen engines can provide flexible, schedulable sustainable power to support future renewable energy systems,” he stated. According to Teir, the successful trial shows that hydrogen technology is ready for commercial use. The next challenge is accelerating the development of regulations, investment, and infrastructure that support the utilisation of hydrogen as part of the future energy system. “We have proven that this technology is ready. Now, the focus must be on creating the right environment to scale it up, supported by firm regulation, investment clarity, and the necessary infrastructure to accelerate the growth of renewable energy and sustainable fuels like hydrogen. The technology is here – now it is time to scale it up,” Teir said. Green hydrogen is considered to have a strategic role in low-carbon energy systems because it produces no carbon emissions when used. Additionally, hydrogen can function as an energy storage medium from solar and wind generation and be reused when electricity production from renewables declines. The technology’s presence becomes increasingly relevant as global renewable energy capacity is projected to reach nearly 4,600 gigawatts (GW) by 2030. Under such conditions, electricity systems require flexible resources capable of maintaining grid stability when renewable energy supply fluctuates. Spain was chosen as the test location because it is one of the countries aggressively developing renewable energy whilst reducing dependence on fossil fuels. In June 2026, a number of Wärtsilä customers from various countries also witnessed the engine’s operation firsthand as part of the commercial validation process. Wärtsilä’s commitment to hydrogen technology development has also been realised in Indonesia. In November 2025, Wärtsilä together with PLN Indonesia Power successfully conducted a hydrogen blending test on a Wärtsilä 50DF engine at the Pesanggaran Power Plant in Bali. In that test, the hydrogen blend reached 23% under partial load conditions and showed improved combustion efficiency as well as reduced carbon emissions compared to using pure natural gas. Kari Punnonen, Energy Business Director Australasia at Wärtsilä Energy, said the tests in Spain and Indonesia demonstrate the flexibility of Wärtsilä’s engine technology in supporting the energy transition. “Developments such as the Bermeo hydrogen trial and the Pesanggaran Bali hydrogen blending test highlight the future-ready and fuel-flexible nature of Wärtsilä engine technology. Through close collaboration with our customers and partners in Indonesia, we are actively exploring how these capabilities can support Indonesia’s transition towards clean energy,” he said. Through the development of hydrogen technology, Wärtsilä believes that flexible engine-based power plants can be one of the solutions to maintain electricity system reliability whilst supporting decarbonisation targets in various countries.