Wärtsilä Tests 100% Hydrogen Engine Connected to Spain's National Grid
Technology group Wärtsilä has commenced the validation of its latest 1s00% hydrogen engine, which is directly connected to the Spanish national electricity grid in Bermeo, in the country’s northern region. This trial serves as the world’s first demonstration of a large-scale pure hydrogen engine supplying electricity to a national grid.
This step is considered a significant milestone in the development of sustainable fuel-based power generation technology. Through this testing, Wärtsilä aims to prove that power generation engines can operate using 100% hydrogen while supporting energy systems increasingly dominated by renewable energy sources.
The test is being conducted using the Wärtsilä 31H2 engine, part of the Wärtsilä 31 platform, which is one of the highest-efficiency four-stroke multi-fuel engines in the world. The engine is described as the largest pure hydrogen engine currently undergoing performance verification in Bermeo.
Rasmus Teir, Director of Strategy, Technology & Decarbonisation at Wärtsilä, stated that the development of hydrogen technology is a vital part of addressing global energy transition challenges.
“This is a trial for the future of renewable energy. As countries rapidly scale up wind and solar energy, one of the greatest challenges facing the energy transition is how to maintain a reliable and sustainable power supply during periods of low renewable generation or surges in demand. Currently, our Wärtsilā 31H2 hydrogen engine is operating with 100% hydrogen and supplying power to the Spanish national grid, demonstrating that large-scale hydrogen engines can provide flexible and dispatchable sustainable power to support future renewable energy systems,” he said, as quoted from a press release.
According to Teir, the success of the trial indicates that hydrogen technology is ready for commercial use. The next challenge is to accelerate the development of regulations, investment, and infrastructure to support the use 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 robust regulation, investment clarity, and the necessary infrastructure to accelerate the growth of renewable energy and sustainable fuels such as hydrogen. The technology exists – now it is time to scale it,” said Teir.
Green hydrogen is considered to have a strategic role in low-carbon energy systems because it produces no carbon emissions during use. Additionally, hydrogen can serve as an energy storage medium for solar and wind power, to be used when renewable electricity production decreases.
The relevance of this technology is increasing alongside the projected global renewable energy capacity, which is expected to reach nearly 4,600 gigawatts (GW) by 2030. In such a scenario, electricity systems require flexible resources capable of maintaining grid stability during fluctuations in renewable energy supply.
Spain was chosen as the testing location because it is one of the countries aggressively developing renewable energy while reducing dependence on fossil fuels. In June 2026, several Wärtsilä customers from various countries also witnessed the operation of the engine 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 blend 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, showing improved combustion efficiency and a reduction in carbon emissions compared to using pure natural gas.
Kari Punnonen, Energy Business Director Australasia for Wärtsilä Energy, stated that the tests in both 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 blend test highlight the future-ready and fuel-flexible nature of Wärtsilä’s 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 this hydrogen technology, Wärtsilä believes that flexible engine-based power plants can serve as a solution to maintain the reliability of electricity systems while supporting decarbonisation targets in various countries.