Technology group Wärtsilä has started validation of a new 100% hydrogen engine to power Spain’s national electricity grid in Bermeo, northern Spain – the world’s first demonstration of a large-scale, 100% hydrogen engine.

The trial marks a major step forward in proving that engine technology can operate on 100% sustainable fuels such as hydrogen, building on Wärtsilä’s earlier launch of the world’s first large-scale 100% hydrogen-ready engine power plant and opening a clear pathway towards fully renewable power systems. With global renewable energy generation set to grow by almost 4,600 GW by 2030, flexible technologies capable of balancing grids during periods of low wind and solar output are becoming increasingly critical.

Green hydrogen produces no carbon emissions, enabling clean power generation while supporting the decarbonization of renewable-heavy grids. It can store excess renewable electricity and provide reliable power when wind or solar generation drops, helping to stabilize the system and improve energy reliability.

The Wärtsilä 31H2 engine, part of the Wärtsilä 31 platform, one of the world’s most efficient multi-fuel 4-stroke engines, shows that hydrogen can move beyond theory into real-world energy infrastructure. The Wärtsilä 31H2 engine is the world’s largest pure hydrogen engine, with performance currently being verified in Bermeo.

Rasmus Teir, Director of Technology Strategy & Decarbonization at Wärtsilä, said, “This is a trial for the future of renewable power. As countries rapidly scale wind and solar energy, one of the biggest challenges facing the energy transition is how to maintain reliable electricity supplies sustainably during periods of low renewable generation or spikes in demand. Today, 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 the flexible, dispatchable sustainable power needed to support future renewable energy systems.”

“We have proven the technology is ready. Now, the focus must be on creating the right environment to scale it, underpinned by decisive regulation, investment clarity, and the infrastructure needed to accelerate the growth of renewable energy and sustainable fuels like hydrogen. The technology is here – now it’s time to scale it.”

The Wärtsilä 31 based power plant is designed to support rapidly growing, energy-intensive industries – including data centers, manufacturing facilities and industry – with flexible, sustainable power generation, and off-grid environments.

Spain, as one of the forerunners in renewable energy adaption, provided an ideal location for the trial thanks to its efforts to reduce exposure to fossil fuel volatility, making it a strong test bed for demonstrating the future potential of hydrogen technologies.

In June 2026, Wärtsilä’s customers from around the world witnessed the operation of the engine, marking a significant milestone in its commercial validation.