Representing over €300m ($352m) of investment, the electrolyser plant is expected to produce 15,000 tonnes of green hydrogen per year. Repsol is expected to use the hydrogen to decarbonise its industrial processes.

Enagás Renovable holds a 25% stake in the project, adding to its portfolio of nearly 20 hydrogen projects under development in Spain.

The European Commission and the Spanish government have recognised the initiative as an Important Project of Common European Interest (IPCEI), with €155m ($135m) in funding allocated through the Institute for Diversification and Saving of Energy (IDAE).

The company said it is the Iberian Peninsula’s largest producer and consumer, responsible for 60% of Spain’s output and 4% of Europe’s total consumption.

The Cartagena site is already central to Repsol’s hydrogen strategy.

Earlier this year, Repsol produced 6.5 tonnes of turquoise hydrogen there using biomethane as an alternative to natural gas, leveraging its existing reforming infrastructure.

Repsol said the initiative supports demand for biomethane and advances a circular economy approach, building on earlier pilot production at the site in 2021.

This came shortly after the Spanish oil and gas firm scaled back its broader green hydrogen ambitions, pausing several planned projects in 2024.