Iberdrola Tests Molten-Salt Steam at Bayer's Aspirin Plant in Spain

• Iberdrola España began testing renewable steam supply to Bayer's La Felguera plant, which makes the active ingredient of Aspirin.
• A molten-salt heat store, a 15-MW PPA and 2.5 MW of on-site solar are set to replace fossil fuels.
• Tests run to the end of 2026; the EU grant fiche lists Dec. 31 as the start of operation.

Iberdrola España has begun testing a system that supplies renewable steam to Bayer's plant in La Felguera, in northern Spain's Asturias region, the companies said on Nov. 4 and Nov. 5. The site makes acetylsalicylic acid, the active ingredient of Aspirin, for markets worldwide.

The installation replaces fossil-fuel steam with electrified steam production and a molten-salt thermal storage system using technology from Spain's Inerco. Power is stored as heat when renewable output is high and prices are low, then turned into steam when the factory needs it. A 15-MW long-term power purchase agreement and a 2.5-MW self-consumption solar array cover the entire steam demand. Bayer buys the steam under a heat purchase agreement, and Iberdrola put the investment at more than €18 million ($20.2 million).

The companies say the project will avoid about 6,500 tonnes of CO2 a year. The European Union's Innovation Fund project fiche gives a lower figure: 55,171 tonnes of CO2 equivalent over the first ten years. The fund backs the project, Green Heat Asturias, with an €8.04 million grant.

The project in numbers

• 32.4 GWh of saturated steam a year at 24 bar, per the EU fiche.
• 15 MW under a long-term renewable PPA, plus 2.5 MW of on-site solar.
• 95.9% overall energy efficiency, per the EU fiche.
• 3.7 MW of average steam output over 8,760 hours a year (list.solar calculation).
• 5,517 tonnes of CO2 a year on the EU's ten-year estimate, versus the companies' 6,500 (list.solar calculation).
• About €2,770 ($3,110) of investment per tonne of annual CO2 avoided (list.solar calculation).
• 44.7% at most of the investment is covered by the EU grant (list.solar calculation).

The heat plant sits on the site of Iberdrola's Lada coal-fired power station in Langreo, closed in 2020, according to Iberdrola España. Bayer has bought renewable power from Iberdrola since 2020. With steam added, the site will be fully decarbonized, the utility said. Other industrial sites take different routes: in Coventry, England, the MTC added a 786-kW solar thermal roof.

David Martínez, chief executive of Iberdrola Energía España, called it Spain's first large steam electrification project with thermal storage. He said the technology could decarbonize up to 50% of the heat Spanish industry uses.

Tests run to year-end, and the EU fiche lists Dec. 31, 2026, as the entry-into-operation date. When the partners signed the deal in April 2025, they budgeted €17 million and targeted completion by June 2026.