Spanish gas grid operator Enagas SA (<a href="https://www.bolsasymercados.es/bme-exchange/es/Mercados-y-Cotizaciones/Acciones/Mercado-Continuo/Ficha/Enagas-ES0130960018" target="_blank">BME:ENG</a>) and Belgian chemicals group Solvay SA (<a href="https://live.euronext.com/en/product/equities/BE0003470755-XBRU" target="_blank">EBR:SOLB</a>) have signed an agreement to develop a hydrogen storage facility in underground salt caverns in Polanco, in the northern Spanish region of Cantabria, the companies said.