The venture capital arm of the French industrial gases company Air Liquide has taken minority stakes in three European start-up firms. France-based McPhy Energy develops generators that produce hydrogen by water electrolysis; it then stores the gas as solid magnesium hydride. Another French firm, Solumix, makes an insulating material from natural raw materials. Air Liquide says Solumix can benefit from its technology in the field of porous materials. And Xylowatt, based in Belgium, has developed technology for producing synthesis gas from biomass.