Dallas-based HollyFrontier said last week it selected Haldor Topsoe’s HydroFlex sustainable renewable fuel technology to produce clean renewable diesel from various feedstocks at its Navajo refinery in Artesia, N.M. Danish company Topsoe will license its HydroFlex technology to Artesia Renewable Diesel Co. as well as supply basic engineering, equipment, catalysts and technical services for the new RDU unit, which is scheduled to be completed in early 2022.