German steel producer Salzgitter AG<a href="https://www.boerse-frankfurt.de/equity/salzgitter-ag" target="_blank"> (ETR:SZG) </a>has signed a preliminary agreement to purchase green hydrogen from local energy group Uniper SE <a href="https://www.boerse-frankfurt.de/equity/uniper-se-na-o-n-1" target="_blank">(ETR:UN01)</a> to support its planned production of almost carbon dioxide-neutral steel.