Spanish energy group Repsol YPF said yesterday it would seek to develop the use of farm waste as a fuel additive along with engineering firm Abengoa and sugar company Azucarera Ebro Agricolas. Organic ethanol, or bioethanol, is obtained from fermentation of cereal and other farm waste and may be used directly as an additive or transformed into gasoline additive Ethyl Tertio Butyl Ether (ETBE), Repsol YPF said in a statement.