 Suppliers of biofuels in the UK wishing to claim RTFCs must report to the RFA through the online ‘RFA Operating System (ROS)' the volume of biofuel they supply, and its carbon and sustainability characteristics.The RFA ensures that the data is verifiable and robust, and has a continual program of testing and reviewing its systems to ensure that they are resilient to the possibility of fraud.To make a positive contribution to a low carbon future, biofuels must be sustainable.