Hydrogen (H) is a renewable energy supply that is returned to its source, water, in the process of generating energy. It does so without carbon or any other harmful emissions and its carbon footprint in the energy generation cycle is lower than that of any other renewable. Therefore, given recent advances in fuel cell technology, it is an attractive and realistic option as a mass market transport fuel. However, to reach such a market, the confidence of both the public and safety regulatory bodies will need to be gained. Specifically, H tank failure probabilities on vehicles will need to be orders of magnitude less than those in existing industrial H usage, a major challenge given that transport is a relatively uncontrolled environment. A continuous monitoring safety assurance sensor unit for vehicle H tanks, which stores a record that can be read during routine vehicle services, is proposed. This will greatly reduce failure probabilities, through early detection of H embrittlement (HE), fatigue defects and diffusion leakage. Other main project innovations include the use of passive acoustic emission (AE) sensing to keep system costs at a small fraction of the cost of a vehicle H fuel tank.