Late Award - Optimizing the Cost and Performance of Composite Cylinders for H2 Storage using a Graded Construction

The U.S. DOE is very interested in promoting on-board vehicular hydrogen storage systems that will enable a driving range of greater than 300 miles while meeting packaging, cost, safety, and performance requirements. State-of-the-art hydrogen storage vessels that meet these requirements are currently very expensive to manufacture due to high carbon fiber costs. This work addresses the need for lower- cost tanks by utilizing recently-developed, low-cost fibers and graded composite designs. The Phase I/Phase II project seeks to reduce the cost of hydrogen storage vessels for fuel cell powered cars by 25% by using low-cost carbon fibers in a graded construction of the vessel wall. CTD performed detailed design iterations using laminate analysis and finite element analysis to optimize the design and minimize the cost of a 700 bar hydrogen storage vessel using a graded construction, demonstrating that a 25% reduction in cost is feasible if suitable lower cost fibers are available. CTD also investigated low cost fiber options developed by Oak Ridge National Laboratory (ORNL). Target areas for improvement, including the need to develop methods for handling large fiber tows and improving fiber and matrix interactions were identified. In Phase II, fiber handling, fiber sizing, and polymer matrix materials will be optimized to provide the best combination of low cost and high performance for hydrogen storage vessels. This work will include the fabrication and testing of composite laminates, as well as burst tubes or small tanks. Commercial Applications and Other Benefits: In addition to optimizing the cost of 700 bar hydrogen storage vessels, low-cost composite structures have application in wind and tidal turbine blades, as well as in automotive and marine structures.