Highly Efficient Smart Tanks for Hydrogen Storage

The commercial success of the Fuel Cell Electric Vehicles will require significant reductions in the cost of hydrogen fueling.Current fueling stations require pre-cooling equipment that chills the hydrogen to -40°C; this is needed to offset the temperature rise caused by compression during fueling and keep the polymer liner of the vehicle’s tank below its maximum operating temperature of 85?C.If the precooling requirement could be reduced or eliminated, the cost of delivered hydrogen could be significantly reduced.TDA Research is developing a smart hydrogen storage tank that incorporates novel cooling schemes to quickly dissipate/absorb the heat of compression and keep the hydrogen gas temperature well below the tank design temperature of 85°C.TDA’s design maximizes the heat transfer area and the heat transfer coefficients to quickly dissipate the heat throughout the refueling process.Our system has a minimal impact on the cost, weight, volume and fill time, and increases the well-to-power plant efficiency.In the Phase I of the project, we designed and carried out CFD modeling to demonstrate that we can carry out re-fueling from ambient temperature conditions, eliminating the precooling requirements at the station.We also completed a preliminary design of the smart hydrogen storage tank for FCEVs and compared it against the DOE baseline 700 bar system.TDA’s system is only 14.6 % larger in weight and 6.9% in volume, but has a higher gravimetric and volumetric capacity (1.1 kg/kWh and 0.68 L/kWh respectively, compared to (1.04 kg/kWh and 0.60 L/kWh for the baseline system) when using hydrogen at 0°C and 25°C for refueling (instead of at -40°C).It completely eliminates the pre-cooling needs of the fueling station providing a greater than 15% improvement in well-to-power plant efficiency, lowering cost of hydrogen delivered by $0.6/kg.In Phase II we will optimize key parameters, complete a detailed design of the smart tank and then fabricate full-scale prototype units.The full scale-prototype units will be tested at the National Renewable Energy Laboratory’s hydrogen refueling test facility at design pressures of 700 bar to show the merits of the technology.Based upon the results, we will generate a production plan that includes both Manufacturing and Quality Assurance Plans.The smart hydrogen tank designs developed here for fuel cell electric vehicles will also be applicable to compressed natural gas tanks.In both applications it will lower the cost of dispensing, open significant market opportunities for vehicles running on hydrogen and natural gas, offering environmental benefits and long-term US energy independence.