The Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) has issued a solicitation for applied research and development projects on hydrogen storage technologies for on-board vehicular applications.
EERE is seeking applications in two categories. The first includes projects supportive of and complementary to the activities of any of the existing Hydrogen Storage Centers of Excellence in Metal Hydrides, Chemical Hydrogen Storage, and Carbon-Based Materials.
Projects in this category must help establish important new technical approaches or capabilities not presently available at the Centers. A funded project may become a Center partner.
The second is independent R&D projects that address one of three technical topics: 1) Materials Discovery; 2) Engineering Science; or 3) Systems, Safety and Environmental Analyses.
EERE is not seeking projects involving cylindrical high pressure or liquid on-board storage tanks and off-board storage, and will not review such for this solicitation.
Total funding available for the solicitation is $6 million, with a per-award cap of $2 million.
For transportation, the overarching technical challenge for hydrogen storage is how to store the amount of hydrogen required for a conventional driving range (greater than 300 miles), within the vehicular constraints of weight, volume, efficiency, safety, and cost. (Earlier post.)
The key technical challenges, according to the DOE, for all approaches of vehicular hydrogen storage include:
System Volume and Weight. The volume and weight of current hydrogen storage systems are too high, resulting in inadequate vehicle range.
System Cost. The cost of on-board hydrogen storage systems is too high, particularly in comparison with conventional storage systems for petroleum fuels.
Efficiency. Energy efficiency is a challenge for all hydrogen storage approaches. The energy required to get hydrogen in and out is an issue for on-board reversible materials. Life-cycle energy efficiency is a challenge for chemical hydrogen storage in which the by-product is regenerated off board the vehicle. Thermal management for charging and releasing hydrogen from the storage system needs to be optimized to increase overall efficiency for all approaches.
Durability and Operability. Durability of hydrogen storage systems is inadequate. Storage media, materials of construction and balance-of-plant components are needed that allow hydrogen storage systems with a lifetime of at least 1,500 cycles and with tolerance to hydrogen fuel contaminants. An additional durability issue for material-based approaches is the delivery of sufficient quality hydrogen for the vehicle power plant.
Charging and Discharging Rates. Hydrogen refueling times—especially for material-based systems—are too long. DOE wants to see hydrogen storage systems with refueling times of less than three minutes for a 5kg of hydrogen charge, over the lifetime of the system. Thermal management that enables quicker refueling is a critical issue that must be addressed. Also, all storage system approaches must be able to supply sufficient flow rate of hydrogen to the vehicle power plant (e.g. fuel cell or internal combustion engine) to meet the required power demand.
Thermal Management. In general, the main technical challenge is heat removal upon re-filling of hydrogen for on-board reversible materials within fueling time requirements. On-board reversible materials typically require heat to release hydrogen on board the vehicle. Heat must be provided to the storage media at reasonable temperatures to meet the flow rates needed by the vehicle power plant, preferably using the waste heat of the power plant. Depending upon the chemistry, chemical hydrogen approaches often are exothermic upon release of hydrogen to the power plant, or optimally thermal neutral. By virtue of the chemistry used, chemical hydrogen approaches require significant energy to regenerate the spent material and by-products prior to re-use; this done off the vehicle.
Codes & Standards. Applicable codes and standards for hydrogen storage systems and interface technologies have yet to be established. Standardized hardware and operating procedures, and applicable codes and standards, are required.
Life-Cycle and Efficiency Analyses. Systematic analyses for the full life-cycle cost, efficiency, and environmental impact for hydrogen storage systems are required.
Additional issues specific to reversible material-based hydrogen storage systems (i.e. materials that may be charged and discharged reversibly on board a vehicle) are:
Lack of Understanding of Hydrogen Physisorption and Chemisorption. An improved understanding of the fundamentals and optimization of adsorption/absorption and desorption kinetics are needed to optimize hydrogen uptake and release capacity rates. An understanding of chemical reactivity and material properties, particularly with respect to exposure under different conditions (air, moisture, etc.) is also lacking.
Reproducibility of Performance. Standard test protocols for evaluation of hydrogen storage materials are lacking. Reproducibility of performance both in synthesis of the material/media and measurement of key hydrogen storage performance metrics is an issue. Standard test protocols related to performance over time such as accelerated aging tests as well as protocols evaluating materials safety properties and reactivity over time are also lacking.
Additional issues specific to chemical hydrogen storage systems (i.e. materials that may discharge hydrogen on board but need to be regenerated off board) are:
Regeneration Processes. Low-cost, energy efficient regeneration processes have not been established. Full life-cycle analyses need to be performed to understand cost, efficiency and environmental impacts.
By-Product/Spent Material Removal. he refueling process is potentially complicated by removal of the by-product and/or spent material. System designs must be developed to address this issue and the infrastructure requirements for off-board regeneration.
|DOE Targets for on-Board Hydrogen Storage Systems|
(ICE and fuel cell, Range >300 miles)
|System Gravimetric Capacity
(kg H2/kg system)
(kg H2/L system)
|Storage System Cost||$/kWh net
$/gge at pump
|Operating ambient temperature||ºC||-20/50||-30/50||-40/60|
|Min/max delivery temperature||ºC||-30/85||-40/85||-40/85|
|Cycle life variation||% of mean (min)/ % confidence||N/A||90/90||99/90|
|Cycle life (¼ tank to full)||Cycles||500||1,000||1,500|
|Min delivery pressure from tank||Atm (abs) Fuel cell
|Max delivery pressure||Atm (abs)||100||100||100|
|System fill time||min||10||3||2.5|
|Minimum full flow rate||(g/s)/kW||0.02||0.02||0.02|
|Start time to full flow (20ºC)||s||15||5||5|
|Start time to full flow (-20ºC)||(g/s)/kW||30||15||15|
|Start time to full flow (20ºC)||s||15||5||5|
|Transient response (10%-90% and 90%-0%||s||1.75||0.75||0.75|
|Fuel purity (H2 from storage)||% H2||99.99 (dry basis)|
|Loss of useable H2||(g/h)kg H2stored||1||0.1||0.05|
Funding Opportunity Announcement: Research and Development for On-Board Vehicular Hydrogen Storage