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Hydrogen Storage


Lifecycle Verification of Polymeric Storage

Leakage of hydrogen through the liners of on-board storage tanks is a concern, and the stresses caused by cyclical temperature excursions can compromise tank durability. Ultra-high environmental temperatures can promote large hydrogen permeation rates and hydrogen saturation in the liner material. Ultra-low environmental temperatures can severely stress liner materials and possibly induce microcracking. Failure modes for the liner's performance (based on the interaction of high pressure and extreme temperature cycling) might be possible. Hydrogen leakage through a liner microcracked by extreme temperature cycling could accelerate under sustained high temperature and pressure, or hydrogen saturation of the reinforcement layers external to the liner could put backpressure on the liner as the tank pressure decreases during vehicle operation, causing the liner to separate from the reinforcement layers.

To address this issue, ORNL is performing hydrogen permeation verification measurements on storage tank liner materials using an internally heated, high-pressure permeation test vessel (IHPV). The IHPV has been recently modified to provide rapid thermal cycling of polymeric liner specimens between -30° and 85°C at a rate of about two temperature cycles per hour. This cycling is done while the liner specimens are differentially pressurized to 430 and 860 bar (6,250 and 12,500 psi).

Project Documents:

Contact: Barton Smith, smithdb@ornl.gov

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1) High-Strength Carbon Fibers for Hydrogen Storage Vessels and 2) Higher Strength Carbon Fiber from Commercial Textile Precursors (PAN-MA) for Hydrogen Storage

High strength carbon fiber enables the manufacture of durable, lightweight, compressed hydrogen storage vessels for use in high pressure storage.  Unfortunately, current high strength carbon fiber products are too expensive to meet DOE goals for storage system costs. This project leverages previous and ongoing work of the Vehicle Technologies program to develop a low-cost, high strength carbon fiber for less demanding applications with similar goals to commercialize resulting technology via industry partnerships. 

Contact: Felix L. Paulauskas, paulauskasfl@ornl.gov

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Technology Development in Metal Hydride-based Hydrogen Storage

Basic research is essential for identifying novel materials and processes that can provide potential breakthroughs needed to attain 6 wt.%  H2 for onboard vehicle storage. Metal hydrides are one class of materials that exhibit the potential to achieve this DOE Hydrogen Program goal. This project seeks to develop the chemistry for a hydrogen storage system based on complex hydrides such as the borohydrides or the alanates. ORNL is collaborating with Metal Hydride Center of Excellence partners in developing new materials and synthetic methods for producing materials as well as in studying chemical reactions. The chemistries of liquid and volatile metal borohydrides such as Al(BH4)3, Ti(BH4)3, and Zr(BH)4 are being developed.

Borohydride complexes of Al, Ti, and Zr have been shown to be precursors for the chemical vapor deposition of metal borides with the evolution of H2 as a by-product.  This work will focus on making the reaction reversible.  Volatile or liquid hydrogen storage materials are anticipated to have some engineering advantages for scale-up such as ease of heat and mass transfer.  This work has demonstrated that the thermal decomposition of Al(BH4)3 (which contains 16.8 wt.% hydrogen) at less than 200°C leads to the reversible formation of AlH(BH4)2 and diborane (B2H6).

Related Publication:

  • "Metal borohydrides as Hydrogen Storage Materials: The Study of the Thermal Decomposition of Al(BH4)3,” Douglas A. Knight, Gilbert M. Brown, Ralph H. Ilgner, and Robert M. Smithwick, III, paper presented at the ACS National Meeting, Boston, MA, August 19, 2007.

Contact: Gilbert Brown, browngm1@ornl.gov

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Single-Walled Carbon Nanohorns for Hydrogen Storage and Catalyst Supports

The goal of this project is to control the synthesis and processing of single-walled carbon nanohorns (SWNH), a novel form of carbon, as a medium with tunable porosity of optimizing hydrogen storage. The morphology of the SWNHs including their shape, surface area, and pore size are tuned during both synthesis and post-processing for optimal hydrogen storage in accordance with theory and modeling.

A high temperature, tunable pulse-width laser vaporization technique to synthesize SWNHs with variable morphology at ~20 g/hr rates has been developed at ORNL. Post-processing treatments have been developed to tailor the pore size and surface area of the SWNHs and to decorate them with metal catalyst clusters. High surface area (1,900 m2/g) SWNH materials with variable pore size and metal-decorated SWNHs have been demonstrated with metals (Pt, Pd) resulting in catalyst-assisted hydrogen storage. Hydrogen storage capability measurements have demonstrated hydrogen uptake of SWNHs at 0.2-0.8 wt% at room temperature and 1-3.5% at 77K.

Contact: David Geohegan, geohegandb@ornl.gov

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