Metal Hydride Compression

Technical Report · Mon Oct 01 00:00:00 EDT 2018

DOI:https://doi.org/10.2172/1481555· OSTI ID:1481555

Johnson, Terry A. ^[1]; Mallow, Anne ^[1]; Bowman, Robert C. ^[2]; Smith, Barton D. ^[2]; Jensen, Craig ^[3]; Anovitz, Lawrence ^[2]

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1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Hawaii Hydrogen Carriers LLC, Honolulu, HI (United States)

Conventional hydrogen compressors often contribute over half of the cost of hydrogen stations, have poor reliability, and have insufficient flow rates for a mature fuel cell vehicle market. Fatigue associated with their moving parts including cracking of diaphragms and failure of seals leads to failure in conventional compressors, which is exacerbated by the repeated starts and stops expected at fueling stations. Furthermore, the conventional lubrication of these compressors with oil is generally unacceptable at fueling stations due to potential fuel contamination. MH technology offers a very good alternative to both conventional (mechanical) and newly developed (electrochemical, ionic liquid pistons) methods of hydrogen compression. Advantages of MH compression include simplicity in design and operation, absence of moving parts, compactness, safety and reliability, and the possibility to utilize waste industrial heat to power the compressor. Beyond conventional H₂ supply via pipelines or tanker trucks, another attractive scenario is the on-site generation and delivery of pure H₂ at pressure (> 875 bar) for refueling vehicles at electrolysis, wind, or solar H2 production facilities in distributed locations that are too remote or widely distributed for cost effective bulk transport. MH hydrogen compression utilizes a reversible heat-driven interaction of a hydride-forming metal alloy with hydrogen gas to form the MH phase and is a promising process for hydrogen energy applications. To deliver hydrogen continuously, each stage of the compressor must consist of multiple MH beds with synchronized hydrogenation & dehydrogenation cycles. Multistage pressurization allows achievement of greater compression ratios using reduced temperature swings compared to single stage compressors. The objectives of this project are to investigate and demonstrate on a laboratory scale a twostage MH hydrogen gas compressor with a feed pressure of >100 bar and a delivery pressure > 875 bar of high purity H₂ gas using the scheme shown in Figure 1. Progress to date includes the selection of metal hydrides for each compressor stage based on experimental characterization of their thermodynamics, kinetics, and hydrogen capacities for optimal performance with respect to energy requirements and efficiency. Additionally, final bed designs have been completed based on trade studies and all components have been ordered. The prototype two-stage compressor will be fabricated, assembled, and experimentally evaluated in FY19.

• Research Organization: Sandia National Lab. (SNL-CA), Livermore, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Hydrogen Fuel Cell Technologies Office
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1481555
• Report Number(s): SAND-2018-12180R; 669084
• Country of Publication: United States
• Language: English