{
  "patent_number": "US 7846599",
  "country": "US",
  "title": "How a High-Temperature Fuel Cell System Starts, Stops, and Recycles Fuel",
  "original_title": "Method for high temperature fuel cell system start up and shutdown",
  "summary": "This patent describes a fuel cell system that uses a smaller, secondary fuel cell to power itself during startup and shutdown, and to recycle hydrogen from its exhaust during normal operation.",
  "what_it_does": "The patent outlines a method for operating a fuel cell system, specifically focusing on its start-up and shut-down phases, and how it handles fuel during normal operation. During normal, \"steady state\" operation, a main \"fuel cell stack\" (like a Solid Oxide Fuel Cell or Molten Carbonate Fuel Cell, per claims 7 and 13) converts fuel into electricity. The exhaust from this main stack then goes to a \"PEM stack\" (a Proton Exchange Membrane fuel cell/electrolyzer). This PEM stack operates in \"electrolysis mode\" (claim 4) to separate hydrogen from the exhaust and feeds that hydrogen back into the main fuel cell stack's fuel supply, making the system more efficient. When starting up or shutting down, the PEM stack switches roles. It receives its own fuel and air (claims 1 and 9) and generates power to run \"auxiliary components\" (claim 1) of the system, such as pumps or heaters, ensuring a smooth and controlled transition.",
  "what_it_does_not_cover": [
    "Fuel cell systems that do not include a separate PEM stack for both power generation and hydrogen recycling.",
    "Systems where the PEM stack does not provide power to auxiliary components during start-up or shut-down.",
    "Systems where the PEM stack does not operate in electrolysis mode to separate hydrogen from the main fuel cell stack's exhaust.",
    "Methods that do not involve recycling separated hydrogen from the PEM stack back into the main fuel cell stack's fuel inlet stream.",
    "Fuel cell systems that do not involve a 'fuel cell stack' (specifically SOFC or MCFC in some claims) and a 'PEM stack' working together in these defined roles."
  ],
  "filed": "2008-06-03",
  "granted": "2010-12-07",
  "expires": "2028-06-03",
  "status": "active",
  "holder": "Bloom Energy",
  "holder_url": "https://patentbrief.org/company/bloom-energy",
  "inventors": [
    {
      "name": "Arne Ballantine",
      "url": "https://patentbrief.org/inventor/arne-ballantine"
    },
    {
      "name": "James McElroy",
      "url": "https://patentbrief.org/inventor/james-mcelroy"
    }
  ],
  "times_cited": 26,
  "tags": [
    "energy",
    "power_generation",
    "fuel_cells",
    "industrial_equipment"
  ],
  "abstract": "A fuel cell system includes a fuel cell stack and a PEM stack for providing power to the system in a start up or shut down operating mode and hydrogen to the fuel cell stack in a steady state operating mode.",
  "url": "https://patentbrief.org/patent/us/7846599/method-for-high-temperature-fuel-cell-system-start-up-and-shutdown",
  "markdown_url": "https://patentbrief.org/patent/us/7846599/method-for-high-temperature-fuel-cell-system-start-up-and-shutdown/md",
  "google_patents_url": "https://patents.google.com/patent/US7846599",
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}