Abstract: Various disclosed embodiments include thermionic energy converters with a thermal concentrating hot shell and emitters for thermionic energy converters. In some embodiments, an illustrative thermionic energy converter includes: an emitter electrode; a hot shell configured to concentrate heat flow toward the emitter electrode; a collector electrode; and a cold shell that is thermally isolated from the hot shell.

Abstract: Systems for producing hydrogen gas for local distribution, consumption, and/or storage, and related devices and methods are disclosed herein. A representative system includes a pyrolysis reactor system that can be coupled to a supply of reaction material that includes a hydrocarbon. The pyrolysis reactor system includes one or more combustion components positioned to transfer heat to the reaction material to convert the hydrocarbon into an output that includes hydrogen gas and carbon particulates. The pyrolysis reactor system also includes a carbon separation system positioned to separate the hydrogen gas the carbon particulates in the output. In various embodiments, the system also includes components to locally consume the filtered hydrogen gas, such as a power generator, heating appliance, and/or a combined heat and power device.

Abstract: Systems for producing hydrogen gas for local distribution, consumption, and/or storage, and related devices and methods are disclosed herein. A representative system includes a pyrolysis reactor that can be coupled to a supply of reaction material that includes a hydrocarbon. The reactor includes one or more flow channels positioned to transfer heat to the reaction material to convert the hydrocarbon into an output that includes hydrogen gas and carbon particulates. The system also includes a carbon separation system operably coupled to the pyrolysis reactor to separate the hydrogen gas the carbon particulates in the output. In various embodiments, the system also includes components to locally consume the filtered hydrogen gas.

Abstract: Various disclosed embodiments include thermionic energy converters with a thermal concentrating hot shell and emitters for thermionic energy converters. In some embodiments, an illustrative thermionic energy converter includes: an emitter electrode; a hot shell configured to concentrate heat flow toward the emitter electrode; a collector electrode; and a cold shell that is thermally isolated from the hot shell.