<p>A family of flow-through turboexpander-generators (TEG) has been developed by Calnetix Technologies for hydrogen and natural gas pressure letdown (PLD) applications. &nbsp;TEG units can be installed to generate power throughout the hydrogen (and natural gas) distribution network using existing pressure differentials wherever a Joule-Thompson valve is located.&nbsp; These can be upstream, at terminal stations, and downstream, near governor stations.&nbsp; The expander drives a synchronous permanent magnet (PM) high-speed generator (HSG) supported by active magnetic bearings (AMB).&nbsp; This paper describes the innovative axial flow-through system architecture, including the use of process gas for cooling the HSG rotor and stator. &nbsp;This AMB supported expander allows for oil-free operation in a hydrocarbon medium.&nbsp; The primary focus of the paper will be the economic analysis of the application, including a payback calculation and net return on investment (ROI) over the projected useful lives of the machine.&nbsp; The impact of various balance-of-plant options on the net payback calculation is shown: placement of a&nbsp;heat source&nbsp;relative to the TEG, location of control electronics relative to the hazardous zone, and thrust load balancing methodology.&nbsp; A cost-benefit analysis for various TEG subsystem design choices will also be presented: motor design, bearing design, and impact of material compatibility.&nbsp; Finally, a comparison of this technology with other clean energy solutions is presented, using the Levelized Cost of Electricity (LCOE) formulation.</p>

The Development of Turboexpander-Generators for Gas Pressure Letdown Part II: Economic Analysis

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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