A Detailed Assessment for the Potential use of Waste Hydrogen Gas at Stennis Space Center

Stennis Space Center (SSC) is NASA’s primary liquid rocket engine test facility. As such, large amounts of liquid hydrogen are used as a rocket propellant. This liquid hydrogen is stored in insulated vessels throughout the center where significant portions of the propellant boils off due to heat leak. The resulting boiloff hydrogen gas is currently considered a waste product and is subsequently burned in flare stacks for safety purposes. Because waste hydrogen is a significant cost loss to the facility, SSC is interested in identifying a method of utilizing the boiloff hydrogen for electrical power generation rather than simply flaring it off as an expensive waste gas. This power could then be used on-site to offset the cost of purchasing commercially-generated electricity.

The objective of this study was to identify and estimate the cost of one or more approaches of utilizing waste hydrogen for power generation. To simplify the scope of the problem, this study was limited to the boiloff source of the run tank at one test stand which consistently produces 500 gallons of hydrogen gas every day. This study used the results of several previous studies that also examined different ways of allaying the waste hydrogen problem. Using literature from these previous efforts as a starting point, a market review was conducted to find potential systems of hydrogen-fueled energy generation that are currently available. Candidate systems were considered based upon their compatibility with requirements dictated by the test stand and related infrastructure. These requirements were developed from technical data and drawings and supplemented with knowledge gained during a site visit to the test stand.

The market review revealed only a single viable option: a hydrogen-fueled 4.9-L reciprocating engine and generator set.

A high-level design of the supporting infrastructure was carried out in order to conduct a reasonably accurate cost analysis once a prime mover and generator system was selected. Gas and water piping systems were developed, electrical equipment needs were identified, and a general site layout determined. Cost estimates were then made for materials, equipment, installation labor, maintenance and prime contractor expenses.

With the performance of the power generation system, capital and variable expenditures known, life cycle cost analysis metrics were calculated. Impacts of the developed system on the environment were also assessed.