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In 2021, the White House proposed a 50-52% reduction in greenhouse gas emissions by the year 2030; therefore, there is significant interest in energy sources and processes that reduce carbon dioxide emissions. This paper presents a sensitivity analysis of a nuclear microreactor-powered design for concurrent hydrogen (H2) and ammonia (NH3) production, with a focus on wastewater treatment plant applications. Wastewater with organic materials (e.g., municipal wastewater, swine lagoon waste, and food waste) are the analyzed feedstocks. The system integrates the anaerobic digestion of wastewater sludge with a Brayton cycle-based power generation unit heated by the microreactor. Using empirical data and an analytical model, the paper investigates the system's response to variations in key operational parameters. The sensitivity analysis explores the influence of parameters such as the chemical oxygen demand of the feedstock, compressor isentropic efficiency, and reactor temperature and pressure on H2 and NH3 production rates, Brayton cycle efficiency, and carbon dioxide emissions. Highlights from this analysis show a nonlinear dependence for Brayton efficiency on reactor temperature, the proportionality of ammonia and hydrogen production on chemical oxygen demand values, the major impact of compressor isentropic efficiency, and the minimal response from changing the pressure of steam methane reforming. These results signify opportunities to improve the system and ultimately lead to lowered greenhouse gas emissions.
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Reports from the Frontier: Electrifying Chemical Transformations and Separations to Valorize Wastewater Nitrogen
Ammonia is an essential compound to modern society, underpinning fertilizer production and chemical manufacturing. Global ammonia demand currently exceeds 150 million tons a year and is projected to increase over 2% annually. Over 96% of ammonia is currently generated through the Haber-Bosch (HB) process, in which steam-reformed hydrogen reacts with nitrogen under reaction conditions that consume 1–2% of global energy and contribute 1.2–1.4% of anthropogenic CO2 emissions every year. In an environmental context, ammonia is a form of reactive nitrogen. Large amounts of reactive nitrogen, such as HB ammonia, accumulate in the biosphere because 80% of wastewater globally is discharged without treatment. The resulting skew in the global nitrogen cycle leads to imbalanced ecosystems and threatens water quality. Conventional water treatment removes reactive nitrogen by converting it to N2 (biological nitrification–denitrification); at HB facilities, the N2 is then cycled back to produce ammonia. Directly valorizing reactive nitrogen in waste streams would shortcut the use of N2 as an intermediate in water remediation and ammonia production, allowing savings in energy, emissions, and costs. Indeed, treating nitrogen as a resource to recover rather than simply a pollutant to remove aligns with the US National Academy of Engineering’s call to manage the nitrogen cycle, a challenge central to chemical manufacturing and ecosystem protection.
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- Award ID(s):
- 2132007
- PAR ID:
- 10454802
- Date Published:
- Journal Name:
- The Electrochemical Society Interface
- Volume:
- 32
- Issue:
- 2
- ISSN:
- 1064-8208
- Page Range / eLocation ID:
- 29 to 31
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1149/2.F04232IF
