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At least 127 records · Page 7

Development and Demonstration of a Reduced-Order PWR Power Dispatch Simulator

This report describes the development, modeling, and results of a reduced-order thermal power dispatch pressurized water reactor (RO-TPD-PWR) power plant simulator that incorporates coupled electrical and thermal power dispatch to an industrial process. The simulator is built on models that have been developed in previous work, including a Rancor Microworld model previously developed by INL and the University of Idaho [Ref] and reactor core and secondary system models that have been published previously [Ref]. The simulator also includes a scalable model of a high temperature electrolysis (HTE) system that has been developed at INL. A particular benefit of the Rancor Microworld model is that it is compatible with a human-system interface (HMI) that has already been developed by the Human System Simulation Laboratory (HSSL) at INL that can emulate the control room of a PWR for realistic human-in-the-loop studies with mock nuclear power plant operating procedures. The results of these human-in-the-loop tests will be compared with similar tests using a commercial full-scope generic PWR (GPWR) simulator that has been modified to include thermal power dispatch, referred to as the TPD-GPWR [ , ]. The simplicity of the RO-TPD-PWR helps to better understand and verify the results of the TPD-GPWR, which employs >1,000 variables and has much greater complexity. A second key purpose of the RO-TPD-PWR simulator is that its relative simplicity allows it scale between lab-size equipment (~100 kW) and full-scale nuclear power plants (~1 GW) by adjusting only a few parameters in the models, such as fluid masses and heat exchanger areas. The RO-TPD-PWR simulator will be used to guide the controls of lab tests, so that equipment in those tests, such as the Thermal Energy Distribution System (TEDS) and pilot-scale high temperature electrolysis (HTE) units at scales of 50-250 kW, may operate in a manner that is relevant to full-scale PWR operations.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Water Electrolysis for In-Situ Resource Utilization (ISRU)

Sending humans to Mars for any significant amount of time will require capabilities and technologies that enable Earth independence. To move towards this independence, the resources found on Mars must be utilized to produce the items needed to sustain humans away from Earth. To accomplish this task, NASA is studying In Situ Resource Utilization (ISRU) systems and techniques to make use of the atmospheric carbon dioxide and the water found on Mars. Among other things, these substances can be harvested and processed to make oxygen and methane. Oxygen is essential, not only for sustaining the lives of the crew on Mars, but also as the oxidizer for an oxygen-methane propulsion system that could be utilized on a Mars ascent vehicle. Given the presence of water on Mars, the electrolysis of water is a common technique to produce the desired oxygen. Towards this goal, NASA designed and developed a Proton Exchange Membrane (PEM) water electrolysis system, which was originally slated to produce oxygen for propulsion and fuel cell use in the Mars Atmosphere and Regolith COllector/PrOcessor for Lander Operations (MARCO POLO) project. As part of the Human Exploration Spacecraft Testbed for Integration and Advancement (HESTIA) project, this same electrolysis system, originally targeted at enabling in situ propulsion and power, operated in a life-support scenario. During HESTIA testing at Johnson Space Center, the electrolysis system supplied oxygen to a chamber simulating a habitat housing four crewmembers. Inside the chamber, oxygen was removed from the atmosphere to simulate consumption by the crew, and the electrolysis system's oxygen was added to replenish it. The electrolysis system operated nominally throughout the duration of the HESTIA test campaign, and the oxygen levels in the life support chamber were maintained at the desired levels.

Lee, Kristopher A.↗

Lightside Atmospheric Revitalization System

The system was studied as a replacement to the present baseline LiOH system for extended duration shuttle missions. The system consists of three subsystems: a solid amine water desorbed regenerable carbon dioxide removal system, a water vapor electrolysis oxygen generating system, and a Sabatier reactor carbon dioxide reduction system. The system is designed for use on a solar powered shuttle vehicle. The majority of the system's power requirements are utilized on the Sun side of each orbit, when solar power is available.

Colling, A. K.↗

Feasibility Testing of Silver Electrolysis for Disinfection of Spacecraft Potable Water Systems

Anodic dissolution of silver electrodes, or “silver electrolysis,” is being investigated as a means of introducing biocidal silver into potable water on exploration spacecraft. A proof-of-concept prototype of a silver electrolysis reactor was developed, and feasibility was demonstrated for imparting a target silver concentration into a spacecraft water system. Prototype testing showed that the primary initial concerns related to the technology - inefficiencies of electrolysis in low conductivity water, the potential formation of resistive oxides on the electrode surfaces, and the potential for release of electrolytically-generated silver particles to the effluent water - were not problematic over the duration of the feasibility testing. The testing also demonstrated advantages of the technology, including the ability to consistently deliver silver at targeted concentrations and the ability to directly correlate the silver concentration to measurements of water conductivity. On the other hand, the reliability of the system has not yet been demonstrated. During prototype testing, intermittent periods of poor reactor performance manifested as a decrease in voltage accompanied by a decrease in silver output. It was determined that the cause of this behavior was silver-based deposits on inter-electrode wetted surfaces forming a conductive “bridge” between electrodes. Ongoing testing and refinement of the prototype reactor design seek to elucidate the root cause the bridging phenomenon and identify associated mitigation strategies. Once resolved, long-term performance testing is planned as part of continued development of the electrolytic silver dosing system.

Silver↗

Development status of solid polymer electrolyte water electrolysis for manned spacecraft life support systems

Details of the design and system verification test results are presented for a six-man-rated oxygen generation system. The system configuration incorporates components and instrumentation for computer-controlled operation with automatic start-up/shutdown sequencing, fault detection and isolation, and with self-contained sensors and controls for automatic safe emergency shutdown. All fluid and electrical components, sensors, and electronic controls are designed to be easily maintainable under zero-gravity conditions. On-board component spares are utilized in the system concept to sustain long-term operation (six months minimum) in a manned spacecraft application. The system is centered on a 27-cell solid polymer electrolyte water electrolysis module which, combined with the associated system components and controls, forms a total system envelope 40 in. high, 40 in. wide, and 30 in. deep.

Nuttall, L. J.↗

Roll-to-Roll Direct Coating of Catalyst Inks on Membrane Films: Progress and Challenges

Further development of low temperature electrolysis (LTE) systems is of importance to ensure the renewable hydrogen production for hydrogen-based energy systems. The membrane electrode assembly (MEA) is a key component of the LTE system and typically contains a catalyst coated membrane (CCM). To enable the U.S. Department of Energy's hydrogen production cost goal of $2/kg, high volume manufacturing processes will be required to lower manufacturing costs of the CCM. A promising way for high-throughput manufacturing of CCM is using roll-to-roll (R2R) methods that allow the direct coating of electrodes on membrane films. However, there are many challenges with this methodology, both in the coating process as well as with web handling. In this talk, we discuss the membrane-ink interaction by evaluating the solvent uptake of a Nafion membrane system and verify the coatability of various inks through lab-scale coatings onto this system. Furthermore, rheology and surface tension data of the ink will be discussed together with the resulting morphology of the coated electrodes. The R2R-processed CCMs will finally be analyzed using electrochemical performance data and the results put in context with the challenges that the mass production of CCMs for LTE system faces to date.

39 EE - Hydrogen and Fuel Cell Technologies (EE-3F↗

Trade Study of Five In-Situ Propellant Production System for a Mars Sample Return Mission

One of the goals of NASA''s HEDS enterprise is to establish a long-term human presence on Mars at a fraction of the cost of employing today''s technology. The most direct method of reducing mission cost is to reduce the launch mass of the spacecraft. If the propellants for the return phase of the mission are produced on Mars, the total spacecraft mass could be reduced significantly. An interim goal is a Mars Sample Return (MSR) mission, which is proposed to demonstrate the feasibility of in-situ propellant production (ISPP). Five candidate ISPP systems for producing two fuels and oxygen from the Martian atmosphere are considered in this design trade-off study:(1) Zirconia cell with methanol synthesis, (2) Reverse water gas shift (RWGS) with water electrolysis and methanol synthesis, (3) Sabatier process for methane production with water electrolysis, (4) Sabatier process with water electrolysis and partial methane pyrolysis, and (5) Sabatier/RWGS combination with water electrolysis. These systems have been the subject of numerous previous analytical studies and laboratory demonstrations. In this investigation, the systems are objectively compared on the basis of thermochemical performance models using a commonly used chemical plant analysis software package. The realistic effects of incomplete chemical conversion and gas phase separator performance are included in these models. This study focuses on the chemical processing and product separation subsystems. The CO2 compression upstream of the chemical plane and the liquefaction/storage components are not included here.

Green, S. T.↗

The Concept and Analytical Investigation of CO2 and Steam Co-Electrolysis for Resource Utilization in Space Exploration

CO2 acquisition and utilization technologies will have a vital role in designing sustainable and affordable life support and in situ fuel production architectures for human and robotic exploration of Moon and Mars. For long-term human exploration to be practical, reliable technologies have to be implemented to capture the metabolic CO2 from the cabin air and chemically reduce it to recover oxygen. Technologies that enable the in situ capture and conversion of atmospheric CO2 to fuel are essential for a viable human mission to Mars. This paper describes the concept and mathematical analysis of a closed-loop life support system based on combined electrolysis of CO2 and steam (co-electrolysis). Products of the coelectrolysis process include oxygen and syngas (CO and H2) that are suitable for life support and synthetic fuel production, respectively. The model was developed based on the performance of a co-electrolysis system developed at Idaho National Laboratory (INL). Individual and combined process models of the co-electrolysis and Sabatier, Bosch, Boudouard, and hydrogenation reactions are discussed and their performance analyses in terms of oxygen production and CO2 utilization are presented.

McKellar, Michael G.↗

Life cycle analysis of a hydrogen production system based on solid oxide electrolysis cells integrated with different energy and wastewater sources

Hydrogen production via water electrolysis is a promising and evolving technology. The solid oxide electrolysis cell (SOEC) is one of the several technologies for this purpose. They are alternatives to the traditional hydrogen production from fossil fuels to enhance global energy decarbonization. However, in the bid for sustainability and a green economy, these technologies are not free from causing some environmental burdens. Using life cycle assessment (LCA), the greenhouse gas emission and degree of environmental impacts by these technologies can be identified and measured throughout their lifespan. This study addresses how to quantify these CO 2 emission impacts for an electrolytic system with different energy sources. The LCA of a novel integrated hydrogen production SOEC system with energy from solar photovoltaic and bituminous powerplant is performed using simaPro, the leading global LCA solution software. Measuring the environmental impact of the electrolytic operation in terms of weight, the bituminous powerplant poses damage which is, on average 700% more than solar PV. The thermal-to-hydrogen efficiency of the SOEC system is 56%, and a probable 28% reduction in carbon footprint with heat integration. The steam generation and the manufacturing of the SOEC have a very high environmental impact potential on the system. Here, we recommend LCA and net energy analysis is carried out for every new hydrogen technology and adequate comparison to enhance sustainable and green economy.

08 HYDROGEN↗

Optimal operations of a nuclear-based integrated energy system: A mixed integer program approach

A nuclear-based integrated energy system (IES), consisting of multiple carbon-free energy generation and conversion technologies to meet heterogeneous end-use demands, offers a promising approach to decarbonizing the U.S. economy. Operating such an IES is challenging due to its complexity and the diverse end-use demands, such as heating and electricity. This paper aims to address the optimal operation of an IES composed of a small modular reactor (SMR), a steam manifold, a balance of plant (BOP), a high-temperature steam electrolysis (HTSE) system, a district heating (DH) network, and electrical grids. We formulate the system’s operation as a mixed integer linear programming (MILP) problem to maximize net revenues from sales of electricity and hydrogen. To evaluate the efficacy of the proposed model, we conduct a 24-hour simulation considering day-ahead (DA) electricity prices from CAISO and a varying DH demand profile with hourly resolution. The simulation results show that our model effectively optimizes the operation by selling electricity during on-peak periods and purchasing electricity for hydrogen production during off-peak periods, while satisfying operating constraints within the IES.

08 HYDROGEN↗

Performance and Durability Investigation of Thin, Low Crossover Proton Exchange Membranes for Water Electrolyzers

The goal of this project was to fabricate and study the performance and durability implications of thin, mechanically reinforced membranes containing gas recombination catalysts (GRCs) for advanced proton exchange membrane water electrolysis (PEMWE) systems. The thinner membranes, optimized for a PEMWE environment, dramatically reduced the proton transport resistance across the membrane, improving the overall efficiency of the PEMWE system. At the same time, the GRC technology was deployed to recombine crossover hydrogen from the cathode with oxygen from the anode to form water within the membrane. This reaction mitigated the buildup of hydrogen in the oxygen stream, ensuring safe operation of the PEMWE system. Capabilities to measure the gas crossover in both an ex-situ screening cell and in operando application testing were developed over the course of the project to track membrane progress and quantify deliverables. State of the art roll to roll manufacturing technologies were leveraged to fabricate the membranes on a commercial scale, where the membrane structure was precisely tuned and GRC distributed within the membrane structure.

08 HYDROGEN↗

Advanced technology lightweight fuel cell program

The potential of the alkaline electrolyte fuel cell as the power source in a multi hundred kilowatt orbital energy storage system was studied. The total system weight of an electrolysis cell energy storage system was determined. The tests demonstrated: (1) the performance stability of a platinum on carbon anode catalyst configuration after 5000 hours of testing has no loss in performance; (2) capability of the alkaline fuel cell to operate to a cyclical load profile; (3) suitability of a lightweight graphite electrolyte reservoir plate for use in the alkaline fuel cell; (4) long life potential of a hybrid polysulfone cell edge frame construction; and (5) long term stability of a fiber reinforced potassium titanate matrix structure. The power section tested operates with passive water removal eliminating the requirement for a dynamic hydrogen pump water separator thereby allowing a powerplant design with reduced weight, lower parasite power, and a potential for high reliability and extended endurance. It is concluded that two perovskites are unsuitable for use as a catalyst or as a catalyst support at the cathode of an alkaline fuel cell.

Martin, R. E.↗

Space Station propulsion - Advanced development testing of the water electrolysis concept at MSFC

The successful demonstration at Marshall Space Flight Center (MSFC) that the water electrolysis concept is sufficiently mature to warrant adopting it as the baseline propulsion design for Space Station Freedom is described. In particular, the test results demonstrated that oxygen/hydrogen thruster, using gaseous propellants, can deliver more than two million lbf-seconds of total impulse at mixture ratios of 3:1 to 8:1 without significant degradation. The results alao demonstrated succcessful end-to-end operation of an integrated water electrolysis propulsion system.

Jones, Lee W.↗