Maximilian B. Gorensek

Quantifying Individual Potential Contributions of the Hybrid Sulfur Electrolyzer

The hybrid sulfur cycle has been investigated as a means to produce clean hydrogen efficiently on a large scale by first decomposing H 2 SO 4 to SO 2 , O 2 , and H 2 O and then electrochemically oxidizing S0 2 back to H 2 SO 4 with the cogeneration of H 2 . Thus far, it has been determined that the total cell potential for the hybrid sulfur electrolyzer is controlled mainly by water transport in the cell. Water is required at the anode to participate in the oxidation of SO 2 to H 2 SO 4 and to hydrate the membrane. In addition, water transport to the anode influences the concentration of the sulfuric acid produced. The resulting sulfuric acid concentration at the anode influences the equilibrium potential of and the reaction kinetics for SO 2 oxidation and the average conductivity of the membrane. A final contribution to the potential loss is the diffusion of SO 2 through the sulfuric acid to the catalyst site. Here, we extend our understanding of water transport to predict the individual contributions to the total cell potential.

Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 6: Process Heat and Hydrogen Co-Generation PIRTs

A Phenomena Identification and Ranking Table (PIRT) exercise was conducted to identify potential safety-0-related physical phenomena for the Next Generation Nuclear Plant (NGNP) when coupled to a hydrogen production or similar chemical plant. The NGNP is a very high-temperature reactor (VHTR) with the design goal to produce high-temperature heat and electricity for nearby chemical plants. Because high-temperature heat can only be transported limited distances, the two plants will be close to each other. One of the primary applications for the VHTR would be to supply heat and electricity for the production of hydrogen. There was no assessment of chemical plant safety challenges. The primary application of this PIRT is to support the safety analysis of the NGNP coupled one or more small hydrogen production pilot plants. However, the chemical plant processes to be coupled to the NGNP have not yet been chosen; thus, a broad PIRT assessment was conducted to scope alternative potential applications and test facilities associated with the NGNP. The hazards associated with various chemicals and methods to minimize risks from those hazards are well understood within the chemical industry. Much but not all of the information required to assure safe conditions (separation distance, relative elevation, berms) is known for a reactor coupled to a chemical plant. There is also some experience with nuclear plants in several countries that have produced steam for industrial applications. The specific characteristics of the chemical plant, site layout, and the maximum stored inventories of chemicals can provide the starting point for the safety assessments. While the panel identified events and phenomena of safety significance, there is one added caveat. Multiple high-temperature reactors provide safety-related experience and understanding of reactor safety. In contrast, there have been only limited safety studies of coupled chemical and nuclear plants. The work herein provides a starting point for those studies; but, the general level of understanding of safety in coupling nuclear and chemical plants is less than in other areas of high-temperature reactor safety.

Development of a Sulfur Dioxide Depolarized Electrolyzer for Hydrogen Production Using the Hybrid Sulfur Thermochemical Process

The Hybrid Sulfur Process is a leading candidate among the thermochemical cycles being developed to use heat from advanced nuclear reactors to produce hydrogen via watersplitting. It has the potential for high efficiency, competitive cost of hydrogen, and it has been demonstrated at a laboratory scale to confirm performance characteristics. The major developmental issues with the HyS Process involve the design and performance of a sulfur dioxide depolarized electrolyzer, the key component for conducting the electrochemical step in the process. This paper will discuss the development program and current status for the SDE being conducted at the Savannah River National Laboratory.Copyright

Safety Related Physical Phenomena for Coupled High-Temperature Reactors and Hydrogen Production Facilities

High-temperature reactors are a potential low-carbon source of high-temperature heat for chemical plants—including hydrogen production plants and refineries. Unlike electricity, high temperature heat can only be transported limited distances; thus, the reactor and chemical plants will be close to each other. A critical issue is to understand potential safety challenges to the reactor from the associated chemical plant events to assure nuclear plant safety. The U.S. Nuclear Regulatory Commission (NRC) recently sponsored a Phenomena Identification and Ranking Table (PIRT) exercise to identify potential safety-related physical phenomena for high-temperature reactors coupled to a hydrogen production or similar chemical plant. The ranking process determines what types of chemical plant transients and accidents could present the greatest risks to the nuclear plant and thus the priorities for safety assessments. The assessment yielded four major observations. Because the safety philosophy for most chemical plants (dilution) is different than the safety philosophy for nuclear power plants (containment), this difference must be recognized and understood when considering safety challenges to a nuclear reactor from coupled chemical plants or refineries. Accidental releases of hydrogen from a hydrogen production facility are unlikely to be a major hazard for the nuclear plant assuming some minimum separation distances. Many chemical plants under accident conditions can produce heavy ground-hugging gases such as oxygen, corrosive gases, and toxic gases that can have major off-site consequences because of the ease of transport from the chemical plant to off-site locations. Oxygen presents a special concern because most proposed nuclear hydrogen processes convert water into hydrogen and oxygen; thus, oxygen is the primary byproduct. These types of potential accidents must be carefully accessed. Last, the potential consequences of the failure of the intermediate heat transport loop that moves heat from the reactor to the chemical plant must be carefully assessed.Copyright

An Efficient Hybrid Sulfur Process Using PEM Electrolysis With a Bayonet Decomposition Reactor

The Hybrid Sulfur (HyS) Process is being developed to produce hydrogen by water-splitting using heat from advanced nuclear reactors. It has the potential for high efficiency and competitive hydrogen production cost, and has been demonstrated at a laboratory scale.Copyright