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The proliferation of variable renewable energy resources that generate electrical power from solar and wind is a critical step in achieving a climate neutral and sustainable energy system. The successful implementation of these electrical power generators is limited due to the uncontrollable nature of their availability to produce electrical power. One method by which to shift this energy production temporally and spatially to the time and place of its demand is the production of hydrogen as a chemical energy carrier. However, this approach would require large-scale infrastructure investments to produce, store, and transport hydrogen gas. One proposed strategy for the storage and transport of hydrogen is to blend with natural gas and inject it into pre-existing natural gas infrastructure. Hydrogen gas blended into natural gas in this way can contribute to the decarbonization of the natural gas system, however it is not as valuable in terms of its economic and carbon reduction potential. This value could be recovered if the separation of high-purity hydrogen gas from a blended gas system is done in an efficient manner. Electrochemical hydrogen separation is a well-established technology for efficient hydrogen separation, which can be accomplished by electrochemical hydrogen pump (EHP) based on a proton conducting membrane (PEM). The EHP works to separate hydrogen by facilitating the electrochemical process of oxidation of hydrogen at an anode and subsequent evolution of hydrogen gas at a cathode, while other gaseous impurities are ideally unable to permeate through the membrane. The goal of this work is to investigate the potential of electrochemical separation as a highly efficient means of separating trace volumetric quantities of hydrogen gas from natural gas by using high-temperature proton exchange membrane (HT-PEM). To investigate the efficacy of this approach, a high temperature proton exchange membrane electrochemical hydrogen pump (HT-PEM EHP) based on phosphoric acid doped polybenzimidazole (PA-PBI) PEM is tested in hydrogen/methane gaseous blends while also testing the impacts of varying phosphoric acid contents in the membrane electrode assembly. Operando X-ray CT testing of the PA-PBI HT-PEM EHP is implemented to investigate the structure of the cell during pump operation under varying acid content and humidification. A two-dimensional cell model of the PBI-PA based HT-PEM EHP is developed and validated with cell testing data as well as with data from X-ray CT measurements. The emphasis of the model is on the electrochemical performance of the cell under mass transport limiting conditions and the influence of varying acid contents in the MEA. HT-PEM EHP based on a quaternary ammonium biphosphate anion ion-pair coordinated with polyphenylene (PA-QAPOH) membrane were investigated experimentally to determine their stability and performance in EHP configuration. The presence of phosphanated polypentafluorostyrene (PWN) and Nafion® ionomeric binders in the electrodes of the ion-pair EHP was found to be critical to the stability of the ion-pair EHP. Ion-pair EHP performance was characterized with respect to cell temperature and relative humidity, and the separation of high purity H2 gas from pipeline natural gas and H2 blends was demonstrated. The suitability of alternative sulfonic acid ionomers in the ion-pair HT-PEM EHP was measured and compared to state of the art HT-PEM EHP based on sol-gel PBI-PA membrane for low concentration hydrogen gas concentration blends in methane and in natural gas.

Proton exchange membrane electrolyzers (PEMEZ) are an attractive technology choice as the principal piece of equipment in power-to-gas (P2G), however their usage within the context of P2G has not yet been thoroughly investigated, and no pilot plants for power-to-gas with PEMEZ have as yet been realized in the United States. In this study, a PEM electrolyzer was modified to have dynamic dispatch capabilities, then subsequently operated and studied in detail as a part of the UC Irvine P2G demonstration. The system operated at sustained part load conditions and load followed variable renewable energy resources. Furthermore, the impact on emissions due to the addition of hydrogen to the high pressure natural gas fuel feed to the University of California Irvine (UCI) Central Plant’s combustion turbine is analyzed.Solar PV load following was found to have minimal impact on system efficiency in producing hydrogen from electrolysis, however wind load following did result in sustained low load conditions that did impact system efficiency significantly. Reduced efficiency due to sustained low part load conditions could be circumvented by cycling PEMEZ off completely and starting up as the load signal reached the minimum effective point again. The effective compression of hydrogen electrochemically in the PEMEZ was demonstrated to nearly match the efficiency of ideal isothermal compression using a semi-empirical model developed from sustained part load operation testing of the PEMEZ.Addition of hydrogen to the natural gas fired combustion turbine showed very little likelihood of impact on emissions of criteria pollutants (CO, NOx). A slightly significant correlation between reduction in natural gas usage, and by extension emissions of CO2, was noted.

Nitric oxide and a broad spectrum of hormones, drugs and toxins raise intracellular cGMP concentration and thereby regulate a great variety of cellular functions. The major receptor for cGMP is the cGMP-dependent protein kinases (cGKs). We have demonstrated that like mammalian organisms, C. elegans has two cGKs. The cgk-1 gene is alternatively spliced to produce three isoforms designated cgk-1A, B, and C. In addition, the cgk-2 gene has been partially cloned and it is also alternatively spliced to produce a predicted full-length transcript and a smaller transcript designated cgk-2sm that encodes only a catalytic domain. Green fluorescence protein (GFP) analysis reveals that the promoter region of cgk-1C drives GFP expression in many tissues including intestine, body wall muscles, ventral nerve cord and a small subset of neurons in the head. Radiometric kinase assays demonstrate that CGK-1C is preferentially activated by cGMP over cAMP and autophosphorylation assays demonstrate that cGMP stimulates autophosphorylation of CGK-1C. Furthermore, CGK-1C has two functional cyclicnucleotide-binding sites that behave kinetically like the mammalian cyclic nucleotide binding sites. The smaller transcript (cgk-2sm) has been cloned, expressed in HEK-T cells and shown by kinase assay to be constitutively active. Finally, RNAi studies suggest that both cgk-1 and 2 modulate motility in larva stage nematodes. These studies lay the foundation for the identification and isolation of novel upstream activators and novel downstream substrates of cGMP-dependent protein kinases.