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1. Towards Sustainable Integration: Techno-Economic Analysis and Future Perspectives of Co-Located Wind and Hydrogen Energy Systems

   https://doi.org/10.1115/1.4063971  

   Li, Honglin; Zhang, Jie (February 2024, Journal of Mechanical Design)

   Abstract This article presents a comprehensive study that focuses on the techno-economic analysis of co-located wind and hydrogen energy integration within an integrated energy system (IES). The research investigates four distinct cases, each exploring various configurations of wind farms, electrolyzers, batteries, hydrogen storage tanks, and fuel cells. To obtain optimal results, the study employs a sophisticated mathematical optimization model formulated as a mixed-integer linear program. This model helps determine the most suitable component sizes and hourly energy scheduling patterns. The research utilizes historical meteorological data and wholesale market prices from diverse regions as inputs, enhancing the study’s applicability and relevance across different geographical locations. Moreover, sensitivity analyses are conducted to assess the impact of hydrogen prices, regional wind profiles, and potential future fluctuations in component prices. These analyses provide valuable insights into the robustness and flexibility of the proposed IES configurations under varying market conditions and uncertainties. The findings reveal cost-effective system configurations, strategic component selections, and implications of future energy scenarios. Specifically comparing to configurations that only have wind and battery combinations, we find that incorporating an electrolyzer results in a 7% reduction in the total cost of the IES, and utilizing hydrogen as the storage medium for fuel cells leads to a 26% cost reduction. Additionally, the IES with hybrid hydrogen and battery energy storage achieves even higher and stable power output. This research facilitates decision-making, risk mitigation, and optimized investment strategies, fostering sustainable planning for a resilient and environmentally friendly energy future. 

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2. The Effect of Liquid Hydrogen Tank Size on Self-Pressurization and Constant-Pressure Venting

   https://doi.org/10.3390/hydrogen4030030  

   Matveev, Konstantin I; Leachman, Jacob W (September 2023, Hydrogen)

   Hydrogen represents a promising renewable fuel, and its broad application can lead to drastic reductions in greenhouse gas emissions. Keeping hydrogen in liquid form helps achieve high energy density, but also requires cryogenic conditions for storage as hydrogen evaporates at temperatures of about 20 K, which can lead to a large pressure build-up in the tank. This paper addresses the unsteady thermal modeling of cryogenic tanks with liquid hydrogen. Considering the liquid and vapor phases in the tank as two nodes with averaged properties, a lumped-element method of low computational cost is developed and used for simulating two regimes: self-pressurization (also known as autogenous pressurization, or pressure build-up in the closed tank due to external heat leaks) and constant-pressure venting (when some hydrogen is let out of the tank to maintain pressure at a fixed level). The model compares favorably (within several percent for pressure) to experimental observations for autogenous pressurization in a NASA liquid hydrogen tank. The two processes of interest in this study are numerically investigated in tanks of similar shapes but different sizes ranging from about 2 to 1200 m3. Pressure and temperature growth rates are characterized in closed tanks, where the interfacial mass transfer manifests initial condensation followed by more pronounced evaporation. In tanks where pressure is kept fixed by venting some hydrogen from the vapor domain of the tank, the initial venting rate significantly exceeds evaporation rate, but after a settling period, magnitudes of both rates approach each other and continue evolving at a slower pace. The largest tank demonstrates a six-times-lower pressure rise than the smallest tank over a 100 h period. The relative boil-off losses in continuously vented tanks are found to be approximately proportional to the inverse of the tank diameter, thus generally following simple Galilean scaling with a few percent deviation due to scale effects. The model developed in this work is flexible for analyzing a variety of processes in liquid hydrogen storage systems, raising efficiencies, which is critically important for a future economy based on renewable energy. 

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3. Renewable energy storage via efficient reversible hydrogenation of piperidine captured CO ₂

   https://doi.org/10.1039/C8GC00954F  

   Lu, Mi; Zhang, Jianghao; Yao, Yao; Sun, Junming; Wang, Yong; Lin, Hongfei (January 2018, Green Chemistry)

   The storage of renewable energy is the major hurdle during the transition of fossil resources to renewables. A possible solution is to convert renewable electricity to chemical energy carriers such as hydrogen for storage. Herein, a highly efficient formate-piperidine-adduct (FPA) based hydrogen storage system was developed. This system has shown rapid reaction kinetics of both hydrogenation of piperidine-captured CO 2 and dehydrogenation of the FPA over a carbon-supported palladium nano-catalyst under mild operating conditions. Moreover, the FPA solution based hydrogen storage system is advantageous owing to the generation of high-purity hydrogen, which is free of carbon monoxide and ammonia. In situ ATR-FTIR characterization was performed in order to provide insight into the reaction mechanisms involved. By integrating this breakthrough hydrogen storage system with renewable hydrogen and polymer electrolyte membrane fuel cells (PEMFC), in-demand cost-effective rechargeable hydrogen batteries could be realized for renewable energy storage. 

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4. Hydrogen Blending in Gas Pipeline Networks—A Review

   https://doi.org/10.3390/en15103582  

   Mahajan, Devinder; Tan, Kun; Venkatesh, T.; Kileti, Pradheep; Clayton, Clive R. (May 2022, Energies)

   Replacing fossil fuels with non-carbon fuels is an important step towards reaching the ultimate goal of carbon neutrality. Instead of moving directly from the current natural gas energy systems to pure hydrogen, an incremental blending of hydrogen with natural gas could provide a seamless transition and minimize disruptions in power and heating source distribution to the public. Academic institutions, industry, and governments globally, are supporting research, development and deployment of hydrogen blending projects such as HyDeploy, GRHYD, THyGA, HyBlend, and others which are all seeking to develop efficient pathways to meet the carbon reduction goal in coming decades. There is an understanding that successful commercialization of hydrogen blending requires both scientific advances and favorable techno-economic analysis. Ongoing studies are focused on understanding how the properties of methane-hydrogen mixtures such as density, viscosity, phase interactions, and energy densities impact large-scale transportation via pipeline networks and end-use applications such as in modified engines, oven burners, boilers, stoves, and fuel cells. The advantages of hydrogen as a non-carbon energy carrier need to be balanced with safety concerns of blended gas during transport, such as overpressure and leakage in pipelines. While studies on the short-term hydrogen embrittlement effect have shown essentially no degradation in the metal tensile strength of pipelines, the long-term hydrogen embrittlement effect on pipelines is still the focus of research in other studies. Furthermore, pressure reduction is one of the drawbacks that hydrogen blending brings to the cost dynamics of blended gas transport. Hence, techno-economic models are also being developed to understand the energy transportation efficiency and to estimate the true cost of delivery of hydrogen blended natural gas as we move to decarbonize our energy systems. This review captures key large-scale efforts around the world that are designed to increase the confidence for a global transition to methane-hydrogen gas blends as a precursor to the adoption of a hydrogen economy by 2050. 

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5. Renewable natural gas: A case study of Minnesota

   https://doi.org/10.1016/j.biombioe.2024.107163  

   Hoffman, Alicia; Kurumbail, Unni; Rhodes, Noah; Anderson, Jamey; Anex, Robert (April 2024, Biomass and Bioenergy)

   Garcia-Perez, Manuel (Ed.)

   Renewable natural gas (RNG) often generates usable energy from waste products, reduces methane emissions, and creates new revenue streams. However, not all RNG projects are financially or technically feasible. We assessed the total RNG potential of currently available local waste feedstocks in the state of Minnesota and analyzed the financial and technical limitations for project development. We found that under ideal production conditions the RNG potential from municipal solid waste, dairy and hog farm manure, and municipal wastewater solids in the state could replace approximately 7.5% of current Minnesota natural gas use. We find that technical and financial factors such as project size, financing, and distance to an existing pipeline further reduce the number of feasible RNG project sites in Minnesota. Virtual pipelines – trucking RNG short distances to pipeline injection stations – improved the modeled profitability of 124 out of 175 projects (71%) by decreasing transmission costs. No projects are financially feasible without state or federal renewable fuel credit programs because direct sale of RNG alone does not cover project costs. Dairy manure projects have the lowest levelized cost of energy, the highest total revenue, and the shortest payback period compared to municipal solid waste landfill and wastewater treatment plant projects of similar size. This difference is because manure anaerobic digestion projects are eligible for larger credits under renewable fuel credit programs than municipal solid waste landfills and wastewater treatment plants, but this credit system limits end-use of the RNG to vehicle fuel. Our contribution helps provide an outline for the magnitude of current natural gas use in Minnesota replaceable via RNG projects. 

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