Kg Of H2 Research Articles

NiFe-Prussian blue analogs catalyst for glucose electrolytic hydrogen production and biomass valorization

Making green hydrogen from natural biomass glucose electrolysis represents a successful win-win scenario which not only achieves energy-efficient hydrogen production but also yields high-value-added chemicals. Herein, we report a NiFe-PBA catalyst synthesized by a facile co-precipitation method for glucose electrooxidation reaction (GOR). Benefiting from the unique ligand structure and the optimal electron, the Ni1·6Fe-PBA achieves a current density of 50 mA cm⁻2 at a potential of only 1.42 V versus Reversible Hydrogen Electrode (RHE), and it maintains potential stability for 50 h. Through an intermittent multipotential-step method it was known that NiOOH is the active site of GOR. Based on the superior GOR activity of this catalyst, we constructed a two-electrode glucose electrolysis hydrogen making system. At a current density of 50 mA cm⁻2, this system reduced the voltage of 230 mV compared to traditional water electrolysis. This improvement significantly reduces energy consumption, requiring only 43.4 kWh to produce 1 kg of H2, saving 6.1 kWh of energy power. To our excitement, we analyzed the electrolyte after stability measurement and found the production of GRA, an important platform molecule for chemical industry and medical treatment. This research provides a promising and sustainable approach for efficient hydrogen production and the value-up of biomass feed-stock.

Galvanostatic Electroshock Synthesis of Low Loading Au-Pt Nanoalloys onto Gas Diffusion Electrodes as Multifunctional Electrocatalysts for a Glycerol-Fed Electrolyzer.

Water electrolysis is increasingly considered a viable solution for meeting the world's growing energy demands and mitigating environmental issues. An inventive strategy to mitigate the energy requirements involves substituting the energy-intensive oxygen evolution reaction (OER) with biomass-derived glycerol electrooxidation. Nonetheless, the synthesis of electrocatalysts for controlling the selectivity towards added-value chemicals at the anode and efficient H2 generation at the cathode remains a critical bottleneck. Herein, we implemented a galvanostatic electroshock synthesis approach to control the reduction kinetics of Au(III) and Pt(IV) to grow ultra-low amount of gold-platinum alloys on a gas diffusion electrode (12-26 µgmetal cm‒2) for glycerol-fed hydroxide anion exchange membrane based electrolyzer. The symmetric GDE-Au100-xPtx||GDE-Au100-xPtx systems showed a notable improvement in electrolyzer performance (GDE-Au64Pt36 = 201 mA cm-2) as compared to monometallic versions (GDE-Au100Pt0 = 18 mA cm-2, GDE-Au0Pt100 = 81 mA cm-2). Chromatography (HPLC) analysis underscores the critical importance of bulk electrolysis methodology (galvanostatic vs potentiostatic) for the efficient conversion of glycerol into high-value-added products. Regarding the electrical energy required to produce 1 kg of H2 for such an electrolyzer fed at the anode with glycerol, our results confirm a drastic decrease by a factor of at least two compared with conventional water electrolysis.

An Overview of the Efficiency and Long-Term Viability of Powered Hydrogen Production

This work studies the efficiency and long-term viability of powered hydrogen production. For this purpose, a detailed exploration of hydrogen production techniques has been undertaken, involving data collection, information authentication, data organization, and analysis. The efficiency trends, environmental impact, and hydrogen production costs in a landscape marked by limited data availability were investigated. The main contribution of this work is to reduce the existing data gap in the field of hydrogen production by compiling and summarizing dispersed data. The findings are expected to facilitate the decision-making process by considering regional variations, energy source availability, and the potential for technological advancements that may further enhance the economic viability of electrolysis. The results show that hydrogen production methods can be identified that do not cause significant harm to the environment. Photolysis stands out as the least serious offender, producing 0 kg of CO2 per kg of H2, while thermolysis emerges as the major contributor to emissions, with 20 kg of CO2 per kg of H2 produced.

Investigation of hybrid power-to-hydrogen/natural gas and hydrogen-to-X system in Cameroon

In Sub-Saharan Africa (SSA), the capacity to generate energy faces significant hurdles. Despite efforts to integrate renewable energy sources and natural gas power plants into the energy portfolio, the desired reduction in environmental impact and alleviation of energy poverty remain elusive. Hence, exploring a spectrum of hybrid technologies, encompassing storage and hydrogen-based solutions, is imperative to optimize energy production while mitigating harmful emissions. To exemplify this necessity, the 216 MW Kribi gas power plant in Cameroon is the case study. The primary aim is to investigate cutting-edge emissions and energy schemes within the SSA. This paper assessed the minimum complaint load technique and four power-to-fuel options from technical, financial, and environmental perspectives to assess the viability of a natural gas fuel system powered with hydrogen in a hybrid mode. The system generates hydrogen by using water electrolysis, with photovoltaic electricity and gas power plant. This research also assesses process efficiency, storage capacity, annual costs, carbon avoided costs, and production prices for various fuels. Results showed that the LCOE from a photovoltaic solar plant is 0.19$/kWh, with the Power-to-Hydrogen process (76.2% efficiency) being the most efficient, followed by the ammonia and urea processes. The study gives a detailed examination of the hybrid hydrogen natural gas fuel system. According to the annual cost breakdown, the primary costs are associated with the acquisition of electrical energy and electrolyser CAPEX and OPEX, which account for 95% of total costs. Urea is the cheapest mass fuel. However, it costs more in terms of energy. Hydrogen is the most cost-effective source of energy. In terms of energy storage and energy density by volume, the methane resulted as the most suitable solution, while the ammonia resulted as the best H2 storage medium in terms of kg of H2 per m3 of storage (108 kgH2/m3). By substituting the fuel system with 15% H2, the environmental effects are reduced by 1622 tons per year, while carbon capture technology gathered 16,664 tons of CO2 for methanation and urea operations, yielding a total carbon averted cost of 21 $/ton.

Magnetic field-assisted water splitting at ternary NiCoFe magnetic Nanocatalysts: Optimization study

This study addresses the enhanced splitting of water into H2 and O2 assisted with applied magnetic field at ternary NiCoFe catalyst. The catalyst's activity towards water electrolysis is enhanced in the presence of AC-induced magnetic field (B = 720 μT) and approaches the performance of Pt/C∥IrO2. That is the overpotential at a current density of 10 mA cm−2 (η10) is reduced by 90 mV and 210 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Besides, a significant reduction in the cell voltage of 0.3 V and a power saving of 215.6 kWh during the production of one kg of H2 are obtained when AC magnetic field of 720 μT is applied. A markedly high stability of the catalyst is obtained under magnetic field during a prolonged electrolysis. The magnetohydrodynamic effect is believed to drive water electrolysis at NiCoFe film by reducing the ohmic potential drop across the electrode/solution interface, and increases the rate of charge transfer at the catalyst surface. The results are explained by capacitance measurements revealing maximum capacitance of NiFeCo catalyst in the presence of AC magnetic flux of 720 μT. Thus, favourable adsorption conditions lead to accelerated kinetics of OER and HER.

Process optimization of integrated hydrogen production process with local resources

This study aimed to develop a superstructure to determine the hydrogen pathway based on optimum economic and environmental performances. Some potential biomass waste for hydrogen synthesis were considered. Two case studies were conceptualized to evaluate the mathematical model. Case 1 considered the economic performance of the model with the objective function of minimizing total cost. Case 2 was a multi-objective scenario which examined both the economic and environmental performances of the model. For case 1, steam gasification of palm kernel shell was chosen as the optimal hydrogen synthesis pathway with the total cost targeted as $ 0.64 million per year. For case 2, an annual total cost of $ 0.68 million was recorded. Besides, 4438572.96 kg CO2-eq was released per kg of H2 produced.

MOF-on-MOF-Derived Ultrafine Fe2P-Co2P Heterostructures for High-Efficiency and Durable Anion Exchange Membrane Water Electrolyzers.

The alkaline hydrogen evolution reaction (HER) in an anion exchange membrane water electrolyzer (AEMWE) is considered to be a promising approach for large-scale industrial hydrogen production. Nevertheless, it is severely hampered by the inability to operate tolerable HER catalysts consistently under low overpotentials at ampere-level current densities. Here, we develop a universal ligand-exchange (MOF-on-MOF) modulation strategy to synthesize ultrafine Fe2P and Co2P nanoparticles, which are well anchored on N and P dual-doped carbon porous nanosheets (Fe2P-Co2P/NPC). In addition, benefiting from the downshift of the d-band center and the interfacial Co-P-Fe bridging, the electron-rich P site is triggered, which induces the redistribution of electron density and the swapping of active centers, lowering the energy barrier of the HER. As a result, the Fe2P-Co2P/NPC catalyst only requires a low overpotential of 175 mV to achieve a current density of 1000 mA cm-2. The solar-driven water electrolysis system presents a record-setting and stable solar-to-hydrogen conversion efficiency of 20.36%. Crucially, the catalyst could stably operate at 1000 mA cm-2 over 1000 h in a practical AEMWE at an estimated cost of US$0.79 per kilogram of H2, which achieves the target (US$2 per kg of H2) set by the U.S. Department of Energy (DOE).

Gate-to-gate life cycle analysis of a pilot-scale solar driven two-step thermochemical hydrogen sulfide decomposition for hydrogen production

Hydrogen is one of the most viable options towards decarbonization. It is crucial to upscale the hydrogen economy considering the current state of the environment due to the adverse effects of climate change. In this study, a gate-to-gate Life cycle assessment (LCA) was conducted on a hydrogen sulfide splitting model that replicates a pilot-scale plant by integrating the two-step solar thermochemical H2S decomposition using SimaPro version 9.4.0 software. This analysis starts from the treatment of H2S gas released by the refineries as waste and ends at the production and storage stage of hydrogen. There are two functional units used in this study which are ‘1 kg of H2’ to assess the operational phase of the simulation plant and ‘1 unit of H2S splitting plant’ to determine the environmental performance of the construction of the plant. The top three most impacted midpoint level categories in the operational phase are human carcinogenic toxicity (HTP), freshwater ecotoxicity and marine ecotoxicity with an amount of 3.66 × 10−4, 1.10 × 10−4, and 1.40 × 10−4 kg 1,4-DCB respectively. Electricity has a higher relative contribution to this technology due to the high amount of steel used during the construction of solar tower. Meanwhile, treating H2S leaves a positive impact towards every midpoint indicator, mainly on terrestrial acidification, fine particulate matter formation and ionizing radiation. The H2S splitting technology was set as the baseline to compare with various other H2 production technologies. Scenario analysis was assessed by setting the solar-powered electricity as the baseline and was compared with electricity from different sources such as wind, nuclear and the United Arab Emirates (UAE) grid for the H2S splitting plant. Moreover, uncertainty analysis using Monte Carlo simulation suggests that the probability of gaining results of HTP is the highest between 3.62 × 10−4 to 1.34 × 10−3 kg 1,4-DCB. It can be concluded that electricity powered by renewable sources significantly reduces the environmental burden from the scenario analysis conducted.

Global Hydrogen Production During High‐Pressure Serpentinization of Subducting Slabs

AbstractSerpentinization is among the most important, and ubiquitous, geological processes in crustal–upper mantle conditions (<6 GPa, <600°C), altering the rheology of rocks and producing H2 that can sustain life. While observations are available to quantify serpentinization in terrestrial and mid‐ocean ridge environments, measurements within subduction zone environments are far more sparse. To overcome this difficulty, we design a methodology to quantify and offer a first‐order estimate of the magnitude of “slab‐serpentinization” that has occurred over the last 5 Ma within the world's subduction zones by coupling four discrete tectonic and geophysical datasets—(a) raster grids of relic abyssal peridotite (peridotite exhumed from slow spreading mid‐ocean ridges but unaffected by pre‐subduction serpentinization) within ocean basins, (b) slab geometry, (c) thermal profiles and a (d) plate‐tectonic model. Averaged per year, our results suggest that 4.2–24 • 107 kg of H2 per annum could be generated from “slab‐serpentinization” within a subduction zone. Our estimate is 1–2 orders of magnitude lower than what is thought to be produced at mid‐ocean ridges, and of a similar magnitude to what could occur when including serpentinization at trench flexure and possible mantle wedge serpentinization. Higher hydrogen production is correlated most strongly with the spreading history of ocean basins, underlaying the importance of the tectonic history of a slab prior to subduction.

Evaluación de Electrolizadores Alcalinos y PEM para Producción de Hidrógeno Verde de Fuentes Hidroeléctricas en el Ecuador

Introducción The yearly increase in energy demand has encouraged the scientific community to find new sources of energy production without affecting the environment. Renewable technologies have become extremely popular due to the low greenhouse emissions and availability of natural energy sources (wind, sun, water, earth, tides, etc.), However, because of the intermittent energy generation from renewable sources, it is complex to rely on these technologies to guarantee the energy supply. Therefore, over the last decade, hydrogen has become increasingly studied as an energy carrier to replace current energy production technologies based on fossil fuels. Hydrogen can be easily coupled with other energy sources, increasing the efficiency of the systems. Nevertheless, hydrogen cannot be found in nature on its own and needs to be produced, currently, the most efficient method for green hydrogen generation is based on the electrolysis of water, this electrochemical process relies on the availability of water and the efficiency and correct selection of the electrolyser. Thus, this research evaluates the Alkaline and Proton Exchange Membrane (PEM) electrolysers for green hydrogen generation using water from hydroelectric power plants in Ecuador. Objetivos Evaluate Alkaline and PEM electrolysers for green hydrogen generation from hydroelectric power in Ecuador Método The methodology consists of a literature review of different brands of alkaline and PEM electrolysers selecting the ones with the highest efficiencies. For the analysis of data and information processing, quantitative methods were used. Finally, a sample of 9 hydroelectric plants was obtained for the study (Molino, Mazar, Agoyán, San Francisco, Pucará, La Península, Illuchi N 1, Illuchi N 2, Marcel Laniado). Principales resultados Different electrolyser manufacturers were analysed: Nel ASA producer of alkaline as well as PEM electrolysers, among them several models were evaluated NEL A 300, NEL A 485, NEL A 1000, NEL A 3880 with alkaline technology, and NEL MC 250, NEL M 5000 with PEM technology. H-TECH Electronic Co.Ltd with its model H-TEC HCS 10 using PEM technology. SIEMENS Energy, with its electrolyser technology PEM Silyzer 300 and McPhy with Mclyzer alkaline technology. All models were evaluated with the data from the 9 hydroelectric plants. Using technical data from the selected electrolysers and availability factor (90 %) from the hydroelectric plants, the potential of hydrogen production per year was calculated. The NEL A 3880 model with a system factor of 94% and a power of 14.7 MW displays the highest hydrogen production for alkaline technology, while the NEL MC 250, with an efficiency of 79% and 1 MW of power using PEM technology shows the highest hydrogen generation, these results are achieved for the Agoyan hydroelectric plant. Conclusiones The alkaline electrolysers show a better hydrogen generation capacity, achieving a total of 300 x 10e6 Kg of H2 per year with the NEL A 3880 model, in comparison with the PEM electrolyser technology that accounts for a maximum hydrogen production of 214 x 10e6 Kg of H2 per year. These results from the evaluation of the electrolysers show that it is feasible to establish a system for green hydrogen production based on hydroelectric power plants in Ecuador. The authors acknowledge the financial support received from the Universidad Técnica de Ambato and Dirección de Investigación y Desarrollo (DIDE) through the research project number PFICM28 “ANÁLISIS DE FACTIBILIDAD DE GENERACIÓN DE HIDRÓGENO VERDE MEDIANTE FUENTES DE ENERGÍA HIDROELÉCTRICA EN EL ECUADOR”.

Refinery Off-Gas as Feed to a Hydrogen Production Facility: Performance Lifting of the Steam Reforming Technique

Refinery off-gas is one of the major causes of air pollution, where its reuse, through channeling into other plant setups to recover some of its constituent gases (via a steam reforming technique), is described as one of its best handling measures. A nominal off-gas containing 2.898% hydrogen (H2), 83.794% methane, 1.505% carbon dioxide, 1.103% nitrogen, 10.6% sulfur and 0.1% argon was fed to a plant to produce 37.52 kg of H2. To lift the performance of the multiple interconnected process units enhancing the generation of H2, temperature and pressure in the reactors were manipulated against the heat duty and H2 yield, where it was found that the two dependent variables are sensitive to changes made during Aspen Plus sensitivity analysis. Replacing some process units also shows significant improvement in the recovery of H2 gas. Adequate control of the synthesis process as exemplified in this work, will lead to smooth realization of the target end-product which is of high economic value; basically, looking at its potential for the manufacture of other useful materials it is already known for.

A sodium-ion-conducted asymmetric electrolyzer to lower the operation voltage for direct seawater electrolysis

Hydrogen produced from neutral seawater electrolysis faces many challenges including high energy consumption, the corrosion/side reactions caused by Cl-, and the blockage of active sites by Ca2+/Mg2+ precipitates. Herein, we design a pH-asymmetric electrolyzer with a Na+ exchange membrane for direct seawater electrolysis, which can simultaneously prevent Cl- corrosion and Ca2+/Mg2+ precipitation and harvest the chemical potentials between the different electrolytes to reduce the required voltage. In-situ Raman spectroscopy and density functional theory calculations reveal that water dissociation can be promoted with a catalyst based on atomically dispersed Pt anchored to Ni-Fe-P nanowires with a reduced energy barrier (by 0.26 eV), thus accelerating the hydrogen evolution kinetics in seawater. Consequently, the asymmetric electrolyzer exhibits current densities of 10 mA cm−2 and 100 mA cm−2 at voltages of 1.31 V and 1.46 V, respectively. It can also reach 400 mA cm−2 at a low voltage of 1.66 V at 80 °C, corresponding to the electricity cost of US$1.36 per kg of H2 ($0.031/kW h for the electricity bill), lower than the United States Department of Energy 2025 target (US$1.4 per kg of H2).

Onshore hydrogen production from boil-off gas (BOG) via natural gas steam reforming process: Process simulation and techno-economic analysis

Growing demand for cleaner energy resources has led to the increased global production of liquefied natural gas (LNG). At the same time, there are some economic and environmental impacts from LNG evaporation forming the boil-off gas (BOG) during production, storage, loading, transportation, and unloading. This study presents the technical and economic aspects of BOG utilization to a value-added hydrogen product (H2) at LNG exporting terminals using a steam reforming production process. The steady-state process simulation using Aspen HYSYS software achieves an overall C1+ process conversion of 100% with an H2 gas product purity of 99.99%. Heat integration between the recycle stream and the final purification section presents 12% energy savings. Additionally, the process revealed production costs as low as $0.23/kg of H2 produced, which is competitive with production from resources such as coal and natural gas. The low cost enabled the investigation of three monetization pathways: direct H2 sales to domestic markets, liquefied H2 sales to international markets, and ammonia sales to international markets. The production profitability of H2 sales as the liquefied H2 product shows the highest NPV of $66.2 billion for a project with a lifetime of 25 years and an interest rate of 10%. These approaches empower decision-makers to diversify selling portfolios in the LNG industry and support the transition to H2 using existing infrastructure.

Efficiently selective C(O-)-C bond cleavage for full lignocellulose upgrading coupled with energy-saving hydrogen production by Ir single-atom electrocatalyst

The valorization of full lignocellulose is of considerable relevance for the simplification of native biomass refining and environmental preservation. Here, its complex compositions (carbohydrate and lignin derivatives) with C(O-)-C units were convergently upgraded into relatively single carboxylic acids with high yields (up to 99%) via oxidative cleavage by Ir single-atom electrocatalysts (Ir-NiFeO@NF). Theoretical calculations revealed that single Ir atoms helped accelerate the nucleophilic reaction by promoting the adsorption of reactants and the generation of active sources (OH*). Ir-NiFeO@NF demonstrated dual functionality by outperforming not only lignocellulose oxidation (≤ 1.35 VRHE) but also H2 evolution (26 mV), resulting in an overall cell that required only 1.33 VRHE at 10 mA cm−2. As a proof-of-concept effort, the lignocellulosic cell went forward to upgrade black liquor, saving 11 kWh of energy compared to commercial water electrolysis for making 1 kg of H2. This work will stimulate the advancement of comprehensively economic and sustainable biomass refining and fuel generation.

Techno-economic sustainability assessment for bio-hydrogen production based on hybrid blend of biomass: A simulation study

This study investigates the potential use of a blend of different types of biomass for sustainable bio-hydrogen production through steam gasification. Simulation models were developed and optimized using Aspen Plus V.11 to achieve optimal bio-hydrogen production while minimizing carbon monoxide production and maintaining a set amount of carbon dioxide concentration in the syngas. The effects of varying the composition of the feedstock material and steam to biomass ratio on hydrogen yield were investigated for five different blends, including leather and municipal solid waste. The study found that the composition of the feedstock played a crucial role in gasification, with higher calorific values for blends containing higher leather content. Additionally, the study showed that specific energy consumption decreased with an increase in total heat duty for four out of the five blends, with Case V having the lowest specific energy consumption of 39.28 kW/kmol of bio H2. The economic analysis further established the potential for the effective utilization of hybrid biomass for renewable bio-hydrogen production. The optimal case V provides total capital cost of USD 1.42 × 106 and the operating cost of the proposed system accounts to USD 2.99 × 105/yr. The unit production cost involved for the optimal case is USD 0.66/kg of H2. Overall, this study provides a basis for further investigation of hybrid biomass blends as a source of renewable energy.

Life cycle assessment of earth-abundant photocatalysts for enhanced photocatalytic hydrogen production

Hydrogen (H2) can play a critical role in global greenhouse gas (GHG) mitigation. Photocatalytic water splitting using solar radiation is a promising H2 technology. Titanium dioxide (TiO2) and carbon nitride (g–C3N4)–based photocatalysts are the most widely used photocatalytic materials because of their activity and abundance. Several attempts have been made to improve the photocatalytic performance of these materials in terms of their activity level, life span, response to visible radiation, and stability. However, the environmental impacts of these modifications are often not included in existing studies. This research, therefore, develops a cradle-to-grave life cycle assessment (LCA) framework to evaluate and compare the GHG footprints of four alternative pathways: TiO2 nanorods and fluorine-doped carbon nitride quantum dots embedded with TiO2 (CNF: TNR/TiO2), g-C3N4, and g-C3N4/BiOI composite. Unlike most studies that focus only on certain stages such as laboratory-scale photocatalytic fabrication, this study includes utility-scale cell production, assembly, operation, and end of life to give a more accurate and precise environmental performance estimation. The results show that g-C3N4/BiOI has the lowest GHG footprint (0.38 kg CO2 eq per kg of H2) and CNF: TNR/TiO2 has the lowest energy payback time (0.4 years). In every pathway, energy use in material extraction processes makes up the largest GHG contribution, between 83% and 89%. Sensitivity and uncertainty analyses were conducted under the impact of various input parameters on the life cycle GHG emissions of hydrogen production. Photocatalytic water splitting is highly feasible for adaptation as a mainstream hydrogen production pathway in the future.

Carbon-neutral hydrogen production from natural gas via electrified steam reforming: Techno-economic-environmental perspective

This study proposes and evaluates a novel carbon-neutral hydrogen (H2) production process from natural gas through electrified steam methane reforming (e-SMR) with renewable electricity. The process model consists of different unit technologies such as reforming, water–gas shift, hydrogen pressure swing adsorption, and CO2 capture, along with heat recovery. Then, we evaluated the techno-economic-environmental performance of the proposed e-SMR process by comparing it with the conventional fired-heating steam methane reforming (f-SMR). By employing an electrically driven reformer using renewable energy, e-SMR outperforms f-SMR with less natural gas consumption, higher energy efficiency of 78.7%, and lower net CO2eq emission of 5.28 kg CO2eq/kg H2 and captured 5.58 kg CO2/kg H2; however, it has a drawback, i.e., higher H2 unit production cost (UPC) of 3.49 $/kg with a capacity of 7.06 ton/day. Sensitivity and uncertainty analyses identified the major cost drivers of UPC, such as the prices of natural gas, renewable electricity, and interest rates, as well as economic risks and uncertainties. The economic viability of e-SMR was determined by investigating multiple plant capacities, natural gas markets, renewable energy prices, and possible future CO2 selling prices. According to the investigation, currently, the US and India show promise for e-SMR, with abundant and affordable natural gas and renewable energy resources, both priced at around 3.49 $/kg of H2, respectively. Furthermore, the global 2030's scenario with 45 $/MWh of renewable electricity, and capture CO2 credit of 35 $/ton is observed at 3.40 $/kg H2, compared with that of 2050 at 2.91 $/kg H2. e-SMR is well adaptable to many countries' energy mix because it is flexible to utilize hybrid primary energy input, conventional natural gas as feedstock, and conventional/renewable energy for utilities.

The development of techno-economic assessment models for hydrogen production via photocatalytic water splitting

Photocatalytic water splitting using solar radiation is among the promising H2 technologies. Titanium dioxide (TiO2)- and carbon nitride (g-C3N4)-based photocatalysts are the most widely used photocatalytic materials given their activity under visible light and their abundance. Several attempts have been made to improve the photocatalytic performance of these materials in terms of activity level, life span, response to visible radiation, and stability. However, the economic viability of the large-scale deployment of these modifications is not well evaluated in the existing literature. This study develops a bottom-up techno-economic assessment framework to determine the H2 production costs in four alternative pathways: TiO2 nanorods, fluorine-doped carbon nitride quantum dot-embedded TiO2 (CNF: TNRs/TiO2), g-C3N4, and g-C3N4/BiOI composite. Sensitivity and uncertainty analyses were also conducted to understand the impact of input parameters on the hydrogen production cost. The levelized costs of hydrogen (LCOH) are 4.9-0.70+0.75,5.7-0.65+0.45,5.8-1.15+0.55,and7.8-0.95+0.45 USD per kg of H2 produced for TNRs, CNF: TNRs, g-C3N4-S, and BiOI/g-C3N4-S, respectively. In every pathway, the largest contribution is from capital investment and labour costs; together they make up around 75 % of the total cost. Material cost accounts for 13–29 % of the overall cost. The developed information can help in making investment decisions and policy formulation.

Linking Life Cycle and Integrated Assessment Modeling to Evaluate Technologies in an Evolving System Context: A Power-to-Hydrogen Case Study for the United States.

Carbon-neutral hydrogen (H2) can reduce emissions from hard-to-electrify sectors and contribute to a net-zero greenhouse gas economy by 2050. Power-to-hydrogen (PtH2) technologies based on clean electricity can provide such H2, yet their carbon intensities alone do not provide sufficient basis to judge their potential contribution to a sustainable and just energy transition. Introducing a prospective life cycle assessment framework to decipher the non-linear relationships between future technology and energy system dynamics over time, we showcase its relevance to inform research, development, demonstration, and deployment by comparing two PtH2 technologies to steam methane reforming (SMR) across a series of environmental and resource-use metrics. We find that the system transitions in the power, cement, steel, and fuel sectors move impacts for both PtH2 technologies to equal or lower levels by 2100 compared to 2020 per kg of H2 except for metal depletion. The decarbonization of the United States power sector by 2035 allows PtH2 to reach parity with SMR at 10 kg of CO2e/kg H2 between 2030 and 2050. Updated H2 radiative forcing and leakage levels only marginally affect these results. Biomass carbon removal and storage power technologies enable carbon-negative H2 after 2040 at about -15 kg of CO2e/kg H2. Still, both PtH2 processes exhibit higher impacts across most other metrics, some of which are worsened by the decarbonization of the power sector. Observed increases in metal depletion and eco- and human toxicity levels can be reduced via PtH2 energy and material use efficiency improvements, but the power sector decarbonization routes also warrant further review and cradle-to-grave assessments to show tradeoffs from a systems perspective.

Capacity assessment and cost analysis of geologic storage of hydrogen: A case study in Intermountain-West Region USA

Hydrogen is an integral component of the current energy transition roadmap to decarbonize the economy and create an environmentally-sustainable future. However, surface storage options (e.g., tanks) do not provide the required capacity or durability to deploy a regional or nationwide hydrogen economy. In this study, we have analyzed the techno-economic feasibility of the geologic storage of hydrogen in depleted gas reservoirs, salt caverns, and saline aquifers in the Intermountain-West (I-WEST) region. We have identified the most favorable candidate sites for hydrogen storage and estimated the volumetric storage capacity. Our results show that the geologic storage of hydrogen can provide at least 72% of total energy consumption of the I-WEST region in 2020. We also calculated the capital and levelized costs of each storage option. We found that a depleted gas reservoir is the most cost-effective candidate among the three geologic storage options. Interestingly, the cushion gas type plays a significant role in the storage cost when we consider hydrogen storage in saline aquifers. The levelized costs of hydrogen storage in depleted gas reservoirs, salt caverns, and saline aquifers with large-scale storage capacity are approximately $1.15, $2.50, and $3.27 per kg of H2, respectively. This work provides essential guidance for the geologic hydrogen storage in the I-WEST region.