Solar hydrogen production in urban areas of Mexico: towards hydrogen cities

Many efforts have been made to assess the potential of green hydrogen production at global, regional, and national levels using Geographic Information Systems (GIS); however, many dismiss the possibility of producing hydrogen in urban settlements. In order to reveal the true potential of these areas, it is essential to provide arguments that allow evaluation of the feasibility of promoting and impulsing the concept of hydrogen cities. Based on this idea, this work assesses the monthly and annual potential of solar hydrogen in urban areas of Mexico using actual measurements of sunshine duration as electrolyzer production times. Moreover, as light transportation is crucial for cities, we examine the substitution of gasoline with hydrogen and its cost throughout the year. These constitute the main contribution of the present work.This study departs from the geographical and technical potential of solar energy, and by using GIS, the amount of hydrogen production per unit of area (Ton/(km² year)) was computed. The levelized cost of hydrogen production (LCOH) is also evaluated, using two of the most popular and commercial electrolysis technologies: PEM and Alkaline.Our results revealed that Mexican urban areas have a high potential to produce solar hydrogen, having an average annual production that varies from 1991.8 Ton/km² to 4338.3 Ton/km² according to the region. The total solar hydrogen potential of all Mexican urban places is 9.39 MTon/year, which could satisfy up to 42.6 times the 2020 hydrogen demand of Mexico. We found that the national gasoline consumption could be replaced by H₂, requiring between 42% and 52% of the total urban production.Additionally, the national average of LCOH was found to be about 6.25 USD/kg for alkaline electrolyzer and 9.50 USD/kg for PEM technology, considering the yearly average sunshine duration of 3237 h/year, which means that Mexico could be competitive at large-scale hydrogen production by using Alkaline technology. Our findings have the potential to impact positively on the country since they provide information to facilitate the derivation of public policies from a rigorous and technical perspective.     

Renewable hydrogen production: A techno-economic comparison of photoelectrochemical cells and photovoltaic-electrolysis

The present paper reports a techno-economic analysis of two solar assisted hydrogen production technologies: a photoelectrochemical (PEC) system and its major competitor, a photovoltaic system connected to a conventional water electrolyzer (PV-E system). A comparison between these two types was performed to identify the more promising technology based on the levelized cost of hydrogen (LCOH). The technical evaluation was carried out by considering proven designs and materials for the PV-E system, and a conceptually design for the PEC system extrapolated to future, commercial scale.The LCOH for the off-grid PV-E system was found to be 6.22 $/kg_H2, with a solar to hydrogen efficiency of 10.9%. For the PEC system, with a similar efficiency of 10%, the LCOH was calculated to be much higher, namely 8.43 $/kg_H2. A sensitivity analysis reveals a great uncertainty in the LCOH of the prospective PEC system. This implies that much effort would be needed for this technology to become competitive on the market.Therefore we conclude that the potential techno-economic benefits that PEC systems offer over PV-E are uncertain, and even in the best case, limited. While research into photoelectrochemical cells remains of interest, it presents a poor case for dedicated investment in the technology's development and scale-up.     

Techno-economic optimization of PV system for hydrogen production and electric vehicle charging stations under five different climatic conditions in India

India is one of the most populous countries in the world, and this has implications for its energy consumption. The country's electricity generation and road transport are mostly dominated by fossil fuels. As such, this study assessed the techno-economics and environmental impact of a solar photovoltaic power plant for both electricity and hydrogen production at five different locations in India (i.e., Chennai, Indore, Kolkata, Ludhiana, and Mumbai). The hydrogen load represents a refueling station for 20 hydrogen fuel cell vehicles with a tank capacity of 5 kg for each location. According to the results, the highest hydrogen production occurred at Kolkata with 82,054 kg/year, followed by Chennai with 79,030 kg/year. Ludhiana, Indore, and Mumbai followed with 78,524 kg/year, 76,935 kg/year and 74,510 kg/year, respectively. The levelized cost of energy (LCOE) for all locations ranges between 0.41 and 0.48 $/kWh. Mumbai recorded the least LCOH of 3.00 $/kg. The total electricity that could be generated from all five cities combined was found to be about 25 GWh per annum, which translates to an avoidable emission of 20,744.07 metric tons of CO₂e. Replacing the gasoline that could be used to fuel the vehicles with hydrogen will result in a CO₂ reduction potential of 2452.969 tons per annum in India. The findings indicate that the various optimized configurations at the various locations could be economically viable to be developed.     

Analyzing the levelized cost of hydrogen in refueling stations with on-site hydrogen production via water electrolysis in the Italian scenario

Hydrogen refueling infrastructures with on-site production from renewable sources are an interesting solution for assuring green hydrogen with zero CO₂ emissions. The main problem of these stations development is the hydrogen cost that depends on both the plant size (hydrogen production capacity) and on the renewable source.In this study, a techno-economic assessment of on-site hydrogen refueling stations (HRS), based on grid-connected PV plants integrated with electrolysis units, has been performed. Different plant configurations, in terms of hydrogen production capacity (50 kg/day, 100 kg/day, 200 kg/day) and the electricity mix (different sharing of electricity supply between the grid and the PV plant), have been analyzed in terms of electric energy demands and costs.The study has been performed by considering the Italian scenario in terms of economic streams (i.e. electricity prices) and solar irradiation conditions.The levelized cost of hydrogen (LCOH), that is the more important indicator among the economic evaluation indexes, has been calculated for all configurations by estimating the investment costs, the operational and maintenance costs and the replacement costs.Results highlighted that the investment costs increase proportionally as the electricity mix changes from Full Grid operation (100% Grid) to Low Grid supply (25% Grid) and as the hydrogen production capacity grows, because of the increasing in the sizes of the PV plant and the HRS units. The operational and maintenance costs are the main contributor to the LCOH due to the annual cost of the electricity purchased from the grid.The calculated LCOH values range from 9.29 €/kg (200 kg/day, 50% Grid) to 12.48 €/kg (50 kg/day, 100% Grid).     

Techno – Economic assessment of flexible decarbonized hydrogen and power co-production based on natural gas dry reforming

The need for flexible power plants could increase in the future as variable renewable energy (VRE) share will increase in the power grid. These power plants could balance the increasing strain on electricity grids by renewables. The proposed plant in this paper can adapt to these ramps in electricity demand of the power grid by maintaining a constant feed and producing also high purity hydrogen. Dry methane reforming (DMR) is incorporated into a flexible power plant model and the key performance indicators are calculated from a techno-economic perspective. The net output of the plant is 450 MW with the possibility to lower power production and produce hydrogen, maintaining a high CO₂ capture rate (72%). Two cases are compared to the base case to quantify: (i) energy and cost penalties for CO₂ capture and (ii) advantages of flexible power plant operation. The levelized cost of electricity (LCOE) for the base case is 67 Euro/MWh, the addition of a carbon capture unit increases it to 82 Euro/MWh. In the case of flexible operation, both the LCOE and levelized cost of hydrogen (LCOH) are calculated and the two depend on the cost allocation factor. The LCOE ranges from 65 to 85 Euro/MWh while the LCOH from 0.15 to 0.073 Euro/Nm³. The DMR power plant presented in Cases 1 and 2 present little advantages in today's market conditions however, the flexible plant (Case 3) can be viable option in balancing VRE.     

Evaluating the competitiveness and uncertainty of offshore wind-to-hydrogen production: A case study of Poland

Offshore wind is currently the most rapidly growing renewable energy source on a global scale. The increasing deployment and high economic potential of offshore wind have prompted considerable interest in its use for hydrogen production. In this context, this study develops a Monte Carlo-based framework for assessing the competitiveness of offshore wind-to-hydrogen production. The framework is designed to evaluate the location-based variability of the levelised cost of hydrogen (LCOH) and explore the uncertainty that exists in the long-term planning of hydrogen production installations. The case study of Poland is presented to demonstrate the application of the framework. This work provides a detailed analysis of the LCOH considering the geographical coordinates of 23 planned offshore wind farms in the Baltic Sea. Moreover, it presents a comparative analysis of hydrogen production costs from offshore and onshore wind parks in 2030 and 2050. The results show that hydrogen from offshore wind could range between €3.60 to €3.71/kg H₂ in 2030, whereas in 2050, it may range from €2.05 to €2.15/kg H₂.     

Large-scale decomposition of green ammonia for pure hydrogen production

It is acknowledged that Hydrogen has a decisive role to play in insuring a reliable and efficient penetration of renewable electricity in the energy mix. Nonetheless, building a sustainable Hydrogen Economy is faced with numerous challenges across the value chain. Namely, large-scale production and storage are still open issues that need to be addressed. A promising solution is to store renewable H₂ in the form of green ammonia often referred to as Power-to-Ammonia. Thus unlocking all available infrastructure for ammonia to effectively store and export hydrogen in bulk. In this value chain, the missing link is ammonia cracking to recover back hydrogen at high purities. The present work explores a technical solution to recover hydrogen from ammonia at large-scale. Through an exhaustive technoeconomic analysis, we have demonstrated the feasibility of large-scale production of pure H₂ from ammonia. The designed Ammonia-to-H₂ plant operates at a thermal efficiency of 68.5% to produce 200 MTPD of pure hydrogen at 250 bar. Furthermore, this study has established a final estimation of the Levelized Cost of Hydrogen (LCOH) from green ammonia. It was revealed that LCOH is mostly dependent on green ammonia cost, which in turn varies with renewable electricity cost.     

Renewable-powered hydrogen economy from Australia's perspective

This article broadly reviews the state-of-the-art technologies for hydrogen production routes, and methods of renewable integration. It outlines the main techno-economic enabler factors for Australia to transform and lead the regional energy market. Two main categories for competitive and commercial-scale hydrogen production routes in Australia are identified: 1) electrolysis powered by renewable, and 2) fossil fuel cracking via steam methane reforming (SMR) or coal gasification which must be coupled with carbon capture and sequestration (CCS). It is reported that Australia is able to competitively lower the levelized cost of hydrogen (LCOH) to a record $(1.88–2.30)/kg_H2 for SMR technologies, and $(2.02–2.47)/kg_H2 for black-coal gasification technologies. Comparatively, the LCOH via electrolysis technologies is in the range of $(4.78–5.84)/kg_H2 for the alkaline electrolysis (AE) and $(6.08–7.43)/kg_H2 for the proton exchange membrane (PEM) counterparts. Nevertheless, hydrogen production must be linked to the right infrastructure in transport-storage-conversion to demonstrate appealing business models.     

Renewable electrolytic hydrogen potential in Algeria

The present paper deals with the assessment of the renewable hydrogen production potential in Algeria. The studied system produces hydrogen by electrolysis of water; electricity is supplied by a photovoltaic generator. Adequate mathematical models were used to calculate the electrolytic hydrogen production. Detailed hourly simulations were used to assess the potential for the entire country and to draw it maps. Throughout this study, the influence of the tilt angle of a photovoltaic generator has been investigated. It has been observed that the tilt angle has an impact on solar energy received by the photovoltaic generator, the produced solar electrical power and the rate of hydrogen production. We have calculated the optimal angles to maximize each element. We were particularly interested in the optimal angle to maximize hydrogen production. We found that the solar hydrogen potential for Algeria varies from 0.10 Nm³/m²/d to 0.14 Nm³/m²/d. This potential is quite significant, especially in the arid region of southeastern Algeria. The lowest potential is located in the northeast region. For stand-alone systems, it is important to assess the minimum available level, as their sizing takes into account the most unfavorable case. This level is between 0.07 Nm³/m²/d and 0.13 Nm³/m²/d. This shows that, even for a stand-alone system, the potential is quite high. Finally, we provide robust correlations that allow calculating the potential and the angle of inclination maximizing it for the whole of Algeria.     

Thermoeconomic analysis and artificial neural network based genetic algorithm optimization of geothermal and solar energy assisted hydrogen and power generation

The study aims to optimize the geothermal and solar-assisted sustainable energy and hydrogen production system by considering the genetic algorithm. The study will be useful by integrating hydrogen as an energy storage unit to bring sustainability to smart grid systems. Using the Artificial Neural Network (ANN) based Genetic Algorithm (GA) optimization technique in the study will ensure that the system is constantly studied in the most suitable under different climatic and operating conditions, including unit product cost and the plant's power output. The water temperature of the Afyon Geothermal Power Plant varies between 70 and 130 °C, and its mass flow rate varies between 70 and 150 kg/s. In addition, the solar radiation varies between 300 and 1000 W/m² for different periods. The net power generated from the region's geothermal and solar energy-supported system is calculated as 2900 kW. If all of this produced power is used for hydrogen production in the electrolysis unit, 0.0185 kg/s hydrogen can be produced. The results indicated that the overall energy and exergy efficiencies of the integrated system are 4.97% and 16.0%, respectively. The cost of electricity generated in the combined geothermal and solar power plant is 0.027 $/kWh if the electricity is directly supplied to the grid and used. The optimized cost of hydrogen produced using the electricity produced in geothermal and solar power plants in the electrolysis unit is calculated as 1.576 $/kg H₂. The optimized unit cost of electricity produced due to hydrogen in the fuel cell is calculated as 0.091 $/kWh.     

A novel hybrid energy system for hydrogen production and storage in a depleted oil reservoir

Renewable and carbon free energy relates to the sustainable development of human beings while hydrogen production by renewables and hydrogen underground storage ensure the stable and economic renewable energy supply. A hybrid energy system combining hydrogen production by offshore wind power with hydrogen storage in depleted oil reservoirs was constructed along with a mathematical model where the Weibull distribution, Wind turbine power function, Faraday's law, continuity equation, Darcy's law, state equation of real gas, Net Present Value (NPV) and the concept of leveling were adopted to clarify the system characteristics. For the case of a depleted oil field in the Bohai Bay, China, the annual hydrogen production, annual levelized cost of hydrogen and payback period are 2.62 × 10⁶ m³, CNY 34.6/kgH₂ and 7 years, respectively. Sensitivity analysis found that the wind speed impacted significantly on system NPV and LCOH, followed by hydrogen price and stratum pressure.     

A Techno-Economic Analysis of solar hydrogen production by electrolysis in the north of Chile and the case of exportation from Atacama Desert to Japan

H₂ production from solar electricity in the region of the Atacama Desert – Chile – has been identified as strategical for global hydrogen exportation. In this study the full supply chain of solar hydrogen has been investigated for 2018 and projected to scenarios for 2025-2030. Multi-year hourly electrical profiles data have been used from real operating PV plants and simulated Concentrated Solar Power “CSP” plants with Thermal Energy Storage “TES” as well as commercial electricity Power Purchase Agreement “PPA” prices reported in the Chilean electricity market were considered. The Levelized Cost of Hydrogen “LCOH” of each production pathway is calculated by a case-sensitive techno-economic MATLAB/Simulink model for utility scale (multi-MW) alkaline and PEM electrolyser technologies. Successively, different distribution, storage and transportation configurations are evaluated based on the 2025 Japanese case study according to the declared H₂ demand. Transport in the form of liquefied hydrogen (LH₂) and via ammonia (NH₃) carrier is compared from the port of Antofagasta, CL to the port of Osaka, JP.     

OPTIMIZATION OF COLLECTOR AREA IN SOLAR WATER HEATING SYSTEMS

Domestic household thermosyphons are economically feasible and are used by over than 70% of houses in Palestine. Although domestic solar water heating for commercial applications has a good potential, only a few systems have been installed in Palestine. A systematic sizing approach for the solar system is presented in this paper and applied to a certain case study. The solar system sizing is based on the life-cycle cost LCC analysis. For the chosen case study of domestic water heating for a hotel, with hot water consumption of 2600 liters per day, the optimum collector area was found to be 37 m², the solar fraction of heating 0.78, the LCC of system is SI 3778, with annual savings of 1338$/year and a pay back period of 3 years. With this optimized system, the cost of water heating is 1.8 $/m³comparing with 2.6 $/m³ for the conventional system.     

Comparative techno-economic study of typically combustion-less hydrogen production alternatives

A techno-economic study is performed for a large scale combustion-less hydrogen production process based on Steam Methane Reforming (SMR). Two process versions relying on different renewable heat sources are compared: (1) direct solar heating from a concentrated solar power system, and (2) radiation from resistive electrical heaters (electric SMR). Both processes are developed around an integrated micro-reactor technology, incorporating in a monolithic block most sub-processes needed to perform SMR. A baseline techno-economic scenario with low-cost feedstock and electricity, priced at $4/MMBtu and $0.04/kWh respectively, results in an LCOH of $2.31/kg_H2 for solar SMR and $1.59/kg_H2 for electric SMR. Results further show that solar SMR is currently more attractive economically than electric SMR coupled with distributed wind power systems, but electric SMR is more favourable in the long term due to the expected future improvements in the LCOE and capacity factor of wind power systems.     

Techno-economic analysis of the Ca-Cu process integrated in hydrogen plants with CO2 capture

In this work, a techno-economic analysis of a hydrogen production plant based on the Ca-Cu process has been carried out. The simulation of the whole hydrogen production plant has been performed, including the calculation of the Ca-Cu fixed bed reactors system using a sharp front modelling approach. From the analyses carried out, it has been demonstrated that the optimal operation point from the energy performance point of view is reached when fuel needed for sorbent regeneration is entirely supplied by the off-gas from the PSA hydrogen purification unit, which corresponds to operating the plant with the minimum steam-to-carbon ratio in the reforming step. Moreover, lowering the operating pressure of the Ca-Cu system results beneficial from the hydrogen production efficiency, but the CO₂ emissions and the economics worsen.The Ca-Cu based hydrogen production plant operating at a high pressure has been demonstrated to be cost efficient with respect to a benchmark hydrogen production plant based on conventional fired tubular reformer and CO₂ capture by MDEA absorption. A hydrogen production cost of 0.178 €/Nm³ and a CO₂ avoided cost of 30.96 €/ton have been calculated for this Ca-Cu hydrogen production plant, which are respectively 8% and 52% lower than the corresponding costs of the benchmark.     

Solar thermochemical plant analysis for hydrogen production with the copper–chlorine cycle

In this article, a solar-based method of generating hydrogen from the copper–chlorine water-splitting cycle is developed and evaluated. An analysis is performed for solar plants with different hydrogen production capacities at three locations across Canada. Operating parameters of the solar field and the storage units are presented. The thermal efficiency and cost parameters of the hydrogen plant are also examined. A binary mixture of 60% NaNO₃ and 40% KNO₃ is used as the molten salt for solar energy storage. Different hydrogen production rates are analyzed. Since the solar irradiation in Calgary is much less than Toronto and Sarnia in the winter, it is found that a larger storage unit is required. The size of the storage unit increases for larger hydrogen production rates. The results support the feasibility of solar thermochemical Cu–Cl cycle as a promising and efficient pathway for large-scale production of hydrogen.     

Optimizing hybrid offshore wind farms for cost-competitive hydrogen production in Germany

Nearly 96% of the world's current hydrogen production comes from fossil-fuel-based sources, contributing to global greenhouse gas emissions. Hydrogen is often discussed as a critical lever in decarbonizing future power systems. Producing hydrogen using unsold offshore wind electricity may offer a low-carbon production pathway and emerging business model. This study investigates whether participating in an ancillary service market is cost competitive for offshore wind-based hydrogen production. It also determines the optimal size of a hydrogen electrolyser relative to an offshore wind farm. Two flexibility strategies for offshore wind farms are developed in this study: an optimal bidding strategy into ancillary service markets for offshore wind farms that build hydrogen production facilities and optimal sizing of Power-to-Hydrogen (PtH) facilities at wind farms. Using empirical European power market and wind generation data, the study finds that offshore-wind based hydrogen must participate in ancillary service markets to generate net positive revenues at current levels of wind generation to become cost competitive in Germany. The estimated carbon abatement cost of “green” hydrogen ranges between 187 EUR/tonCO₂e and 265 EUR/tonCO₂e. Allowing hydrogen producers to receive similar subsidies as offshore wind farms that produce only electricity could facilitate further cost reduction. Utilizing excess and intermittent offshore wind highlights one possible pathway that could achieve increasing returns on greenhouse gas emission reductions due to technological learning in hydrogen production, even under conditions where low power prices make offshore wind less competitive in the European electricity market.     

Techno-economic assessment of hydrogen pipe storage in decommissioned wellbores sourced from surplus renewable electricity

Wellbore decommissioning is the final stage in the life cycle of any oil or gas well and involves placing acceptable well barriers to seal the wellbore. Operators have the obligation to decommission wells safely once they reach the end of their life. This study explores the prospects of repurposing near-to-decommission wellbores for pipe storage, forming a hydrogen-based energy storage system for containing hydrogen produced from surplus renewable electricity. It offers two pathways for hydrogen consumption, 1) Power-to-Hydrogen and 2) Power-to-Power. A conceptual design is presented to repurpose a wellbore into pipe storage to store hydrogen in its gaseous form. The storability of the pipe depends on pipe characteristics, including diameter and length as well as working pressure. Monte Carlo simulations are performed to calculate levelized cost of storage (LCOS) and levelized cost of hydrogen (LCOH) for the proposed method. The LCOS is in the range of 1.33 A$/(kgH₂) and 1.66 A$/(kgH₂). LCOH including the storage cost is obtained to be in the range of 5.22 A$/(kgH₂) and 6.50 A$/(kgH₂). This system can potentially integrate green hydrogen into local economies by managing decommissioning costs for the creation of a storage solution for green hydrogen.     

Membrane reactors for green hydrogen production from biogas and biomethane: A techno-economic assessment

This work investigates the performance of a fluidized-bed membrane reactor for pure hydrogen production. A techno-economic assessment of a plant with the production capacity of 100 kg_H2/day was carried out, evaluating the optimum design of the system in terms of reactor size (diameter and number of membranes) and operating pressures. Starting from a biomass source, hydrogen production through autothermal reforming of two different feedstock, biogas and biomethane, is compared.Results in terms of efficiency indicates that biomethane outperforms biogas as feedstock for the system, both from the reactor (97.4% vs 97.0%) and the overall system efficiency (63.7% vs 62.7%) point of views. Nevertheless, looking at the final LCOH, the additional cost of biomethane leads to a higher cost of the hydrogen produced (4.62 €/kg_H2@20 bar vs 4.39 €/kg_H2@20 bar), indicating that at the current price biogas is the more convenient choice.     

Nickel powder blended activated carbon cathodes for hydrogen production in microbial electrolysis cells

Although pure Ni catalysts can achieve a hydrogen production rate similar to Pt in microbial electrolysis cells (MECs), a reduction in the amount of Ni used is needed to reduce the cost. In this study, nickel powder (pNi) was blended with activated carbon (AC) to reduce the mass of Ni used, while improving catalytic activity for the hydrogen evolution reaction (HER) by increasing the active surface area. Ni powder blended AC cathodes (AC-pNi) were fabricated at different nickel powder loadings (4.8, 19, 46 mg/cm² with AC and 77 mg/cm² without AC as control). AC-pNi4.8 (Ni loading: 4.8 mg/cm²) produced higher hydrogen production rates (0.38 ± 0.04 L-H₂/L-d) than pNi77 (0.28 ± 0.02 L-H₂/L-d) with a 16 times less Ni loading. Cathodic hydrogen recovery of using the AC-pNi4.8 (98 ± 5%) was also higher than pNi77 (82 ± 4%), indicating catalytic activities were improved by AC blending. Nickel dissolution into the catholyte after completion of each cycle was negligible for AC-pNi4.8 (<0.2 mg/L), while Ni dissolution was detected for pNi77 (5–10 mg/L). These results indicate that AC blending with Ni powder can improve hydrogen production in MECs while minimizing the amount of Ni in the cathode.