Catching the hydrogen train: economics-driven green hydrogen adoption potential in the United Arab Emirates

The establishment of a hydrogen economy for domestic use and energy exports is increasingly attractive to fossil fuel exporting countries. This paper quantifies the potential of green hydrogen in the United Arab Emirates, using an integrated adoption model based on global technoeconomic trends and local costs. We consider the impact of varying hydrogen, oil, natural gas, and carbon prices on the economics of green H₂ adoption. In our Business-As-Usual (BAU) scenario, we observe economic viability in UAE industries between 2032 and 2038 at H₂ prices between $0.95/kg and $1.35/kg based on electrolyzer cost assumptions, solar forecasts and learning rates. We also note rapid scale-up to large export-oriented production capacities across our scenarios. However, if cost reductions slow or gas prices return to historical lows, additional interventions such as carbon pricing would be required to fully decarbonize in alignment with the 2050 net-zero target.     

A systematic review on green hydrogen for off-grid communities –technologies,advantages, and limitations

Approximately 3.5 billion people worldwide lack reliable and sustainable energy services, mostly in poor off-grid areas of developing countries. Variable renewable energies are options for these communities. However, their high intermittence and complex storage limit their benefits. Green hydrogen research has advanced significantly to the point that some scholars consider it the future's clean energy solution. Multiple applications within the transport, electricity and storage sectors have been envisaged. However, little has been discussed about its potential to provide affordable, dependable, and sustainable energy for the world's poorest. This paper addresses this gap by analyzing the literature on green hydrogen research, its technologies, and its potential implementation in off-grid communities. First, a quantitative bibliometric approach is developed to size and make sense of the green hydrogen research literature. Then, an in-depth review is performed following Dawood et al.'s four-corners framework, categorizing hydrogen research into production, storage, use, and safety. This systematic review unveils green hydrogen's most promising technologies for off-grid applications. It identifies their advantages, limitations, and barriers to widespread dissemination. Thus, this study's primary contributions lie in determining the relationship between published works and identifying gaps in considering green hydrogen as a viable energy alternative for the poor.     

Prospects and challenges for green hydrogen production and utilization in the Philippines

The Philippines is exploring different alternative sources of energy to make the country less dependent on imported fossil fuels and to reduce significantly the country's CO₂ emissions. Given the abundance of renewable energy potential in the country, green hydrogen from renewables is a promising fuel because it can be utilized as an energy carrier and can provide a source of clean and sustainable energy with no emissions. This paper aims to review the prospects and challenges for the potential use of green hydrogen in several production and utilization pathways in the Philippines. The study identified green hydrogen production routes from available renewable energy sources in the country, including geothermal, hydropower, wind, solar, biomass, and ocean. Opportunities for several utilization pathways include transportation, industry, utility, and energy storage. From the analysis, this study proposes a roadmap for a green hydrogen economy in the country by 2050, divided into three phases: I–green hydrogen as industrial feedstock, II–green hydrogen as fuel cell technology, and III–commercialization of green hydrogen. On the other hand, the analysis identified several challenges, including technical, economic, and social aspects, as well as the corresponding policy implications for the realization of a green hydrogen economy that can be applied in the Philippines and other developing countries.     

Towards The Hydrogen Economy: Estimation of green hydrogen production potential and the impact of its uses in Ecuador as a case study

The estimation of the green hydrogen (H₂) production potential represents the initial stage on the road to integrating the Hydrogen Economy into the energy systems of a country or region. This article has two purposes; the first focuses on identifying and analyzing studies on the amount of green H₂ obtainable in countries and regions across the globe. In total, 64 studies in 29 countries are reported, of which the geographical distribution of the estimates of green H₂ potential is obtained. Additionally, the most widely used renewable energy sources and the conversion technologies favored for their production were identified. The Americas and Argentina were the continents and the country, respectively, with the largest number of studies. At the same time, solar photovoltaic (PV) and electrolysis are the most studied production methods. The second purpose is to quantify the total potential of green H₂ in the Republic of Ecuador and explore its uses as an energy vector and chemical input in niches of opportunity detected from the analysis of its energy balance. In this regard, the total potential of green H₂ in Ecuador of 4.38 × 10⁸ tons/year is obtained, being the production of electrolytic H₂ with PV electricity the one with the highest contribution. The amount of H₂ available satisfies, in excess, the demand for the proposed uses: as fuel and chemical input. These results contribute to the knowledge of the object of study by making visible the interest of the countries in having such estimates and identifying the most attractive production route in the first place, and secondly, providing essential elements for the development of more detailed research and energy planning on the gradual incorporation of the Hydrogen Economy in Ecuador.     

The potential and economic viability of hydrogen production from the use of hydroelectric and wind farms surplus energy in Brazil: A national and pioneering analysis

Energy security is an issue at stake in governments all over the world, and also in Brazil. Although the country's energetic matrix is largely based on hydropower sources, the need for diversification is increasingly needed. The possibility of hybrids between hydropower and wind power for hydrogen production emerges as a clean alternative source for energy security. In high-throughput seasons, excess energy could be used to produce hydrogen, which could supply shortages of energy. This study shows the potential for producing hydrogen in Brazil, using excess energy from hydroelectric and wind farms. Taking into account one hour per day of surplus energy production, it would be possible to generate 6.50E+09 Nm³.y⁻¹ of H₂. On the other hand, considering two and three hours, the H₂ generation would be equal to 1.30E+10 Nm³.y⁻¹ and 2.00E+10 Nm³.y⁻¹, respectively. This study calculated the economic viability for hydrogen production, at a cost of 0.303 USD.kWh⁻¹, a higher cost if compared to that of the wind and hydroelectric plants.     

Recent advances in membrane technologies for hydrogen purification

Planet Earth is facing accelerated global warming due to greenhouse gas emissions from human activities. The United Nations agreement at the Paris Climate Conference in 2015 highlighted the importance of reducing CO₂ emissions from fossil fuel combustion. Hydrogen is a clean and efficient energy carrier and a hydrogen-based economy is now widely regarded as a potential solution for the future of energy security and sustainability. Although hydrogen can be produced from water electrolysis, economic reasons dictate that most of the H₂ produced worldwide, currently comes from the steam reforming of natural gas and this situation is set to continue in the foreseeable future. This production process delivers a H₂-rich mixture of gases from which H₂ needs to be purified up to the ultra-high purity levels required by fuel cells (99.97%). This driving force pushes for the development of newer H₂ purification technologies that can be highly selective and more energy efficient than the traditional energy intensive processes of pressure swing adsorption and cryogenic distillation. Membrane technology appears as an obvious energy efficient alternative for producing the ultra-pure H₂ required for fuel cells. However, membrane technology for H₂ purification has still not reached the maturity level required for its ubiquitous industrial application. This review article covers the major aspects of the current research in membrane separation technology for H₂ purification, focusing on four major types of emerging membrane technologies (carbon molecular sieve membranes; ionic-liquid based membranes; palladium-based membranes and electrochemical hydrogen pumping membranes) and establishes a comparison between them in terms of advantages and limitations.     

Techno-economic analysis of green methanol plant with optimal design of renewable hydrogen production: A case study in China

Using renewable energy to convert carbon dioxide (CO₂) into methanol has gained extensive attention. This study focuses on a green methanol plant which contains both upstream green hydrogen-electricity production system and downstream CO₂-based methanol synthesis. Three configurations were designed and optimized for the upstream off-grid hydrogen-electricity production system to obtain the minimum hydrogen cost. The optimization was conducted based on hourly meteorological data at Ordos, Inner Mongolia, China, as well as the hydrogen and electricity consumption by the downstream CO₂ hydrogenation unit. On top of that, an integrative techno-economic analysis was conducted on the entire green methanol plant. Furthermore, the effect of key parameters and carbon tax on the economy of such green methanol plant was also explored. The results indicate that (1) for Ordos, the green methanol plant adopting photovoltaic-wind powered hydrogen production system (PV-Wind-H₂-methanol) with oxygen selling has the lowest levelized cost of methanol, of which the upstream green hydrogen-electricity production system occupies 77%; (2) byproduct oxygen selling and CO₂ source option has a significant effect on the methanol cost; (3) for PV-Wind-H₂-methanol system, wind turbine cost is the most influential economic factor. To make the methanol cost of the PV-Wind-H₂-methanol system to be lower than the conventional methanol cost, the cost of wind turbines and PV needs to be reduced by at least 50% at the same time; (4) if considering carbon tax, the PV-Wind-H₂-methanol system will have potential to compete with conventional methanol plant.     

Enhancement of biological hydrogen production using green alga Chlorococcum minutum

It is estimated that the fossil fuel reserves are going to deplete continuously due to extensive usage. In order to cope with this crisis, it is necessary to increase the efforts towards production of biofuels such as biological hydrogen (H₂). It is well-known fact that the biological hydrogen is a clean and ideal energy and liberates high amount of energy per unit mass. Several groups are working for the large scale production of H₂ chemically and also using photosynthetic organisms, but output is not satisfactory. The best way to achieve enhancement of H₂ is through altering the photosynthetic process by applying various stress conditions or by natural selection. In the process of selection, Chlorococcum minutum was found with improved H₂ output when compared to model green alga Chlamydomonas reinhardtii in a massively parallel and competitive high-throughput screen of different green algae. Both the species belongs to class chlorophyceae of green algae and live in fresh water conditions. In extent various light, pH and temperature conditions were applied and achieved the enhancement of H₂ production in this species under in vitro settings. Augmented hydrogenase activity was found in Chlorococcum minutum when compared to model alga and this may be one of the reason behind improved H₂ output. Hence this species may be considered as one of the best species with respect to H₂ production and also this work may be useful for future renewable energy research.     

Green hydrogen-based pathways and alternatives: Towards the renewable energy transition in South America's regions–Part B

Hydropower compounds most of the energy matrix of the countries of the Latin America and Caribbean region (LAC). Considering the concern in reducing Green House Gases emissions (GHG) from hydropower plants and hydrogen production from fossil sources, green hydrogen (H₂) appears as an energy vector able to mitigate this impact. Improving the efficiency of the plant and producing renewable energy the element is an interesting alternative from the ecological and economic point of view. This study aims to estimate the potential of H₂ production from wasted energy, through the electrolysis of water in hydroelectric plants in Colombia and Venezuela. The construction of two scenarios allowed obtaining a difference, considering a spilled flow of 2/3 in the first scenario and 1/3 in the second. In Colombia, hydrogen production reached 3.39 E+08 Nm³ at a cost of 2.05 E+05 USD/kWh in scenario1, and 1.70 E+08 Nm³ costing 4.10 E+05 USD/kWh in scenario 2. Regarding the Venezuelan context, the country obtained lower production values of H₂, ranging between 7.76 E+07 Nm³.d^?1 and 4.31 E+07 Nm³.d^?1, and production cost between 9.45 E+09 USD/kWh and 1.89 E+10 USD/kWh. Thus, the final cost for the production and storage of H₂ was estimated at 0.2239 USD.kg^?1. Ultimately, Colombia and Venezuela have a large potential to supply the demand for nitrogen fertilizers with green ammonia production, apply green hydrogen in manufacturing and use the surplus for energy substitution of Liquefied Petroleum Gas - LPG. In Colombia, the chemical energy offered is equivalent to 6.681 E+11 MJ/year^?1 and in Venezuela, the result is equal to 1.697 E+11 MJ/year^?1 in the conservative scenario. Finally, the countries have great potential for the diversification of the energy matrix and the insertion of renewables in the system.     

Towards the Hydrogen Economy in Paraguay: Green hydrogen production potential and end-uses

This study was conducted to estimate the potential for green H₂ in Paraguay. A total production potential of 22.5 × 10⁶ tons/year was obtained with a main contribution (93.34%) from solar photovoltaic. The greatest potential for producing H₂ from solar and wind resources is in the Western region, and from hydro resources is in the Eastern region of the country. Two end-uses of green H₂ were assessed: (1) automotive transportation, replacing gasoline and diesel; and (2) residential energy, replacing firewood and LPG for cooking in households across the country. In 16 of the 17 departments, green H₂ is able to replace the overall consumption of gasoline and diesel, as well as firewood and LPG. Finally, energy service cost (mobility), environmental aspects and CO₂ emissions were considered for three urban mobility technologies for the Metropolitan Area of Asunción. Results show that the mobility cost of fuel cell hybrid electric buses is still very high in comparison to diesel buses and battery electric buses. However, when a longer driving range is required, fuel cell hybrid electric buses could become a viable alternative in the long term. From an environmental point of view, green H₂ used in fuel cell hybrid electric buses has the potential to save about 96% of CO₂ emissions in comparison to diesel buses. It is concluded that the estimated green H₂ production potential favors the incorporation of the Hydrogen Economy in Paraguay.     

A correct perspective for hydrogen from engineered diagenesis

Wind and solar photovoltaic electricity production have already reached very low levels of levelized cost of energy (LCOE). Electrolyzers have already reached high efficiencies which are further improving, while costs are dramatically reducing. They are commercial products. Green hydrogen (H₂) is the product of excess wind and solar electricity, specifically electricity that will be otherwise wasted, without the huge energy storage needed presently almost completely missing. By growing the installed capacity of wind and solar power plants, there will be a non-dispatchable production by wind and solar more often in excess, but sometimes also in defect, of the grid demand, in presence of limited energy storage. H₂ is one of the key energy storage technologies needed to ensure grid stability. Production of H₂ above what is needed to stabilize the grid significantly helps in applications such as land, and sea but especially air transport where the storage of energy onboard in a fuel is preferable to the storage of energy as electricity into a battery. The engineered diagenesis for H₂ is unlikely better than green hH₂. Apart from being a nice idea to be proven workable, with a technology readiness level (TRL) presently of zero, and thus impossible to be objectively compared with commercial products, the engineered diagenesis for H₂, even if possible, also does not help with non-dispatchable renewable energy production. The concept may also have negative environmental aspects similar to fracking which have not been considered yet, and also bear huge economic costs in addition to environmental. Here we review the pros and cons of this novel technology, which once proven workable, which is not the case yet, should be considered as a possible way to complement rather than replace green H₂ production.     

A power-law sensitivity analysis of the hydrogen-producing metabolic pathway in Chlamydomonas reinhardtii

Melis et al. have demonstrated that the green alga Chlamydomonas reinhardtii, when deprived of sulfur, can produce hydrogen gas for 70 h, then can resume hydrogen gas production after a brief period of “recharging” in the presence of sulfur. Here we describe an S-system model of H₂ production by C. reinhardtii. Through that model we investigate the sensitivity of H₂ production to photosynthetic efficiency, and to contention for the protons produced by the photolysis of water, between hydrogen production on the one hand, and ATP consumption by cellular functions outside the H₂ production path on the other. The model identifies for experimental investigation several potential systemic constraints on any genetic re-engineering effort aimed at increasing the H₂ production efficiency of the alga.     

Integrated biological hydrogen production

Biological systems offer a variety of ways by which to generate renewable energy. Among them, unicellular green algae have the ability to capture the visible portion of sunlight and store the energy as hydrogen (H₂). They hold promise in generating a renewable fuel from nature's most plentiful resources, sunlight and water. Anoxygenic photosynthetic bacteria have the ability of capturing the near infrared emission of sunlight to produce hydrogen while consuming small organic acids. Dark anaerobic fermentative bacteria consume carbohydrates, thus generating H₂ and small organic acids. Whereas efforts are under way to develop each of these individual systems, little effort has been undertaken to combine and integrate these various processes for increased efficiency and greater yields. This work addresses the development of an integrated biological hydrogen production process based on unicellular green algae, which are driven by the visible portion of the solar spectrum, coupled with purple photosynthetic bacteria, which are driven by the near infrared portion of the spectrum. Specific methods have been tested for the cocultivation and production of H₂ by the two different biological systems. Thus, a two-dimensional integration of photobiological H₂ production has been achieved, resulting in better solar irradiance utilization (visible and infrared) and integration of nutrient utilization for the cost-effective production of substantial amounts of hydrogen gas. Approaches are discussed for the cocultivation and coproduction of hydrogen in green algae and purple photosynthetic bacteria entailing broad utilization of the solar spectrum. The possibility to improve efficiency even further is discussed, with dark anaerobic fermentations of the photosynthetic biomass, enhancing the H₂ production process and providing a recursive link in the system to regenerate some of the original nutrients.     

A review of recent advances in hydrogen purification for selective removal of oxygen: Deoxo catalysts and reactor systems

As a response to climate change caused by a surge in greenhouse gas emissions and the associated transition to sustainable energy systems, hydrogen (H₂) is considered as an attracting alternative energy source. In that context, water electrolysis combined with renewable energy source, so called green H₂, has been recently receiving great attention from worldwide. However, for stable use of H₂ as an energy source in various type of fuel cells to produce electricity, the purity of H₂ must not only meet the required level but also be maintained stably. Among possible impurities in the produced H₂ steam, oxygen (O₂) must be controlled below certain level in any circumstances for safety, hence catalytic purification for intensive and selective removal of O₂ in H₂ steam is nowadays regarded as an essential technology for commercial application of green H₂ because of the intermittent nature of renewable energy. Nevertheless, the catalytic purification technology, especially the technology for catalyst and process development, is still in the basic stage, and the reported technologies have not been systemically organized yet. Therefore, this review 1) briefly summarizes the developmental trends and current available technologies of various H₂ purification technologies, such as membrane separation, pressure swing adsorption, metal hydride, and cryogenic separation 2) and introduces the developmental of deoxo catalysts and catalytic H₂ purification technologies with future research perspectives and suggestions.     

Emerging technologies for hydrogen production from wastewater

Wastewater treatment is essential to shield the environment. The production of H₂ is substantial for prospering its applications in diversified sectors; hence the study of wastewater treatment for H₂ production is accomplished. Various technologies have been developed and studied considering the potential of wastewater to generate hydrogen-rich gas. These technologies have different mechanisms, diversified setups, and processes. Perhaps these technologies are proven to be exceptional exposures for hydrogen production. Fortunately, a valuable contribution to the environment and the H₂ economy is that some technological processes have been promoted to synthesize H₂ from lab scale to pilot scale. Contemplating such comprehensive exposure to H₂ synthesis from wastewater, the critical information of eight emerging technologies, including their mechanism and reaction parameters influencing the process, pros, cons, and future developmental scopes, are described in this review by classifying them into three different classes, namely light-dependent technologies, light-independent technologies, and other technologies.     

Insights into low-carbon hydrogen production methods: Green,blue and aqua hydrogen

The primary aim of this study is to provide insights into different low-carbon hydrogen production methods. Low-carbon hydrogen includes green hydrogen (hydrogen from renewable electricity), blue hydrogen (hydrogen from fossil fuels with CO₂ emissions reduced by the use of Carbon Capture Use and Storage) and aqua hydrogen (hydrogen from fossil fuels via the new technology). Green hydrogen is an expensive strategy compared to fossil-based hydrogen. Blue hydrogen has some attractive features, but the CCUS technology is high cost and blue hydrogen is not inherently carbon free. Therefore, engineering scientists have been focusing on developing other low-cost and low-carbon hydrogen technology. A new economical technology to extract hydrogen from oil sands (natural bitumen) and oil fields with very low cost and without carbon emissions has been developed and commercialized in Western Canada. Aqua hydrogen is a term we have coined for production of hydrogen from this new hydrogen production technology. Aqua is a color halfway between green and blue and thus represents a form of hydrogen production that does not emit CO₂, like green hydrogen, yet is produced from fossil fuel energy, like blue hydrogen. Unlike CCUS, blue hydrogen, which is clearly compensatory with respect to carbon emissions as it captures, uses and stores produced CO₂, the new production method is transformative in that it does not emit CO₂ in the first place. In order to promote the development of the low-carbon hydrogen economy, the current challenges, future directions and policy recommendations of low-carbon hydrogen production methods including green hydrogen, blue hydrogen, and aqua hydrogen are investigated in the paper.     

Solid air hydrogen liquefaction,the missing link of the hydrogen economy

The most challenging aspect of developing a green hydrogen economy is long-distance oceanic transportation. Hydrogen liquefaction is a transportation alternative. However, the cost and energy consumption for liquefaction is currently prohibitively high, creating a major barrier to hydrogen supply chains. This paper proposes using solid nitrogen or oxygen as a medium for recycling cold energy across the hydrogen liquefaction supply chain. When a liquid hydrogen (LH2) carrier reaches its destination, the regasification process of the hydrogen produces solid nitrogen or oxygen. The solid nitrogen or oxygen is then transported in the LH2 carrier back to the hydrogen liquefaction facility and used to reduce the energy consumption cooling gaseous hydrogen. As a result, the energy required to liquefy hydrogen can be reduced by 25.4% using N₂ and 27.3% using O₂. Solid air hydrogen liquefaction (SAHL) can be the missing link for implementing a global hydrogen economy.     

A mathematical,economic and energetic appraisal of biomethane and biohydrogen production from Brazilian ethanol plants' waste: Towards a circular and renewable energy development

The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm³.d^?1 of hydrogen, equal 3.04E+08 ton per year. CH₄ and H₂ production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy.     

Using three chemical looping reactors in ammonia production process – A novel plant configuration for a green production

Production of three pure streams of H₂, N₂ and CO₂ makes the chemical looping reactors as an attractive intermediate technology to provide the feedstock of ammonia synthesis loop. As a goal of paper, for the first time, a novel and green plant configuration using three chemical looping reactors is proposed for ammonia production in which needed hydrogen and nitrogen are produced by means of a process simpler than the conventional technologies. Due to the reduction in plant units and also 30% increase in production ratio and simultaneously production of economically valuable by-products of H₂, N₂ and CO₂, significant potential for investment cost reduction along with CO₂ capture and storage can be anticipated. Moreover, the proposed plant for ammonia production is very flexible in terms of adjusting the desired main products.     

Light metal hydride-based hydrogen storage system: Economic assessment in Argentina

Motivated by the high potential for hydrogen production from renewable resources in Argentina, the economic feasibility of employing light complex metal hydrides as hydrogen storage materials for mobile applications in Argentina is explored for the first time. Three main costs are analyzed: green H₂, H₂ storage system based on Mg(NH₂)₂–LiH and storage tank. Considering the production of H₂ by electrolysis using wind energy, a cost of ~5 USD/kg H₂ is obtained. The cost of hydride matrix is crucial and competitive values are viable only if the synthesis route starts from Mg⁰ and Li⁰, allowing reducing the total hydride matrix cost from ~2200 to ~4900 USD. The cost of a modular configuration tank with 4 kg of H₂ capacity is estimated to be ~5300–6700 USD. A cost ratio higher than of 2:1 is obtained between storage systems based on amides and high pressure systems.