'Beyond Li-Ion Technology' - A status review.

Li-ion battery is currently considered to be the most proven technology for energy storage systems when it comes to the overall combination of energy, power, cyclability and cost. However, there are continuous expectations for cost reduction in large-scale applications, especially in electric vehicles and grids, alongside growing concerns over safety, availability of natural resources for lithium, and environmental remediation. Therefore, industry and academia have consequently shifted their focus towards "beyond Li-ion technologies". In this respect, other non-Li-based alkali-ion/polyvalent-ion batteries, non-Li-based all solid-state batteries, fluoride-ion/ammonium-ion batteries, redox-flow batteries, sand batteries and hydrogen fuel cells etc. are becoming potential cost-effective alternatives. While there has been notable swift advancement across various materials, chemistries, architectures, and applications in this field, a comprehensive overview encompassing high-energy "beyond Li-ion" technologies, along with considerations of commercial viability, is currently lacking. Therefore, in this review article, a rationalized approach is adopted to identify notable 'post-Li' candidates. Their pros and cons are comprehensively presented by discussing the fundamental principles in terms of material characteristics, relevant chemistries, and architectural developments that make a good high-energy 'beyond Li' storage system. Furthermore, a concise summary outlining the primary challenges of each system is provided, alongside the potential strategies being implemented to mitigate these issues. Additionally, the extent to which these strategies have positively influenced the performance of these 'post-Li' technologies is discussed.

Some inconvenient truths about decarbonization, the hydrogen economy, and power-to-X technologies.

The decarbonization of the energy sector has been a subject of research and of political discussions for several decades, gaining significant attention in the last years. It is commonly acknowledged that the most obvious way to achieve decarbonization is the use of renewable energy sources. Within the context of the energy sector decarbonization, many mainly industrialized countries recently started developing national plans to establish a hydrogen-based economy in the very near future. The plans for green hydrogen initially try to (a) target sectors that are difficult to decarbonize and (b) address issues related to the storage and transportation of CO2-free energy. To achieve almost complete decarbonization, electric power must be generated exclusively from renewable sources. In so-called Power-to-X (PtX) technologies, green hydrogen is generated from electricity and subsequently converted to another energy carrier which can be further stored, transported and used. In PtX, X stands, for example, for liquid hydrogen, methanol or ammonia. The challenges associated with decarbonization include those associated with (a) the expansion of renewable energies (e.g., high capital demand, political and social issues), (b) the production, transportation, and storage of hydrogen and the energy carriers denoted by X in PtX (e.g., high cost and low overall efficiency), and (c) the expected significant increase in the demand for electrical energy. The paper discusses whether and under which conditions the current national and international hydrogen plans of many industrialized countries could lead to a maximization of decarbonization in the world. It concludes that, in general, as long as the conditions for generating large excess amounts of green electricity are not met, the quick establishment of a hydrogen economy could not only be very expensive, but also counterproductive to the worldwide decarbonization efforts.

Li-Mediated Electrochemical Nitrogen Fixation: Key Advances and Future Perspectives.

The electrochemical nitrogen reduction reaction holds great potential for ammonia production using electricity generated from renewable energy sources and is sustainable. The low solubility of nitrogen in aqueous media, poor kinetics, and intrinsic competition by the hydrogen evolution reaction result in meager ammonia production rates. Attributing measured ammonia as a valid product, not an impurity, is challenging despite rigorous analytical experimentation. In this regard, Li-mediated electrochemical nitrogen reduction is a proven method providing significant ammonia yields. Herein, fundamental advances and insights into the Li-mediated strategy are summarized, emphasizing the role of lithium, reaction parameters, cell designs, and mechanistic evaluation. Challenges and perspectives are presented to highlight the prospects of this strategy as a continuous, stable, and modular approach toward sustainable ammonia production.

Nanomaterials enhancing the solid-state storage and decomposition of ammonia.

Hydrogen is ideal for producing carbon-free and clean-green energy with which to save the world from climate change. Proton exchange membrane fuel cells use to hydrogen to produce 100% clean energy, with water the only by-product. Apart from generating electricity, hydrogen plays a crucial role in hydrogen-powered vehicles. Unfortunately, the practical uses of hydrogen energy face many technical and safety barriers. Research into hydrogen generation and storage and reversibility transportation are still in its very early stages. Ammonia (NH3) has several attractive attributes, with a high gravimetric hydrogen density of 17.8 wt% and theoretical hydrogen conversion efficiency of 89.3%. Ammonia storage and transport are well-established technologies, making the decomposition of ammonia to hydrogen the safest and most carbon-free option for using hydrogen in various real-time applications. However, several key challenges must be addressed to ensure its feasibility. Current ammonia decomposition technologies require high temperatures, pressures and non-recyclable catalysts, and a sustainable decomposition mechanism is urgently needed. This review article comprehensively summarises current knowledge about and challenges facing solid-state storage of ammonia and decomposition. It provides potential strategic solutions for developing a scalable process with which to produce clean hydrogen by eliminating possible economic and technical barriers.

Mining Nontraditional Water Sources for a Distributed Hydrogen Economy.

Securing decarbonized economies for energy and commodities will require abundant and widely available green H2. Ubiquitous wastewaters and nontraditional water sources could potentially feed water electrolyzers to produce this green hydrogen without competing with drinking water sources. Herein, we show that the energy and costs of treating nontraditional water sources such as municipal wastewater, industrial and resource extraction wastewater, and seawater are negligible with respect to those for water electrolysis. We also illustrate that the potential hydrogen energy that could be mined from these sources is vast. Based on these findings, we evaluate the implications of small-scale, distributed water electrolysis using disperse nontraditional water sources. Techno-economic analysis and life cycle analysis reveal that the significant contribution of H2 transportation to costs and CO2 emissions results in an optimal levelized cost of hydrogen at small- to moderate-scale water electrolyzer size. The implications of utilizing nontraditional water sources and decentralized or stranded renewable energy for distributed water electrolysis are highlighted for several hydrogen energy storage and chemical feedstock applications. Finally, we discuss challenges and opportunities for mining H2 from nontraditional water sources to achieve resilient and sustainable economies for water and energy.

A solution to renewable hydrogen economy for fuel cell buses - A case study for Zhangjiakou in North China.

Fuel cell vehicles fueled with renewable hydrogen is recognized as a life-cycle carbon-free option for the transport sector, however, the profitability of the H2 pathway becomes a key issue for the FCV commercialization. By analyzing the actual data from the Zhangjiakou fuel cell transit bus project, this research reveals it is economically feasible to commercialize FCV in areas with abundant renewable resources. Low electricity for water electrolysis, localization of H2 supply, and curtailed end price of H2 refueling effectively reduce the hydrogen production, delivery and refueling cost, and render a chance for the profitability of refueling stations. After the fulfillment of the intense deployment of both vehicles and hydrogen stations for the 2022 Winter Olympics, the H2 pathway starts to make a profit thereafter. The practices in the Zhangjiakou FCB project offer a solution to the hydrogen economy, which helps to break the chicken-egg dilemma of vehicles and hydrogen infrastructure.

Comparative Analysis of Energy and Exergy Performance of Hydrogen Production Methods.

The study of the viability of hydrogen production as a sustainable energy source is a current challenge, to satisfy the great world energy demand. There are several techniques to produce hydrogen, either mature or under development. The election of the hydrogen production method will have a high impact on practical sustainability of the hydrogen economy. An important profile for the viability of a process is the calculation of energy and exergy efficiencies, as well as their overall integration into the circular economy. To carry out theoretical energy and exergy analyses we have estimated proposed hydrogen production using different software (DWSIM and MATLAB) and reference conditions. The analysis consolidates methane reforming or auto-thermal reforming as the viable technologies at the present state of the art, with reasonable energy and exergy efficiencies, but pending on the impact of environmental constraints as CO2 emission countermeasures. However, natural gas or electrolysis show very promising results, and should be advanced in their technological and maturity scaling. Electrolysis shows a very good exergy efficiency due to the fact that electricity itself is a high exergy source. Pyrolysis exergy loses are mostly in the form of solid carbon material, which has a very high integration potential into the hydrogen economy.

Hydrogen Isotope Absorption in Unary Oxides and Nitrides with Anion Vacancies and Substitution.

The absorption states of hydrogen isotopes in various ceramic materials were investigated by density functional theory. For pristine ceramic materials, main-group oxides do not form any bond with a hydrogen atom. However, transition metal oxides form hydroxyl groups and absorb hydrogen atoms. Main-group and transition metal nitrides form ionic bonds between a hydrogen atom and the surrounded cation. For anion-deficient ceramic materials, hydrogen atoms are negatively charged because of excess electrons induced by anion vacancies, and ionic bonds form with the surrounded cation, which stabilizes the hydrogen absorption state. N substitutional doping into oxides introduces an electron hole, while O substitutional doping into the nitrides introduces an excess of electrons. Therefore, hydrogen isotopes form covalent bonds in N-substituted oxides, and form hydride ions in O-substituted nitrides. Thus, Al2 O3 , SiO2 , CrN, and TiN are promising materials as hydrogen permeation barriers.

Exploration of heterogeneous catalyst for molecular hydrogen ortho-para conversion.

Molecular hydrogen (H2) ortho-para conversion (O/P conversion) proceeds slowly at low temperatures accompanying a heat release. Thus, catalysts for accelerating this conversion rate are highly demanded in terms of the storage and utilization of liquid H2. The catalysts for this purpose are experimentally screened by examining a broad range of materials covering magnetic, non-magnetic, metallic, and nonmetallic oxides. The primary conclusions obtained are summarized below. (1) active materials are required to be non-metallic and to bear the cations with ionic radii smaller than the bond length of H2. (2) Metallic materials have almost no activity irrespective of with or without magnetism (3) The activity of materials belonging to (1) is largely enhanced when the constituting cation has a magnetic moment. In addition, there is a class of materials for which the activity is distinctly enhanced just upon substitution by the foreign ions.

Hydrogen energy systems: Technologies, trends, and future prospects.

This review critically examines hydrogen energy systems, highlighting their capacity to transform the global energy framework and mitigate climate change. Hydrogen showcases a high energy density of 120 MJ/kg, providing a robust alternative to fossil fuels. Adoption at scale could decrease global CO2 emissions by up to 830 million tonnes annually. Despite its potential, the expansion of hydrogen technology is curtailed by the inefficiency of current electrolysis methods and high production costs. Presently, electrolysis efficiencies range between 60 % and 80 %, with hydrogen production costs around $5 per kilogram. Strategic advancements are necessary to reduce these costs below $2 per kilogram and push efficiencies above 80 %. Additionally, hydrogen storage poses its own challenges, requiring conditions of up to 700 bar or temperatures below -253 °C. These storage conditions necessitate the development of advanced materials and infrastructure improvements. The findings of this study emphasize the need for comprehensive strategic planning and interdisciplinary efforts to maximize hydrogen's role as a sustainable energy source. Enhancing the economic viability and market integration of hydrogen will depend critically on overcoming these technological and infrastructural challenges, supported by robust regulatory frameworks. This comprehensive approach will ensure that hydrogen energy can significantly contribute to a sustainable and low-carbon future.

Computational Design for Enhanced Hydrogen Storage on the Newly Synthesized 2D Polyaramid via Titanium and Zirconium Decoration.

2D polyaramid (2DPA) is a porous and polymeric material that has been synthesized recently. Titanium and zirconium decoration over 2DPA increases their affinity for hydrogen substantially, making them suitable for onboard and reversible hydrogen storage, particularly in light-duty vehicles. By decorating a single unit cell of 2DPA with two transition metal (TM) atoms, hydrogen storage of up to 6.422 and 6.792 wt % of H2 with average binding energies of -0.399 and -0.480 eV is predicted for 2DPA + Ti and 2DPA + Zr, respectively. The binding of Ti and Zr with 2DPA is accompanied by a flow of charge (-1.474e for Ti and -1.696e for Zr) from the TM toward the 2DPA sheet. Further, the interaction between H2 and the TM may proceed via Kubas interaction between the d orbital of the TM in 2DPA + TM and H 1s orbitals of H2, with a net flow of charge from the TM toward H2 (-0.218e for Ti and -0.391e for Zr). The desorption of H2 bound to 2DPA + Zr is endothermic (∼0.57 eV) and close in magnitude to the binding energy of the first H2 (∼-0.544 eV). The 2DPA + TM systems show structural and dynamic stability at high temperatures, as evident from ab initio molecular dynamics simulations and phonon spectra. The movement of TM atoms across the 2DPA sheet to form clusters may be hindered by the considerable barrier energy (∼4.9 eV for Ti). Through these systematic density functional theory simulations, we predict that Ti- and Zr-decorated 2DPA are high-performance hydrogen storage materials and can be explored by experimentalists.

Simulation and feasibility assessment of a green hydrogen supply chain: a case study in Oman.

The transition to sustainable energy is crucial for mitigating climate change impacts. This study addresses this imperative by simulating a green hydrogen supply chain tailored for residential cooking in Oman. The supply chain encompasses solar energy production, underground storage, pipeline transportation, and residential application, aiming to curtail greenhouse gas emissions and reduce the levelized cost of hydrogen (LCOH). The simulation results suggest leveraging a robust 7 GW solar plant. Oman achieves an impressive annual production of 9.78 TWh of green hydrogen, equivalent to 147,808 tonnes of H2, perfectly aligning with the ambitious goals of Oman Vision 2040. The overall LCOH for the green hydrogen supply chain is estimated at a highly competitive 6.826 USD/kg, demonstrating cost competitiveness when benchmarked against analogous studies. A sensitivity analysis highlights Oman's potential for cost-effective investments in green hydrogen infrastructure, propelling the nation towards a sustainable energy future. This study not only addresses the pressing issue of reducing carbon emissions in the residential sector but also serves as a model for other regions pursuing sustainable energy transitions. The developed simulation models are publicly accessible at https://hychain.co.uk , providing a valuable resource for further research and development in the field of green hydrogen supply chains.

Efficient Atomically Dispersed Co/N-C Catalysts for Formic Acid Dehydrogenation and Transfer Hydrodeoxygenation of Vanillin.

Atomically dispersed catalysts have gained considerable attention due to their unique properties and high efficiency in various catalytic reactions. Herein, a series of Co/N-doped carbon (N-C) catalysts was prepared using a metal-lignin coordination strategy and employed in formic acid dehydrogenation (FAD) and hydrodeoxygenation (HDO) of vanillin. The atomically dispersed Co/N-C catalysts showed outstanding activity, acid resistance, and long-term stability in FAD. The improved activity and stability may be attributed to the high dispersion of Co species, increased surface area, and strong Co-N interactions. XPS and XAS characterization revealed the formation of Co-N3 centers, which are assumed to be the active sites. In addition, DFT calculations demonstrated that the adsorption of formic acid on single-atom Co was stronger than that on Co13 clusters, which may explain the high catalytic activity. The Co/N-C catalyst also showed promising performance in the transfer HDO of vanillin with formic acid, without any external additional molecular H2.

Assessing the role of low-emission hydrogen: A techno-economic database for hydrogen pathways modelling.

Hydrogen is globally acknowledged as a versatile energy carrier crucial for decarbonization in multiple sectors. Many countries have initiated the development of national hydrogen roadmaps and strategies, recognizing hydrogen as a strategic resource for achieving sustainable energy transitions. Formulating these guidelines for future action demands a solid technical foundation to facilitate well-informed decision-making. Energy system modelling has emerged as a significant scientific tool to assist governments and ministries in designing hydrogen pathways assessments based on scientific outcomes. The first step in the modelling process involves gathering, curating, and managing techno-economic data, a process that is often time-consuming and hindered by the unavailability and inaccessibility of data sources. This paper introduces an open techno-economic dataset encompassing key technologies within the hydrogen supply chain, spanning from production to end-use applications. Energy modelers, researchers, policymakers, and stakeholders can leverage this dataset for energy planning models, with a specific focus on hydrogen pathways. The presented data is designed to promote modelling studies that are retrievable, reusable, repeatable, reconstructable, interoperable, and auditable (U4RIA). This enhanced transparency aims to foster greater public trust, scientific reproducibility, and increased collaboration amongst academia, industry, and government in producing technical reports that underpin national hydrogen roadmaps and strategies.

Factors affecting the economy of green hydrogen production pathways for sustainable development and their challenges.

In a hydrogen economy, the primary energy source for industry, transportation, and power production is hydrogen gas. Green hydrogen can be generated and utilized in an environmentally friendly and sustainable manner; it seeks to displace fossil fuels. Finding a clean alternative energy source is becoming more crucial due to the depletion of fossil fuels and the major environmental pollution issues they bring when utilized extensively. The paper's objective is to analyze the factors affecting the economy of green hydrogen production pathways for sustainable development to decarbonize the world and the associated challenges faced in terms of technological, social, infrastructure, and people's perceptions while adopting green hydrogen. To achieve this, the research looked at a variety of areas relevant to green hydrogen, such as production techniques, industry applications, benefits for society and the environment, and challenges that need to be overcome before the technology is widely used. The most recent methods of producing hydrogen from fossil fuels, such as steam methane, partial oxidation, autothermal, and plasma reforming, as well as renewable energy sources including biomass and thermochemical reactions and water splitting. Grey hydrogen is now the least expensive type of hydrogen, but, in the future, green hydrogen's levelized cost of hydrogen (LCOH) is expected to be less than $2 per kilogram of hydrogen.

A perspective on three sustainable hydrogen production technologies with a focus on technology readiness level, cost of production and life cycle environmental impacts.

Hydrogen will play an indispensable role as both an energy vector and as a molecule in essential products in the transition to climate neutrality. However, the optimal sustainable hydrogen production system is not definitive due to challenges in energy conversion efficiency, economic cost, and associated marginal abatement cost. This review summarises and contrasts different sustainable hydrogen production technologies including for their development, potential for improvement, barriers to large-scale industrial application, capital and operating cost, and life-cycle environmental impact. Polymer electrolyte membrane water electrolysis technology shows significant potential for large-scale application in the near-term, with a higher technology readiness level (expected to be 9 by 2030) and a levelized cost of hydrogen expected to be 4.15-6 €/kg H2 in 2030; this equates to a 50% decrease as compared to 2020. The four-step copper-chlorine (Cu-Cl) water thermochemical cycle can perform better in terms of life cycle environmental impact than the three- and five-step Cu-Cl cycle, however, due to system complexity and high capital expenditure, the thermochemical cycle is more suitable for long-term application should the technology develop. Biological conversion technologies (such as photo/dark fermentation) are at a lower technology readiness level, and the system efficiency of some of these pathways such as biophotolysis is low (less than 10%). Biomass gasification may be a more mature technology than some biological conversion pathways owing to its higher system efficiency (40%-50%). Biological conversion systems also have higher costs and as such require significant development to be comparable to hydrogen produced via electrolysis.

Dehazing redox homeostasis to foster purple bacteria biotechnology.

Purple non-sulfur bacteria (PNSB) show great potential for environmental and industrial biotechnology, producing microbial protein, biohydrogen, polyhydroxyalkanoates (PHAs), pigments, etc. When grown photoheterotrophically, the carbon source is typically more reduced than the PNSB biomass, which leads to a redox imbalance. To mitigate the excess of electrons, PNSB can exhibit several 'electron sinking' strategies, such as CO2 fixation, N2 fixation, and H2 and PHA production. The lack of a comprehensive (over)view of these redox strategies is hindering the implementation of PNSB for biotechnology applications. This review aims to present the state of the art of redox homeostasis in phototrophically grown PNSB, presenting known and theoretically expected strategies, and discussing them from stoichiometric, thermodynamic, metabolic, and economic points of view.

Advancing Electrode Properties through Functionalization for Solid Oxide Cells Application: A Review.

Hydrogen energy has emerged as the only renewable which is capable of sustaining the prevalent energy crisis in conjunction with other intermittent sources. In this connection, solid oxide cell (SOC) is the most sustainable solid-state devices capable of recycling and reproducing green hydrogen fuel. It is operable in reversible modes viz, fuel cell (FC) and electrolysis cell (EC). SOC is capable of engaging multiple fuels thereby promoting carbon neutral planet. The all-solid design further augments the optimization of cost, efficiency, durability and endurance at higher temperature. Electrodes are therefore, an important component which is responsible for electrocatalytic processing of fuel and oxidant for higher recyclability of cell/stack. The present review article embarks a detailed overview on the past and present status of electrode composition, heterointerface engineering applicable for SOC's. Recent trends in electrode engineering and the possibilities for advancement in SOC is also reviewed with respect to both experimental and computational aspects.

Financing the hydrogen industry: exploring demand and supply chain dynamics.

The hydrogen industry has garnered substantial attention as a pivotal solution in addressing the intricate challenges of energy transition and achieving decarbonization across diverse sectors. The efficacy of deploying hydrogen technologies hinges upon the availability of robust financing mechanisms that can adequately support the dynamic demands and intricate supply chain intricacies inherent in the hydrogen sector. This comprehensive study is underpinned by a rigorous and systematic review of prior research on the hydrogen economy, leveraging authoritative databases including Web of Science, Scopus, and a range of consultancy-based reports. The study meticulously assesses the escalating interest in hydrogen as a paramount clean energy alternative, emphasizing its significance in propelling the multifaceted development and expansion of hydrogen supply chain dynamics. Furthermore, this research critically scrutinizes the intricate financial facets of the hydrogen sector, with a specific focus on delineating the drivers of demand and unraveling the complexities interwoven within the supply chain. Building upon this analysis, the study offers a forward-looking perspective on hydrogen financing, which considers emerging technologies, evolving policy landscapes, and dynamic market trends. In the face of existing global constraints within the hydrogen supply chain, innovative financing mechanisms such as green bonds, project financing underwritten by risk guarantees through public-private partnership paradigms, venture capital-equity models, and carbon pricing mechanisms emerge as indispensable tools poised to address these challenges effectively.

Microbial hydrogen economy alleviates colitis by reprogramming colonocyte metabolism and reinforcing intestinal barrier.

With the rapid development and high therapeutic efficiency and biosafety of gas-involving theranostics, hydrogen medicine has been particularly outstanding because hydrogen gas (H2), a microbial-derived gas, has potent anti-oxidative, anti-apoptotic, and anti-inflammatory activities in many disease models. Studies have suggested that H2-enriched saline/water alleviates colitis in murine models; however, the underlying mechanism remains poorly understood. Despite evidence demonstrating the importance of the microbial hydrogen economy, which reflects the balance between H2-producing (hydrogenogenic) and H2-utilizing (hydrogenotrophic) microbes in maintaining colonic mucosal ecosystems, minimal efforts have been exerted to manipulate relevant H2-microbe interactions for colonic health. Consistent with previous studies, we found that administration of hydrogen-rich saline (HS) ameliorated dextran sulfate sodium-induced acute colitis in a mouse model. Furthermore, we demonstrated that HS administration can increase the abundance of intestinal-specific short-chain fatty acid (SCFA)-producing bacteria and SCFA production, thereby activating the intracellular butyrate sensor peroxisome proliferator-activated receptor γ signaling and decreasing the epithelial expression of Nos2, consequently promoting the recovery of the colonic anaerobic environment. Our results also indicated that HS administration ameliorated disrupted intestinal barrier functions by modulating specific mucosa-associated mucolytic bacteria, leading to substantial inhibition of opportunistic pathogenic Escherichia coli expansion as well as a significant increase in the expression of interepithelial tight junction proteins and a decrease in intestinal barrier permeability in mice with colitis. Exogenous H2 reprograms colonocyte metabolism by regulating the H2-gut microbiota-SCFAs axis and strengthens the intestinal barrier by modulating specific mucosa-associated mucolytic bacteria, wherein improved microbial hydrogen economy alleviates colitis.