Production & Supply Chain

Hydrogen can be produced from a broad range of renewable energy sources acting as a unique energy hub providing low or zero emission energy to all energy consuming sectors. Technically and efficiently producing hydrogen from renewable sources is a key enabler for these developments.<br/>Traditionally hydrogen has been produced from fossil sources by steam methane reforming of natural gas. At present the technology of choice to produce renewable ‘green’ hydrogen is water electrolysis using renewable electricity. The FCH JU has been supporting research and development of electrolyser technology and application projects aiming to increase the energy efficiency of electrolytic hydrogen production from renewable sources and to reduce costs.<br/>This study complements these activities by focusing on renewable hydrogen generation other than electrolysis. In this report these alternative hydrogen generation technologies are described characterized by their technical capabilities maturity and economic performance and assessed for their future potential.<br/>A methodology has been devised to first identify and structure a set of relevant green hydrogen pathways (eleven pathways depicted in the figure below) analyse them at a level of detail allowing a selection of those technologies which fit into and promise early commercialization in the framework of FCH 2 JU’s funding program.<br/>These originally proposed eleven pathways use solar thermal energy sunlight or biomass as major energy input.

Given the limited sources of fossil fuels mankind should find new ways to meet its energy demands. In this regard geothermal and solar energy are acknowledged as reliable safe promising and clean means for this purpose. In this research study a comparative analysis is applied on geothermal and solar-driven multi-generation systems for clean electricity and hydrogen production through energy and exergy assessments. The system consists of an organic Rankine cycle a proton electrolyte membrane electrolyzer and a thermoelectric generator subsystem. The Engineering Equation Solver software has been utilized in order to model the system and obtain the output contours sensitivity analysis and exergy destruction. The results were calculated considering the ambient temperature of Bandar Abbas city as a case study considering the geothermal system due to better performance in comparison to the solar system. According to the sensitivity analysis the turbine efficiency evaporator inlet temperature thermoelectric generator suitability criterion pump efficiency and evaporator inlet mass flow rate are the most influential parameters. Also the exergy analysis showed that the utmost system's exergy destruction is pertinent to the evaporator and the least is related to the pump. In addition the system produces 352816 kWh and 174.913 kg of electrical power and hydrogen during one year.

In this work the design of the hardware architecture to implement an algorithm for optimizing the Hydrogen Productivity Rate (HPR) in a Microbial Electrolysis Cell (MEC) is presented. The HPR in the MEC is maximized by the golden section search algorithm in conjunction with a super-twisting controller. The development of the digital architecture in the implementation step of the optimization algorithm was developed in the Very High Description Language (VHDL) and synthesized in a Field Programmable Gate Array (FPGA). Numerical simulations demonstrated the feasibility of the proposed optimization strategy embedded in an FPGA Cyclone II. Results showed that only.

The growing consumption of global energy has posed serious challenges to environmental protection and energy supplies. A promising solution is via introducing clean and sustainable energy sources including photoelectrochemical hydrogen fuel production. 2D materials such as transition metal trichalcogenphosphites (MPCh₃) are gaining more and more interest for their potential as photocatalysts. Crystals of transition metal selenophosphites namely MnPSe₃ FePSe₃ and ZnPSe₃ were tested as photocatalysts for the hydrogen evolution reaction (HER). ZnPSe3 is the one that exhibited the lowest overpotential and the higher response to the light during photocurrent experiments in acidic media. For this reason among the crystals in this work it is the most promising for the photocatalyzed production of hydrogen.

Solutions that simulate hydrometallurgical base metal process streams with high nickel (Ni) and minor platinum (Pt) concentrations were used to create Pt/Ni nanoparticles on TiO₂ nanotube surfaces. For this electrochemical deposition – redox replacement (EDRR) was used that also allowed to control the nanoparticle size density and Pt/Ni content of the deposited nanoparticles. The Pt/Ni nanoparticle decorated titanium dioxide nanotubes (TiO₂ nanotubes) become strongly activated for photocatalytic hydrogen (H₂) evolution. Moreover EDRR facilitates nanoparticle formation without the need for any additional chemicals and is more effective than electrodeposition alone. Actually a 10000-time enrichment level of Pt took place on the TiO₂ surface when compared to Pt content in the solution with the EDRR method. The results show that hydrometallurgical streams offer great potential as an alternative raw material source for industrial catalyst production when coupled with redox replacement electrochemistry.

Climate policy objectives require zero emissions across all sectors including steelmaking. The fundamental process changes needed for reaching this target are yet relatively unexplored. In this paper we propose and assess a potential design for a fossil-free steelmaking process based on direct reduction of iron ore with hydrogen. We show that hydrogen direct reduction steelmaking needs 3.48 MWh of electricity per tonne of liquid steel mainly for the electrolyser hydrogen production. If renewable electricity is used the process will have essentially zero emissions. Total production costs are in the range of 361–640 EUR per tonne of steel and are highly sensitive to the electricity price and the amount of scrap used. Hydrogen direct reduction becomes cost competitive with an integrated steel plant at a carbon price of 34–68 EUR per tonne CO2 and electricity costs of 40 EUR/MWh. A key feature of the process is flexibility in production and electricity demand which allows for grid balancing through storage of hydrogen and hot-briquetted iron or variations in the share of scrap used.

Hydrogen produced from renewable electricity will play an important role in deep decarbonisation of industry. However adding large electrolyser capacities to a low-carbon electricity system also increases the need for additional electricity generation from variable renewable energies. This will require hydrogen production to be variable unless other sources provide sufficient flexibility. Existing sources of flexibility in hydro-thermal systems are hydropower and thermal generation which are both associated with sustainability concerns. In this work we use a dispatch model for the case of Sweden to assess the power system operation with large-scale electrolysers assuming that additional wind power generation matches the electricity demand of hydrogen production on average. We evaluate different scenarios for restricting the flexibility of hydropower and thermal generation and include 29 different weather years to test the impact of variable weather regimes. We show that (a) in all scenarios electrolyser utilisation is above 60% on average (b) the inter-annual variability of hydrogen production is substantial if thermal power is not dispatched for electrolysis and (c) this problem is aggravated if hydropower flexibility is also restricted. Therefore either long-term storage of hydrogen or backup hydrogen sources may be necessary to guarantee continuous hydrogen flows. Large-scale dispatch of electrolysis capacity supported by wind power makes the system more stable if electrolysers ramp down in rare hours of extreme events with low renewable generation. The need for additional backup capacities in a fully renewable electricity system will thus be reduced if wind power and electrolyser operation are combined in the system.

Developing non-precious catalysts as Pt substitutes for electrochemical hydrogen evolution reaction (HER) with superior stability in acidic electrolyte is of critical importance for large-scale low-cost hydrogen production from water. Herein we report a CoCrFeNiAl high-entropy alloy (HEA) electrocatalyst with self-supported structure synthesized by mechanical alloying and spark plasma sintering (SPS) consolidation. The HEA after HF treatment and in situ electrochemical activation for 4000 cycles of cyclic voltammetry (HF-HEAa2) presents favourable activity with overpotential of 73 mV to reach a current density of 10 mA cm⁻² and a Tafel slope of 39.7 mV dec⁻¹. The alloy effect of Al/Cr with Co/Fe/Ni at atomic level high-temperature crystallization as well as consolidation by SPS endow CoCrFeNiAl HEA with high stability in 0.5 M H₂SO₄ solution. The superior performance of HF-HEAa2 is related with the presence of metal hydroxides/oxides groups on HEA.

Hydrogen is a zero-carbon footprint energy source with high energy density that could be the basis of future energy systems. Membrane-based water electrolysis is one means by which to produce high-purity and sustainable hydrogen. It is important that the scientific community focus on developing electrolytic hydrogen systems which match available energy sources. In this review various types of water splitting technologies and membrane selection for electrolyzers are discussed. We highlight the basic principles recent studies and achievements in membrane-based electrolysis for hydrogen production. Previously the NafionTM membrane was the gold standard for PEM electrolyzers but today cheaper and more effective membranes are favored. In this paper CuCl–HCl electrolysis and its operating parameters are summarized. Additionally a summary is presented of hydrogen production by water splitting including a discussion of the advantages disadvantages and efficiencies of the relevant technologies. Nonetheless the development of cost-effective and efficient hydrogen production technologies requires a significant amount of study especially in terms of optimizing the operation parameters affecting the hydrogen output. Therefore herein we address the challenges prospects and future trends in this field of research and make critical suggestions regarding the implementation of comprehensive membrane-based electrolytic systems.

Variable renewable energy (VRE) is expected to play a major role in the decarbonization of the electricity sector. However decarbonization via VRE requires a fleet of flexible dispatchable plants with low CO2 emissions to supply clean power during times with limited wind and sunlight. These plants will need to operate at reduced capacity factors with frequent ramps in electricity output posing techno-economic challenges. This study therefore presents an economic assessment of a new near-zero emission power plant designed for this purpose. The gas switching reforming combined cycle (GSR-CC) plant can produce electricity during times of low VRE output and hydrogen during times of high VRE output. This product flexibility allows the plant to operate continuously even when high VRE output makes electricity production uneconomical. Although the CO2 avoidance cost of the GSR-CC plant (€61/ton) was similar to the benchmark post-combustion CO2 capture plant under baseload operation GSR-CC clearly outperformed the benchmark in a more realistic scenario where continued VRE expansion forces power plants into mid-load operation (45% capacity factor). In this scenario GSR-CC promises a 5 %-point higher annualized investment return than the post-combustion benchmark. GSR-CC therefore appears to be a promising concept for a future scenario with high VRE market share and CO2 prices provided that a large market for clean hydrogen is established.

Titanium dioxide (TiO₂ ) has been widely investigated for photocatalytic H₂ evolution and photoelectrochemical (PEC) water splitting since 1972. However its wide bandgap (3.0–3.2 eV) limits the optical absorption of TiO₂ for sufficient utilization of solar energy. Blackening TiO₂ has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities and aroused widespread research interest. In this article we reviewed the recent progress of black TiO₂ for photocatalytic H₂ evolution and PEC water splitting along with detailed introduction to its unique structural features optical property charge carrier transfer property and related theoretical calculations. As summarized in this review article black TiO₂ could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting and continuous efforts are deserved for improving its solar hydrogen efficiency.

Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a good fit for solar technologies such as concentrated solar power and photovoltaics. However a thorough comparison between the two solar technologies as well as investigating the infrastructure of the United Arab Emirates for a well-to-ship hydrogen pathway is yet to be fully carried out. Therefore in this study we aim to provide a full model for solar hydrogen production and delivery by evaluating the potential of concentrated solar power and photovoltaics in the UAE then comparing two different pathways for hydrogen delivery based on the location of hydrogen production sites. A Solid Oxide Cell Electrolyzer (SOEC) is used for technical comparison while the shortest routes for hydrogen transport were analyzed using Geographical Information System (GIS). The results show that CSP technology coupled with SOEC is the most favorable pathway for large-scale hydrogen from solar energy production in the UAE for export purposes. Although PV has a slightly higher electricity potential compared to CSP around 42 GWh/km2 to 41.1 GWh/km2 respectively CSP show the highest productions rates of over 6 megatons of hydrogen when the electrolyzer is placed at the same site as the CSP plant while PV generates 5.15 megatons when hydrogen is produced at the same site with PV plants; meanwhile hydrogen from PV and CSP shows similar levels of 4.8 and 4.6 megatons of hydrogen respectively when electrolyzers are placed at port sites. Even considering the constraints in the UAE’s infrastructure and suggesting new shorter electrical transmission lines that could save up to 0.1 megatons of hydrogen in the second pathway production at the same site with CSP is still the most advantageous scenario.

Membrane reactors for hydrogen production can increase both the hydrogen production efficiency at small scale and the electric efficiency in micro-cogeneration systems when coupled with Polymeric Electrolyte Membrane fuel cells. This paper discusses the achievements of three European projects (FERRET FluidCELL BIONICO) which investigate the application of the membrane reactor concept to hydrogen production and micro-cogeneration systems using both natural gas and biofuels (biogas and bio-ethanol) as feedstock. The membranes used to selectively separate hydrogen from the other reaction products (CH4 CO2 H2O etc.) are of asymmetric type with a thin layer of Pd alloy (<5 μm) and supported on a ceramic porous material to increase their mechanical stability. In FERRET the flexibility of the membrane reactor under diverse natural gas quality is validated. The reactor is integrated in a micro-CHP system and achieves a net electric efficiency of about 42% (8% points higher than the reference case). In FluidCELL the use of bio-ethanol as feedstock for micro-cogeneration Polymeric Electrolyte Membrane based system is investigated in off-grid applications and a net electric efficiency around 40% is obtained (6% higher than the reference case). Finally BIONICO investigates the hydrogen production from biogas. While BIONICO has just started FERRET and FluidCELL are in their third year and the two prototypes are close to be tested confirming the potentiality of membrane reactor technology at small scale.

In our factsheet where we debunk 3 myths around hydrogen production and water consumption: electrolysis uses vast amounts of water; electrolysis uses freshwater resources only and electrolysis is bound to create water stress in water-scarce regions.

According to European Directive 2014/94/EU hydrogen providers have the responsibility to prove that their hydrogen is of suitable quality for fuel cell vehicles. Contaminants may originate from hydrogen production transportation refuelling station or maintenance operation. This study investigated the probability of presence of the 13 gaseous contaminants (ISO 14687-2) in hydrogen on 3 production processes: steam methane reforming (SMR) process with pressure swing adsorption (PSA) chlor-alkali membrane electrolysis process and water proton exchange membrane electrolysis process with temperature swing adsorption. The rationale behind the probability of contaminant presence according to process knowledge and existing barriers is highlighted. No contaminant was identified as possible or frequent for the three production processes except oxygen (frequent for chlor-alkali membrane process) carbon monoxide (frequent) and nitrogen (possible) for SMR with PSA. Based on it a hydrogen quality assurance plan following ISO 19880-8 can be devised to support hydrogen providers in monitoring the relevant contaminants.

The catalytical activity for the hydrogen evolution reaction (HER) of the electrodeposited Ni–Mo/WC composites is examined in 1 M KOH solution. The structure surface morphology and surface composition is investigated using the scanning electron microscopy X-ray diffraction and X-ray photoelectron spectroscopy. The electrocatalytic properties for the HER is evaluated based on the cathodic polarization electrochemical impedance cyclic voltammetry and chronopotentiometry methods. The obtained results prove the superior catalytic activity for the HER of Ni–Mo/WC composites to Ni–Mo alloy. The catalytic activity of Ni–Mo/WC electrodes is determined by the presence of WC nanoparticles and Mo content in the metallic matrix. The best electrocatalytic properties are identified for Ni–Mo/WC composite with the highest Mo content and the most oxidized surface among the studied coatings. The impedance results reveal that the observed improvement in the catalytic activity is the consequence of high real surface area and high intrinsic catalytic activity of the composite.

In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state we have prepared a series of cocrystals derived from an asymmetric β-diketone benzoyl-4-pyridoylmethane (b4pm) as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (ipfb) 12- 13- and 14-diiodotetraflorobenzene (12tfib 13tfib and 14tfib) and 135-triiodo-246-trifluorobenzene (135titfb). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of b4pm in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable in vacuo than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone benzoyl-3-pyridoylmethane (b3pm); however all attempts were unsuccessful which is attributed to more effective crystal packing of b3pm isomer compared to b4pm which reduced the probability of cocrystal formation.

Condensation of hydrogen Rydberg atoms (highly electronically excited) into the lowest energy state of condensed hydrogen i.e. the ultra-dense hydrogen phase H(0) has gained increased attention not only from the fundamental aspects but also from the applied point of view. The physical properties of ultra-dense hydrogen H(0) were recently reviewed summarizing the results reported in 50 publications during the last ten years. The main application of H(0) so far is as the fuel and working medium in nuclear particle generators and nuclear fusion reactors which are under commercial development. The first fusion process showing sustained operation above break-even was published in 2015 (AIP Advances) and used ultra-dense deuterium D(0) as fuel. The first generator giving a high-intensity muon flux intended for muon-catalyzed fusion reactors was patented in 2017 using H(0) as the working medium. Here we first focus on the different nuclear processes using hydrogen isotopes for energy generation and then on the detailed processes of formation of H(0). The production of H(0) employs heterogeneous catalysts which are active in hydrogen transfer reactions. Iron oxide-based alkali promoted catalysts function well but also platinum group metals and carbon surfaces are active in this process. The clusters of highly excited Rydberg hydrogen atoms H(l) are formed upon interaction with alkali Rydberg matter. The final conversion step from ordinary hydrogen Rydberg matter H(l) to H(0) is spontaneous and does not require a solid surface. It is concluded that the exact choice of catalyst is not very important. It is also concluded that the crucial feature of the catalyst is to provide excited alkali atoms at a sufficiently high surface density and in this way enabling formation and desorption of H(0) clusters. Finally the relation to industrial catalytic processes which use H(0) formation catalysts is described and some important consequences like the muon and neutron radiation from H(0) are discussed.

Direct CO₂ hydrogenation to hydrocarbons is a promising method of reducing CO2 emissions along with producing value-added products. However reactor design and performance have remained a challenging issue because of low olefin efficiency and high water production as a by-product. Accordingly a one-dimensional non-isothermal mathematical model is proposed to predict the membrane reactor performance and statistical analysis is used to assess the effects of important variables such as temperatures of reactor (Tr:A) shell (Ts:B) and tube (Tt:C) as well as sweep ratio (θ:D) and pressure ratio (φ:E) and their interactions on the products yields. In addition the optimized operating conditions are also obtained to achieve maximum olefin yields. Results reveal that interacting effects comprising AB (TrTs) AC (TrTt) AE (Trφ) BC (TsTt) CE (Ttφ) CD (Ttθ) and DE (θφ) play important roles on the product yields. It is concluded that higher temperatures at low sweep and pressure ratios can maximize the yields of olefins while simultaneously the yields of paraffins are minimized. In this regard optimized values for Tr Ts Tt θ and φ are determined as 325 °C 306.96 °C 325 °C 1 and 1 respectively.

Climate change and global warming as well as growing global demand for hydrocarbons in industrial sectors make great incentives to investigate the utilization of CO₂ for hydrocarbons production. Therefore finding an in-depth understanding of the CO₂ hydrogenation reactors along with simulating reactor responses to different operating conditions are of paramount importance. However the reaction mechanisms for CO₂ hydrogenation and their corresponding kinetic parameters have been disputable yet. In this regard considering the previously proposed Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism which considered CO₂ hydrogenation as a combination of reverse water gas shift (RWGS) and Fischer-Tropsch (FT) reactions and using a one-dimensional pseudo-homogeneous non-isothermal model kinetic parameters of the rate expressions are estimated via fitting experimental and modelling data through a novel swarm intelligence optimization technique called dragonfly algorithm (DA). The predicted reactants conversion using DA algorithm are closer to the experimental data (with about 4% error) comparing to those obtained by the artificial bee colony (ABC) algorithm and are in significant agreement with available literature data. The proposed model is used to assess the effect of reactor configuration on the performance and temperature fluctuations. Results show that axial flow spherical reactor (AFSR) and radial flow spherical reactor (RFSR) exhibiting the same surface area with that of the cylindrical reactor (CR) i.e. AFSR-2 and RFSR-2-i are the most efficient exhibiting hydrocarbons selectivity of 40.330% and 40.286% at CO₂ conversion of 53.763% and 53.891%. In addition it is revealed that the location of the jacket has an essential role in controlling the reactor temperature.

A detailed thermodynamic analysis of the sorption enhanced chemical looping reforming of methane (SE-CL-SMR) using CaO and NiO as CO2 sorbent and oxygen transfer material (OTM) respectively was conducted. Conventional reforming (SMR) and sorption enhanced reforming (SE-SMR) were also investigated for comparison reasons. The results of the thermodynamic analysis show that there are significant advantages of both sorption enhanced processes compared to conventional reforming. The presence of CaO leads to higher methane conversion and hydrogen purity at low temperatures. Addition of the OTM in the SECL-SMR process concept minimizes the thermal requirements and results in superior performance compared to SE-SMR and SMR in a two-reactor concept with use of pure oxygen as oxidant/sweep gas.

Hydrogen sulfide (H₂S) is an important mediator of inflammatory processes. However controversial findings also exist and its underlying molecular mechanisms are largely unknown. Recently the byproducts of H₂S per-/polysulfides emerged as biological mediators themselves highlighting the complex chemistry of H₂S. In this study we characterized the biological effects of P* a slow-releasing H₂S and persulfide donor. To differentiate between H₂S and polysulfide-derived effects we decomposed P* into polysulfides. P* was further compared to the commonly used fast-releasing H₂S donor sodium hydrogen sulfide (NaHS). The effects on oxidative stress and interleukin-6 (IL-6) expression were assessed in ATDC5 cells using superoxide measurement qPCR ELISA and Western blotting. The findings on IL-6 expression were corroborated in primary chondrocytes from osteoarthritis patients. In ATDC5 cells P* not only induced the expression of the antioxidant enzyme heme oxygenase-1 via per-/polysulfides but also induced activation of Akt and p38 MAPK. NaHS and P* significantly impaired menadione-induced superoxide production. P* reduced IL-6 levels in both ATDC5 cells and primary chondrocytes dependent on H₂Srelease. Taken together P* provides a valuable research tool for the investigation of H₂S and per-/polysulfide signalling. These data demonstrate the importance of not only H₂S but also per-/polysulfides as bioactive signaling molecules with potent anti-inflammatory and in particular antioxidant properties.

Copper cobalt oxide nanoparticles (CCO NPs) were synthesized as an oxygen evolution electrocatalyst via a simple co-precipitation method with the composition being controlled by altering the precursor ratio to 1:1 1:2 and 1:3 (Cu:Co) to investigate the effects of composition changes. The effect of the ratio of Cu2+/Co3+ and the degree of oxidation during the co-precipitation and annealing steps on the crystal structure morphology and electrocatalytic properties of the produced CCO NPs were studied. The CCO1:2 electrode exhibited an outstanding performance and high stability owing to the suitable electrochemical kinetics which was provided by the presence of sufficient Co3+ as active sites for oxygen evolution and the uniform sizes of the NPs in the half cell. Furthermore single cell tests were performed to confirm the possibility of using the synthesized electrocatalyst in a practical water splitting system. The CCO1:2 electrocatalyst was used as an anode to develop an anion exchange membrane water electrolyzer (AEMWE) cell. The full cell showed stable hydrogen production for 100 h with an energetic efficiency of >71%. In addition it was possible tomass produce the uniform highly active electrocatalyst for such applications through the co-precipitation method.

Photoelectrochemical reforming of plastic waste offers an environmentally-benign and sustainable route for hydrogen generation. Nonetheless little attention was paid to develop electrocatalysts that can efficiently and selectively catalyze oxidative transformation of valueless plastic wastes into valued chemicals. Herein we report on facile electrosynthesis of nickel-phosphorus nanospheres (nanoNi-P) and their versatility in catalyzing hydrogen generation water oxidation and reforming of polyethylene terephthalate (PET). Notably composite of nanoNi-P with carbon nanotubes (CNT/nanoNi-P) requires −180 mV overpotential to drive hydrogen generation at -100 mA cm⁻². Besides CV-activated nanoNi-P (nanoNi-P(CV)) was shown to be capable of reforming PET into formate with high selectivity (Faradic efficiency= ∼100 %). Efficient and selective generation of hydrogen and formate from PET reforming is realized utilizing an Earth-abundant photoelectrochemical platform based on nanoNi-P(CV)-modified TiO2 nanorods photoanode and CNT/nanoNi-P cathode. This work paves a path for developing artificial leaf for simultaneous environmental mitigation and photosynthesis of renewable fuels and valued chemicals.

We report volumetric analysis techniques to analyze the transport properties of hydrogen dissolved in cylindrical-shaped polymers. The techniques utilize the volume measurement of the released hydrogen from rubber by gas collection in a graduated cylinder after charging sample with high-pressure hydrogen and subsequent decompression. We further improve the graduated cylinder with some modifications such as reading the electrical capacitance of the water level using electrodes and changing the sample loading position. From the measurement results the uptake (C∞) diffusion coefficient (D) and solubility (S) of hydrogen are quantified with an upgraded diffusion analysis program. These methods are applied to three cylindrical rubbers. Dual adsorption behaviors with increasing pressure are observed for all the samples. C∞ follows Henry’s law up to ~15 MPa whereas Langmuir model applies up to 90 MPa. D shows Knudsen and bulk diffusion behavior below and above pressure respectively. A COMSOL simulation is compared with experimental observations.

In the present work an Ir/CeO₂ catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques i.e. X-ray photoelectron spectroscopy (XPS) transmission electron microscopy (TEM) scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study modifying parameters such as temperature the mass of the catalyst stirring speed and concentration of base in order to find the optimal conditions of reaction which allow performing the test in a kinetically limited regime.

Hydrogen production from biomass pyrolysis is economically and technologically attractive from the perspectives of energy and the environment. The two-stage catalytic pyrolysis of pine sawdust for hydrogen-rich gas production is investigated using nano-NiO/Al2O3 as the catalyst at high temperatures. The influences of residence time (0–30 s) and catalytic temperature (500–800 ◦C) on pyrolysis performance are examined in the distribution of pyrolysis products gas composition and gas properties. The results show that increasing the residence time decreased the solid and liquid products but increased gas products. Longer residence times could promote tar cracking and gas-phase conversion reactions and improve the syngas yield H2/CO ratio and carbon conversion. The nano-NiO/A12O3 exhibits excellent catalytic activity for tar removal with a tar conversion rate of 93% at 800 ◦C. The high catalytic temperature could significantly improve H2 and CO yields by enhancing the decomposition of tar and gas-phase reactions between CO2 and CH4 . The increasing catalytic temperature increases the dry gas yield and carbon conversion but decreases the H2/CO ratio and low heating value.

Hydrogen is deemed necessary for the realization of a sustainable society especially when renewable energy is used to generate hydrogen. As most of the photon-driven hydrogen production methods are not commercially available yet this study has investigated the techno economic and overall performance of four different solar-to hydrogen methods and photovoltaics-based electrolysis methods in the Netherlands. It was found that the photovoltaics-based electrolysis is the cheapest option with production cost of 9.31 $/kgH2. Production cost based on photo-catalytic water splitting direct bio-photolysis and photoelectrochemical water splitting are found to be 18.32 $/kgH2 18.45 $/kgH2 and 18.98 $/kgH2 respectively. These costs are expected to drop significantly in the future. Direct bio-photolysis (potential cost of 3.10 $/kgH2) and photo-catalytic water splitting (3.12 $/kgH2) may become cheaper than photovoltaics-based electrolysis. Based on preferences of three fictional technology investors i.e. a short-term a green and a visionary investor the overall performance of these methods are determined. Photovoltaics-based electrolysis is the most ideal option with photoelectrochemical water splitting a complementary option. While photovoltaics-based electrolysis has an advantage on the short-term because it is a non-integrated energy system on the long-term this might lead to relatively higher cost and performance limitations. Photochemical water splitting are integrated energy systems and have an advantage on the long-term because they need a relatively low theoretical overpotential and benefit from increasing temperatures. Both methods show performance improvements by the use of quantum dots. Bio-photolysis can be self-sustaining and can use wastewater to produce hydrogen but sudden temperature changes could lead to performance decrease.

The pursuing of inter-regional power transmission to address renewable power curtailment in China has resulted in disappointing gains. This paper evaluates the case of local green ammonia production to address this issue. An improved optimization-based simulation model is applied to simulate lifetime green manufacturing and the impacts of main institutional incentives and oxygen synergy on investment are analysed. Levelized cost of ammonia is estimated at around 820 USD/t which is about twice the present price. The operating rate ammonia price the electrical efficiency of electrolysers and the electricity price are found to be the key factors in green ammonia investment. Carbon pricing and value-added tax exemption exert obvious influences on the energy transition in China. A subsidy of approximately 450 USD/t will be required according to the present price; however this can be reduced by 100 USD/t through oxygen synergy. Compared to inter-regional power transmission green ammonia production shows both economic and environmental advantages. Therefore we propose an appropriate combination of both options to address renewable power curtailment and the integration of oxygen manufacturing into hydrogen production. We consider the findings and policy implications will contribute to addressing renewable power curtailment and boosting the hydrogen economy in China.

Given the increase in population and energy demand worldwide alternative methods have been adopted for the production of hydrogen as a clean energy source. This energy offers an alternative energy source due to its high energy content and without emissions to the environment. In this bibliometric analysis of energy production using electrolysis and taking into account the different forms of energy production. In this analysis it was possible to evaluate the research trends based on the literature in the Scopus database during the years 2011–2021. The results showed a growing interest in hydrogen production from electrolysis and other mechanisms with China being the country with the highest number of publications and the United States TOP in citations. The trend shows that during the first four years of this study (2011–2014) the average number of publications was 74 articles per year from 2015 to 2021 where the growth is an average of 209 articles the journal that published the most on this topic is Applied Energy followed by Energy contributing with almost 33% in the research area. Lastly the keyword analysis identified six important research points for future discussions which we have termed clusters. The study concludes that new perspectives on clean hydrogen energy generation environmental impacts and social acceptance could contribute to the positive evolution of the hydrogen energy industry.

CCS is an emissions reduction technology critical to meeting global climate targets. The Global Status of CCS 2019 documents important milestones for CCS over the past 12 months its status across the world and the key opportunities and challenges it faces. We hope this report will be read and used by governments policy-makers academics media commentators and the millions of people who care about our climate.

The rapid increase in anthropogenic greenhouse gas concentrations in the last several decades means that the effects of climate change are fast becoming the familiar horsemen of a planetary apocalypse. Catalysis one of the pillars of the chemical and petrochemical industries will play a critical role in the effort to reduce the flow of greenhouse gases into the atmosphere. This Special Issue is timely as it provides a collection of high-quality manuscripts in a diverse range of topics which include the production of green hydrogen via water electrolysis the steam reforming of ethanol propane or glycerol the dry reforming of methane and the autothermal reforming of diesel surrogate fuel. The topic of the transformation of biomass waste to chemicals is also well represented as is the tackling of CO₂ emissions via novel utilization technologies. The Editors are grateful to all authors for their valuable contributions and confident that this Special Issue will prove valuable to scholars university professors and students alike.

For many electrochemical devices that use carbon-based materials such as electrolyzers supercapacitors and batteries oxygen functional groups (OFGs) are considered essential to facilitate electron transfer. Researchers implement surface-active OFGs to improve the electrocatalytic properties of graphite felt electrodes in vanadium flow batteries. Herein we show that graphitic defects and not OFGs are responsible for lowering the activation energy barrier and thus enhance the charge transfer properties. This is proven by a thermal deoxygenation procedure in which specific OFGs are removed before electrochemical cycling. The electronic and microstructural changes associated with deoxygenation are studied by quasi in situ X-ray photoelectron and Raman spectroscopy. The removal of oxygen groups at basal and edge planes improves the activity by introducing new active edge sites and carbon vacancies. OFGs hinder the charge transfer at the graphite–electrolyte interface. This is further proven by modifying the sp2 plane of graphite felt electrodes with oxygen-containing pyrene derivatives. The electrochemical evolution of OFGs and graphitic defects are studied during polarization and long-term cycling conditions. The hypothesis of increased activity caused by OFGs was refuted and hydrogenated graphitic edge sites were identified as the true reason for this increase.

Rod-like molybdenum carbide (Mo₂C) microcrystals were obtained from the pyrolysis of Mo-containing organic-inorganic hybrid composite. We investigated the photocatalytic H₂ evolution activity of Mo₂C by constructing a Mo₂C-dye sensitizer photocatalyst system. A high quantum efficiency of 29.7% was obtained at 480 nm. Moreover Mo₂C catalyst can be easily recycled by simple filtration.

Renewable power-to-hydrogen (P2H) technology is one of the most promising solutions for fulfilling the increasing global demand for hydrogen and to buffer large-scale fluctuating renewable energies. The high-power high-current ac/dc converter plays a crucial role in P2H facilities transforming medium-voltage (MV) ac power to a large dc current to supply hydrogen electrolyzers. This work introduces the general requirements and overviews several power converter topologies for P2H systems. The performances of different topologies are evaluated and compared from multiple perspectives. Moreover the future trend of eliminating the line frequency transformer (LFT) is discussed. This work can provide guidance for future designing and implementing of power-electronics-based P2H systems.

Minerals are essential components in many of today’s rapidly growing clean energy technologies – from wind turbines and electricity networks to electric vehicles. Demand for these minerals will grow quickly as clean energy transitions gather pace. This new World Energy Outlook Special Report provides the most comprehensive analysis to date of the complex links between these minerals and the prospects for a secure rapid transformation of the energy sector.



Alongside a wealth of detail on mineral demand prospects under different technology and policy assumptions it examines whether today’s mineral investments can meet the needs of a swiftly changing energy sector. It considers the task ahead to promote responsible and sustainable development of mineral resources and offers vital insights for policy makers including six key IEA recommendations for a new comprehensive approach to mineral security."





Link to International Energy Agency website

Titanium dioxide coatings have potential applications including photocatalysts for solar assisted hydrogen production solar water disinfection and self-cleaning windows. Herein we report the use of suspension plasma spraying (SPS) for the deposition of conformal titanium dioxide coatings. The process utilises a nanoparticle slurry of TiO₂ (ca. 6 and 12 nm respectively) in water which is fed into a high temperature plasma jet (ca. 7000–20 000 K). This facilitated the deposition of adherent coatings of nanostructured titanium dioxide with predominantly anatase crystal structure. In this study suspensions of nano-titanium dioxide made via continuous hydrothermal flow synthesis (CHFS) were used directly as a feedstock for the SPS process. Coatings were produced by varying the feedstock crystallite size spray distance and plasma conditions. The coatings produced exhibited ca. 90–100% anatase phase content with the emainder being rutile (demonstrated by XRD). Phase distribution was homogenous throughout the coatings as determined by micro-Raman spectroscopy. The coatings had a granular surface with a high specific surface area and consisted of densely packed agglomerates interspersed with some melted material. All of the coatings were shown to be photoactive by means of a sacrificial hydrogen evolution test under UV radiation and compared favourably with reported values for CVD coatings and compressed discs of P25.

One of the most important requirements concerning the quality of natural gases guaranteeing their safe use involves providing the proper level of their odorization. This allows for the detection of uncontrolled leakages of gases from gas networks installations and devices. The concentration of an odorant should be adjusted in such a manner that the gas odor in a mixture with air would be noticeable by users (gas receivers). A permanent odor of gas is guaranteed by the stability of the odorant molecule and its resistance to changes in the composition of odorized gases. The article presents the results of experimental research on the impact of a hydrogen additive on the stability of tetrahydrothiophene (THT) mixtures in methane and in natural gas with a hydrogen additive. The objective of the work was to determine the readiness of measurement infrastructures routinely used in monitoring the process of odorizing natural gas for potential changes in its composition. One of the elements of this infrastructure includes the reference mixtures of THT used to verify the correctness of the readings of measurement devices. The performed experimental tests address possible changes in the composition of gases supplied via a distribution network resulting from the introduction of hydrogen. The lack of interaction between hydrogen and THT has been verified indirectly by assessing the stability of its mixtures with methane and natural gas containing hydrogen. The results of the presented tests permitted the identification of potential hazards for the safe use of gas from a distribution network resulting from changes in its composition caused by the addition of hydrogen.

Global trade of green hydrogen will probably become a vital factor in reaching climate neutrality. The sunbelt of the Earth has a great potential for large-scale hydrogen production. One promising pathway to solar hydrogen is to use economically priced electricity from photovoltaics (PV) for electrochemical water splitting. However storing electricity with batteries is still expensive and without storage only a small operating capacity of electrolyser systems can be reached. Combining PV with concentrated solar power (CSP) and thermal energy storage (TES) seems a good pathway to reach more electrolyser full load hours and thereby lower levelized costs of hydrogen (LCOH). This work introduces an energy system model for finding cost-optimal designs of such PV/CSP hybrid hydrogen production plants based on a global optimization algorithm. The model includes an operational strategy which improves the interplay between PV and CSP part allowing also to store PV surplus electricity as heat. An exemplary study for stand-alone hydrogen production with an alkaline electrolyser (AEL) system is carried out. Three different locations with different solar resources are considered regarding the total installed costs (TIC) to obtain realistic LCOH values. The study shows that a combination of PV and CSP is an auspicious concept for large-scale solar hydrogen production leading to lower costs than using one of the technologies on its own. For today’s PV and CSP costs minimum levelized costs of hydrogen of 4.04 USD/kg were determined for a plant located in Ouarzazate (Morocco). Considering the foreseen decrease in PV and CSP costs until 2030 cuts the LCOH to 3.09 USD/kg while still a combination of PV and CSP is the most economic system.

Climate change mitigation efforts are in dire need of greener and more versatile fuel al‐ ternatives to fossil fuels. Green hydrogen being both renewable and flexible has the potential to offset fossil fuels as the primary fuel source. Countries around the world are planning to develop their green hydrogen industries and accurate potential assessment is vital. This study employed the consolidation of a geographic information system (GIS) and the analytical hierarchy process (AHP) technique of multicriteria decision making (MCDM) for the potential assessment of green hydrogen in southern Thailand through the selection of suitable sites for solar‐based green hy‐ drogen production. Technical economic and environmental criteria with 10 sub‐criteria were con‐ sidered for the selection of suitable sites. With 0.243 (24.3%) weight the distance from protected areas turned out to be the most important sub‐criterion whereas the criterion of elevation with a 0.017 (1.7%) score was considered the least important. Southern Thailand is a well‐suited area for solar‐based green hydrogen production with a 4302 km2 area of high suitability and a 3350 km2 area of moderate suitability. These suitable areas can be utilized to develop the green hydrogen industry of Thailand and the method developed can be employed for the assessment of green hydrogen potential in other parts of the country. Studies like these are vital for the development of green hydrogen road maps for Thailand to develop its hydrogen policy and promote investments in the sector.

Biomass gasification for energy purposes has several advantages such as the mitigation of global warming and national energy independency. In the present work the data from an innovative and intensified steam/oxygen biomass gasification process integrating a gas filtration step directly inside the reactor are presented. The produced gas at the outlet of the 1 MWth gasification pilot plant was analysed in terms of its main gaseous products (hydrogen carbon monoxide carbon dioxide and methane) and contaminants. Experimental test sets were carried out at 0.25–0.28 Equivalence Ratio (ER) 0.4–0.5 Steam/Biomass (S/B) and 780–850 °C gasification temperature. Almond shells were selected as biomass feedstock and supplied to the reactor at approximately 120 and 150 kgdry/h. Based on the collected data the in-vessel filtration system showed a dust removal efficiency higher than 99%-wt. A gas yield of 1.2 Nm³dry/kgdaf and a producer gas with a dry composition of 27–33%v H2 23–29%v CO 31–36%v CO₂ 9–11%v CH₄ and light hydrocarbons lower than 1%v were also observed. Correspondingly a Low Heating Value (LHV) of 10.3–10.9 MJ/Nm³dry and a cold gas efficiency (CGE) up to 75% were estimated. Overall the collected data allowed for the assessment of the preliminary performances of the intensified gasification process and provided the data to validate a simulative model developed through Aspen Plus software.

The grand challenges in renewable energy lie in our ability to comprehend efficient energy conversion systems together with dealing with the problem of intermittency via scalable energy storage systems. Relatively little progress has been made on this at grid scale and two overriding challenges still need to be addressed: (i) limiting damage to the environment and (ii) the question of environmentally friendly energy conversion. The present review focuses on a novel route for producing hydrogen the ultimate clean fuel from the Sun and renewable energy source. Hydrogen can be produced by light-driven photoelectrochemical (PEC) water splitting but it is very inefficient; rather we focus here on how electric fields can be applied to metal oxide/water systems in tailoring the interplay with their intrinsic electric fields and in how this can alter and boost PEC activity drawing both on experiment and non-equilibrium molecular simulation.

Dark fermentation is an anaerobic digestion process of biowaste used to produce hydrogen- for generation of energy- that however releases high amounts of polluting volatile fatty acids such as acetic acid in the environment. In order for this biohydrogen production process to become more competitive the volatile fatty acids stream can be utilized through conversion to high added-value metabolites such as omega-3 fatty acids. The docosahexaenoic acid is one of the two most known omega-3 fatty acids and has been found to be necessary for a healthy brain and proper cardiovascular function. The main source is currently fish which obtain the fatty acid from the primary producers microalgae through the food chain. Crypthecodinium cohnii a heterotrophic marine microalga is known for accumulating high amounts of docosahexaenoic acid while offering the advantage of assimilating various carbon sources such as glucose ethanol glycerol and acetic acid. The purpose of this work was to examine the ability of a C. cohnii strain to grow on different volatile fatty acids as well as on a pre-treated dark fermentation effluent and accumulate omega-3. The strain was found to grow well on relatively high concentrations of acetic butyric or propionic acid as main carbon source in a fed-batch pH-auxostat. Most importantly C. cohnii totally depleted the organic acid content of an ultra-filtrated dark fermentation effluent after 60 h of fed-batch cultivation therefore offering a bioprocess not only able to mitigate environmental pollutants but also to provide a solution for a sustainable energy production process. The accumulated docosahexaenoic acid content was as high as 29.8% (w/w) of total fatty acids.

Hydrogen is an ideal clean energy source that can be used as an energy storage medium for renewable energy sources. The water electrolysis hydrogen production technology which is one of the mainstream hydrogen production methods can be used to produce high-purity hydrogen and other energy sources can be converted into hydrogen storage by electrolysis. Hydrogen production by alkaline water electrolysis and hydrogen production by PEM electrolysis are all water electrolysis hydrogen production technologies that have been industrially applied. From the application point of view the paper compares the working principle of the two kinds of electrolyzers the process flow of hydrogen production equipment advantages and disadvantages. This article provides a reference for relevant researchers.

Presently hydrogen is for ~50% produced by steam reforming of natural gas – a process leading to significant emissions of greenhouse gas (GHG). About 30% is produced from oil/naphtha reforming and from refinery/chemical industry off-gases. The remaining capacity is covered for 18% from coal gasification 3.9% from water electrolysis and 0.1% from other sources. In the foreseen future hydrogen economy green hydrogen production methods will need to supply hydrogen to be used directly as fuel or to generate synthetic fuels to produce ammonia and other fertilizers (viz. urea) to upgrade heavy oils (like oil sands) and to produce other chemicals. There are several ways to produce H2 each with limitations and potential such as steam reforming electrolysis thermal and thermo-chemical water splitting dark and photonic fermentation; gasification and catalytic decomposition of methanol. The paper reviews the fundamentals and potential of these alternative process routes. Both thermo-chemical water splitting and fermentation are marked as having a long term but high "green" potential.

Carbon capture and storage (CCS) continues to make significant progress around the world against a backdrop of greater climate action from countries and private companies. The Global Status of CCS 2021 demonstrates the critical role of CCS as nations and industry accelerate to net-zero.<br/>The report provides detailed analyses of the global project pipeline international policy finance and emerging trends. In addition four regional overviews highlight the rapid development of CCS across North America Asia Pacific Europe and nearby regions and the Gulf Cooperation Council states.

In electrolyzers Faraday’s efficiency is a relevant parameter to assess the amount of hydrogen generated according to the input energy and energy efficiency. Faraday’s efficiency expresses the faradaic losses due to the gas crossover current. The thickness of the membrane and operating conditions (i.e. temperature gas pressure) may affect the Faraday’s efficiency. The developed models in the literature are mainly focused on alkaline electrolyzers and based on the current and temperature change. However the modeling of the effect of gas pressure on Faraday’s efficiency remains a major concern. In proton exchange membrane (PEM) electrolyzers the thickness of the used membranes is very thin enabling decreasing ohmic losses and the membrane to operate at high pressure because of its high mechanical resistance. Nowadays high-pressure hydrogen production is mandatory to make its storage easier and to avoid the use of an external compressor. However when increasing the hydrogen pressure the hydrogen crossover currents rise particularly at low current densities. Therefore faradaic losses due to the hydrogen crossover increase. In this article experiments are performed on a commercial PEM electrolyzer to investigate Faraday’s efficiency based on the current and hydrogen pressure change. The obtained results have allowed modeling the effects of Faraday’s efficiency by a simple empirical model valid for the studied PEM electrolyzer stack. The comparison between the experiments and the model shows very good accuracy in replicating Faraday’s efficiency.

Developing high-performance electrocatalysts toward hydrogen evolution reaction is important for clean and sustainable hydrogen energy yet still challenging. Herein we report a single-atom strategy to construct excellent metal-organic frameworks (MOFs) hydrogen evolution reaction electrocatalyst (NiRu_0.13-BDC) by introducing atomically dispersed Ru. Significantly the obtained NiRu_0.13-BDC exhibits outstanding hydrogen evolution activity in all pH especially with a low overpotential of 36 mV at a current density of 10 mA cm⁻² in 1 M phosphate buffered saline solution which is comparable to commercial Pt/C. X-ray absorption fine structures and the density functional theory calculations reveal that introducing Ru single-atom can modulate electronic structure of metal center in the MOF leading to the optimization of binding strength for H₂O and H* and the enhancement of HER performance. This work establishes single-atom strategy as an efficient approach to modulate electronic structure of MOFs for catalyst design.

Alkaline water electrolysis (AWE) is a mature hydrogen production technology and there exists a range of economic assessments for available technologies. For advanced AWEs which may be based on novel polymer-based membrane concepts it is of prime importance that development comes along with new configurations and technical and economic key process parameters for AWE that might be of interest for further economic assessments. This paper presents an advanced AWE technology referring to three different sites in Europe (Germany Austria and Spain). The focus is on financial metrics the projection of key performance parameters of advanced AWEs and further financial and tax parameters. For financial analysis from an investor’s (business) perspective a comprehensive assessment of a technology not only comprises cost analysis but also further financial analysis quantifying attractiveness and supply/market flexibility. Therefore based on cash flow (CF) analysis a comprehensible set of metrics may comprise levelised cost of energy or respectively levelized cost of hydrogen (LCH) for cost assessment net present value (NPV) for attractiveness analysis and variable cost (VC) for analysis of market flexibility. The German AWE site turns out to perform best in all three financial metrics (LCH NPV and VC). Though there are slight differences in investment cost and operation and maintenance cost projections for the three sites the major cost impact is due to the electricity cost. Although investment cost is slightly lower and labor cost is significantly lower in Spain the difference can not outweigh the higher electricity cost compared to Germany. Given the assumption that the electrolysis operators are customers directly and actively participating in power markets and based on the regulatory framework in the three countries in this special case electricity cost in Germany is lowest. However as electricity cost is profoundly influenced by political decisions as well as the implementation of economic instruments for transforming electricity systems toward sustainability it is hardly possible to further improve electricity price forecasts.

The direct hydrogenation of CO₂ to dimethyl ether (DME) is a promising technology for CO₂ valorisation. In this work a 1D phenomenological reactor model is developed to evaluate and optimize the performance of a membrane reactor for this conversion otherwise limited by thermodynamic equilibrium and temperature gradients. The co-current circulation of a sweep gas stream through the permeation zone promotes both water and heat removal from the reaction zone thus increasing overall DME yield (from 44% to 64%). The membrane properties in terms of water permeability (i.e. 4·10⁻⁷ mol·Pa⁻¹m−2s⁻¹) and selectivity (i.e. 50 towards H₂ 30 towards CO₂ and CO 10 towards methanol) for optimal reactor performance have been determined considering for the first time non-ideal separation and non-isothermal operation. Thus this work sheds light into suitable membrane materials for this applications. Then the non-isothermal performance of the membrane reactor was analysed as a function of the process parameters (i.e. the sweep gas to feed flow ratio the gradient of total pressure across the membrane the inlet temperature to the reaction and permeation zone and the feed composition). Owing to its ability to remove 96% of the water produced in this reaction the proposed membrane reactor outperforms a conventional packed bed for the same application (i.e. with 36% and 46% improvement in CO₂ conversion and DME yield respectively). The results of this work demonstrate the potential of the membrane reactor to make the CO₂ conversion to DME a feasible process.