Production & Supply Chain

Non-catalytic thermal methane cracking (TMC) is an alternative for hydrogen manufacturing and traditional commercial processes in small-scale hydrogen generation. Supplying the high-level temperatures (850–1800°C) inside the reactors and reactor blockages are two fundamental challenges for developing this technology on an industrial scale (Mahdi Yousefi and Donne 2021). A regenerative reactor could be a part of a solution to overcome these obstacles. This study conducted an experimental study in a regenerative reactor environment between 850 and 1170°C to collect the conversion data and investigate the reactor efficiency for TMC processes. The results revealed that the storage medium was a bed for carbon deposition and successfully supplied the reaction’s heat with more than 99.7% hydrogen yield (at more than 1150°C). Results also indicated that the reaction rate at the beginning of the reactor is much higher and the temperature dependence in the early stages of the reaction is considerably higher. However after reaching a particular concentration of Hydrogen at each temperature the influence of temperature on the reaction rate decreases and is almost constant. The type of produced carbon in the storage medium and its auto-catalytic effect on the reactions were also investigated. Results showed that carbon black had been mostly formed but in different sizes from 100 to 2000 nm. Increasing the reactor temperature decreased the size of the generated carbon. Pre-produced carbon in the reactor did not affect the production rate and is almost negligible at more than 850°C.

At the heart of most Power-to-X (PtX) concepts is the utilization of renewable electricity to produce hydrogen through the electrolysis of water. This hydrogen can be used directly as a final energy carrier or it can be converted into for example methane synthesis gas liquid fuels electricity or chemicals. Technical demonstration and systems integration are of major importance for integrating PtX into energy systems. As of June 2020 a total of 220 PtX research and demonstration projects in Europe have either been realized completed or are currently being planned. The central aim of this review is to identify and assess relevant projects in terms of their year of commissioning location electricity and carbon dioxide sources applied technologies for electrolysis capacity type of hydrogen post-processing and the targeted field of application. The latter aspect has changed over the years. At first the targeted field of application was fuel production for example for hydrogen buses combined heat and power generation and subsequent injection into the natural gas grid. Today alongside fuel production industrial applications are also important. Synthetic gaseous fuels are the focus of fuel production while liquid fuel production is severely under-represented. Solid oxide electrolyzer cells (SOECs) represent a very small proportion of projects compared to polymer electrolyte membranes (PEMs) and alkaline electrolyzers. This is also reflected by the difference in installed capacities. While alkaline electrolyzers are installed with capacities between 50 and 5000 kW (2019/20) and PEM electrolyzers between 100 and 6000 kW SOECs have a capacity of 150 kW. France and Germany are undertaking the biggest efforts to develop PtX technologies compared to other European countries. On the whole however activities have progressed at a considerably faster rate than had been predicted just a couple of years ago.

Over the past decade energy demand has witnessed a drastic increase mainly due to huge development in the industry sector and growing populations. This has led to the global utilization of renewable energy resources and technologies to meet this high demand as fossil fuels are bound to end and are causing harm to the environment. Solar PV (photovoltaic) systems are a renewable energy technology that allows the utilization of solar energy directly from the sun to meet electricity demands. Solar PV has the potential to create a reliable clean and stable energy systems for the future. This paper discusses the different types and generations of solar PV technologies available as well as several important applications of solar PV systems which are “Large-Scale Solar PV” “Residential Solar PV” “Green Hydrogen” “Water Desalination” and “Transportation”. This paper also provides research on the number of solar papers and their applications that relate to the Sustainable Development Goals (SDGs) in the years between 2011 and 2021. A total of 126513 papers were analyzed. The results show that 72% of these papers are within SDG 7: Affordable and Clean Energy. This shows that there is a lack of research in solar energy regarding the SDGs especially SDG 1: No Poverty SDG 4: Quality Education SDG 5: Gender Equality SDG 9: Industry Innovation and Infrastructure SDG 10: Reduced Inequality and SDG 16: Peace Justice and Strong Institutions. More research is needed in these fields to create a sustainable world with solar PV technologies.

On this weeks show we discuss with Graham Cooley the CEO of ITM Power how his company has expanded from a research company on AIM in the early 2000’s to one of the largest electrolyser manufacturers in the world. On the show we also ask Graham to talk about how the hydrogen market has evolved where he sees the potential growth trajectory for the industry and how ITM sees its role within this space.

The podcast can be found on their website

Natural gas based hydrogen production with carbon capture and storage is referred to as blue hydrogen. If substantial amounts of CO2 from natural gas reforming are captured and permanently stored such hydrogen could be a low-carbon energy carrier. However recent research raises questions about the effective climate impacts of blue hydrogen from a life cycle perspective. Our analysis sheds light on the relevant issues and provides a balanced perspective on the impacts on climate change associated with blue hydrogen. We show that such impacts may indeed vary over large ranges and depend on only a few key parameters: the methane emission rate of the natural gas supply chain the CO2 removal rate at the hydrogen production plant and the global warming metric applied. State-of-the-art reforming with high CO2 capture rates combined with natural gas supply featuring low methane emissions does indeed allow for substantial reduction of greenhouse gas emissions compared to both conventional natural gas reforming and direct combustion of natural gas. Under such conditions blue hydrogen is compatible with low-carbon economies and exhibits climate change impacts at the upper end of the range of those caused by hydrogen production from renewable-based electricity. However neither current blue nor green hydrogen production pathways render fully “net-zero” hydrogen without additional CO2 removal.

Today we are joined by our good friends from Enapter. The company is a leader in the clean hydrogen sector focused on AEM electrolyzer technology and innovative software solutions that make it possible to rapidly deploy and scale hydrogen production assets. For those who follow the hydrogen sector regularly it’s been hard not to hear Enapter-related news in 2021 and its impressive trajectory as they have gone public announced the plans for a brand new production facility in Germany (on which they have now begun construction) and most recently the announcement that Enapter was selected as the winner of the prestigious Earthshot prize. To do that we are absolutely delighted to have with us all the way from his home base in Thailand Thomas Chrometzka Chief Strategy Officer at Enapter and one of the people that we enjoy having on the show so much that we have brought him back again to fill us in on what he and Enapter are up to and what they have planned for the future of hydrogen.

The podcast can be found on their website

This is the inaugural episode of the EAH: Deep Dive podcast mini-series! Our first episode features the co-founders of Enapter Vaitea Cowan and Jan Justus-Schmidt. Enapter is a young company that has made a big splash in the hydrogen space with their modular scalable AEM electrolyzer technology. Last year they made headlines with their successful public offering on the DAX and the company is expected to be a the forefront of the hydrogen sector again in 2021 as they begin construction of their mass production facility in Germany and announce the upcoming Generation Hydrogen event on May 19 2021.

The podcast can be found on their website

There is a significant push to reduce carbon dioxide (CO2) emissions and develop low-cost fuels from renewable sources to replace fossil fuels in applications such as energy production. As a result CO2 conversion has gained widespread attention as it can reduce the accumulation of CO2 in the atmosphere and produce fuels and valuable industrial chemicals including carbon monoxide alcohols and hydrocarbons. At the same time finding ways to store energy in batteries or energy carriers such as hydrogen (H2) is essential. Water electrolysis is a powerful technology for producing high-purity H2 with negligible emission of greenhouse gases and compatibility with renewable energy sources. Additionally the electrolysis of organic compounds such as lignin is a promising method for localised H2 production as it requires lower cell voltages than conventional water electrolysis. Industrial wastewater can be employed in those organic electrolysis systems due to their high organic content decreasing industrial pollution through wastewater disposal. Electrocoagulation indirect electrochemical oxidation anodic oxidation and electro-Fenton are effective electrochemical methods for treating industrial wastewater. Furthermore bioenergy technology possesses a remarkable potential for producing H2 and other value-added chemicals (e.g. methane formic acid hydrogen peroxide) along with wastewater treatment. This paper comprehensively reviews these approaches by analysing the literature in the period 2012–2022 pointing out the high potential of using electrolytic cells for energy and environmental applications.

This paper investigates an integrated system where solar energy system (with 75MWp bifacial PV arrays) and nuclear power plant (with 2×10MWt HTR-10 type pebble bed reactors) are hybridized and integrated with a 72MWe capacity high-temperature solid oxide electrolysis (SOE) unit to produce hydrogen fresh water and electrical power. Bifacial PV plant is integrated to system for supplying electricity with a low LCOE and zero-carbon system. A Rankine cycle is integrated to generate power from the steam that generated from nuclear heat. According to the available irradiance; the steam is diverted between steam turbine and high-temperature electrolyzer for hydrogen and power generation. Multi-effect desalination unit is integrated to exploit the excess heat to generate fresh water. A system performance assessment is carried out by energy and exergy efficiencies thermodynamically. The bifacial PV plant is analyzed in six selected latitudes in order to assess the feasibility and applicability of the system. Numerous time-dependent analyses are carried out to study the effects of varying inputs such as solar radiation intensity. For 20MWt nuclear 75MWp solar capacity; hydrogen productions are found to be between 0.036 and 0.562kg/s. Among the Northern Hemisphere latitudes the peak daily hydrogen production rate is expected to reach 25.9 tons of hydrogen per day for the 75 °N case mostly with the influence of low temperature and high albedo. The pitch distance change is increased the hydrogen production rate by 28% between 3 m and 7 m tracker spacing. The overall system energy efficiency is obtained between 21.8% and 24.2% where the overall system exergy efficiency is found between 18.6% and 21.1% under dynamic conditions for the 45°N latitude case.

Natural gas (Methane) is currently the primary source of catalytic hydrogen production accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However the SMR process suffers with insufficient catalytic activity low long-term stability and excessive energy input mostly due to the handling of large amount of CO2 coproduced. With the demand for anticipated hydrogen production to reach 122.5 M tons in 2024 novel and upgraded catalytic processes are desired for more effective utilization of precious natural resources. In this review we summarized the major descriptors of catalyst and reaction engineering of the SMR process and compared the SMR process with its derivative technologies such as dry reforming with CO2 (DRM) partial oxidation with O2 autothermal reforming with H2O and O2. Finally we discussed the new progresses of methane conversion: direct decomposition to hydrogen and solid carbon and selective oxidation in mild conditions to hydrogen containing liquid organics (i.e. methanol formic acid and acetic acid) which serve as alternative hydrogen carriers. We hope this review will help to achieve a whole picture of catalytic hydrogen production from methane.

Steam methane reforming (SMR) is the dominant process for hydrogen production which produce large amount of carbon dioxide (CO2) as a by-product. To address concerns about carbon emissions there is an increasing focus on blue hydrogen to mitigate carbon emissions during hydrogen production. However the commercialization of blue hydrogen production (BHP) is hindered by the challenges of high cost and energy consumption. This study proposes a new configuration to address these challenges which is characterized by: (a) the use of piperazine (PZ) as a solvent which has a high CO2 absorption efficiency; (b) a more efficient heat exchange configuration which recovers the waste exergy from flue gas; (c) the advanced flash stripper (AFS) was adopted to reduce the capital cost due to its simpler stripper configuration. In addition the technical and economic performance of the proposed energy and cost-saving blue hydrogen production (ECSB) process is investigated and compared with the standard SMR process. The detailed models of the SMR process and the post-combustion carbon capture (PCC) process were developed and integrated in Aspen plus® V11. The results of the technical analysis showed that the ECSB process with 30 wt.% PZ achieves a 36.3 % reduction in energy penalty when compared to the standard process with 30 wt.% Monoethanolamine (MEA). The results of the economic analysis showed that the lowest levelized cost of blue hydrogen (LCBH) was achieved by the ECSB process with 30 wt.% PZ. Compared to the BHP process with 30 wt.% MEA the LCBH was reduced by 19.7 %.

Hydrogen production by electrolysis is considered an essential means of consuming renewable energy in the future. However the current assessment of the potential of renewable energy electrolysis for hydrogen production is relatively simple and the perspective is not comprehensive. Here we established a Combined Wind and Solar Electrolytic Hydrogen system considering the influence of regional wind-solar-load characteristics and transmission costs to evaluate the hydrogen production potential of 31 provincial-level regions in China in 2050. The results show that in 2050 the levelized cost of hydrogen (LCOH) in China’s provincial regions will still be higher than 10 ¥/kg which is not cost-competitive compared to the current hydrogen production from fossil fuels. It is more cost-effective to deploy wind turbines than photovoltaic in areas with similar wind and solar resources or rich in wind resources. Wind-solar differences impact LCOH equipment capacity configuration and transmission cost composition while load fluctuation significantly impacts LCOH and electricity storage configuration. In addition the sensitivity analysis of 11 technical and economic parameters showed differences in the response performance of LCOH changes to different parameters and the electrolyzer conversion efficiency had the most severe impact. The analysis of subsidy policy shows that for most regions (except Chongqing and Xizang) subsidizing the unit investment cost of wind turbines can minimize LCOH. Nevertheless from the perspective of comprehensive subsidy effect subsidy cost and hydrogen energy development it is more cost-effective to take subsidies for electrolysis equipment with the popularization of hydrogen

Hydrogen is a low or zero-carbon energy source that is considered the most promising and potential energy carrier of the future. In this study the energy sources feedstocks and various methods of hydrogen production from power generation are comparatively investigated in detail. In addition this study presents an economic assessment to evaluate cost-effectiveness based on different economic indicators including sensitivity analysis and uncertainty analysis. Proton exchange membrane fuel cell (PEMFCs) technology has the most potential to be developed compared to several other technologies. PEMFCs have been widely used in various fields and have advantages (i.e. start-up zero-emissions high power density). Among the various sources of uncertainty in the sensitivity analysis the cost estimation method shows inflationary deviations from the proposed cost of capital. This is due to the selection process and untested technology. In addition the cost of electricity and raw materials as the main factors that are unpredictable.

Niger offers the possibility of producing green hydrogen due to its high solar energy potential. Due to the still growing domestic oil and coal industry the use of green hydrogen in the country currently seems unlikely at the higher costs of hydrogen as an energy vector. However the export of green hydrogen to industrialized countries could be an option. In 2020 a hydrogen partnership has been established between Germany and Niger. The potential import of green hydrogen represents an option for Germany and other European countries to decarbonize domestic energy supply. Currently there are no known projects for the electrolytic production of hydrogen in Niger. In this work potential hydrogen demand across electricity and transport sectors is forecasted until 2040. The electricity demand in 2040 is expected at 2934 GWh and the gasoline and diesel demand at 964 m3 and 2181 m3 respectively. Accordingly the total hydrogen needed to supply electricity and the transport sector (e.g. to replace 1% gasoline and diesel demand in 2040) is calculated at 0.0117 Mt. Only a small fraction of 5% of the land area in Niger would be sufficient to generate the required electricity from solar PV to produce hydrogen.

By adding energy as hydrogen to the biomass-to-liquid (BtL) process several published studies have shown that carbon efficiency can be increased substantially. Hydrogen can be produced from renewable electrical energy through the electrolysis of water or steam. Adding high-temperature thermal energy to the gasifier will also increase the overall carbon efficiency. Here an economic criterion is applied to find the optimal distribution of adding electrical energy directly to the gasifier as opposed to the electrolysis unit. Three different technologies for electrolysis are applied: solid oxide steam electrolysis (SOEC) alkaline water electrolysis (AEL) and proton exchange membrane (PEM). It is shown that the addition of part of the renewable energy to the gasifier using electric heaters is always beneficial and that the electrolysis unit operating costs are a significant portion of the costs. With renewable electricity supplied at a cost of 50 USD/MWh and a capital cost of 1500 USD/kW installed SOEC the operating costs of electric heaters and SOEC account for more than 70% of the total costs. The energy efficiency of the electrolyzer is found to be more important than the capital cost. The optimal amount of energy added to the gasifier is about 37–39% of the energy in the biomass feed. A BtL process using renewable hydrogen imports at 2.5 USD/kg H2 or SOEC for hydrogen production at reduced electricity prices gives the best values for the economic objective.

A combined ultra-short-term wind power prediction strategy with high robustness based on least squares support vector machine (LSSVM) has been proposed in order to solve the wind abandonment caused by wind power randomness and realize efficient hydrogen production under wide power fluctuation. Firstly the original wind power data is decomposed into sub-modes with different bandwidth by variational modal decomposition (VMD) which reduces the influence of random noise and mode mixing significantly. Then dragonfly algorithm (DA) is introduced to optimize LSSVM kernel function and the combined ultra-short-term wind power prediction strategy which meets the time resolution and accuracy requirements of electrolytic cell control has been established finally. This model is validated by a wind power hydrogen production demonstration project output in the middle east of China. The superior prediction accuracy for high volatility wind power data is verified and the algorithm provides theoretical basis to improve the control of wind power hydrogen production system

The combination of methane steam reforming technology and CCS (Carbon Capture and Storage) technology has great potential to reduce carbon emissions in the process of hydrogen production. Different from the traditional idea of capturing CO2 (Carbon Dioxide) in the exhaust gas with high work consumption this study simultaneously focuses on CO2 separation from fuel gas and recycling. A new hydrogen production system is developed by methane steam reforming coupled with carbon capture. Separated and captured high-purity carbon dioxide could be recycled for methane dry reforming; on this basis a new methane-dry-reforming-driven hydrogen production system with a carbon dioxide reinjection unit is innovatively proposed. In this study the energy flow and irreversible loss in the two newly developed systems are analyzed in detail through energy and exergy balance analysis. The advantages are explored from the perspective of hydrogen production rate natural gas consumption and work consumption. In addition in consideration of the integrated performance an optimal design analysis was conducted. In terms of hydrogen production the new system based on dry reforming is better with an advantage of 2.41%; however it is worth noting that the comprehensive thermal performance of the new steam reforming system is better reaching 10.95%. This study provides new ideas for hydrogen production from a low carbon emission perspective and also offers a new direction for future distributed energy system integration.

Political and scientific discussions on changing German energy supply mix and challenges of such energy transition are already well established. At the supply level energy storage seems to be the biggest challenge ahead for such transition. Hydrogen could be one of the solutions for future energy transition if it is produced using renewable energy resources. In order to analyze the future role of hydrogen its economic performance analysis is inevitable. This has been done in this research for a case study site in Cologne. The potential of hydrogen production with the use of solar electricity powered electrolyzers (alkaline and proton exchange membrane (PEM)) has been analyzed. Both grid connected and off grid modes of solar hydrogen production are considered. Economic performance results are presented for six scenarios. Hydrogen produced with the grid connected solar photovoltaics system coupled with alkaline electrolyzers was found the cheapest with the levelized cost of hydrogen (LCOH) at 6.23 V/kg. These costs are comparable with the current hydrogen price at commercial refueling station in Cologne. On the other hand the LCOH of off grid systems with both alkaline and PEM electrolyzers is expensive as expected the most expensive LCOH among six scenarios reached to 57.61 V/kg.

Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14% and 73% and for wind between 3.3% and 143% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore the procedures for planning and dimensioning of selected systems can be drastically simplified.

This study presents a comprehensive methodology to evaluate plants that integrate renewable energy sources and hydrogen generation devices. The paper focuses on presenting the methods for devices’ operation assessment taking into account the annual operation. Multiple effectiveness indices have been presented. On the basis of experimental investigation with the hydrogen generator the methods for assessing its operation during start-up phase and sudden change in the supply current were proposed. The results of the experiments and the provided mathematical models show that dynamics of the hydrogen generator should be taken into account when selecting the suitable device for cooperation with variable renewable energy. It is especially important for multiple start-ups throughout the day due to significant differences in the amount of hydrogen produced by devices characterized by the same efficiency yet various time constants. Methodology for selecting the optimal nominal power for hydrogen generator to cooperate with given renewable sources was developed. It was proven the optimal power depends on the type of the renewable source and minimal load of the hydrogen generator. Several case studies including the integration of wind and solar energy farms to yield a 10 MW renewable energy farm were considered and the minimal load of the hydrogen generator impacts the annual operation of the device has been presented. The paper provides a set of tools to contribute to the development of sustainable energy plants. The methods proposed in this paper are universal and can be used for various renewable energy sources.

Renewable energy complementary hydrogen production can enhance the full consumption of renewable energy and reduce the abandonment of wind and solar power. The integration of renewable energy and hydrogen production equipment through existing multi-terminal DC systems can reduce new power lines construction and save investment in distribution equipment. For integrated renewable energy/hydrogen energy in an existing multi-terminal DC system this paper investigates its potential of hydrogen production based on renewable energy while ensuring the normal performance of the existing system being not affected. The typical structure and control strategy of the integrated renewable energy/hydrogen energy in multi-terminal DC system are firstly described. Then the state space model of the system is constructed and the key parameters affecting the hydrogen production capacity are studied by using the eigenvalues analysis method. Finally the corresponding system simulation model and test platform are built and the theoretical analysis results are verified and the potential of using multi-terminal DC system to enhance hydrogen production is quantitatively analyzed. The proposed scheme can enhance the hydrogen production potential from renewable energy meanwhile the normal performance of the existing system is not affected.

Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

Due to there is no better way to exploit depleted gas reservoirs and hydrogen can generate from natural gas combustion. In this paper the possibility of in‐situ hydrogen generation in air injected gas reservoirs was determined through pseudo dynamic experiments. The study indicated that highertemperature and steam/methane ratio can generate more hydrogen and the temperature should not be lower than 600 °C within gas reservoirs. The debris has positive catalysis for hydrogen generation. The maximum mole fraction of hydrogen was 26.63% at 600 °C.

Renewable energy DC hydrogen production has become a new development trend. Due to the interaction between the weak damping of DC network and the negative impedance characteristics of power supply of hydrogen production the actual available power of renewable and hydrogen energy DC interconnection system will be lower than its rated setting value. To solve this problem this paper proposes an intelligent damping control to realize the rated power operation of hydrogen generation power source and significantly improve the hydrogen generation performance. In this paper the nonlinear model under typical control strategies is established in order to adapt to different degrees of disturbance and the damping controller is designed based on state feedback including feedback control law and damping generation formula. On this basis an intelligent method of damping control is proposed to support rapid decision-making. Finally the intelligent damping control method is verified by simulation analysis. It realizes rated power of power supply of hydrogen production by generating only a small amount of damping power and superimposing it on the hydrogen production power

The usage of fossil fuels to generate energy and the lack of wastewater treatment in Mexico are two issues that can be addressed at the same time while developing wastewater treatment technologies that incorporate energy recovery in their process train. We carried out a systematic review based on the PRISMA methodology to identify and review studies regarding energy recovery using wastewater as a substrate in Mexico. Peer-reviewed papers were identified through Scopus Web of Knowledge and Google Scholar using a timeframe of 22 years that represented from 2000 to 2022. After applying the selection criteria we identified 31 studies to be included in the final review starting from 2007. The kind of energy product type of technology used substrate wastewater amount of energy produced and main parameters for the operation of the technology were extracted from the papers. The results show that methane is the most researched energy recovery product from wastewater followed by hydrogen and electricity and the technology used to archive it is an up-flow anaerobic sludge bed (UASB) reactor to produce methane and hydrogen. In addition microbial fuel cells (MFCs) were preferred to produce electricity. According to our data more energy per kgCOD removed could be obtained with methane-recovering technologies in the Mexican peer-reviewed studies compared with hydrogen recovery and electricity production.

Hydrogen is the most efficient energy carrier. Hydrogen can be obtained from different sources of raw materials including water. Among many hydrogen production methods eco-friendly and high purity of hydrogen can be obtained by water electrolysis. However In terms of sustainability and environmental impact PEM water electrolysis was considered as most promising techniques for high pure efficient hydrogen production from renewable energy sources and emits only oxygen as byproduct without any carbon emissions. Moreover the produced hydrogen (H₂) and oxygen (O₂) directly used for fuel cell and industrial applications. However overall water splitting resulting in only 4% of global industrial hydrogen being produced by electrolysis of water mainly due to the economic issues. Nowadays increased the desire production of green hydrogen has increased the interest on PEM water electrolysis. Thus the considerable research has been completed recently in the development of cost effective electrocatalysts for PEM water electrolysis. In this present review we discussed about the recent developments in the PEM water electrolysis including high performance low cost HER and OER electrocatalysts and their challenges new and old related to electrocatalysts and PEM cell components also addressed. This review will contribute further research improvements and a road map in order to support in developing the PEM water electrolyser as a commercially feasible hydrogen production purpose.

Pressure is mounting on the natural gas and LNG community to reduce methane emissions and this is most urgent in EU countries following the adoption of much tougher greenhouse gas reduction targets of 2030 and the publication of the European Commission’s Methane Strategy. With rapidly declining indigenous EU production and therefore rising import dependence there are increasing calls for emissions from imported pipeline gas and LNG to be quantified and based on actual measurements as opposed to standard emission factors. The Methane Strategy promises to be a significant milestone in that process. Companies which are supplying (or intending to supply) natural gas to the EU – the largest global import market for pipeline gas and a very significant market for LNG – would be well advised to pay close attention to how the regulation of methane emissions is unfolding and to make an immediate and positive response. Failure to do so could accelerate the demise of natural gas in European energy balances faster than would otherwise have been the case and shorten the time available for transition to decarbonised gases – specifically hydrogen – using existing natural gas infrastructure.<br/>This EU initiative will (and arguably already has) attracted attention from non-EU governments and companies involved in global gas and LNG trade. We have already seen deliveries of `carbon neutral’ LNG cargos to Asia as well as a long-term LNG contract in which the greenhouse gas content of cargos will be measured reported and verified (MRV) according to an agreed methodology. Natural gas and LNG exports if based on these standards or those set out in the EU Methane Strategy may be able to command premium prices from buyers eager to demonstrate their own GHG reduction credentials to governments customers and civil society.

Two electrolysis technologies fed with renewable energy sources are promising for the production of CO₂-free hydrogen and enabling the transition to a hydrogen society: Alkaline Electrolyte (AE) and Polymer Electrolyte Membrane (PEM). However limited information exists on the potential environmental impacts of these promising sustainable innovations when operating on a large-scale. To fill this gap the performance of AE and PEM systems is compared using ex-ante Life Cycle Assessment (LCA) technology analysis and exploratory scenarios for which a refined methodology has been developed to study the effects of implementing large-scale sustainable hydrogen production systems. Ex-ante LCA allows modelling the environmental impacts of hydrogen production exploratory scenario analysis allows modelling possible upscaling effects at potential future states of hydrogen production and use in vehicles in the Netherlands in 2050. A bridging tool for mapping the technological field has been created enabling the combination of quantitative LCAs with qualitative scenarios. This tool also enables diversity for exploring multiple sets of visions. The main results from the paper show with an exception for the “ozone depletion” impact category (1) that large-scale AE and PEM systems have similar environmental impacts with variations lower than 7% in all impact categories (2) that the contribution of the electrolyser is limited to 10% of all impact categories results and (3) that the origin of the electricity is the largest contributor to the environmental impact contributing to more than 90% in all impact categories even when renewable energy sources are used. It is concluded that the methodology was applied successfully and provides a solid basis for an ex-ante assessment framework that can be applied to emerging technological systems.

A vision of hydrogen based economy and clean sustainable fossil fuels-free world inspires the scientific community to put much effort into the development of visible-light-driven photochemistry and efficient solar energy harvesting. The unique features of plasmonic nanomaterials such as capability of significant electric field amplification an extreme local heating generation of high energy charge carriers and broad tunability of optical properties coupled to catalytically active surfaces provide an exciting opportunity for hydrogen production with solar photochemistry. This review sums up recent progress in the development of plasmonic thermophotocatalysis paying particular attention to sustainable production of hydrogen. We approach the subject from a broad bottom-up perspective beginning with the brief description of plasmon-related phenomena and plasmon-assisted photochemistry through the demonstration of various plasmonic nanostructures their synthesis and hydrogen production efficiency ending with the idea of continuous-flow reactors and their future implementation in hydrogen production by plasmonic thermophotocatalysis. Finally we summarize the review and highlight the remaining challenges that have to be faced before the widespread commercialization of this technology.

Palladium (Pd) membranes are a promising enabling technology for power generation and hydrogen production with CO2 capture. SINTEF has developed and patented a flexible technology to produce Pd-alloy membranes that significantly improves flux and thereby reduces material costs. Reinertsen AS and SINTEF aim to demonstrate the Pd membrane technology for H2 separation on a side stream of the Statoil Methanol Plant at Tjeldbergodden Norway. In the present article we present the upscaling of the membrane manufacturing process together with the membrane module and skid design and construction.

Interest in blue hydrogen production technologies is growing. Some researchers have evaluated the environmental and/or economic feasibility of producing blue hydrogen but a holistic assessment is still needed. Many aspects of hydrogen production have not been investigated. There is very limited information in the literature on the impact of plant size on production and the extent of carbon capture on the cost and life cycle greenhouse gas (GHG) emissions of blue hydrogen production through various production pathways. Detailed uncertainty and sensitivity analyses have not been included in most of the earlier studies. This study conducts a holistic comparative cost and life cycle GHG emissions’ footprint assessment of three natural gas-based blue hydrogen production technologies – steam methane reforming (SMR) autothermal reforming (ATR) and natural gas decomposition (NGD) to address these research gaps. A hydrogen production plant capacity of 607 tonnes per day was considered. For SMR based on the percentage of carbon capture and capture points we considered two scenarios SMR-52% (indicates 52% carbon capture) and SMR-85% (indicates 85% carbon capture). A scale factor was developed for each technology to understand the hydrogen production cost with a change in production plant size. Hydrogen cost is 1.22 1.23 2.12 1.69 2.36 1.66 and 2.55 $/kg H2 for SMR ATR NGD SMR-52% SMR-85% ATR with carbon capture and sequestration (ATR-CCS) and NGD with carbon capture and sequestration (NGD-CCS) respectively. The results indicate that when uncertainty is considered SMR-52% and ATR are economically preferable to NGD and SMR-85%. SMR-52% could outperform ATR-CCS when the natural gas price decreases and the rate of return increases. SMR-85% is the least attractive pathway; however it could outperform NGD economically when CO2 transportation cost and natural gas price decrease. Hydrogen storage cost significantly impacts the hydrogen production cost. SMR-52% SMR-85% ATR-CCS and NGD-CCS have scale factors of 0.67 0.68 0.54 and 0.65 respectively. The hydrogen cost variation with capacity shows that operating SMR-52% and ATR-CCS above hydrogen capacity of 200 tonnes/day is economically attractive. Blue hydrogen from autothermal reforming has the lowest life cycle GHG emissions of 3.91 kgCO2eq/kg H2 followed by blue hydrogen from NGD (4.54 kgCO2eq/kg H2) SMR-85% (6.66 kgCO2eq/kg H2) and SMR-52% (8.20 kgCO2eq/kg H2). The findings of this study are useful for decision-making at various levels.

Currently hydrogen is mainly produced through steam reforming of natural gas. However this conventional process involves environmental and energy security concerns. This has led to the development of alternative technologies for (potentially) green hydrogen production. In this work the environmental and energy performance of biohydrogen produced in Europe via steam reforming of glycerol and bio-oil is evaluated from a life-cycle perspective and contrasted with that of conventional hydrogen from steam methane reforming. Glycerol as a by-product from the production of rapeseed biodiesel and bio-oil from the fast pyrolysis of poplar biomass are considered. The processing plants are simulated in Aspen Plus® to provide inventory data for the life cycle assessment. The environmental impact potentials evaluated include abiotic depletion global warming ozone layer depletion photochemical oxidant formation land competition acidification and eutrophication. Furthermore the cumulative (total and non-renewable) energy demand is calculated as well as the corresponding renewability scores and life-cycle energy balances and efficiencies of the biohydrogen products. In addition to quantitative evidence of the (expected) relevance of the feedstock and impact categories considered results show that poplar-derived bio-oil could be a suitable feedstock for steam reforming in contrast to first-generation bioglycerol.

Hydrogen is regarded to be one of the most promising renewable and clean energy sources. Finding a highly efficient and cost-effective catalyst to generate hydrogen via water splitting has become a research hotspot. Two-dimensional materials with exotic structural and electronic properties have been considered as economical alternatives. In this work 2D SnSe films with high quality of crystallinity were grown on a mica substrate via molecular beam epitaxy. The electronic property of the prepared SnSe thin films can be easily and accurately tuned in situ by three orders of magnitude through the controllable compensation of Sn atoms. The prepared film normally exhibited p-type conduction due to the deficiency of Sn in the film during its growth. First-principle calculations explained that Sn vacancies can introduce additional reactive sites for the hydrogen evolution reaction (HER) and enhance the HER performance by accelerating electron migration and promoting continuous hydrogen generation which was mirrored by the reduced Gibbs free energy by a factor of 2.3 as compared with the pure SnSe film. The results pave the way for synthesized 2D SnSe thin films in the applications of hydrogen production.

The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar) step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH) is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle) and solar-to-fuel energy conversion efficiency (ηsolar´to´fuel) attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar´to´fuel both increase with decreasing TH due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance in the case where TH = 2280 K ηcycle = 24.4% and ηsolar´to´fuel = 29.5% (without heat recuperation) while ηcycle = 31.3% and ηsolar´to´fuel = 37.8% (with 40% heat recuperation).

There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. Australia’s Chief Scientist Alan Finkel recently prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of the ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been commissioned by the Department of Industry Innovation and Science to develop heat maps that show areas with high potential for future hydrogen production. The study is technology agnostic in that it considers hydrogen production via electrolysis using renewable energy sources and also fossil fuel hydrogen coupled with carbon capture and storage (CCS). The heat maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential and the availability of water are the most important factors with various infrastructural considerations playing a secondary role. In the case of fossil fuel hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the heat maps. In this report we present 5 different heat map scenarios reflecting different assumptions in the geospatial analysis and also reflecting to some degree the different projected timeframes for hydrogen production. The first three scenarios pertain to renewable energy and hydrogen There is significant interest in Australia both federally and at the state level to develop a hydrogen production industry. In August 2018 Australia’s Chief Scientist Dr Alan Finkel prepared a briefing paper for the COAG Energy Council outlining a road map for hydrogen. It identifies hydrogen has the potential to be a significant source of export revenue for Australia in future years assist with decarbonising Australia’s economy and could establish Australia as a leader in low emission fuel production.

As part of ongoing investigations into the hydrogen production potential of Australia Geoscience Australia has been engaged by the Department of Industry Innovation and Science to develop maps that show areas with high potential for future hydrogen production. The study is technology agnostic but considers only low carbon production processes. It includes hydrogen production via electrolysis using renewable energy sources (referred to as renewable hydrogen) as well as fossil fuel-derived hydrogen coupled with carbon capture and storage (CCS) (referred to as CCS hydrogen). The maps presented in this work are synthesized from the key individual national-scale datasets that are relevant for hydrogen production. In the case of hydrogen from electrolysis renewable energy potential (from wind solar and hydro resources) and the availability of water are the most important factors while various infrastructure considerations also play a role. In the case of CCS hydrogen proximity to gas and coal resources water and availability of carbon storage sites are the important parameters that control the spatial distribution of potential hydrogen production. In this report we present five different scenarios that reflect key differences in technologies for hydrogen production and the requirements of those technologies. Using geospatial analysis each scenario is translated into a heat map that shows regional trends in potential for hydrogen production based on access to underpinning resources and existing infrastructure.

Three scenarios explore the future potential for renewable hydrogen produced by electrolysis. These demonstrate a high potential for hydrogen production in the future near many Australian coastal areas which is even larger if infrastructure is available to transport renewable power generated from inland areas to the coast. Results also show significant future potential for hydrogen production in inland areas where water is available. The final two scenarios focus on the future potential for CCS hydrogen: a 2030 scenario and a 2050 scenario. A key factor in future CCS hydrogen potential is related to the timeframes for the availability of geological storage resources for CO_2.

Harnessing solar energy and converting it into renewable fuels by chemical processes such as water splitting and carbon dioxide (CO₂ ) reduction is a highly promising yet challenging strategy to mitigate the effects arising from the global energy crisis and serious environmental concerns. In recent years covalent organic framework (COF)-based materials have gained substantial research interest because of their diversified architecture tunable composition large surface area and high thermal and chemical stability. Their tunable band structure and significant light absorption with higher charge separation efficiency of photoinduced carriers make them suitable candidates for photocatalytic applications in hydrogen (H₂) generation CO₂ conversion and various organic transformation reactions. In this article we describe the recent progress in the topology design and synthesis method of COF-based nanomaterials by elucidating the structure-property correlations for photocatalytic hydrogen generation and CO₂ reduction applications. The effect of using various kinds of 2D and 3D COFs and strategies to control the morphology and enhance the photocatalytic activity is also summarized. Finally the key challenges and perspectives in the field are highlighted for the future development of highly efficient COF-based photocatalysts.

In this perspective on hydrogen carriers we focus on the needs for the development of robust active catalysts for the release of H₂ from aqueous formate solutions which are non-flammable non-toxic thermally stable and readily available at large scales at reasonable cost. Formate salts can be stockpiled in the solid state or dissolved in water for long term storage and transport using existing infrastructure. Furthermore formate salts are readily regenerated at moderate pressures using the same catalyst as for the H₂ release. There have been several studies focused on increasing the activity of catalysts to release H₂ at moderate temperatures i.e. < 80 °C below the operating temperature of a proton exchange membrane (PEM) fuel cell. One significant challenge to enable the use of aqueous formate salts as hydrogen carriers is the deactivation of the catalyst under operating conditions. In this work we provide a review of the most efficient heterogeneous catalysts that have been described in the literature their proposed modes of deactivation and the strategies reported to reactivate them. We discuss potential pathways that may lead to deactivation and strategies to mitigate it in a variety of H₂ carrier applications. We also provide an example of a potential use case employing formate salts solutions using a fixed bed reactor for seasonal storage of energy for a microgrid application.

In this present investigation a packed-filter bioreactor was employed to produce hydrogen utilizing an expired soft drink as a substrate. The effects of feeding substrate concentrations ranging from 19.51 10.19 5.34 3.48 to 2.51 g total sugar/L were examined and the position of the packed filter installed in the bioreactor at dimensionless heights (h/H) of 1/4 2/4 3/4 and 4/4 was studied. The results revealed that with a substrate concentration of 20 g total sugar/L and a hydraulic retention time (HRT) of 1 h a packed filter placed at the half-height position of the bioreactor (h/H 2/4) has the optimal hydrogen production rate hydrogen yield and average biomass concentration in the bioreactor resulting in 55.70 ± 2.42 L/L/d 0.90 ± 0.06 mol H₂/mol hexose and 17.86 ± 1.09 g VSS/L. When feeding substrate concentrations varied from 20 10 to 5 g total sugar/L with the packed-filter position at h/H 2/4 Clostridium sp. Clostridium tyrobutyricum and Bifidobacterium crudilactis were the predominant bacteria community. Finally it was discovered that the packed-filter bioreactor can produce stable hydrogen in high-strength organic effluent.

The most profitable offshore energy resources are usually found away from the coast. Nevertheless the accessibility and grid integration in those areas are more complicated. To avoid this problematic large scale hydrogen production is being promoted for far offshore applications. The main objective of this paper is to analyze the ability of wave energy converters to maximize hydrogen production in hybrid wind and wave far offshore farms. To that end wind and wave resource data are obtained from ERA5 for different locations in the Atlantic ocean and a Maximum Covariance Analysis is proposed for the selection of the most representative locations. Furthermore the suitability of different sized wave energy converters for auxiliary hydrogen production in the far offshore wind farms is also analysed. On that account the hydrodynamic parameters of the oscillating bodies are obtained via simulations with a Boundary Element Method based code and their operation is modelled using the software tool Matlab. The combination of both methodologies enables to perform a realistic assessment of the contribution of the wave energy converters to the hydrogen generation of an hybrid energy farm especially during those periods when the wind turbines would be stopped due to the variability of the wind. The obtained results show a considerable hydrogen generation capacity of the wave energy converters up to 6.28% of the wind based generation which could remarkably improve the efficiency of the far offshore farm and bring important economical profit. Wave energy converters are observed to be most profitable in those farms with low covariance between wind and waves where the disconnection times of the wind turbines are prone to be more prolonged but the wave energy is still usable. In such cases a maximum of 101.12 h of equivalent rated production of the wind turbine has been calculated to be recovered by the wave energy converters.

Chemical looping with iron-based oxygen carriers enables the production of hydrogen from various fossil and biogenic primary energy sources. In applications with real producer gases such as biogas or gasified biomass hydrogen sulfide represents one of the most challenging contaminants. The impact of H2S on the reactivity of a Fe2O3/Al2O3 oxygen carrier material in chemical looping hydrogen production was investigated in the present work. First potential sulfur deactivation mechanisms are discussed in detail on the basis of thermodynamic data. Afterwards an experimental study in a fixed-bed reactor system gave experimental evidence on the fate of sulfur in chemical looping hydrogen systems. The chemisorption of hydrogen sulfide (H2S) was identified as the main cause for the accumulative adsorption of H2S in the reduction phase and was confirmed by ex-situ ICP-EOS analysis. In the subsequent steam oxidation step significant quantities of H2S were released resulting in an undesirable contamination of the hydrogen product gas. The reason was found as weakened sulfur bonds through increasing reactor temperatures caused by the exothermic oxidation reactions. In additional air oxidation steps no further contaminants as sulfur dioxide were identified. A profound interpretation was achieved through the fulfillment of the overall sulfur mass balance within a mean deviation of 3.7%. Quantitative investigations showed that the hydrogen consumption decreased by 12% throughout the reduction phase in the event of 100 ppm H2S in the feed gas

Hydrogen sourced from energy recovery processes and conversion of waste materials is a method of providing both a clean fuel and a sustainable waste management alternative to landfill and incineration. The question is whether waste-to–hydrogen can become part of the zero-carbon future energy mix and serve as one of the cleaner hydrogen sources which is economically viable and environmentally friendly. This work critically assessed the potential of waste as a source of hydrogen production via various thermochemical (gasification and pyrolysis) and biochemical (fermentation and photolysis) processes. Research has shown hydrogen production yields of 33.6 mol/kg and hydrogen concentrations of 82% from mixed waste feedstock gasification. Biochemical methods such as fermentation can produce hydrogen up to 418.6 mL/g. Factors including feedstock quality process requirements and technology availability were reviewed to guide technology selection and system design. Current technology status and bottlenecks were discussed to shape future development priorities. These bottlenecks include expensive production and operation processes heterogeneous feedstock low process efficiencies inadequate management and logistics and lack of policy support. Improvements to hydrogen yields and production rates are related to feedstock processing and advanced energy efficiency processes such as torrefaction of feedstock which has shown thermal efficiency of gasification up to 4 MJ/kg. This will affect the economic feasibility and concerns around required improvements to bring the costs down to allow waste to viewed as a serious competitor for hydrogen production. Recommendations were also made for financially competitive waste-to-hydrogen development to be part of a combined solution for future energy needs.

For a green economy to be possible in the near future hydrogen production from water is a sought-after alternative to fossil fuels. It is however important to put things into context with respect to global CO2 emission and the role of hydrogen in curbing it. The present world annual production of hydrogen is about 70 million metric tons of which almost 50% is used to make ammonia NH3 (that is mostly used for fertilizers) and about 15% is used for other chemicals [1]. The hydrogen produced worldwide is largely made by steam CH4 reforming (SMR) which is one of the most energy-intensive processes in the chemical industry [2]. It releases based on reaction stoichiometry 5.5 kg of CO2 per 1 kg of H2 (CH4+ 2 H2O → CO2 + 4 H2). When the process itself is taken into account in addition the production [3] becomes about 9 kg of CO2 per kg of H2 and this ratio can be as high as 12 [4]. This results in the production of about one billion tons/year of CO2. The world annual CO2 emission from fossil fuels is however much larger: it is about 36 billion tons of which roughly 25% is emitted while generating electricity and heat 20% due to transport activity and 20% from other industrial processes. Because of the link between global warming and CO2 emissions there is an increasing move towards finding alternative approaches for energy vectors and their applications.

Gasification of municipal solid waste (MSW) with subsequent utilization of syngas in gas engines/turbines and solid oxide fuel cells can substantially increase the power generation of waste-to-energy facilities and optimize the utilization of wastes as a sustainable energy resources. However purification of syngas to remove multiple impurities such as particulates tar HCl alkali chlorides and sulfur species is required. This study investigates the feasibility of high temperature purification of syngas from MSW gasification with the focus on catalytic tar reforming and desulfurization. Syngas produced from a downdraft fixed-bed gasifier is purified by a multi-stage system. The system comprises of a fluidized-bed catalytic tar reformer a filter for particulates and a fixed-bed reactor for dechlorination and then desulfurization with overall downward cascading of the operating temperatures throughout the system. Novel nano-structured nickel catalyst supported on alumina and regenerable Ni-Zn desulfurization sorbent loaded on honeycomb are synthesized. Complementary sampling and analysis methods are applied to quantify the impurities and determine their distribution at different stages. Experimental and thermodynamic modeling results are compared to determine the kinetic constraints in the integrated system. The hot purification system demonstrates up to 90% of tar and sulfur removal efficiency increased total syngas yield (14%) and improved cold gas efficiency (12%). The treated syngas is potentially applicable in gas engines/turbines and solid oxide fuel cells based on the dew points and concentration limits of the remaining tar compounds. Reforming of raw syngas by nickel catalyst for over 20 h on stream shows strong resistance to deactivation. Desulfurization of syngas from MSW gasification containing significantly higher proportion of carbonyl sulfide than hydrogen sulfide traces of tar and hydrogen chloride demonstrates high performance of Ni-Zn sorbents.

Proton exchange membrane water electrolysis (PEMWE) is a key technology for future sustainable energy systems. Proton exchange membrane (PEM) electrolysis cells use iridium one of the scarcest elements on earth as catalyst for the oxygen evolution reaction. In the present study the expected iridium demand and potential bottlenecks in the realization of PEMWE for hydrogen production in the targeted GW a−1 scale are assessed in a model built on three pillars: (i) an in-depth analysis of iridium reserves and mine production (ii) technical prospects for the optimization of PEM water electrolyzers and (iii) PEMWE installation rates for a market ramp-up and maturation model covering 50 years. As a main result two necessary preconditions have been identified to meet the immense future iridium demand: first the dramatic reduction of iridium catalyst loading in PEM electrolysis cells and second the development of a recycling infrastructure for iridium catalysts with technical end-of-life recycling rates of at least 90%.

Hydrogen is an environmentally friendly biofuel which if widely used could reduce atmospheric carbon dioxide emissions. The main barrier to the widespread use of hydrogen for power generation is the lack of technologically feasible and—more importantly—cost‐effective methods of production and storage. So far hydrogen has been produced using thermochemical methods (such as gasification pyrolysis or water electrolysis) and biological methods (most of which involve anaerobic digestion and photofermentation) with conventional fuels waste or dedicated crop biomass used as a feedstock. Microalgae possess very high photosynthetic efficiency can rapidly build biomass and possess other beneficial properties which is why they are considered to be one of the strongest contenders among biohydrogen production technologies. This review gives an account of present knowledge on microalgal hydrogen production and compares it with the other available biofuel production technologies.

Producing hydrogen from water using a redox mediator on solid electrocatalyst particles in a reactor offers several advantages over classical electrolysis in terms of safety membrane degradation purity and flexibility. Herein vanadium-mediated hydrogen evolution on a commercial and low-cost Mo2C electrocatalyst is studied through the development of a reaction kinetics model. Based on a proposed mechanistic reaction scheme we established a kinetic rate law dependent on the concentration of V2+ the state-of-charge of the vanadium electrolyte from a vanadium redox flow battery and the amount of available catalytic sites on solid Mo2C. Kinetic experiments in transient conditions reveals a first-order dependence on both the concentration of V2+ and the concentration of catalytic active sites and a power law with an exponential factor of 0.57 was measured on the molar ratio V2+/V3+ i.e. on the electrochemical driving force generated on the Mo2C particles. The kinetic rate law was validated by studying the rate of reaction in steady-state conditions using a specially developed rotating ring-disk device (RRD) methodology. The kinetic model was demonstrated to be a useful tool to predict the hydrogen production via the chemical oxidation of V2+ over Mo2C at low pH (> 1 M H2SO4). For a perspective the model was implemented in a semi-batch reactor. The simulations highlight the optimal state-of-charge (SOC) to carry out the reaction in an efficient way for a given demand in hydrogen.

Industrial hydrogen production via alkaline water electrolysis (AEL) is a mature hydrogen production method. One argument in favor of AEL when supplied with renewable energy is its environmental superiority against conventional fossil-based hydrogen production. However today electricity from the national grid is widely utilized for industrial applications of AEL. Also the ban on asbestos membranes led to a change in performance patterns making a detailed assessment necessary. This study presents a comparative Life Cycle Assessment (LCA) using the GaBi software (version 6.115 thinkstep Leinfelden-Echterdingen Germany) revealing inventory data and environmental impacts for industrial hydrogen production by latest AELs (6 MW Zirfon membranes) in three different countries (Austria Germany and Spain) with corresponding grid mixes. The results confirm the dependence of most environmental effects from the operation phase and specifically the site-dependent electricity mix. Construction of system components and the replacement of cell stacks make a minor contribution. At present considering the three countries AEL can be operated in the most environmentally friendly fashion in Austria. Concerning the construction of AEL plants the materials nickel and polytetrafluoroethylene in particular used for cell manufacturing revealed significant contributions to the environmental burden.

The use of hydrogen as energy carrier is a promising option to decarbonize both energy and transport sectors. This paper presents an advanced techno-economic model for calculation of optimal dispatch of large-scale multi MW electrolysis plants in order to obtain a more accurate evaluation of the feasibility of business cases related to the supply of this fuel for different end uses combined with grid services' provision. The model is applied to the Spanish case using different scenarios to determine the minimum demand required from the FCEV market so that electrolysis facilities featuring several MW result in profitable business cases. The results show that grid services contribute to the profitability of hydrogen production for mobility given a minimum but considerable demand from FCEV fleets.

In the last two years or so there has been increasing interest in hydrogen as an energy source in Australia and around the world. Notably this is not the first time that hydrogen has caught our collective interest. Most recently the 2000s saw a substantial investment in hydrogen research development and demonstration around the world. Prior to that the oil crises of the 1970s also stimulated significant investment in hydrogen and earlier still the literature on hydrogen was not lacking. And yet the hydrogen economy is still an idea only.<br/>So what if anything might be different this time?<br/>This is an important question that we all need to ask and for which the author can only give two potential answers. First our need to make dramatic reductions in greenhouse gas (GHG) emissions has become more pressing since these previous waves of interest. Second renewable energy is considerably more affordable now than it was before and it has consistently outperformed expectations in terms of cost reductions by even its strongest supporters.<br/>While this dramatic and ongoing reduction in the cost of renewables is very promising our need to achieve substantial GHG emission reductions is the crucial challenge. Moreover meeting this challenge needs to be achieved with as little adverse social and economic impact as possible.<br/>When considering what role hydrogen might play we should first think carefully about the massive scale and complexity of our global energy system and the typical prices of the major energy commodities. This provides insights into what opportunities hydrogen may have. Considering a temperate country with a small population like Australia we see that domestic natural gas and transport fuel markets are comparable to and even larger than the electricity market on an energy basis.

The potentials of phenolic productions from lignin and black liquor (BL) via hydrothermal technology with the aids of alkalis and hydrogen donors were investigated by conducting batch experiments in micro-tube reactors with 300 °C sub-critical water as the solvent. The results showed that all the employed alkalis improved lignin degradation and thus phenolics production and the strong alkalis additionally manifested deoxygenation to produce more phenolics free of methoxyl group(s). Relatively hydrogen donors more visibly facilitated phenolics formation. Combination of strong alkali and hydrogen donors exhibited synergistically positive effects on producing phenolics (their total yield reaching 22 wt%) with high selectivities to phenolics among which the yields of catechol and cresols respectively peaked 16 and 3.5 wt%. BL could be hydrothermally converted into phenolics at high yields (approaching 10 wt% with the yields of catechol and cresols of about 4 and 2 wt% respectively) with the aids of its inherent alkali and hydrogen donors justifying its cascade utilization.