Publications

The storage of hydrogen in materials has received a significant amount of attention in recent years because this approach is widely thought to be one of the most promising solutions to the problem of storing hydrogen for use as an alternative energy carrier in a safe compact and affordable form. However there have been a number of high profile cases in which erroneous or irreproducible data have been published. Meanwhile the irreproducibility of research results in a wide range of disciplines has been the subject of an increasing amount of attention due to problems with some of the data in the literature. In this Perspective we provide a summary of the problems that have affected hydrogen storage material research. We also discuss the reasons behind them and possible ways of reducing the likelihood of further problems occurring in the future.

From a permeability and selectivity perspective supported thin-film Pd–Ag membranes are the best candidates for high-purity hydrogen recovery for methane-hydrogen mixtures from the natural gas grid. However the high hydrogen flux also results in induced bulk-to-membrane mass transfer limitations (concentration polarization) especially when working at low hydrogen concentration and high pressure which further reduces the hydrogen permeance in the presence of mixtures. Additionally Pd is a precious metal and its price is lately increasing dramatically. The use of inexpensive CMSM could become a promising alternative. In this manuscript a detailed comparison between these two membrane technologies operating under the same working pressure and mixtures is presented.<br/>First the permeation properties of CMSM and Pd–Ag membranes are compared in terms of permeance and purity and subsequently making use of this experimental investigation an economic evaluation including capital and variable costs has been performed for a separation system to recover 25 kg/day of hydrogen from a methane-hydrogen mixture. To widen the perspective also a sensitivity analysis by changing the pressure difference membrane lifetime membrane support cost and cost of Pd/Ag membrane recovery has been considered. The results show that at high pressure the use of CMSM is to more economic than the Pd-based membranes at the same recovery and similar purity.

To avoid the potential adverse impacts of climate change from global warming it is suggested that the target of net zero emissions should be reached by this mid-century. Thailand is aiming to achieve carbon neutrality by 2050. Since electricity generation is one of the largest producers of carbon dioxide emission the associated emissions must be greatly reduced to achieve the targets mentioned above. Thus new generation expansion plans must be well developed. This paper discusses the development of generation expansion plans considering Thailand’s latest policies along with enhancement of the existing multi-period linear programming model allowing new electricity generation technologies having low emissions e.g. solar PV with battery and hydrogen blending in natural gas to be integrated into generation expansion planning. Then four generation expansion plans with different levels of hydrogen blending in natural gas are proposed and discussed. It is found that Thailand can achieve carbon neutrality by 2050 by promoting more use of renewable energy altogether with trade-off between land for solar PV installation and amount of hydrogen blended in natural gas. The lesson learned from this study provides crucial information about possible pathways to achieve carbon neutrality in the electricity sector for policy makers in other countries.

In this study fracture surfaces of notched specimens of pearlitic steels subjected to constant extension rate tests (CERTs) are analyzed in an environment causing hydrogen assisted fracture. In order to obtain general results both different notched geometries (to generate quite distinct stress triaxiality distributions in the vicinity of the notch tip) and diverse loading rates were used. The fracture surfaces were classified in relation to four micromechanical models of hydrogen-assisted micro-damage. To this end fractographic analysis in each fracture surface was carried out with a scanning electron microscopy. Generated results increase the number of micromechanical models found in the scientific literature.

The hydrogen economy is a proposition for the distribution of energy by using hydrogen in order to potentially eliminate carbon emissions and end our reliance on fossil fuels. Some futuristic forecasters view the hydrogen economy as the ultimate carbon free economy. Hydrogen operated vehicles are on trial in many countries. The use of hydrogen as an energy source for buildings is in its infancy but research and development is evolving. Hydrogen is generally fed into devices called fuel cells to produce energy. A fuel cell is an electrochemical device that produces electricity and heat from a fuel (often hydrogen) and oxygen. Fuel cells have a number of advantages over other technologies for power generation. When fed with clean hydrogen they have the potential to use less fuel than competing technologies and to emit no pollution (the only bi-product being water). However hydrogen has to be produced and stored in the first instance. It is possible to generate hydrogen from renewable sources but the technology is still immature and the transformation is wasteful. The creation of a clean hydrogen production and distribution economy at a global level is very costly. Proponents of a world-scale hydrogen economy argue that hydrogen can be an environmentally cleaner source of energy to end-users particularly in transportation applications without release of pollutants (such as particulate matter) or greenhouse gases at the point of end use. Critics of a hydrogen economy argue that for many planned applications of hydrogen direct use of electricity or production of liquid synthetic fuels from locally-produced hydrogen and CO2 (e.g. methanol economy) might accomplish many of the same net goals of a hydrogen economy while requiring only a small fraction of the investment in new infrastructure. This paper reviews the hydrogen economy how it is produced and distributed. It then investigates the different types of fuel cells and identifies which types are relevant to the built environment both in residential and nonresidential sections. It concludes by examining what are the future plans in terms of implementing fuel cells in the built environment and discussing some of the needs of built environment sector.



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The location of hydrogen within Ti–Cr–V–Mo alloys has been investigated during hydrogen absorption and desorption using in situ neutron powder diffraction and inelastic neutron scattering. Neutron powder diffraction identifies a low hydrogen equilibration pressure body-centred tetragonal phase that undergoes a martensitic phase transition to a face-centred cubic phase at high hydrogen equilibration pressures. The average location of the hydrogen in each phase has been identified from the neutron powder diffraction data although inelastic neutron scattering combined with density functional theory calculations show that the local structure is more complex than it appears from the average structure. Furthermore the origin of the change in dissociation pressure and hydrogen trapping on cycling in Ti–Cr–V–Mo alloys is discussed.

Hydrogen Embrittlement (HE) leads to deterioration of the fracto-mechanical properties of metals. In spite of vast literature it is still not clearly understood and demands significant research on this topic. For better understanding of the hydrogen effect on fatigue behaviour of metals present work focuses on developing a computational framework for fatigue crack initiation studies in metals in the presence of hydrogen. The developed framework consists of a nonlocal crystal plasticity model coupled with hydrogen transport model to study the fatigue behaviour of hydrogen charged metals. The nonlocal crystal plasticity model accounts for the statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) in polycrytalline metal. Hydrogen transport model on the other hand accounts for diffusion and trapping behavior of hydrogen due to concentration gradient pressure gradient plastic strain-rate with dislocations as the only trapping sites along the slip systems. A polycrystalline representative volume element (RVE) with periodic boundary conditions is used in this study. Fatigue crack initiation criterion is proposed for the simulated RVE with controlled microstructure by considering a critical value of the fatigue indicator parameter (FIP). FIP is formulated based on the experimental observations of several crack initiation sites along the grain boundaries their normal direction with respect to loading direction and the accumulated plastic strain in nickel polycrystalline samples. Developed simulation framework correctly accounts cyclic stress-strain behavior and multiple fatigue crack initiation sites observed experimentally in the presence of hydrogen.

The pyrolysis-catalytic steam reforming of six agricultural biomass waste samples as well as the three main components of biomass was investigated in a two stage fixed bed reactor. Pyrolysis of the biomass took place in the first stage followed by catalytic steam reforming of the evolved pyrolysis gases in the second stage catalytic reactor. The waste biomass samples were rice husk coconut shell sugarcane bagasse palm kernel shell cotton stalk and wheat straw and the biomass components were cellulose hemicellulose (xylan) and lignin. The catalyst used for steam reforming was a 10 wt.% nickel-based alumina catalyst (NiAl2O3). In addition the thermal decomposition characteristics of the biomass wastes and biomass components were also determined using thermogravimetric analysis (TGA). The TGA results showed distinct peaks for the individual biomass components which were also evident in the biomass waste samples reflecting the existence of the main biomass components in the biomass wastes. The results for the two-stage pyrolysis-catalytic steam reforming showed that introduction of steam and catalyst into the pyrolysis-catalytic steam reforming process significantly increased gas yield and syngas production notably hydrogen. For instance hydrogen composition increased from 6.62 to 25.35 mmol g 1 by introducing steam and catalyst into the pyrolysis-catalytic steam reforming of palm kernel shell. Lignin produced the most hydrogen compared to cellulose and hemicellulose at 25.25 mmol g 1. The highest residual char production was observed with lignin which produced about 45 wt.% char more than twice that of cellulose and hemicellulose.

A CsH and KH co-doped Mg(NH₂)₂/2LiH composite was prepared with a composition of Mg(NH₂)₂/2LiH–(0.08 − x)CsH–xKH and the hydrogen storage characteristics was systematically investigated. The results showed that the presence of KH further improved the reaction thermodynamics and kinetics of hydrogen storage in a CsH-containing Mg(NH₂)₂/2LiH system. A sample with 0.04 mol CsH and 0.04 mol KH had optimal hydrogen storage performance; its dehydrogenation could proceed at 130 °C and hydrogenation at 120 °C with 4.89 wt% of hydrogen storage capacity. At 130 °C a 25-fold increase in the dehydrogenation rate was achieved for the CsH and KH co-doped sample. More importantly the CsH and KH co-doped sample also had good cycling stability because more than 97% of the hydrogen storage capacity (4.34 wt%) remained for theMg(NH₂)₂/2LiH–0.04CsH–0.04KH sample after 30 cycles. A structural characterization revealed that added CsH and KH participated in the dehydrogenation and hydrogenation reactions by reversibly forming mixed amides of Li–K and Cs–Mg which caused the improved hydrogen storage thermodynamics and kinetics.

As countries around the world rally behind net zero targets hydrogen is increasingly seen as a missing piece of the energy transformation puzzle to decarbonise harder-to-abate sectors. The possible pathway on which hydrogen might evolve still involves many uncertainties. With the growing momentum to establish a global hydrogen market comes the need for a deeper understanding of its broader effects including geopolitical aspects. IRENA has carried out an in-depth analysis of the geopolitics of hydrogen as part of the work of the Collaborative Framework on the Geopolitics of Energy Transformation (CF-GET). The report builds on IRENA’s substantial body of work in hydrogen and benefits from a wide range of expert input in the fields of energy and geopolitics.

This report considers whether and how hydrogen may disrupt future energy systems reflecting on many of the key themes discussed in the Global Commission’s report A New World – The Geopolitics of the Energy Transformation. The analysis offers insights into how countries and stakeholders can navigate the uncertainties and shape the development of hydrogen markets and outlines policy considerations to help mitigate the geopolitical risks and capitalise on opportunities. Some of the key findings of the report include:

• Hydrogen is part of a much bigger energy transition picture and its development and deployment strategies should not be considered in isolation.
• Setting the right priorities for hydrogen use will be essential for its rapid scale-up and long-term contribution to decarbonisation efforts.
• The 2020s could become the era of a big race for technology leadership as costs are likely to fall sharply with learning and scaling-up of needed infrastructure. Equipment manufacturing offers an opportunity to capture value in the coming years and decades.
• Hydrogen trade and investment flows will spawn new patterns of interdependence and bring shifts in bilateral relations.
• Countries with an abundance of low-cost renewable power could become producers of green hydrogen with commensurate geoeconomic and geopolitical consequences.
• Hydrogen could be an attractive avenue for fossil fuel exporters to help diversify their economies and develop new export industries.
• Supporting the advancement of renewable energy and green hydrogen in developing countries is critical for decarbonising the energy system and can contribute to global equity and stability.
• International co-operation will be necessary to devise a transparent hydrogen market with coherent standards and norms that contribute to climate change efforts meaningfully.