Transmission, Distribution & Storage

Covalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units such as triazine rings or diacetylene bridges. The bandgap charge separation capacity porosity wettability and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks by extension of conjugation by adjustment of the size and crystallinity of the pores and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER) in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally the aspects that need to be improved in the coming years will be discussed such as the degree of dispersibility in water the global photocatalytic efficiency and the robustness and stability of the hybrid systems putting emphasis on both the COF and the metal co-catalyst.

Owing to their extremely high energy density single-bonded polymeric nitrogen and atomic metallic hydrogen are generally regarded as the ultimate energetic materials. Although their syntheses normally require ultrahigh pressures of several hundred gigapascals (GPa) which prohibit direct materials application research on their stability metastability and fundamental properties are valuable for seeking extreme energetic materials through alternative synthetic routes. Various crystalline and amorphous polymeric nitrogens have been discovered between 100 and 200 GPa. Metastability at ambient conditions has been demonstrated for some of these phases. Cubic-gauche and black-phosphorus polymorphs of single-bonded nitrogen are two particularly interesting phases. Their large hystereses warrant further application-inspired basic research of nitrogen. In contrast although metallic hydrogen contains the highest-estimated energy density its picosecond lifetime and picogram quantity make its practical material application impossible at present. “Metallic hydrogen” remains a curiosity-driven basic research pursuit focusing on the pressure-induced evolution of the molecular hydrogen crystal and its electronic band structure from a low-density insulator with a very wide electronic band gap to a semiconductor with a narrow gap to a dense molecular metal and atomic metal and eventually to a previously unknown exotic state of matter. This great experimental challenge is driving relentless advancement in ultrahigh-pressure science and technology.

As the need for duplex stainless steel (DSS) increases it is necessary to evaluate hydrogen stress cracking (HSC) in dissimilar welded joints (WJs) of DSS and carbon steel. This study aims to investigate the effect of the weld microstructure on the HSC behaviour of dissimilar gas-tungsten arc welds of DSS and carbon steel. In situ slow-strain rate testing (SSRT) with hydrogen charging was conducted for transverse WJs which fractured in the softened heat-affected zone of the carbon steel under hydrogen-free conditions. However HSC occurred at the martensite band and the interface of the austenite and martensite bands in the type-II boundary. The band acted as an HSC initiation site because of the presence of a large amount of trapped hydrogen and a high strain concentration during the SSRT with hydrogen charging. Even though some weld microstructures such as the austenite and martensite bands in type-II boundaries were harmless under normal hydrogen-free conditions they had a negative effect in a hydrogen atmosphere resulting in the premature rupture of the weld. Eventually a premature fracture occurred during the in situ SSRT in the type-II boundary because of the hydrogen-enhanced strain-induced void (HESIV) and hydrogen-enhanced localised plasticity (HELP) mechanisms.

For the membrane and spiral walls of the new USC boilers the advanced T24 material was developed. In 2010 however extensive T24 tube weld cracking during the commissioning phase of several newly built boilers was observed. As the dominant root cause Hydrogen Induced - Stress Corrosion Cracking was reported. An investigation into the interaction of the T24 material with hydrogen was launched in order to compare its hydrogen embrittlement susceptibility with that of the T12 steel commonly used for older boiler evaporators. Both base materials and simulated Heat Affected Zone (HAZ) microstructures were tested. Total and diffusible hydrogen in the materials after electrochemical charging were measured. Thermo Desorption Spectrometry was used to gain insights into the trapping behaviour and the apparent diffusion coefficient at room temperature was determined. Based on the hardness and the diffusible hydrogen pick-up capacity of the materials it was concluded that T12 is less susceptible to hydrogen embrittlement than T24 as base material as well as in the HAZ condition and that the HAZ of T24 is more susceptible to hydrogen embrittlement than the base material both in the as welded and in the Post Weld Heat Treated (PWHT) condition. However based on the results of this investigation it could not be determined if the T24 HAZ is less susceptible to hydrogen embrittlement after PWHT.

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria’s current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria’s total energy consumption. To decarbonize energy consumption a substantial increase in energy generation from renewable energy is required. This increase will add to the seasonality of energy supply and amplifies the seasonality in energy demand. In this paper the seasonality of energy supply and demand in a Net-Zero Scenario are analyzed for Austria and requirements for hydrogen storage derived. We looked into the potential usage of hydrogen in Austria and the economics of hydrogen generation and technology and market developments to assess the Levelized Cost of Hydrogen (LCOH). Then we cover the energy consumption in Austria followed by the REN potential. The results show that incremental potential of up to 140 TWh for hydropower photovoltaic (PV) and wind exists in Austria. Hydropower generation and PV is higher in summer- than in wintertime while wind energy leads to higher energy generation in wintertime. The largest incremental potential is PV with agrivoltaic systems significantly increasing the area amenable for PV compared with PV usage only. Battery Electric Vehicles (BEV) and Fuel Cell Vehicles (FCV) use energy more efficiently than Internal Combustion Engine (ICE) cars; however the use of hydrogen for electricity generation significantly decreases the efficiency due to electricity–hydrogen– electricity conversion. The increase in REN use and the higher demand for energy in Austria in wintertime require seasonal storage of energy. We developed three scenarios Externally Dependent Scenario (EDS) Balanced Energy Scenario (BES) or Self-Sustained Scenario (SSS) for Austria. The EDS scenario assumes significant REN import to Austria whereas the SSS scenario relies on REN generation within Austria. The required hydrogen storage would be 10.82 bn m3 for EDS 13.34 bn m3 for BES and 18.69 bn m3 for SSS. Gas and oil production in Austria and the presence of aquifers indicates that sufficient storage capacity might be available. Significant technology development is required to be able to implement hydrogen as an energy carrier and to balance seasonal energy demand and supply.

Hydrogen has been identified as a very promising vector for energy storage especially for heavy mobility applications. For this reason France is making significant investments in this field and use cases need to be evaluated as they are sprouting. In this paper the relevance of H2 in two storage applications is studied: a domestic renewable electricity production system connected to the grid and a collective hydrogen production for the daily bus refill. The investigation consists of the sizing of the system and then the evaluation of its performance according to several criteria depending on case. Optimizations are made using Bayesian and gradient-based methods. Several variations around a central case are explored for both cases to give insights on the impact of the different parameters (location pricing objective etc.) on the performance of the system.Our results show that domestic power-to-power applications (case 1) do not seem to be competitive with electrochemical storage. Meanwhile without any subsidies or incentives such configuration does not allow prosumers to save money (+16% spendings compared to non-equipped dwelling). It remains interesting when self-sufficiency is the main objective (up to 68% of energy is not exchanged). The power-to-gas application (case 2 central case) with a direct use of hydrogen for mobility seems to be more relevant according to our case study we could reach a production cost of green H2 around 5 €/kg similar to the 3–10 $/kg found in literature for 182 houses involved. In both cases H2 follows a yearly cycle charging in summer and discharging in winter (long term storage) due to low conversion efficiency.

This report outlines the key modalities and procedures for the Innovation Fund and focuses on the potential funding implications for CCUS projects. The assessment of the suitability of the Innovation Fund for CCS projects has been completed based on discussion during a workshop hosted by the EU CCUS Projects Network in October 2019. This session was part of the Network’s Thematic Group on Policy Regulation and Public Perception. The session was held according to Chatham House rules to allow the projects present to exchange viewpoints and ideas freely.<br/>Broadly speaking it is hoped that the Innovation Fund Call for Proposal documents expected in mid-2020 will provide more information on how applicants should approach some of the key evaluation criteria namely calculating emissions avoidance for part-chain CCS and CCU projects demonstrating project maturity as well as project innovativeness. Furthermore there remains a concern that the costs for developing sufficient contingent storage sites could be overlooked by the Innovation Fund and EU policies directed towards CCS in general. Finally whereas there does not seem to be any regulatory barriers to blending Innovation Fund financing with Member State subsidies the asynchronous timing between the planned final investment decisions (FIDs) of some of the more advanced projects and the outcomes of the Innovation Fund (expected in 2022) means that certain projects may not be able to benefit from this.

The dislocation and twinning evolution behaviors in high manganese steels Fe-22Mn-0.6C and Fe-17Mn-1.5Al-0.6C have been investigated under tensile deformation with and without diffusive hydrogen. The notched tensile tests were interrupted once primary cracks were detected using the applied direct current potential drop measurement. In parallel the strain distribution in the vicinity of the crack was characterized by digital image correlation using GOM optical system. The microstructure surrounding the crack was investigated by electron backscatter diffraction. Electron channeling contrast imaging was applied to reveal the evolution of dislocations stacking faults and deformation twins with respect to the developed strain gradient and amount of hydrogen. The results show that the diffusive hydrogen at the level of 26 ppm has a conspicuous effect on initiating stacking faults twin bundles and activating multiple deformation twinning systems in Fe-22Mn-0.6C. Eventually the interactions between deformation twins and grain boundaries lead to grain boundary decohesion in this material. In comparison hydrogen does not obviously affect the microstructure evolution namely the twinning thickness and the amount of activated twinning systems in Fe-17Mn-1.5Al-0.6C. The Al-alloyed grade reveals a postponed nucleation of deformation twins delayed onset of the secondary twinning system and develops finer twinning lamellae in comparison to the Al-free material. These observations explain the improved resistance to hydrogen-induced cracking in Al-alloyed TWIP steels.

This paper addresses the size and misorientation effects on hydrogen embrittlement of a four grain nickel aggregate. The grain interior is modelled with orthotropic elasticity and the grain boundary with cohesive zone technique. The grain misorientation angle is parameterized by fixing the lower grains and rotating the upper grains about the out-of-plane axis. The hydrogen effect is accounted for via the three-step hydrogen informed cohesive zone simulation. The grain misorientation exerts an obvious weakening effect on the ultimate strength of the nickel aggregate which reaches its peak at misorientation angles around 20◦ but such effect becomes less pronounced in the case with a pre-crack. The misorientation could induce size effect in the otherwise size independent case without a pre-crack. The contribution of misorientation to the size effect is negligible compare to that caused by the existence of a pre-crack. These findings indicate that the misorientation effect in cases with a deep pre-crack is weaker than expected in shallow-pre-crack situations. Most of these conclusions hold for the hydrogen charging situation except that the ultimate strength is lowered in all the sub-cases due to hydrogen embrittlement. Interestingly it is observed that the size effect becomes less pronounced with hydrogen taken into account which is caused by the fact that hydrogen takes more time to reach the failure initiation site in larger grains.

Decarbonization plays an important role in future energy systems for reducing greenhouse gas emissions and establishing a zero-carbon society. Hydrogen is believed to be a promising secondary energy source (energy carrier) that can be converted stored and utilized efficiently leading to a broad range of possibilities for future applications. Moreover hydrogen and electricity are mutually converted creating high energy security and broad economic opportunities toward high energy resilience. Hydrogen can be stored in various forms including compressed gas liquid hydrogen hydrides adsorbed hydrogen and reformed fuels. Among these liquid hydrogen has advantages including high gravimetric and volumetric hydrogen densities and hydrogen purity. However liquid hydrogen is garnering increasing attention owing to the demand for long storage periods long transportation distances and economic performance. This paper reviews the characteristics of liquid hydrogen liquefaction technology storage and transportation methods and safety standards to handle liquid hydrogen. The main challenges in utilizing liquid hydrogen are its extremely low temperature and ortho- to para-hydrogen conversion. These two characteristics have led to the urgent development of hydrogen liquefaction storage and transportation. In addition safety standards for handling liquid hydrogen must be updated regularly especially to facilitate massive and large-scale hydrogen liquefaction storage and transportation.