Netherlands

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

Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och-Function [1] was fitted on the measured cyclic lifetimes.<br/><br/>The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increased by approximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 environment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes compared to ambient test results. The investigation of the crack surfaces showed distinct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change.

Interest in hydrogen as a carbon-neutral energy carrier is on the rise around the globe including in Europe. In particular power-to-gas as a technology to transform electricity to hydrogen is receiving ample attention. This article scrutinises current updates in the energy law framework of the EU to explain the legal pre-conditions for the various possible applications of power-to-gas technology. It highlights the influence of both electricity and gas legislation on conversion storage and transmission of hydrogen and demonstrates why ‘green’ hydrogen might come with certain legal privileges under the Renewable Energy Directive attached to it as opposed to the European Commission’s so-called ‘clean’ hydrogen. The article concludes by advocating for legal system integration in EU energy law namely merging the currently distinct EU electricity and gas law frameworks into one unified EU Energy Act.

A promising option for storing large-scale quantities of green gases (e.g. hydrogen) is in subsurface rock salt caverns. The mechanical performance of salt caverns utilized for long-term subsurface energy storage plays a signifcant role in long-term stability and serviceability. However rock salt undergoes non-linear creep deformation due to long-term loading caused by subsurface storage. Salt caverns have complex geometries and the geological domain surrounding salt caverns has a vast amount of material heterogeneity. To safely store gases in caverns a thorough analysis of the geological domain becomes crucial. To date few studies have attempted to analyze the infuence of geometrical and material heterogeneity on the state of stress in salt caverns subjected to long-term loading. In this work we present a rigorous and systematic modeling study to quantify the impact of heterogeneity on the deformation of salt caverns and quantify the state of stress around the caverns. A 2D fnite element simulator was developed to consistently account for the non-linear creep deformation and also to model tertiary creep. The computational scheme was benchmarked with the already existing experimental study. The impact of cyclic loading on the cavern was studied considering maximum and minimum pressure that depends on lithostatic pressure. The infuence of geometric heterogeneity such as irregularly-shaped caverns and material heterogeneity which involves diferent elastic and creep properties of the diferent materials in the geological domain is rigorously studied and quantifed. Moreover multi-cavern simulations are conducted to investigate the infuence of a cavern on the adjacent caverns. An elaborate sensitivity analysis of parameters involved with creep and damage constitutive laws is performed to understand the infuence of creep and damage on deformation and stress evolution around the salt cavern confgurations.

This paper presents the results of a demonstration project including building-integrated photovoltaic (BIPV) solar panels a residential building and a hydrogen fuel cell electric vehicle (FCEV) for combined mobility and power generation aiming to achieve a net zero-energy residential building target. The experiment was conducted as part of the Car as Power Plant project at The Green Village in the Netherlands. The main objective was to assess the end-user’s potential of implementing FCEVs in vehicle-to-grid operation (FCEV2G) to act as a local energy source. FCEV2G field test performance with a Hyundai ix35 FCEV are presented. The car was adapted using a power output socket capable of delivering up to 10 kW direct current (DC) to the alternating current (AC) national grid when parked via an off-board (grid-tie) inverter. A Tank-To-AC-Grid efficiency (analogous to Tank- To-Wheel efficiency when driving) of 44% (measured on a Higher Heating Value basis) was obtained when the car was operating in vehicle-to-grid (V2G) mode at the maximum power output. By collecting and analysing real data on the FCEV power production in V2G mode and on BIPV production and household consumption two different operating modes for the FCEV offering balanced services to a residential microgrid were identified namely fixed power output and load following. Based on the data collected one-year simulations of a microgrid consisting of 10 all-electric dwellings and 5 cars with the different FCEV2G modes of operation were performed. Simulation results were evaluated on the factors of autonomy self-consumption of locally produced energy and net-energy consumption by implementing different energy indicators. The results show that utilizing an FCEV working in V2G mode can reduce the annual imported electricity from the grid by approximately 71% over one year and aiding the buildings in the microgrid to achieve a net zero-energy building target. Furthermore the simulation results show that utilizing the FCEV2G setup in both modes analysed could be economically beneficial for the end-user if hydrogen prices at the pump fall below 8.24 €/kg.

The role of hydrogen in future energy systems is widely acknowledged: from fuel for difficult-to-decarbonize applications to feedstock for chemicals synthesis to energy storage for high penetration of undispatchable renewable electricity. While several literature studies investigate such energy systems the details of how electrolysers and renewable technologies optimally behave and interact remain an open question. With this work we study the interplay between (i) renewable electricity generation through wind and solar (ii) electricity storage in batteries (iii) electricity storage via Power-to-H2 and (iv) hydrogen commodity demand. We do so by designing a cost-optimal zero-emission energy system and use the Netherlands as a case study in a mixed integer linear model with hourly resolution for a time horizon of one year. To account for the significant role of wind we also provide an elaborate approach to model broad portfolios of wind turbines. The results show that if electrolyzers can operate flexibly batteries and power-to-H2-to-power are complementary with the latter using renewable power peaks and the former using lower renewable power outputs. If the operating modes of the power-to-H2-to-power system are limited - artificially or technically - the competitive advantage over batteries decreases. The preference of electrolyzers for power peaks also leads to an increase in renewable energy utilization for increased levels of operation flexibility highlighting the importance of capturing this feature both from a technical and a modeling perspective. When adding a commodity hydrogen demand the amount of hydrogen converted to electricity decreases hence decreasing its role as electricity storage medium.

This paper proposes an integration of concentrating solar power (CSP) with a sorption-enhanced steam methane reforming (SE-SMR) process and assesses its overall solar-to-fuel conversion performance. A thermodynamic treatment of the SE-SMR process for H2 production is presented and evaluated in an innovative two reactors system configuration using CSP as a heat input. Four metal carbonate/metal oxide pairs are considered and the equilibrium thermodynamics reveals that CaCO3/CaO pair is the most suitable candidate for this process. Additionally a reactor-scale thermodynamic model is developed to determine the optimum operating conditions for the process. For the carbonation step temperatures between 700 and 900 K and steam-to-methane ratio ≥4 are found to be the most favorable. Furthermore an advanced process model which utilizes operating conditions determined from the reactor-scale model is developed to evaluate the process efficiency. The model predicts that the proposed process can achieve a solar-to-fuel efficiency ~41% for calcination temperature of 1500 K and carbonation temperature of 800 K without considering any solid heat recovery. An additional 2.5% increase in the process efficiency is feasible with the consideration of the solid heat recovery. This study shows the thermodynamic feasibility of integrating the SE-SMR process with CSP technologies.

The design and operation of integrated multi-energy systems require models that adequately describe the behavior of conversion and storage technologies. Typically linear conversion performance or fixed data from technology manufacturers are employed especially for new or advanced technologies. This contribution provides a new modeling framework for electrochemical devices that bridges first-principles models to their simplified implementation in the optimization routine. First thermodynamic models are implemented to determine the on/off-design performance and dynamic behavior of different types of fuel cells and of electrolyzers. Then as such nonlinear models are intractable for use in the optimization of integrated systems different linear approximations are developed. The proposed strategies for the synthesis of reduced order models are compared to assess the impact of modeling approximations on the optimal design of multi-energy systems including fuel cells and electrolyzers. This allows to determine the most suitable level of detail for modeling the underlying electrochemical technologies from an integrated system perspective. It is found that the approximation methodology affects both the design and operation of the system with a significant effect on system costs and violation of the thermal energy demand. Finally the optimization and technology modeling framework is exploited to determine guidelines for the installation of the most suitable fuel cell technology in decentralized multi-energy systems. We show how the installation costs of PEMFC SOFC and MCFC their electrical and thermal efficiencies their conversion dynamics and the electricity price affect the system design and technology selection.

To achieve the Paris Agreement’s long-term temperature goal current energy systems must be transformed. Australia represents an interesting case for energy system transformation modelling: with a power system dominated by fossil fuels and specifically with a heavy coal component there is at the same time a vast potential for expansion and use of renewables. We used the multi-sectoral Australian Energy Modelling System (AUSeMOSYS) to perform an integrated analysis of implications for the electricity transport and selected industry sectors to the mid-century. The state-level resolution allows representation of regional discrepancies in renewable supply and the quantification of inter-regional grid extensions necessary for the physical integration of variable renewables. We investigated the impacts of different CO₂ budgets and selected key factors on energy system transformation. Results indicate that coal-fired generation has to be phased out completely by 2030 and a fully renewable electricity supply achieved in the 2030s according to the cost-optimal pathway implied by the 1.5 °C Paris Agreement-compatible carbon budget. Wind and solar PV can play a dominant role in decarbonizing Australia’s energy system with continuous growth of demand due to the strong electrification of linked energy sectors.

Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys supports deposition/production techniques etc. High flux and cheap membranes yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly when employing the membranes in fluidized bed reactors the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes resistance to hydrogen embrittlement and stability at high temperature.