Life-cycle assessment of hydrogen technologies with the focus on EU critical raw materials and end-of-life strategies

We present the results of a life-cycle assessment (LCA) for the manufacturing and end-of-life (EoL) phases of the following fuel-cell and hydrogen (FCH) technologies: alkaline water electrolyser (AWE), polymer-electrolyte-membrane water electrolyser (PEMWE), high-temperature (HT) and low-temperature (LT) polymer-electrolyte-membrane fuel cells (PEMFCs), together with the balance-of-plant components. New life-cycle inventories (LCIs), i.e., material inputs for the AWE, PEMWE and HT PEMFC are developed, whereas the existing LCI for the LT PEMFC is adopted from a previous EU-funded project. The LCA models for all four FCH technologies are created by modelling the manufacturing phase, followed by defining the EoL strategies and processes used and finally by assessing the effects of the EoL approach using environmental indicators. The effects are analysed with a stepwise approach, where the CML2001 assessment method is used to evaluate the environmental impacts. The results show that the environmental impacts of the manufacturing phase can be substantially reduced by using the proposed EoL strategies (i.e., recycled materials being used in the manufacturing phase and replacing some of the virgin materials). To point out the importance of critical materials (in this case, the platinum-group metals or PGMs) and their recycling strategies, further analyses were made. By comparing the EoL phase with and without the recycling of PGMs, an increase in the environmental impacts is observed, which is much greater in the case of both fuel-cell systems, because they contain a larger quantity of PGMs.     

Review of gas diffusion layer for proton exchange membrane-based technologies with a focus on unitised regenerative fuel cells

Proton exchange membrane (PEM) based technologies (fuel cells and electrolysers) offer promising sustainable power generation and storage solutions for a diverse range of stationary and mobile applications. Unitised regenerative fuel cell (URFC) is an electrochemical cell that can operate both as a fuel cell (FC) and an electrolyser (E). However, for a widespread commercialisation, further improvements are required that address the durability, performance, and cost limitations. One of the main challenging components in developing URFCs is the gas diffusion layer (GDL) as it plays different vital roles, some of which are paradoxical in FC and E-modes. Therefore, in this paper, the published research on GDL of PEM-URFCs as well as relevant studies on PEM fuel cells and electrolysers are critically reviewed. The materials and novel methods to address the corrosion in E-mode are discussed. This is followed by presenting and discussing different properties of GDLs affecting the performance in FC and E-modes: i.e. porosity, thickness, pore size, transport properties, thermal and electrical conductivity, and the GDL compressibility. Finally, the main modifications of the GDLs, such as hydrophobisation and microporous layer application, to improve the performance of a URFC are analysed and discussed.     

Study of hybrid energy system coupling fuel cell,solar thermal system and photovoltaic cell

The present work examines the combination of solar energy systems with Fuel cell. Indeed, fuel cells are green storage systems without any pollution effects. They are supplied by oxygen and hydrogen to produce electricity. That is why it is inescapable to find a source of hydrogen in order to use fuel cell. Several techniques can be adopted to produce hydrogen depending on the availability and the cost of the sources. One of the most utilized techniques is electrolysers. They allow to obtain hydrogen from water by several technologies among them proton exchange membrane (PEM) which is considered in this work. On the other hand, electrolysers need electrical power to operate. A green-green energy system can be constructed by using a renewable energy source to supply fuel cell trough electrolysers. A comparison between two solar systems (Photovoltaic and Parabolic Trough) coupled to fuel cell is performed. A case study on the Lebanese city of Tripoli is carried out. The study shows the performance of each of both combined systems for different parameters and proposes recommendations depending on the considered configuration.     

Life-cycle assessment of fuel cell stacks

Life-cycle assessment is a useful instrument to evaluate the ecological performance of innovative energy systems. This paper investigates the production process of polymer electrolyte fuel cell (PEFC) stacks, identifies the ecological contributions of various components and materials and compares the results with impacts due to utilization of the stacks in a vehicle (i.e. hydrogen or methanol production and direct emissions). The production of fuel cell stacks leads to environmental impacts which cannot be neglected compared to the utilization of the stacks in a vehicle (the actual driving process). These impacts are mainly caused by the platinum group metals for the catalyst and, to a lesser degree, the materials and energy for the flow field plates. The paper identifies several options how to further enhance the environmental advantages of fuel cells.     

A techno-economic appraisal of hydrogen generation and the case for solid oxide electrolyser cells

There is significant interest in alternatives to fossil fuels in order to reduce carbon dioxide emissions. One option is the use of hydrogen in applications such as fuel cells. There are various routes to the production of hydrogen, one being via the electrolysis of water. Water electrolysers are already operational within industry on a small-scale, accounting for 4% of world hydrogen production. These electrolysers operate at low temperatures and require electrical power input that has been shown to be costly due to the limited efficiency of the electrolysis process. However, the use of high temperature solid oxide electrolyser cells (SOECs) has the potential to generate hydrogen with a higher electrical efficiency which may allow electrolysis to become cost competitive with steam methane reforming (SMR), depending on where the heat and electrical power to service the SOEC comes from.This paper examines the various routes to hydrogen production and, in particular electrolysis technologies. The cost of hydrogen production is examined in the context of the source of the electricity and the efficiency of the electrolysis process compared to SMR generation. It is found that to become cost competitive with SMR, the lowest cost electricity is required, sourced either from nuclear or combined cycle gas turbine plants with electrolysis efficiency as high as possible, meaning that SOEC technology is particularly attractive.     

Large-vscale hydrogen production and storage technologies: Current status and future directions

Over the past years, hydrogen has been identified as the most promising carrier of clean energy. In a world that aims to replace fossil fuels to mitigate greenhouse emissions and address other environmental concerns, hydrogen generation technologies have become a main player in the energy mix. Since hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating these systems with other renewable energy systems is becoming very feasible. For example, the coupling of wind or solar systems hydrogen fuel cells as secondary energy sources is proven to enhance grid stability and secure the reliable energy supply for all times. The current demand for clean energy is unprecedented, and it seems that hydrogen can meet such demand only when produced and stored in large quantities. This paper presents an overview of the main hydrogen production and storage technologies, along with their challenges. They are presented to help identify technologies that have sufficient potential for large-scale energy applications that rely on hydrogen. Producing hydrogen from water and fossil fuels and storing it in underground formations are the best large-scale production and storage technologies. However, the local conditions of a specific region play a key role in determining the most suited production and storage methods, and there might be a need to combine multiple strategies together to allow a significant large-scale production and storage of hydrogen.     

Sustainable hydrogen production options and the role of IAHE

In this paper, some potential sustainable hydrogen production options are identified and discussed. There are natural resources from which hydrogen can be extracted such as water, fossil hydrocarbons, biomass and hydrogen sulphide. In addition, hydrogen can be extracted from a large palette of anthropogenic wastes starting with biomass residuals, municipal wastes, plastics, sewage waters etc. In order to extract hydrogen from these resources one needs to use sustainable energy sources like renewables and nuclear. A total of 24 options for sustainable hydrogen production are then identified. Sustainable water splitting is the most important method of hydrogen production. Five sustainable options are discussed to split water, which include electrolysis, high temperature electrolysis, pure and hybrid thermochemical cycles, and photochemical/radiochemical methods. Other 19 methods refer to extraction of hydrogen from other materials than water or in conjunction with water (e.g., coal gasification with CO₂ capture and sequestration). For each case the achievable energy and exergy efficiency of the method were estimated based on state of the art literature screening for each involved process. In addition, a range of hydrogen production capacity is determined for each of the option. For a transition period to hydrogen economy nuclear or solar assisted coal gasification and fossil fuel reforming technologies – with efficiencies of 10–55% including CO₂ sequestration – should be considered as a viable option. Other “ready to be implemented” technology is hydro-power coupled to alkaline electrolysers which shows the highest hydrogen generation efficiency amongst all electrical driven options with 60–65%. Next generation nuclear reactors as to be coupled with thermochemical cycles have the potential to generate hydrogen with 40–43% energy efficiency (based on LHV of hydrogen) and 35–37% exergy efficiency (based on chemical exergy of hydrogen). Furthermore, recycling anthropogenic waste, including waste heat, waste plastic materials, waste biomass and sewage waters, shows also good potential as a sustainable option for hydrogen production. Biomass conversion to hydrogen is found as potentially the most efficient amongst all studied options in this paper with up to 70% energy efficiency and 65% exergy efficiency.     

A new sustainable hydrogen clean energy paradigm

We analyze the feasibility of a novel, hydrogen fuel cell electric generator to provide power with zero noise and emissions for myriad ground based applications. The hydrogen fuel cell electric generator utilizes a novel, scalable apparatus that safely generates hydrogen (H₂) on demand according to a novel method, using a controlled chemical reaction between water (H₂O) and sodium (Na) metal that yields hydrogen gas of sufficient purity for direct use in fuel cells without risk of contaminating sensitive catalysts. The sodium hydroxide (NaOH) byproduct of the hydrogen producing reaction, is collected within the apparatus for later reprocessing by electrolysis, to recover the Na reactant. The detailed analysis shows that the novel, hydrogen fuel cell electric generator will be capable of meeting the clean power requirements for residential and commercial buildings including single family homes and light commercial establishments under a wide range of geographic and climatic conditions.     

Review of hydrogen technologies based microgrid: Energy management systems,challenges and future recommendations

With the significant development of renewable energy sources in recent years, integrating energy storage systems within a renewable energy microgrid is getting more attention as a promising future hybrid energy system configuration. Recently, hydrogen systems are being considered a promising energy storage option that utilised electrolysers to produce and store hydrogen when energy is surplus and re-supply it into microgrids using fuel cells in energy shortage scenarios. To control the energy flow within such hybrid energy systems, designing an energy management system should be considered a critical task, that allows the technical and economic optimal operation of microgrids. This study presents a comprehensive review and analysis of different energy management systems for hydrogen technologies-based microgrids, including the strategies’ objectives, constraints and techniques as well as the optimisation methods and simulation tools. In addition, an insightful discussion of the existing challenges and suggestions for the future research direction has been given.     

Optimized method for photovoltaic-water electrolyser direct coupling

Photovoltaics and electrolyser coupling is one of the most promising options for obtaining hydrogen from a renewable energy source. Both are well known technologies and direct coupling is possible; however, due to high variability of the solar radiation, an efficient relative sizing still presents some challenges. In fact, relative sizing is always a key issue when coupling renewable electric sources to water electrolysers. Few previous works addressed the relative sizing and an easy and efficient method is still missing. This work presents a new method for relative sizing between both components based on simple modelling of both polarisation curves. Modelling and simulation is used for extracting a cloud of maximum power points at all the radiation and temperature conditions for a normalised PV generator. Then, the ideal ratio between the size of components is obtained by fitting a normalised polarisation curve for the electrolyser to this cloud of maximum power points. PV generator and PEM electrolyser models are proposed and the method is applied, as example, to two different PEM water electrolysers. The method helps the relative sizing issue for designing solar hydrogen production systems based on water electrolysis, because it is derived from manufacturer parameters and the used of uncomplicated numerical methods.     

End-of-life of fuel cell and hydrogen products: A state of the art

The Fuel Cells and Hydrogen (FCH) technologies will play an important role in a future where greenhouse gasses emissions need to be reduced. Nevertheless, a huge implementation of these technologies must be addressed taking into account an eco friendly scope not only from the manufacturing perspective but also from the end-of-life scope.A classification of the materials has been done considering the importance of each of them. To obtain a complete overview of the problem, different criteria have been compared: the cost, the scarcity of the material and the affections these materials can cause not only to the environment but also to the humans. This classification has been used to identify which are the most critical materials.Moreover, other transversal issues have been studied as the regulations that apply to FCH technologies from a paneuropean perspective and the strategies to face the end-of-life of this equipment. A holistic point of view has been considered in order to see how the process of dismantling and recycling faces different problems and which milestones to achieve in a future with a deep market penetration are.     

On the ability of pem water electrolysers to provide power grid services

Water electrolysis is considered as a cornerstone technology for the large scale storage of energy and for carbon abatements in the frame of the energy transition. The purpose of this research work was to analyze power grid operational constraints, to design specific load profiles of interest for power grid management and then to use these protocols for the characterization and qualification of polymer electrolyte membrane (PEM) water electrolysers in view of grid balancing services. In the first section, management constraints of European power grids are described and analyzed. Using a typical regulation mechanism as an illustrative example, power specifications for primary and secondary reserve management are specified. The economics of such management procedures is also analyzed. In the second section, some key technical characteristics of PEM water electrolysis stacks are described. Test specifications designed for the qualification of water electrolysers to both primary and secondary reserve markets are defined. In the last section, selected test results are reported and the ability of PEM water electrolysis stacks to provide the services of interest is analyzed. In particular, a set of key performance indicators, designed for the characterization of PEM water electrolysers operating in transient power conditions of interest for grid services, are defined. Test results show the ability of PEM water electrolysis stacks to satisfy the most stringent grid constraints, but remaining limitations are identified. The main innovative contributions of this research work were to design test protocols for both primary and secondary power reserves management, and to demonstrate that PEM water electrolysers can be used for such applications.     

Fuel cells and energy networks of electricity,heat, and hydrogen in residential areas

Fuel cells for domestic purposes have been recently launched in the commercial markets of Japan. They comprise fuel cell stacks, fuel processors that generate hydrogen from natural gas, heat recovery equipment, and hot-water tanks. These systems do not require additional infrastructure and can influence consumer acceptance, however, there are limitations in terms of efficiency and flexibility.     

Evaluation of carbon-supported Pt and Pd nanoparticles for the hydrogen evolution reaction in PEM water electrolysers

Carbon-supported Pt and Pd nanoparticles (CSNs) were synthesized and electrochemically characterized in view of potential application in proton exchange membrane (PEM) water electrolysers. Electroactive metallic nanoparticles were obtained by chemical reduction of precursor salts adsorbed to the surface of Vulcan XC-72 carbon carrier, using ethylene glycol as initial reductant and with final addition of formaldehyde. CSNs were then coated over the surface of electron-conducting working electrodes using an alcoholic solution of perfluorinated polymer. Their electrocatalytic activities with regard to the hydrogen evolution reaction (HER) were measured in sulfuric acid solution using cyclic voltammetry, and in a PEM cell during water electrolysis. Results obtained show that palladium can be advantageously used as an alternative electrocatalyst to platinum for the HER in PEM water electrolysers. Developed electrocatalysts could also be used in PEM fuel cells.     

Green hydrogen as feedstock: Financial analysis of a photovoltaic-powered electrolysis plant

The weather-dependent electricity generation from Renewable Energy Sources (RES), such as solar and wind power, entails that systems for energy storage are becoming progressively more important. Among the different solutions that are being explored, hydrogen is currently considered as a key technology allowing future long-term and large-scale storage of renewable power.Today, hydrogen is mainly produced from fossil fuels, and steam methane reforming (SMR) is the most common route for producing it from natural gas. None of the conventional methods used is GHG-free. The Power-to-Gas concept, based on water electrolysis using electricity coming from renewable sources is the most environmentally clean approach. Given its multiple uses, hydrogen is sold both as a fuel, which can produce electricity through fuel cells, and as a feedstock in several industrial processes. Just the feedstock could be, in the short term, the main market of RES-based hydrogen.In this paper, we present the results obtained from a techno-economic-financial evaluation of a system to produce green hydrogen to be sold as a feedstock for industries and research centres. A system which includes a 200 kW photovoltaic plant and a 180 kW electrolyser, to be located in Messina (Italy), is proposed as a case study. According to the analyses carried out, and taking into account the current development of technologies, it has been found that investment to realise a small-scale PV-based hydrogen production plant can be remunerative.     

Design of an integrated power system using a proton exchange membrane fuel cell

Integrated power systems could be a solution to provide energy to remote communities based on the use of renewable energies (such as wind or sun). This work proposed the design of one of those systems including alkaline water electrolysers, storage tanks and a proton exchange membrane fuel cell for generating of 53 kW (working at 60% of its maximum power). Electrode sizes and the quantity of unit cells proposed in this work were the same as those suggested in the research work by Yang et al., where a phosphoric acid fuel cell was built and studied. The results obtained in that research allowed comparing energy efficiency by scaling a laboratory prototype. The dimensions of the alkaline water electrolysers are the result of satisfying the necessity of fuel and oxidant. The energy consumption results from extrapolating laboratory devices. The integrated power system has a storage tank capacity of 16 h.     

Scientific and engineering issues related to PEM technology: Water electrolysers, fuel cells and unitized regenerative systems

Proton exchange membrane (PEM) technology is used in water electrolysers, H₂/O₂ fuel cells and unitized regenerative fuel cells (URFCs). Such electrochemical devices are of particular interest in view of the so-called hydrogen economy. Several prototypes (kW power range) have been developed and tested in the course of the GenHyPEM project (2005-2008), a STREP research program financially supported by the Commission of the European Communities in the frame of the sixth Framework Programme. The purpose of this communication is to report on the current status of each device in terms of performances and technological development. Current limitations and future perspectives are discussed.     

Hydrogen consumption minimization method based on the online identification for multi-stack PEMFCs system

The proton exchange membrane fuel cell (PEMFC) stacks are not widely used in the field of transportation industry, due to their limited power. Thus, the PEMFC stacks usually connected in parallel or series to meet the load demand power in high-power applications. The hydrogen consumption of multi-stack fuel cells (MFCs) system is related to the efficiency and output power. In addition, the efficiency of PEMFC depends on the applied voltage and other parameters. Consequently, the hydrogen consumption of system changes with varying load, because the system parameters are also varying. It makes reducing the fuel consumption of system a challenging assignment. In order to achieve the goal of minimizing fuel consumption of parallel-connected PEMFCs system, this paper proposes a novel power distribution strategy based on forgetting factor recursive least square (FFRLS) online identification. The FFRLS algorithm is based on data-driven and uses real-time data of the system to improve the estimation accuracy of PEMFC system parameters. On the test bench of parallel-connected PEMFCs system consists of two 300 W PEMFC stacks, PEMFC stack controller, DC/DC converters, and DSP controller etc., a multi-index performance test and comparative analysis are carried out. The results showed that, the performance of proposed power allocation strategy has been successfully validated. In addition, compared with the power average and daisy chain algorithms, the proposed online identification power distribution method can get more satisfactory results. Such as, reducing the hydrogen consumption and improving efficiency.     

Measurement of deuterium isotope separation by polymer electrolyte fuel cell stack

Processes for separating hydrogen isotopes are important for future energy applications. Several separation methods are based on electrolytic process; however, electrolysis consumes large amounts of electric energy. In this study, we demonstrate deuterium isotope separation from a mixture of H₂ and D₂ gases using a polymer electrolyte fuel cell stack. To identify the most efficient process, we investigated two flow patterns for the fuel gas, namely, parallel and serial flow. The electrical power of the stacks depended on the flow pattern when a high current was generated. We attribute this dependence on membrane dehydration and water droplet formation in the serial flow, which passed through the single cells in a straight path. However, the stack with the serial path showed a high separation factor (α = 6.6) indicating enrichment of deuterium water during the operation. The long reaction path of the fuel gas contributed to effective separation. The fuel utilization in individual cells suggested the potential for even more effective separation processes by a serial flow path.     

Recovery and quality of water produced by commercial fuel cells

Fuel cells are devices capable of producing both energy and clean water. Here the concept of using hydrogen as a carrier of water and energy is explored by studying the quality of water produced by two modern commercial fuel cells, a 1 kW residential-scale polymer electrolyte membrane fuel cell (PEMFC) and a larger 300 kW molten carbonate fuel cell (MCFC). The results show that water produced by the PEMFC meets nearly all US Environmental Protection Agency (USEPA) and World Health Organization (WHO) drinking water requirements. Nickel and aluminum concentrations present in the MCFC water as well as pipe material corrosion products (nickel, aluminum and manganese) found in water from both systems are easily controlled. Without using any additional condensing system, it is possible to recover approximately 8% of the theoretical amount of water generated by the fuel cell. The amount of water produced by the PEMFC is sufficient to satisfy drinking water needs in a typical American household if a recovery efficiency of 40% is reached.