End of life of fuel cells and hydrogen products: From technologies to strategies

End-of-Life (EoL) technologies and strategies are needed to support the deployment of fuel cells and hydrogen (FCH) products. This article explores current and novel EoL technologies to recover valuable materials from the stacks of proton exchange membrane fuel cells and water electrolysers, alkaline water electrolysers, and solid oxide fuel cells. Current EoL technologies are mainly based on hydrometallurgical and pyro-hydrometallurgical methods for the recovery of noble metals, while novel methods attempt to recover additional materials through efficient, safe and cost-competitive pathways. Strengths, weaknesses, opportunities and threats of the reviewed EoL technologies are identified under techno-economic, environmental and regulatory aspects. Beyond technologies, strategies for the EoL of FCH stacks are defined mainly based on the role of manufacturers and recovery centres in the short-, mid- and long-term. In this regard, a dual role manufacturer/recovery centre would characterise long-term scenarios within a potential context of a well-established hydrogen economy.     

The influence of degradation effects in proton exchange membrane fuel cells on life cycle assessment modelling and environmental impact indicators

Although proton exchange membrane fuel cell (PEMFC) systems are expected to have lower environmental impacts in the operational phase, compared to conventional energy conversion systems, there are still certain economic, operational, and environmental setbacks. Durability under a wide range of operating conditions presents a challenge because degradation processes affect the PEMFC efficiency. Typically, life cycle assessment (LCA) of PEMFC systems do not include performance degradation. Thus, a novel semi-empirical PEMFC model is developed, which includes degradation effects caused by different operational regimes (dynamic and steady-state). The model is integrated into LCA through life cycle inventory (LCI) to achieve a more realistic and accurate evaluation of environmental impacts. Verification of the model clearly showed that the use of existing LCI models underestimates the environmental impacts. This is especially evident when green hydrogen is used in PEMFC operational phase, where manufacturing phase and maintenance (stack replacements) become more influential. Input parameters of the model can be modified to reflect technological improvements (e.g. platinum loading or durability) and evaluate the effects of future scenarios.     

Thermodynamic analysis of polymer-electrolyte-membrane fuel-cell performance under varying cooling conditions

The cooling capacity and cooling load of a fuel-cell cooling loop govern the operating temperature of the fuel-cell module and its electrical output, efficiency and other thermodynamic aspects. The aim of this work was to analyze the performance of a polymer-electrolyte-membrane fuel-cell (PEMFC) under changing cooling conditions. A back-iteration algorithm was employed to determine the operating temperature of a PEMFC for which thermodynamic performance models were developed for the entropy generation, exergy-destruction and second-law efficiency using an entropy-analysis method. Electrochemical equations for the calculation of the voltage, power and first-law efficiency of the cell were also formulated. A parametric study was performed to evaluate the effects of varying cooling conditions on the energy and exergy efficiency of the PEMFC. The parameters considered include the electric-current density governing the cooling load, the mass flow rate of the coolant and the external thermal resistance of the cooler, which together determine the cooling ability of the fuel-cell cooling loop. Their influences on operating temperature, voltage, power, energy and exergy efficiencies were numerically investigated. The results indicate that although the power output and exhaust heat of PEMFC is mainly dominated by the electric-current density, the impacts of the coolant's mass flow rate and the cooler's external thermal resistance on the voltage, energy and exergy efficiencies of PEMFC module can't be neglected. In the investigated ranges, the gross energy and exergy efficiencies increase with the cooler's external thermal resistance by 3.2% and 2.45%, and decrease with the increase in coolant's mass flow rate by 1.2% and 0.92%, respectively.     

Micro-grid design and life-cycle assessment of a mountain hut's stand-alone energy system with hydrogen used for seasonal storage

Mountain huts, as special, stand-alone, micro-grid systems, are not connected to a power grid and represent a burden on the environment. The micro-grid has to be flexible to cover daily and seasonal fluctuations. Heat and electricity are usually generated with fossil fuels due to the simple on-off operation. By introducing renewable energy sources (RESs), the generation of energy could be more sustainable, but the generation and consumption must be balanced. The paper describes the integration of a hydrogen-storage system (HSS) and a battery-storage system (BattS) in a mountain hut. The HSS involves a proton-exchange-membrane water electrolyser (PEMWE), a hydrogen storage tank (H₂ tank), a PEM fuel cell (PEMFC) and a BattS consisting of lead-acid batteries. Eight micro-grid configurations were modelled using HOMER and evaluated from the technical, environmental and economic points of view. A life-cycle assessment analysis was made from the cradle to the gate. The micro-grid configurations with the HSS achieve, on average, a more than 70% decrease in the environmental impacts in comparison to the state of play at the beginning, but require a larger investment. Comparing the HSS with the BattS as a seasonal energy storage, the hydrogen-based technology had advantages for all of the assessed criteria.     

Impacts of power management on a PEMFC electric vehicle

This paper discusses the impacts of different power management strategies on a fuel-cell vehicle. The study was carried out in three steps: fuel-cell control, power management, and system integration and verification. First, we identified the models of a proton exchange membrane fuel-cell (PEMFC) and designed robust controllers to improve the PEMFC's performance and efficiency. Second, we developed two power management structures—a serial power train and a parallel power train—which consisted of the PEMFC and secondary batteries to provide sustainable power for an electric mobility scooter. Lastly, we used the scooter's driving cycles to compare the performance and efficiency of these two power trains. Then we implemented the power trains on a microprocessor for road test. Based on the results, both power trains are deemed effective in providing continuous power for driving the scooter. In addition, the serial power train, although it uses an extra battery set, is shown to be more efficient than the parallel one.     

退役晶体硅光伏组件的回收技术综述

自2020年起的未来10年,大规模的光伏组件将要退役,如何经济高效地处理废旧光伏组件将成为一大难题.晶体硅光伏组件中的材料种类较多,也难以分离,而且所得到的回收材料价值不高,低于组件回收的成本.但是,若退役晶体硅光伏组件处理不当,将会对生态环境造成极端恶劣的影响.晶体硅光伏组件在土壤中很难降解,如果只是简单的掩埋处理,...     

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.     

Analysis of material and energy consumption of mobile phones in China

Owing to booming mobile phone ownership and a short product innovation cycle, waste mobile phones are flooding China. In 2008, about 560 million mobile phones were produced and 634 million users subscribed to a mobile phone plan in China. These large numbers mean that the charging and disposal of mobile phones has the potential to have significant impacts on the environment. Thus the evaluation of material and energy consumption of mobile phones is an important task in the end-of-life management of electronic products. This paper uses material flow analysis (MFA) and life cycle assessment (LCA) methods to estimate the life cycle impacts of mobile phones in China from manufacturing energy, use phase and generation of waste mobile phones. Results indicate over the mobile phone life cycle, manufacturing accounts for 50% of the total energy consumption, whereas the use phase accounts for only 20%. Mobile phones and supporting infrastructures account for a rapidly increasing 0.17% of Chinese energy use. In 2008, around 77 million units of waste mobile phones were generated in China. To manage this energy use and recover valuable materials recommendations are made to increase lifespan, improve energy efficiency during use and ensure recycling.     

LCAs of a polycrystalline photovoltaic module and a wind turbine

This study compares the environmental impacts of a polycrystalline photovoltaic (PV) module and a wind turbine using the life cycle assessment (LCA) method. This study models landfill disposal and recycling scenarios of the decommissioned PV module and wind turbine, and compares their impacts to those of the other stages in the life cycles. The comparison establishes that the wind turbine has smaller environmental impacts in almost all of the categories assessed. The disposal stage can become a major contributor to the environmental impacts, depending on disposal scenarios. Recycling is an environmentally efficient method, because of its environmental benefits derived from energy savings and resource reclaimed. The end-of-life recycling scenario for a wind turbine has a significant part on the environmental impacts and should not be ignored. However, many factors also influence the degree to which recycling can be beneficial. With the wind turbine recycling scenario, when large quantities of waste are recycled, the potential savings can be quite large, while with the PV module, small quantities of recycled waste mean that the benefits of recycling are not fully reaped.     

Intra-fuel cell stack measurements of transient concentration distributions

Intra-fuel-cell measurements are required to understand detailed fuel-cell chemistry and physics, validate models, optimize system design and control, and realize enhanced efficiency regimes; in comparison, conventional integrated fuel-cell supply and effluent measurements are fundamentally limited in value. Intra-reactor measurements are needed for all fuel cell types. This paper demonstrates the ability of a capillary-inlet mass spectrometer to resolve transient species distributions within operating polymer-electrolyte-membrane (PEM) fuel cells and at temperatures typical of solid-oxide fuel cells (SOFC). This is the first such demonstration of a diagnostic that is sufficiently minimally invasive as to allow measurements throughout an operating fuel cell stack. Measurements of transient water, hydrogen, oxygen and diluent concentration dynamics associated with fuel-cell load switching suggest oxygen-limited chemistry. Intra-PEM fuel cell measurements of oxygen distribution at various fuel-cell loads are used to demonstrate concentration gradients, non-uniformities, and anomalous fuel cell operation.     

基于PEMWE的光伏氢能生产系统的性能分析

提出了利用光伏电能通过质子交换膜水电解池(PEMWE)电解水制氢气的光伏氢能生产系统,实现光伏电能的长期能源存储,其主要元件包括光伏组件、PEMWE、氢气罐和氢气压缩机等。建立了各元件数学模型和系统效率模型,使用MATLAB搭建了基于PEMWE的光伏氢能生产系统的仿真模型,并对其运行性能进行了分析。仿真结果表明,PEMWE可以在变功率模式下将光伏电能转换为氢能,系统效率达70%左右。     

Life cycle analysis and cost of a molten carbonate fuel cell prototype

The LCA is a method enabling the performance of a complete study on the environmental impacts of the product, taking into consideration all its life cycle (“from the cradle to the tomb” or, better “from the cradle to the cradle” when also the maximum recycling/reusing of the materials is provided. There are many procedures to perform an LCA of the consumers’ products. In particular, the SUMMA method (Sustainability Multi-criteria Multi-scale Assessment) allows obtaining a number of indices of efficiency and environmental sustainability which make the LCA assessment much more complete and significant. LCA method often represents the basis for an additional assessment of industrial products and processes, the LCC (Life Cycle Costing) which, allowing the association of economic variables to any phase of the life cycle, represents a useful tool for financial planning and management. The case study analysed in the present work concerns an LCA analysis, using the SUMMA method and the LCC of one small size molten carbonate fuel cell, 2.5 kW, assembled in the Fuel Cells Laboratory within the Educational Pole of Terni at the Università degli Studi di Perugia. For sake of completeness of the results, the methods Ecoindicator99 and Impact2002 + were used in the analysis, as implemented in the used calculation software, the SimaPro 7.1 by PRè Consultants. From the registered results, it emerges that the environmental energy sustainability of the analysed element enables its widespread and in-depth employment in the phase subsequent to the optimisation of the connected economic frame; the scenarios opened by the present work envisage great margins of improvements of said aspects in the future experiments.     

Conceptual design of an integrated thermally self-sustained methanol steam reformer – High-temperature PEM fuel cell stack manportable power generator

We have investigated the concept of an integrated system for small, manportable power units. The focus of this study is the direct thermal coupling of a methanol steam reformer (MSR) and a high-temperature proton exchange membrane fuel cell (HT PEMFC) stack. A recently developed low-temperature (LT) MSR catalyst (CuZnGaO_x) was synthesized and tested in a designed reforming reactor. The experimental data show that at 200 °C the complete conversion of methanol is achievable with a hydrogen yield of 45 cm³ min^?1 g_CAT^?1. An experimental setup for measuring the characteristics of the integrated system was designed and used to measure the characteristics of the two-cell HT PEMFC stack. The obtained kinetic parameters and the HT PEMFC stack characteristics were used in the modeling of the integrated system. The simulations confirmed that the integrated LT MSR/HT PEMFC stack system, which also includes a vaporizer, can achieve a thermally self-sustained working point. The base-case scenario, established on experimental data, predicts a power output of 8.5 W, a methanol conversion of 98.5%, and a gross electrical efficiency (based on the HHV) of the system equal to 21.7%. However, by implementing certain measures, the power output and the electrical efficiency can readily be raised to 11.1 W and 35.5%, respectively.     

A life cycle approach to Green Public Procurement of building materials and elements: A case study on windows

Green Public Procurement (GPP) is a significant policy tool for reducing the environmental impacts of services and products throughout their whole life cycle. Scientific and easily verifiable environmental criteria, based on a life cycle approach, should be developed and used within procurement procedures. In this paper, Life Cycle Assessment (LCA) is applied to wood windows showing how it can support the criteria definition. After a foreword on GPP development in Italy, the evaluation features of the environmental performances of building materials and components are outlined. The LCA case study is then presented, describing the use of the analysis results to define the environmental criteria. LCA allowed to identify the main impacts and the critical processes of the window life cycle, giving a scientific framework to discuss GPP criteria with manufacturers associations and stakeholders. Nevertheless, it couldn’t help neither in identifying detailed criteria for GPP nor to define numerical thresholds to be used as reference in procurement procedures. The appropriate strategies should be selected taking into account the technical status of the market, the standard development and the voluntary industry commitments, involving manufacturers associations. Finally, some elements to develop a structured approach for GPP of construction materials are presented.     

Life Cycle Assessment of concrete manufacturing in small isolated states: the case of Cyprus

Life Cycle Assessment (LCA) is an effective and valuable methodology for identifying the holistic sustainable behaviour of materials and products. It is also useful in analysing the impact a structure has over the course of its life cycle. Currently, there is no sufficient knowhow regarding the life cycle performance of building materials used in the case of small isolated states. This study focuses on the LCA of the production of concrete for the investigation of its environmental impact in isolated island states, using the case of Cyprus as an example. Four different scenarios for the production of 1 tonne of concrete are examined: (i) manufacturing of concrete by transporting raw materials from different locations around the island, (ii) manufacturing of concrete using alternative energy resources, (iii) manufacturing of concrete with reduced transportation needs, and (iv) on-site manufacturing of concrete. The results, in terms of environmental impacts of concrete produced, indicated that the use of renewable electricity instead of fossil-fuelled electricity in isolated states can drastically improve the environmental performance of the end product. Also, the minimisation of transportation distances and the use of locally available resources can also affect, to a degree, the environmental impact of concrete production.

Abbreviations: AP: Acidification Potential; CRC: Completely Recyclable Concrete; GWP: Global Warming Potential; HFO: Heavy Fuel Oil; LCA: Life Cycle Assessment; LCI: Life Cycle Inventory; LCIA: Life Cycle Impact Assessment; MPA: Mineral Products Association; ODP: Ozone Depletion Potential; POCP: Photochemical Ozone Creation Potential; PV: Photovoltaics     

Life cycle assessment of a floating offshore wind turbine

A development in wind energy technology towards higher nominal power of the wind turbines is related to the shift of the turbines to better wind conditions. After the shift from onshore to offshore areas, there has been an effort to move further from the sea coast to the deep water areas, which requires floating windmills. Such a concept brings additional environmental impact through higher material demand. To evaluate additional environmental burdens and to find out whether they can be rebalanced or even offset by better wind conditions, a prospective life cycle assessment (LCA) study of one floating concept has been performed and the results are presented in this paper. A comparison with existing LCA studies of conventional offshore wind power and electricity from a natural gas combined cycle is presented. The results indicate similar environmental impacts of electricity production using floating wind power plants as using non-floating offshore wind power plants. The most important stage in the life cycle of the wind power plants is the production of materials. Credits that are connected to recycling these materials at the end-of-life of the power plant are substantial.     

Optimal heat recovery during polymer electrolyte membrane electrolysis

The severe reduction in the available fossil fuel resources highlights the need to make more use of renewable energy resources (RER), such as solar photovoltaic (PV) modules, wind turbines, hydro-turbines, etc. Hydrogen (H₂) may be seen as a possible alternative fuel which can be produced from renewable energy, as mentioned and a promising contender in the energy storage domain. A hydrogen electrolyser harnesses the energy produced by the RER, in order to produce H₂, which could be stored in its current form to be used at a later stage to generate electrical energy, by means of a fuel cell.In this paper, an optimal switching control of a solid polymer electrolyte membrane water electrolyser (PEMWE) water heating system is presented, in which actual historic exogenous data obtained from a weather station in the considered area is used as inputs for the established model.The main aim of this paper was to develop an optimal control model, which maximizes the removal of the undesired heat from the PEMWE and transferring it to the hot water storage tank (HWST), whilst ensuring sufficient hydrogen is being produced.Simulations of the optimal switching control of a PEMWE water heating system was conducted successfully with the SCIP (Solving Constrained Integer Programs) solver in the optimization toolbox in MATLAB.The optimal switching control model yields a daily energy consumption of 49.85 kWh by the PEMWE compared to an energy consumption of 48.86 kWh by the standard PEMWE system (baseline). The optimal switching control model resulted in 2.51 kg of hydrogen compared to 2.56 kg which is produced by the standard PEMWE system. Moreover, the optimal control model recovered 1.03 kWh of heat successfully which is transferred to the HWST.The optimal control model development and implementation for a PEMWE to maximize the thermal energy recovery from the PEMWE to the HWST whilst ensuring stable H₂ production are presented as one of the main contributions to the study.Secondly, by recovering the generated heat from the PEMWE, the time period for the membrane to degrade to a thickness of 50% could be prolonged by 0.68 years, after which the membrane degradation occurs non-linearly.     

Implications of energy policy on a product system's dynamic life-cycle environmental impact: Survey and model

Successfully developing and manufacturing industrial products requires considering the economic- and environmental-factors that span multiple spatial- and temporal-scales. Here, we propose an integrated approach combining an energy-economic model with a life-cycle assessment to analyze the impacts of energy policies on the dynamic changes in the various environmental impacts of a product system. We employ the Market Allocation (MARKAL) framework to foresee the changes in several economic- and technological-parameters over specific periods for different energy policies. Furthermore, we create a dynamic life-cycle inventory database to assess the changes in the future life-cycle environmental impact of a current product/process system. Our proposed method may guide industry to proactively prepare for the possible effects of different energy policies on their current product/process system's environmental profile so that they can make strategic decisions on modifications to, and investments in their production processes thereby to enhance their environmental- and economic-performance while meeting the various emission-abatement targets.     

Life-cycle assessment in the renewable energy sector

The Polish energy industry is facing challenges regarding energetic safety, competitiveness, improvement of domestic companies and environmental protection. Ecological guidelines concern the elimination of detrimental solutions, and effective energy management, which will form the basis for sustainable development. The Polish power industry is required to systematically increase the share of energy taken from renewable sources in the total energy sold to customers. Besides the economic issues, particular importance is assigned to environmental factors associated with the choice of energy source. That is where life-cycle assessment (LCA) is important. The main purpose of LCA is to identify the environmental impacts of goods and services during the whole life cycle of the product or service. Therefore LCA can be applied to assess the impact on the environment of electricity generation and will allow producers to make better decisions pertaining to environmental protection. The renewable energy sources analysed in this paper include the energy from photovoltaics, wind turbines and hydroelectric power. The goal and scope of the analysis comprise the assessment of environmental impacts of production of 1 GJ of energy from the sources mentioned above. The study will cover the construction, operation and waste disposal at each power plant. Analysis will cover the impact categories, where the environmental influence is the most significant, i.e. resource depletion, global warmth potential, acidification and eutrophication. The LCA results will be shown on the basis of European and Australian research. This analysis will be extended with a comparison between environmental impacts of energy from renewable and conventional sources. This report will conclude with an analysis of possibilities of application of the existing research results and LCA rules in the Polish energy industry with a focus on Poland's future accession to the European Union. Definitions of LCA fundamental concepts, its methodology and application are described in the ISO 14040-14049 series of standards. These standards have already been introduced in some countries, but in Poland they are still at the stage of translation into Polish. Nevertheless some companies in Poland try to assess how their products influence the environment and what are the possibilities of technology improvement in the existing production process reduce their environmental impact.     

Using harmonised life-cycle indicators to explore the role of hydrogen in the environmental performance of fuel cell electric vehicles

This work uses harmonised life-cycle indicators of hydrogen to explore its role in the environmental performance of proton exchange membrane fuel cell (PEMFC) passenger vehicles. To that end, three hydrogen fuel options were considered: (i) conventional, fossil-based hydrogen from steam methane reforming; (ii) renewable hydrogen from biomass gasification; and (iii) renewable hydrogen from wind power electrolysis. In order to increase the robustness of the life-cycle study, the environmental profile of each hydrogen option was characterised by three harmonised indicators: carbon footprint, non-renewable energy footprint, and acidification footprint. When enlarging the scope of the assessment according to a well-to-wheels perspective, the results show that the choice of hydrogen fuel significantly affects the life-cycle performance of PEMFC vehicles. In this regard, the use of renewable hydrogen –instead of conventional hydrogen from steam methane reforming– is essential when pursuing low carbon and energy footprints. Nevertheless, the identification of the most favourable renewable hydrogen option was found to be conditioned by the prioritised life-cycle indicators.