A common sustainability issue, arising in production systems, is the efficient use of resources for providing goods or services. With the increased interest in a hydrogen (H2) economy, the life-cycle ...environmental performance of H2 production has special significance for assisting in identifying opportunities to improve environmental performance and to guide challenging decisions and select between technology paths. Life cycle impact assessment methods are rapidly evolving to analyze multiple environmental impacts of the production of products or processes. This study marks the first step in developing process-based streamlined life cycle analysis (LCA) of several H2 production pathways combining life cycle impacts at the midpoint (17 problem-oriented) and endpoint (3 damage-oriented) levels using the state-of-the-art impact assessment method ReCiPe 2016. Steam reforming of natural gas, coal gasification, water electrolysis via proton exchange membrane fuel cell (PEM), solid oxide electrolyzer cell (SOEC), biomass gasification and reforming, and dark fermentation of lignocellulosic biomass were analyzed. An innovative aspect is developed in this study is an analysis of water consumption associated with H2 production pathways by life-cycle stage to provide a better understanding of the life cycle water-related impacts on human health and natural environment. For water-related scope, Water scarcity footprint (WSF) quantified using Available WAter REmaining (AWARE) method was applied as a stand-alone indicator. The paper discusses the strengths and weaknesses of each production pathway, identify the drivers of environmental impact, quantify midpoint environmental impact and its influence on the endpoint environmental performance. The findings of this study could serve as a useful theoretical reference and practical basis to decision-makers of potential environmental impacts of H2 production systems.
In recognition of the growing global importance of high-temperature fuel cells (HTFCs) as future energy systems, their commercial market take-off needs to be supported by life-cycle performance ...metrics. However, research and application of life cycle approaches and tools are not broadly reflected in fuel cell and hydrogen energy technologies due to technical barriers to data collection and analyzing instruments. In this work, an interactive Excel-based decision support system (DSS) for power-to-gas-to-power life cycle assessment (LCA) and techno-economic analysis is presented. The aim of the proposed model is two-fold. Firstly, promote the availability, exchange, and use of coherent and quality-assured life cycle data in a systematic and uniform way. Secondly, serves as guidance model for scale-up and enable non-expert users to improve the knowledge-base of FC life-cycle performance and set up product eco-profiles at the conceptual design stage of a project. The tool uses cutting-edge LCA methodology LCA-ReCiPe 2016 for key environmental performance indicators and a simple levelized cost of energy (electricity or fuel) for the economic attractiveness. The applicability of the model is tested through a case study on Solid Oxide Fuel Cells (SOFC) demonstrating the capability to acknowledge the trade-offs between possible impacts.
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•A Streamlined Sustainability Assessment Tool for high temperature fuel cells.•The tool reduce the data collection time and increase the practicability of LCA.•Key Environmental Performance Indicators are quantified using LCA-ReCiPe 2016.•Additionally, the levelized cost of electricity and fuel production can be quantified.•The model is useful for simplified energy research LCA studies.
The overturning circulation of the global ocean is critically shaped by deep-ocean mixing, which transforms cold waters sinking at high latitudes into warmer, shallower waters. The effectiveness of ...mixing in driving this transformation is jointly set by two factors: the intensity of turbulence near topography and the rate at which well-mixed boundary waters are exchanged with the stratified ocean interior. Here, we use innovative observations of a major branch of the overturning circulation—an abyssal boundary current in the Southern Ocean—to identify a previously undocumented mixing mechanism, by which deep-ocean waters are efficiently laundered through intensified near-boundary turbulence and boundary–interior exchange. The linchpin of the mechanism is the generation of submesoscale dynamical instabilities by the flow of deepocean waters along a steep topographic boundary. As the conditions conducive to this mode of mixing are common to many abyssal boundary currents, our findings highlight an imperative for its representation in models of oceanic overturning.
The investigation has the aim to study the integration of a molten carbonate fuel cell and a Brayton cycle, that uses supercritical carbon dioxide (S–CO2) as working fluid. The coupling turns out to ...be feasible achieving 56.25% electrical efficiency at the beginning of cell life, and counteracts the degradation of the MCFC (Molten Carbonate Fuel Cell) over time by converting the extra heat to electricity. The proposed system has been compared with a more conventional system based on the integration of a MCFC system with an ORC (Organic Rankine Cycle) turbine. The boost in electrical efficiency obtained with a Brayton cycle is twice that of a recovery system based on an ORC cycle.
•Integrated model of Molten carbonate fuel cell with supercritical CO2 bottom cycle.•MCFC (Molten Carbonate Fuel Cell) black box model validated with real data from a commercial system.•Comparison with an Organic Rankine Cycle recovery shows better performance.
This study reviews the status of life cycle assessment (LCA) of Solid Oxide Fuel Cells (SOFCs) and methodological aspects, communicates SOFC environmental performance, and compares the environmental ...performance with competing power production technologies using a life cycle perspective. Results indicate that power generation using SOFCs can make a significant contribution to the aspired-to greener energy future. Despite superior environmental performance, empirical studies indicate that economic performance is predominantly the highest-ranked criterion in the decision making process. Future LCA studies should attempt to employ comprehensive dynamic multi-criteria environmental impact analysis coupled with economic aspects, to allow a robust comparison of results. A methodology framework is proposed to achieve simultaneously ambitious socio-economic and environmental objectives considering all life cycle stages and their impacts.
•Up-to-date Life cycle thinking literature of Solid Oxide Fuel Cells (SOFCs).•SOFC environmental consequences and benchmarking using a life cycle perspective.•Illustrative Eco-efficiency calculation for energy production technologies.
•A single Molten Carbonate Cell is operated in reversible mode.•Zero-dimensional MCFC fitted model tested in molten carbonate electrolysis cell.•Experimental and numerical comparison of reversible ...molten carbonate cell performance.•Hydrogen and syngas production by Molten Carbonate Electrolysis Cell.•Degradation in reversible molten carbonate cell.
This work summarizes the experimental and numerical activities done in a molten carbonate cell operated in reversible mode using a single cell with an electrodes-electrolyte interface area of 80 cm2. The experimental activity is divided into two sets. Firstly, running the cell only in fuel cell mode in order to compare five electrochemical zero-dimensional models available in literature and choose the one with the smallest deviation with respect to the experimental data, which is applied later in electrolysis mode. The second experimental set is focused on studying the cell working in reversible mode by varying the gas composition entering the fuel electrode and oxygen electrode, the ratio of the flow rate of the oxygen electrode to the fuel electrode and the cell temperature. The results indicate that molten carbonate cells present lower polarization losses in electrolysis mode than in fuel cell mode. According to the parameter variations, a lower cell temperature decreases the performance in both modes; besides, in the fuel electrode the results indicate carbon dioxide reduction apart from the reduction of water; moreover, the oxygen electrode is strongly sensible to the high presence of carbon dioxide that could cause a faster nickel oxide dissolution accelerating the degradation. Throughout the experimental campaign the molten carbonate cell presents a quite high degradation, contrary to previous results of reversible molten carbonate cells carried out using button cells where an improvement was found instead of a degradation. Electrolyte refilling was tried at the end of the second experimental campaign obtaining a significant decrease of internal resistance with a difference of only 20.6% with respect to the initial condition. According to the experimental activity, the fitted model gives a good prediction of the performance in fuel cell mode; however, in electrolysis mode the prediction is weak mainly attributed to the differences in the diffusive phenomena between both operative modes.
The present article explores the key issues for research and development that are common to current state-of-the-art MCFC and SOFC technologies. By analyzing overlapping aspects regarding materials, ...operating conditions and applications of the two types of high-temperature fuel cell (HTFC), the most pressing common challenges are set forth. Similarities between the MCFC and SOFC exist especially on the anode side, given their utilization of nickel as the oxidation catalyst and their suitability for conversion of hydrocarbon fuel. Catalyst deactivation due to contaminant poisoning and carbon deposition thereby emerges as the crucial problem to overcome. A brief review of these mechanisms is given and of relevant studies in the field of HTFCs. The implications on the HTFC catalyst material given by this review are summarized and put forward as lines of research that can be undertaken jointly by players both in MCFC and SOFC development.
•A resource footprint was calculated with an Exergetic Life Cycle Assessment (ELCA).•Twenty environmental impact categories were calculated using LCA-ReCiPe 2016 model.•Levelized cost of electricity ...(LCOE) and sensitivity results were analyzed.•The comparative multi-impact analysis pinpointed the criticalities and advantages.
In this study, exergetic, environmental and economic (3E) analyses have been performed in order to provide sustainability indicators from resource extraction to the final product of stationary power Molten Carbonate Fuel Cells (MCFC) systems (500 kW). Two environmental life cycle impact assessment methods have been selected: the ReCiPe 2016 hierarchical midpoint and endpoint, and the Cumulative Exergy Extraction from the Natural Environment (CEENE). The levelized cost of electricity (LCOE) under technology cost and performance parameters was calculated to analyze the system from the economic point of view. The global warming potential (GWP) is estimated to be 0.549 kg CO2-eq/kWh while acidification (5.06e−4 kg SO2-eq/kWh), eutrophication (9.81e−4 kg P-eq. freshwater/kWh), ozone layer depletion (4.11e−6 kg CFC-11-eq/kWh) and human toxicity (1.07 kg 1,4-DB-eq/kWh). Aggregated CEENE was estimated to be about 8.55 MJex/kWh. Results show that majority of impacts are dominated by fuel supply, while some others are dominated by manufacturing of system. GWP is the only impact category dominated by system operation. Due to potentially high electrical efficiency, MCFC energy systems can lead to lower CEENE and improvements of global warming, fossil fuel and resource scarcity, and photochemical oxidant formation potential with respect to other conventional energy conversion systems. Advances in longer lifetimes of the MCFC stack can help trigger innovation in manufacturing processes and will lead to less resource use of electricity, metal, and minerals, thus less resource scarcity and toxicity related burdens. The baseline LCOE is calculated 0.1265 €/kWh being comparable with the Italian grid (0.15–0.16 €/kWh). The costing results indicate that the unit decreasing the system capital cost could potentially reduce the LCOE by around 25%. Advancing the use of life-cycle thinking in MCFC industry with site-specific data raise systems credibility and enables clarifying the trade-offs between the sustainability pillars, thus designing more sustainable products.
This study aims to review and provide an up to date international life cycle thinking literature with particular emphasis on life cycle assessment (LCA), applied to Molten Carbonate Fuel Cells ...(MCFCs), a technology forcefully entering the field of decentralized heat and power generation. Critical environmental issues, comparison of results between studies and improvement strategies are analyzed and highlighted. The findings stress that MCFC environmental performance is heavily influenced by the current use of non-renewable energy and high material demand of rare minerals which generate high environmental burdens in the manufacturing stage, thereby confirming the prominent role of these processes in a comprehensive LCA study. The comparison of operational phases highlights that MCFCs are robust and able to compete with other mature technologies contributing substantially to airborne emissions reduction and promoting a switch to renewable fuels, however, further progress and market competitiveness urges adoption of an eco-efficiency philosophy to forge the link between environmental and economic concerns. Adopting a well-organized systematic research driven by life cycle models and eco-efficiency principles stakeholders will glean valuable information to make well balanced decisions for improving performance towards the concept ‘producing more quality with less resources’ and accelerate market penetration of the technology.
•State of art of LCA on Molten Carbonate Fuel Cells is reported.•Key LCA concepts, critical issues and best practices are highlighted.•MCFC system implication to environmental impact categories is described.•Cross-sectorial environmental analysis is performed.•Eco-efficiency powerful tool of considering ecology and economy interactions.
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