Device and system design choices for solar energy conversion and storage approaches require holistic design guidelines which simultaneously respect and optimize technical, economic, sustainability, and operating time constraints. We developed a simulation platform which allows for the calculation of solar-to-hydrogen efficiency, hydrogen price, device manufacture and operation energy demand, and the component degradation and replacement time of photo-electrochemical water splitting devices. Utilizing this platform, we assessed 16 different design types representing all possible combinations of a system: i) operating with or without irradiation concentration, ii) utilizing high-performing and highcost or low-performing but low-cost photoabsorbers, iii) utilizing high-performing and high-cost or low-performing but low-cost electrocatalysts, and iv) operating with or without current concentration between the photoabsorber and the electrocatalyst. Our results show that device types exist with a global optimum (a Pareto point), simultaneously maximizing efficiency, while minimizing cost and the energy demand of manufacture and operation. In our examples, these happen to be the device types utilizing high irradiation concentration, as well as expensive photoabsorbers and electrocatalysts. These device types and designs were the most robust to degradation, exhibiting the smallest price sensitivity for increasing degradation rates. Other device types did not show a global optimum, but rather a set of partially optimized designs, i.e. a Pareto front, requiring a compromise and prioritization of either performance, cost, or manufacture and operation energy demand. In our examples, these happen to be the device types using low-cost photoabsorbers. The targeted utilization of irradiation and current concentration predicted that even device types utilizing expensive components can provide competitive solutions to photo-electrochemical water splitting. The quantification of the influence of component degradation on performance allows the suggestion of best practice for device operational time and component replacement. The framework and findings presented here provide holistic design guidelines for photo-electrochemical devices, and support the decision-making process for an integral and practical approach to competitive solar hydrogen production in the future. SignificanceSolar energy is the most abundant renewable energy source on earth. It is dilute, unequally distributed, and intermittent but can be stored, for example, in an energy-dense and transportable fuel such as hydrogen. Photo-electrochemical water-splitting devices convert solar energy into chemical energy integrating photo absorption, charge generation and separation, and electrocatalysis in a single device. The viability of such a device is only possible if four requirements are simultaneously fulfilled: i) high performance, ii) low cost, iii) sustainability, and iv) robustness. All devices developed up to now provide combinations of these aspects but do not sim...
Water-splitting devices that operate with humid air feeds are an attractive alternative for hydrogen production as the required water input can be obtained directly from ambient air. This article presents a novel proof-of-concept microfluidic platform that makes use of polymeric ion conductor (Nafion®) thin films to absorb water from air and performs the electrochemical water-splitting process. Modelling and experimental tools are used to demonstrate that these microstructured devices can achieve the delicate balance between water, gas, and ionic transport processes required for vapor-fed devices to operate continuously and at steady state, at current densities above 3 mA cm. The results presented here show that factors such as the thickness of the Nafion films covering the electrodes, convection of air streams, and water content of the ionomer can significantly affect the device performance. The insights presented in this work provide important guidelines for the material requirements and device designs that can be used to create practical electrochemical hydrogen generators that work directly under ambient air. Broader contextThe large scale deployment of hydrogen production technologies can be triggered by the development of electrolytic devices that function continuously under simple operation schemes. Water-splitting devices that operate under humid air are an attractive alternative to classic alkaline or proton exchange membrane electrolysis systems. In this regard, the implementation of water splitting technologies can be significantly simplified as the water feed could be obtained directly from the environment. Using polymeric ion-conducting materials in a microfluidic platform, this work balances the transport processes that are inherently limiting in devices operated with diluted water feeds, and demonstrates for the first time a vapor-fed microelectrolyzer capable of generating hydrogen at initial current densities above 10 mA cm −2
Solar irradiation concentration is considered a viable strategy for reducing the energy and financial investment of photo-electrochemical hydrogen generation. We quantified and compared the sustainability benefit of this approach to non-concentrating and conventional approaches using life cycle assessment coupled to device performance modeling. We formulated design guidelines to reduce the environmental impact of a device. Model devices were composed of a concentrator module (with tracking, supporting, and framing components), photoabsorbers, membrane-separated electrocatalysts, and a cooling circuit. We selected eight concentrator types covering five concentrating technologies. For each device we studied the effect of the irradiation concentration ratio, electrode to photabsorber area ratio, manufacturing requirements, incoming irradiance, and efficiency of components on sustainability utilizing two indexes: i) the energy yield ratio, and ii) the greenhouse gas yield ratio. Both indexes combine the performance of the system and its environmental impact. Two design guidelines were formulated based on the analysis: i) any concentration-stable photoabsorber and electrocatalyst is equally feasible at concentrations larger than 55, as their performance prevails over their energy demand, and ii) the system needs to be designed at an optimum concentration which depends on: performance, the relative surfaces of the photoabsorber and electrode, and irradiance. The study quantified and confirmed that concentrating solar irradiation has a beneficial effect on sustainability, energy yield, and greenhouse gas emissions compared to non-concentrated approaches. This was true for all concentrating technologies investigated. Consequently, this study provides an eco-performance-based rationale to further pursue the research and development of concentrated photo-electrochemical devices.Broader context: Solar energy is the most abundant energy source but it is distributed and intermittent requiring its conversion and storage for meaningful use. Photoelectrochemical (PEC) conversion approaches provide a practical and impactful storage approach through the development of devices which efficiently and continuously produce low cost hydrogen for several years. A fundamental requirement for any novel technology is its sustainability, which can be assessed by analysis of greenhouse gas emission and energy requirements during all phases of its lifetime. Recent research on these devices focus not only on material selection for photoabsorbers and electrocatalysts, but also on their design. Concentrated solar irradiation has been suggested as an approach to reduce the cost of PEC devices as it replaces a large fraction of expensive materials by less costly collection and concentrating components. However, this approach needs to ensure that the beneficial effects are not overshadowed by additional energy requirements and emissions, and potential efficiency reduction. This article examines the effects of design, material selection, and operatin...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.