MRS Energy & Sustainability

There are few feasible options for sorbents, which can be quickly manufactured and deployed in the event of a major oil spill and so every oil spill is an ecological disaster. This paper aims to provide an understanding of what a realistic, full-scale crude oil spill solution would look like based on the performance of the best sorbents currently available, their costs, and their advantages. Adsorbent materials or “sorbents” described here have been a recent target for research toward applications in environmental cleanup, remediation, and hazardous material containment. These materials contain many compositions, syntheses, and practical manufacturing parameters that make most of them practically and logistically unfit to tackle quantities much larger than a single barrel of oil. Different properties of crude oil and nonpolar materials, such as their viscosity, density, and weathering, can also make these materials seem attractive on a lab scale but underperform in field testing and in practical applications. This review addresses the challenges, advantages, and disadvantages of different technical applications of the superior sorbent materials and material types in the literature. In addition, we discuss the different costs and manufacturing challenges of sorbent materials in real oil spills and what a feasible containment sorbent material might look like.

This perspective article summarizes the operational principles of dual-ion batteries and highlights the main issues in the interpretation and reporting of their electrochemical performance. Secondary dual-ion batteries (DIBs) are emerging stationary energy storage systems that have been actively explored in view of their low cost, high energy efficiency, power density, and long cycling life. Nevertheless, a critical assessment of the literature in this field points to numerous inaccuracies and inconsistencies in reported performance, primarily caused by the exclusion of the capacity of used electrolytes and the use of non-charge-balanced batteries. Ultimately, these omissions have a direct impact on the assessment of the energy and power density of DIBs. Aiming to secure further advancement of DIBs, in this work, we critically review current research pursuits and summarize the operational mechanisms of such batteries. The particular focus of this perspective is put on highlighting the main issues in the interpretation and reporting of the electrochemical performance of DIBs. To this end, we survey the prospects of these stationary storage systems, emphasizing the practical hurdles that remain to be addressed.

The hybrid solar heating systems help in increasing energy savings. However, an optimal configuration along with suitable control strategies will be required to enhance the thermal performance of the system. In the present work, a hybrid solar-gas heating system is built up in Algiers, Algeria, to investigate its thermal performances and thus highlight the annual solar coverage rate. The system consists essentially of two flat plate solar collectors, a gas boiler, and a hot water storage tank. The operation of the installation is controlled by data acquisition card through LabVIEW software. For this purpose, experiment tests have been conducted for different weather conditions on which the hybrid system was operating under three different scenarios simulating working days and weekends. It has been found that temperatures of the storage tank water can reach 36, 34 and 27 °C for days with a global horizontal irradiation of 390, 400 and 533 W/m2, respectively. These preliminary results showed that temperatures of the tank under the steady state operating modes might contribute to the reduction of energy consumption for a given space heating application.

The ternary Cu-Sb- and Cu-Bi-chalcogenides present a rich range of compounds of potential use for large-scale photovoltaics from Earth abundant elements. This paper reviews the state of fundamental knowledge about them, and their technological status with regard to solar cells. Research targets and missing data are highlighted, which may provide opportunities to help realize the goal of sustainable photovoltaics. The family of ternary Cu-Sb- and Cu-Bi-chalcogenides and their solid solutions present a rich selection of potential candidates for Earth-abundant low toxicity photovoltaic (PV) absorber materials. Moreover, they have some novel features imparted by the ns2 lone pair of electrons on the Sb and Bi ions. This review evaluates them as electronic materials, including experimental and theoretical evaluations of their phases, thermodynamic stability, point defects, conductivity, optical data, and PV performances. Formation of the materials in bulk, thin film, and nanoforms and the properties of the materials are critically assessed with relevance to their suitability for PV devices. There is special emphasis on CuSbS2 and CuSbSe2 which form the mainstay of the device literature and provide the most insights into the present-day limitation of the device efficiencies to 3 or 4%. Missing features of the literature are highlighted and clear statements recommending potential research pathways are made, which may help advance the technological performance from its present stuck position.

We report a significant advance in thermally insulating transparent materials: silica-based monoliths with controlled porosity which exhibit the transparency of windows in combination with a thermal conductivity comparable to aerogels. The lack of transparent, thermally insulating windows leads to substantial heat loss in commercial and residential buildings, which accounts for ~4.2% of primary US energy consumption annually. The present study provides a potential solution to this problem by demonstrating that ambiently dried silica aerogel monoliths, i.e., ambigels, can simultaneously achieve high optical transparency and low thermal conductivity without supercritical drying. A combination of tetraethoxysilane, methyltriethoxysilane, and post-gelation surface modification precursors were used to synthesize ambiently dried materials with varying pore fractions and pore sizes. By controlling the synthesis and processing conditions, 0.5–3 mm thick mesoporous monoliths with transmittance >95% and a thermal conductivity of 0.04 W/(m K) were produced. A narrow pore size distribution, <15 nm, led to the excellent transparency and low haze, while porosity in excess of 80% resulted in low thermal conductivity. A thermal transport model considering fractal dimension and phonon-boundary scattering is proposed to explain the low effective thermal conductivity measured. This work offers new insights into the design of transparent, energy saving windows.

Role of MOFs in CO2 chemical conversion; Photocatalytic and electrocatalytic CO2 reduction; Role of linkers and metals in CO2 chemical conversion; and MOF composites and films in CO2 conversion. In this review, we analyze the emerging field of metal–organic frameworks (MOFs) as catalysts for chemical conversion of CO2, with examples ranging from heterogeneous CO2 organic transformation to heterogeneous CO2 hydrogenation, from photocatalytic to electrocatalytic CO2 reduction. We also discuss the role of MOF composites and films in CO2 transformation. Our goal is to have an instrument useful to identify the best MOFs for CO2 conversion.

The present study proposes a model predictive control (MPC)-based energy management strategy (EMS) for a hybrid storage-based microgrid (µG) integrated with a power-to-gas system. EMS has several challenges such as maximum utilization of renewable power, proper control of the operating limits of the state of charge of storage, and balance in demand and supply. Sudden transient power variation in FC and EL can lead to the degradation of these components. The proposed EMS effectively controls the above-mentioned issues in µG operation. Special attention is given to power-sharing between the different FC generators based on the stored hydrogen in the hydrogen storage tanks. Therefore, the amount of stored hydrogen in different storage tanks can be balanced. The EMS is developed and verified in the simulation domain using MATLAB Simulink. Results show that the rate of balancing the stored hydrogen can be adjusted by tuning the weight factors in MPC. Results show that ≈120 min. is taken to balance the amount of stored hydrogen in MH tanks (5000 nominal liters each) for 700 W power-sharing between the two FC units (1 kW each). Output characteristics of fuel cell and electrolyzer and their limitations on the rate of output change are challenges in designing effective EMS. To handle multiple constraints and control objectives, the present study focuses on a control strategy using MPC. The performance of the controller with different weight factors on the control objectives and outputs has been studied in detail.

Hydrogen is a versatile energy storage medium with significant potential for integration into the modernized grid. Advanced materials for hydrogen energy storage technologies including adsorbents, metal hydrides, and chemical carriers play a key role in bringing hydrogen to its full potential. The U.S. Department of Energy Hydrogen and Fuel Cell Technologies Office leads a portfolio of hydrogen and fuel cell research, development, and demonstration activities, including hydrogen energy storage to enable resiliency and optimal use of diverse domestic energy resources. Today, the technology around generating and storing efficient and sustainable energy is rapidly evolving and hydrogen technologies offer versatile options. This perspective provides an overview of the U.S. Department of Energy's (DOE) Hydrogen and Fuel Cell Technologies Office's R&D activities in hydrogen storage technologies within the Office of Energy Efficiency and Renewable Energy, with a focus on their relevance and adaptation to the evolving energy storage needs of a modernized grid, as well as discussion of identified R&D needs and challenges. The role of advanced materials research programs focused on addressing energy storage challenges is framed in the context of DOE's H2@Scale initiative, which will enable innovations to generate cost-competitive hydrogen as an energy carrier, coupling renewables, as well as nuclear, fossil fuels, and the grid, to enhance the economics of both baseload power plants and intermittent solar and wind, to enhance resiliency and avoid curtailment. Continued growth and engagement of domestic and international policy stakeholders, industry partnerships, and economic coalitions supports a positive future outlook for hydrogen in the global energy system.