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This research aims to assess the integration of different fuel cell (FC) options with battery and waste heat recovery systems through a mathematical modelling process to determine the most feasible retrofit solutions for a marine electricity generation plant. This paper distinguishes itself from existing literature by incorporating future cost projection scenarios involving variables such as carbon tax, fuel, and equipment prices. It assesses the environmental impact by including upstream emissions integrated with the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) calculations. Real-time data have been collected from a Kamsarmax vessel to build a hybrid marine power distribution plant model for simulating six system designs. A Multi-Criteria Decision Making (MCDM) methodology ranks the scenarios depending on environmental benefits, economic performance, and system space requirements. The findings demonstrate that the hybrid configurations, including solid oxide (SOFC) and proton exchange (PEMFC) FCs, achieve a deduction in equivalent CO2 of the plant up to 91.79% and decrease the EEXI and the average CII by 10.24% and 6.53%, respectively. Although SOFC-included configurations show slightly better economic performance and require less fuel capacity, the overall performance of PEMFC designs are ranked higher in MCDM analysis due to the higher power density. [ABSTRACT FROM AUTHOR]

Given the increased natural resource consumption of contemporary energy conversion systems, as well as the emissions, waste disposal, and climate changes that accompany them, a critical review of new techniques - known as thermo-economic and thermo-environmental analyses - has been carried out for the evaluation and optimization of energy conversion processes, from the perspectives of thermodynamics, economics, and the environment. Such a review study is essential because of the energy system's impacts on sustainability and performance management requirements, and more importantly, it is crucial to understand the whole picture of performance evaluation of energy systems from the sustainability perspective. The study evaluated the performance and optimization of energy systems and examined the different approaches that integrate the economic, environmental, and second law of thermodynamics for sustainable development. Moreover, to assess the technical, economic, and environmental worth of energy systems and guarantee that the chosen designs are well-suited to a sustainable development framework, a mix of thermodynamic, economic, and environmental indicators is taken into consideration. In this regard, thirteen sustainability indicators for the design, analysis, and performance improvement of energy systems from the viewpoints of thermodynamics, economics, and the environment are presented and discussed. The outcome of this study shows that (i) the sustainability of energy conversion systems can be enhanced with the use of exergy techniques assessment; (ii) by reducing energy losses, exergy efficiency initiatives can lessen their adverse effects on the environment; (iii) the best methods for efficient use of energy resources, low energy production costs, and less environmental impact can be provided by hybrid energy systems; and (iv) use of a single performance metric to optimize the energy process results in improbable outcomes. Hence, multi-criteria techniques should be utilized, allowing for a more comprehensive optimization and planning of sustainable energy systems. Researchers and field engineers working on energy systems' design, modeling, assessment, and performance optimization would find great value in this comprehensive review study. [ABSTRACT FROM AUTHOR]

The energy-exergy and environ-economic (4E) analysis was conducted on a solar still with and without a hybrid thermal energy storage system (TESS) and a solar air heater. The proposed solar still was modified by integrating a rectangular aluminium box filled with paraffin wax and black gravel as the TESS and coupled with a solar air heater. Paraffin wax was selected due to its widespread availability and proven effectiveness in accelerating desalination, improving process uniformity, and maintaining optimal temperature levels. Throughout the experiments, meticulous data on mass loss, air velocity, and temperature were recorded for both conditions. The daily energy efficiency varies from 40.80% to 31.72%, showing a reduction rate with increased water depth. Estimates were made on the average exergy efficiency, losses, outflow, and inflow for the solar still. These were done for both setups. The analysis revealed that CO2 mitigation and credit were more favorable with the TESS. Furthermore, the Energy Payback Time (EPBT) for the hybrid heat storage-based single-slope solar still coupled with a solar air heater is 1.87 years. On the other hand, EPBT values for the hybrid heat storage single-slope solar still and the conventional single-slope solar still were 1.65 years and 0.95 years, respectively. Integrating a thermal energy storage system and solar air heater significantly improved the performance and sustainability of the solar still for desalination, making it a more efficient and environmentally friendly option for freshwater production. [ABSTRACT FROM AUTHOR]

This study presents a simple oil dilution method, known as the bio-mix approach, to enhance the saturated fatty acid levels of non-edible oils by mixing them with highly saturated edible oils. Five raw bio-mix test samples were produced from a blend of unsaturated raw tamarind oil and saturated raw waste cooking oil at different compositions. Among these five samples, raw bio-mix oil with 30% tamarind and 70% waste cooking oil and raw bio-mix oil with 20% tamarind and 80% waste cooking oil were identified as optimum blends based on their lower values of free fatty acids (FFAs). These raw bio-mix oils were then transesterified into bio-mix biodiesel samples using KOH as a catalyst in a transesterification reaction method. A systematic method was employed to enhance the quality and properties of the optimal bio-mix test samples by using ethanol as an additive. The composition of fatty acids and properties of additive blended bio-mix fuels, including viscosity, density, flash point, iodine value, oxidation stability, cetane number, and heating values, were analyzed and compared with the optimal bio-mix samples. The results indicated that 10% of ethanol blended optimum bio-mix fuels had higher levels of saturated fatty acid as well as oxidation stability. However, the flash point, viscosity, unsaturated fatty acids, and higher heating value were decreased when compared to the optimum bio-mix samples. The properties of ethanol blended bio-mix biodiesels were found within the standard limit values specified by the Bureau of Indian Standards and European norms and standards. [ABSTRACT FROM AUTHOR]