Improving energy efficiency and reducing greenhouse gas (GHG) emissions are essential for the transition to low-carbon power systems and sustainable grid infrastructure. Mineral oil-based insulating oil has a higher lifecycle carbon footprint due to petroleum extraction and refining. Natural ester fluids, derived from plant sources, offer lower CO2 emissions, are biodegradable, and are less toxic. They also improve fire safety with a higher flash point. This study presents a life cycle assessment (LCA) of High Oleic Natural Ester (HONE)-based insulating oil as a sustainable alternative for transformer applications. The thermal performance of HONE was evaluated through accelerated thermal aging experiments using both standard Kraft paper and Thermally Upgraded Kraft (TUK) paper insulation systems, benchmarked against mineral oil and conventional natural ester. Results demonstrate that HONE significantly slows cellulose degradation, enabling higher thermal class operation and increased loading without additional loss of life. HONE-filled transformers can operate at hotspot temperatures up to 137 degrees C, allowing up to 27% higher loading than mineral oil-filled units. This enhanced thermal capacity enables the engineering design of smaller, more compact transformers operating at higher load ratings-a direct pathway to material and resource conservation. From an LCA perspective, the transition to HONE-based insulating oil in a sustainably designed transformer is estimated to reduce CO2 emissions by approximately 27% compared to a peak-rated transformer using mineral oil over a 30 years' service life. These findings demonstrate a practical, industrially viable engineering solution at the intersection of sustainable energy infrastructure and chemical engineering.
The progressive deterioration of freshwater resources and the inadequacy of wastewater treatment infrastructure have intensified the demand for low-cost, locally available adsorbent materials. While calcined calcium-based minerals have been studied against single synthetic pollutants, their behavior in real, multi-pollutant wastewater remains largely unexplored. This study addresses that gap through a calcium sulfate/calcium carbonate-dominated mineral adsorbent, with minor silica content, derived from natural limestone via reagent-free calcination at 500 degrees C for 2 h, applied directly to real municipal wastewater across six quality parameters. Characterization by XRD, FTIR, UV-Vis, and SEM-EDX confirmed this multiphase composition, a direct optical band gap of 2.7 eV, and nanometric crystallite sizes of 21.37 +/- 6.09 nm and 22.17 +/- 5.34 nm before and after treatment. Calcination restructured the surface into a porous, acicular morphology with a higher density of active sites. Batch adsorption demonstrated high removal efficiencies for suspended solids (87.1%), chemical oxygen demand (91.0%), and biochemical oxygen demand (96.8%) at an optimal dose and contact time of 15 mg and 120 min, whereas phosphate, nitrite, and ammonium removal remained markedly lower (<= 21%), revealing a clear divergence between organic and inorganic pollutant removal. This divergence reflects three concurrent mechanisms: physical adsorption, ionic interaction, and surface precipitation. These findings establish calcined limestone as a cost-effective adsorbent for wastewater treatment, clarifying the pollutants for which it is best suited.
Asphaltenes are highly aromatic, polar, and undesirable components present in crude oil, possessing a higher percentage in heavier crude oil. In this work, the influence of ultrasound on asphaltene from heavy oil was investigated, and found that asphaltene size was reduced from 10 to 1 mu m at an ultrasound set power of 100%. SEM analysis showed that treated sonicated raw asphaltene (TRasp-100) has more voids and cracks than treated raw asphaltene (TRasp), while BET indicated a higher surface area (40.952 m2/g) for TRasp-100 due to ultrasound, with NMR confirming structural changes, and FTIR showing no significant functional group alterations after sonication. Due to its rich carbon composition, asphaltene was acid-modified and applied as a potent adsorbent for eliminating methyl orange (MO) from wastewater. It was found that ultrasound-treated asphaltene achieved 87% removal of MO at 50 mg/L concentration under pH 4, 313 K, and 90 min contact time, whereas raw asphaltene adsorbed 69% under the same condition. The equilibrium data for ultrasound-influenced asphaltene were evaluated from Freundlich and Langmuir isotherms. To analyze the kinetics, pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations were applied. The thermodynamic parameters , , and were evaluated in this study.
This study presents a thermodynamic assessment of the plasma conversion of livestock-derived agricultural waste, represented by dried mixed manure, using the TERRA equilibrium program. Plasma gasification and plasma pyrolysis were compared within a unified modeling framework to evaluate carbon conversion, gas-phase composition, condensed-phase behavior, and specific energy consumption over 300-3000 K at 1 atm. The results showed that both routes are thermodynamically capable of producing a gas rich in H2 and CO, while complete carbon gasification is achieved at approximately 950 K. Based on the combined behavior of gas quality and energy demand, 1500 K was identified as the most suitable operating point for comparative assessment. At this temperature, the syngas fraction reached 65.2% for plasma gasification and 68.5% for plasma pyrolysis. The predicted condensed products were dominated by stable mineral phases, mainly tricalcium phosphate, magnesium oxide, and calcium sulfide. Overall, plasma pyrolysis favored preservation of reduced combustible species and yielded a slightly richer syngas, whereas plasma gasification showed a modest advantage in terms of lower specific energy demand. Because the difference between the two routes remained small, the results are interpreted cautiously as equilibrium-level tendencies rather than statistically resolved performance margins.
Biodiesels are emerging as alternatives to diesel fuel. However, to be a feasible solution, biodiesels must meet strict criteria including high efficiency and minimal environmental impact. The current study focuses on evaluating ethyl ester biodiesel and its blends with diesel fuel to assess their potential. Biodiesel, derived from sunflower oil through a transesterification process under microwave-assisted heating, serves as the focal point of this experimental investigation. The primary aim is to elucidate the impact of biodiesel blends, ranging from 10% to 100%, on electric generator performance, specifically, brake power (BP), brake thermal efficiency (BTE), and brake specific fuel consumption (BSFC) and on emission levels of carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOx) compared to pure diesel fuel. These evaluations are conducted across various engine loads up to 4 kW. The novelty of this work lies in the integration of microwave-assisted transesterification for rapid biodiesel production with a comprehensive experimental assessment of its direct application in a low-power generator under real operating conditions. The results demonstrate that blending biodiesel with diesel significantly enhances engine performance and reduces emissions, particularly at lower blend ratios (<= 20%), where an improvement of more than 14% in BTE and a reduction of 11% in BSFC were achieved across all loads. CO2 and NOx emissions were significantly reduced compared to diesel fuel for most of BD blends and under all engine loads.
