This study utilizes natural dye extracts from inthanin and mahogany, along with synthesized TiO₂QD as the photoanode, to increase the photoconversion productivity and performance of DSSC. TiO₂QD was produced using the sol-gel technique. Titanium (IV) isopropoxide (TTIP) and isopropanol underwent hydrolysis with constant stirring for 48 h. The TiO₂QD was characterized using SEM. The structure and size of TiO₂QD were determined using SEM analysis, which showed an average crystallite size ranging from 5 to 8.5 nm. A UV-Vis spectrophotometer determined the absorption wavelength of the dye extract. The efficiency and performance of DSSCs enhanced with synthetic TiO₂QD were evaluated by current-voltage (J-V) measurements. The DSSC using mahogany dye extract demonstrated superior photoconversion efficiency, achieving a Voc (open-circuit voltage) of 0.878 V, Isc (short-circuit current) of 0.775 mA/cm2, FF (fill factor) of 83%, and η (overall efficiency) of 0.967%. In comparison, the inthanin dye extract achieved an overall efficiency of 0.783%. The longstanding performance of solar cells, which was improved using a TiO₂QD photoanode and natural dye extracts, was evaluated using a stability test. The test evaluated the long-term performance, stability, and durability of solar cells. Utilizing natural dye extracts and TiO₂QD holds great potential for improving the efficiency and performance of DSSCs. The objective of this study is to upgrade the advancement of DSSC technology by investigating the utilization of its components and their long-term durability.

This study investigated the influence of seasonal variation of fruits, vegetables and agrowastes (FVA) generated in wholesale markets in New Delhi, India, for biogas production. The mechanically pretreated FVA wastes were individually co-digested with waste activated sludge (WAS) under mesophilic conditions for 30 d. The combination of radish leaves with WAS exhibited the highest biogas yield of 407.22 mL/g VS_fed. Later, four different mixed combinations were formulated based on four different seasons (pre-monsoon, monsoon, post-monsoon and winter) to digest using three different inocula: waste activated sludge (WAS), cow dung and anaerobic sludge. The mixed combination of substrates for the winter season co-digested with WAS provided the highest biogas yield of 699.49 mL/g VS_fed. The modified Gompertz model predicted the biogas potential from all the experimental results and simulated that the lignocellulosic substrates exhibited high lag time (> 1). The biodegradability index (BD) was lower (< 50%) for all the individual substrates, other than the case of reactor with radish leaves and WAS. Most of the mixed substrate’s combination exhibited BD above 50% and also showed positive synergistic effects of 1.25 to 1.94, most probably due to the positive attributes of co-digestion strategy. With the future prospects available to improve the digestibility of certain substrates, a thermogravimetric analysis was conducted on them. It suggests that the thermal degradation of each substrate varies according to its individual characteristics. Hence, possibilities of strategizing thermal pretreatment for selected substrates could be further evaluated, delivering improved sustainable energy utilization and enhanced biogas production.

Developing construction materials from biomass and biowaste as a substitute for conventional cement has been receiving immense global interest in recent times, due to issues like greenhouse gas (GHG) emissions (e.g. CO₂), rapid depletion of non-renewable resources, and extensive energy consumption during cement production. Supplementary cementitious materials (SCMs) like fly ash, slag, and natural pozzolans can substitute conventional cement partially and can contribute to reducing GHG emissions and the environmental footprint of cement production. This study aims to prepare bio-based pozzolans from East-Indian lemon grass (Cymbopogon flexuosus) and poultry litter and to investigate the mechanical properties of concrete through their utilization as SCMs. The optimization process involves central composite design (CCD)-based response surface methodology (RSM) for modelling and statistical analyses using experimental data from the study. Analysis of variance (ANOVA) revealed the model’s significance, with coefficient of determination (R ²) of 0.9956. The individual and synergistic effects of the considered factors on compressive strength were analysed using three-dimensional response surface plot. Based on RSM analysis, concrete prepared by substituting 17.57% of ordinary Portland cement with SCM (which was cured for 25.82 days with a water–cement ratio of 0.54) yielded the optimum compressive, flexural and split tensile strengths of 33.94 ± 0.12, 8.78 ± 0.02 and 3.06 ± 0.02 N/mm², respectively. Furthermore, the SCM-mixed concrete exhibited enhanced durability properties compared to traditional ones. The findings also demonstrate the robustness of RSM as a significant tool for optimization of concrete performance. Moreover, the characterization results of pyrolytic lemon grass bio-oil (LG-BO) confirm its bioenergy potential, thereby suggesting its diverse utilization in various applications.

The global energy transition is crucial for all nations due to increasing concerns about energy security and climate change. The low-carbon city pilot (LCCP) policy is an essential project in the energy transition process, but its impact on urban energy transition (ET) and the underlying mechanisms remains unclear. To address this, we use a multi-temporal difference-in-difference (DID) model, analyzing panel data from 277 Chinese cities spanning 2006–2020, to examine the effects of the LCCP policy on urban energy transition. The findings show that the LCCP policy greatly influences urban energy transition, and the findings can withstand a number of robustness tests, particularly the decomposed effects of staggered DID. Moreover, we construct a multiple mediation effect model to identify three pathways through which the policy facilitates energy transition: “LCCP → Government Intervention → ET,” “LCCP → Enterprise Technology Innovation → ET,” and “LCCP → Residents’ Green Consumption Awareness Enhancement → ET.” Heterogeneity analysis demonstrates that first- and second-tier cities, resource-based cities, and eastern cities experience more substantial impacts. Our findings hold vital implications for promoting low-carbon cities and achieving sustainable energy systems.

The Indonesian government is implementing the national biomass co-firing program to rapidly reduce greenhouse gas emissions in power plants on a significant scale in a short time. Unfortunately, the environmental impacts of this program, under actual conditions, have not yet been thoroughly assessed and evaluated. This study involved collaborating with a coal-fired power plant (CFPP) operator in Banten to study actual conditions using life cycle assessment analysis with a cradle-to-gate system. The product category rules were used to determine the environmental impact category. Operational data was used from two coal-fired power plant units, each operating coal-firing and sawdust co-firing with a co-firing ratio (CR) of 11.80%. The results of comparing both units revealed a reduction in the impact of global warming potential by − 19.83%, acidification potential by − 27.67%, eutrophication potential by − 10.85%, photochemical ozone formation potential by − 28.73%, abiotic depletion potential (ADP) fossil by − 7.35%, water scarcity by − 3.05%. However, there were increases in ADP elements by 69.66%, ozone depletion potential (ODP) by 36.30%, and land use (LU) by 1926.74%. A sensitivity analysis was conducted to analyze the environmental impact of increasing the CR from 11.80 to 20.0%, where the study results showed the highest increase in LU. A scenario analysis was employed to estimate the environmental impact of fuels, where the results were sequential as follows: coal, rice husk pellets, sawdust, and woodchips co-firing, with values of 1.23, 1.03, 0.99, and 0.98 kg-CO₂-eq, respectively. Based on the actual conditions, this study's results provide insight into the environmental impact of biomass co-firing operations. It is expected that the results will be used as a reference for developing a strategy to maintain the sustainability of this program for the long term.