Bioenergy has emerged to be among the primary choices for the short- and medium-term replacement of fossil fuels and the reduction in greenhouse gas (GHG) emissions. The most practical method for transforming biomass into biofuel is thermochemical conversion, which may be broken down into combustion, torrefaction, pyrolysis, hydrothermal liquefaction, and gasification. In this study, producing biofuels using a biomass pyrolysis process was investigated. This study explored the pyrolysis process and operating conditions to optimize the process parameters to maximize the desired product yields and quality. The pyrolysis process produces three main products, which are bio-oil, bio-char, and gas. There are three classifications for the pyrolysis method, with each of them producing a majority of a certain product. First, slow pyrolysis is conducted in the temperature range of 300–950 °C and residence time of 330–550 s. It produces around a 30% oil yield and 35% char yield, and thus, the majority yield of slow pyrolysis is char. Second, fast pyrolysis produces around 50% oil, 20% char, and 30% gas yields with a temperature range of 850–1250 °C and a residence time of 0.5–10 s. The average yield of flash pyrolysis was found to be 75% bio-oil, 12% bio-char, and 15% gas, which is conducted within less than 1 s. It was reported that the pyrolysis of biomass was simulated using ASPEN Plus, where the effects of several parameters, such as the temperature, heating rate, and residence time, on the product yield and composition were investigated. Pyrolysis was performed under different conditions ranging from 400 to 600 °C. The effects of different catalysts on the pyrolysis process were studied. It was found that the addition of a catalyst could increase the yield of bio-oil and improve the quality of the product. The optimal operating condition for the pyrolysis process was determined to be a temperature of 500 °C, which resulted in a higher bio-oil yield. It was found that the biofuel yield was enhanced by selecting appropriate raw materials, such as rice husk, along with the pyrolysis temperature (e.g., 450 °C) and particle size (350–800 µm), and using a low residence time and pressure.

Finding alternatives to fossil fuels is extremely important for economic and environmental considerations. Biomass pyrolysis stands out as an efficient method for generating fuels and chemical intermediates. This study explored the influence of wood particle size (ranging from 1 to 3 cm) and pyrolysis temperature (ranging from about 300 to 480 °C) on the process. Characterization of wood residues utilized energy-dispersive X-ray (EDX) and field emission scanning electron microscopy (FE-SEM) to comprehend surface morphology and resultant biochar structure. Results revealed a significant temperature-dependent impact on pyrolysis product concentrations. Biomass composition analysis indicates lignin, hemicellulose, extractive contents, and cellulose percentages at 11.23%, 39%, 2.15%, and 47.62% mass/mass, respectively. Reduction in particle size to less than 2 mm enhances heat transfer, elevating overall bio-oil production. Major bio-oil components comprise phenolics, acids, alcohols, aldehydes, and ketones. Optimal conditions are identified at a wood particle size of 1 cm and a heating temperature of 480 °C. For every 1.0 kg of wood biomass residues, bio-oil, syngas, and biochar yields are 0.38 kg, 0.22 kg, and 0.4 kg, respectively. Notably, the agreement between Aspen Plus simulation and experimental findings underscored the robustness of the study.

The conventional solar still (CSS) unit faces challenges such as low productivity (P_d) and thermal efficiency (η_th) due to the limited temperature difference between the hot water and the cold interior glass cover surfaces (ΔT_w-gi). This study addresses these issues by introducing enhancements in the CSS unit, incorporating a v-corrugated-type basin, internal reflecting mirror, flat-plate solar collector (FPSC) still, and FPSC nanofluids. A v-corrugated-type basin, internal reflecting mirror, FPSC still, and FPSC nanofluids elicited a significant improvement in the distillate productivity (P_d) up to approximately 22.39%, 41.72%, 70.10%, and 104.13% compared to the CSS unit. This increase in the P_d is attributed mainly to a notable raise in the ΔT_w-gi, showing increments of around 34.33%, 52.32%, 77.37%, and 112.87% compared to the CSS unit. Moreover, a v-corrugated basin, internal reflecting mirror, FPSC still, and FPSC nanofluids substantially increased the average daily thermal efficiency (η_th), around 22.01%, 26.71%, 39.57%, and 56.21%, respectively. The results confirmed that integrating the v-corrugated basin, internal reflecting mirror, FPSC still, and FPSC nanofluids within a combined seawater distillation system can significantly enhance the performance of the CSS unit. These different combinations effectively raised the basin water temperature (T_w) and ΔT_w-gi, consequently improving the overall performance of the solar still unit.