In this study, the aerobic degradation of sweet potato (Ipomoea batatas; SP) and diamond yam (Dioscorea rotundata; DY) thermoplastic starch (TPS) blends, combined with polylactic acid (PLA) and varying ratios of citric acid (CA) as a crosslinker, was investigated in compost and seawater environments. After 50 d of composting, weight losses in the SP-TPS/CA/PLA blends were 56.9%, 52.3%, and 77.5%, while those of DY-TPS/CA/PLA were 55.8%, 52.2%, and 62.2% for 0%, 1%, and 5% CA, respectively. In seawater, the SP-TPS/CA/PLA blends showed weight losses of 52.9%, 46.8%, and 61.5%, and the DY-TPS/CA/PLA blends lost 35.2%, 32.1%, and 43.9% for the same CA ratios, respectively. In both media, SEM revealed structural damage, holes, cracks, and changes in coloration, reflecting microbial activity. Additionally, in compost and seawater, TGA results showed that PLA remained the predominant component after 50 d, as most of the degradation occurred on TPS due to its amorphous structure and higher hydrophilicity. In both media, the SP-TPS/CA5/PLA and DY-TPS/CA5/PLA blends exhibited faster degradation, whereas SP-TPS/CA1/PLA and DY-TPS/CA1/PLA displayed higher stability and lower disintegration. Additionally, all blends required over 50 d to degrade completely, as evidenced by the absence of a plateau phase in the biodegradability curves. Statistical analysis showed that, in seawater, the degradation behavior of the blends was similar to cellulose. However, the CA ratio had a greater impact on the compost degradation of the blends with SP-TPS than on DY-TPS. Therefore, the critical factors influencing the degradation of these blends are the starch source and the CA ratio.

Fused deposition modeling (FDM) has gained popularity recently due to its versatility and low cost. Considering that the quality of printed parts depends on many variables, a 3^3 factorial design of experiments was conducted, where three influential parameters in the process were studied: layer height (0.15, 0.2, and 0.25 mm), infill percentage (30%, 60%, and 90%), and shell count (2, 3, and 4), using polylactic acid as the material. Their effects on tensile strength, flexural strength, printing time, and interactions were measured. The maximum tensile and flexural stress obtained were 33.5 MPa and 87.3 MPa, respectively, at a 90% infill percentage. It was found that layer height does not significantly affect mechanical strength, while infill percentage has the most significant influence, followed by the number of shells. The latter two factors show a meaningful interaction. Furthermore, all the studied parameters have a significant impact on printing time.

This study uses life cycle analysis (LCA) to evaluate the environmental impacts of co-firing bituminous coal with agricultural biomass waste, such as coconut and rice husks, emphasising circular economy principles. Seven experimental scenarios with different coal-to-biomass ratios were designed, ranging from pure coal to pure biomass. The results show that Scenario B (100% rice husk) achieved the best overall environmental performance, with the lowest global warming potential (300 kg CO₂ equivalent), eutrophication potential (4.742 kg PO₄ equivalent), and smog formation potential (0.012 kg C₂H₄ equivalent). Additionally, Scenario F (15% biomass mix) recorded the lowest acidification potential (57.39 kg SO₂ eq), indicating that even partial substitution can yield significant environmental benefits. In contrast, Scenario C (100% coal) exhibited the highest acidification (164.08 kg SO₂ eq) and eutrophication (8.82 kg PO₄ eq) potential. Overall, the results demonstrate that co-firing biomass waste significantly reduces pollutant emissions compared to burning coal alone. This study highlights the effectiveness of biomass waste co-firing in mitigating environmental impacts, promoting resource recovery, and supporting a sustainable energy transition within a circular economy framework.

This study evaluates the economic feasibility of implementing renewable energy-based microgrids at the University of Córdoba, Montería, Colombia. Simulations and optimizations were conducted using the HOMER Energy software, considering local renewable resources with significant potential. The analysis identified the combination of grid energy, photovoltaic systems, and a hydrokinetic turbine as the optimal solution, yielding a levelized cost of energy (LCOE) of 0.137 USD/kWh, an internal rate of return (IRR) of 11.9%, and a payback period of approximately 10 years. These results demonstrate the economic viability of microgrid implementation under these specific conditions. In contrast, the use of biomass gasification proved to be financially unviable due to its high initial investment costs, indicating the need for local technological development to reduce these barriers. Overall, the proposed system presents a sustainable and cost-effective alternative for energy generation in university facilities, contributing to energy diversification and long-term environmental benefits.

This study provides a comparative thermochemical analysis of coconut husk, rice husk and mineral coal, assessing their potential for use in sustainable energy applications. Standardised proximate and ultimate analyses, thermogravimetric (TGA/DTG) evaluations and combustibility index measurements were performed under identical laboratory conditions to ensure consistent comparisons could be made. Coconut husk exhibited the lowest ignition temperature (320.88 °C) and the highest combustibility index (2.385). This indicates its suitability for rapid combustion and biochar production. Its low ash and sulphur content enhances its environmental performance. Rice husk demonstrated moderate thermal behaviour and a high ash yield owing to its elevated silica content, suggesting greater potential for non-energy applications, such as silica recovery and advanced materials production. Mineral coal displayed the highest carbon content and calorific value (24.38 MJ/kg), reflecting high energy density, but also a considerable sulphur content that raises environmental concerns. Unlike many studies that address these materials separately, this work provides a direct, side-by-side comparison under controlled conditions. This offers practical insights for selecting materials in energy systems. The results reinforce the potential of agro-industrial residues in cleaner energy strategies, while emphasising the need for emission control measures when using fossil fuels.

Technical and economic aspects for power generation based on residual biomass from rice and corn were evaluated in the department of Córdoba. The physicochemical characteristics of the biomass were determined as a blend for power generation using a conventional Rankine cycle with co-combustion, and the energy potential of the system and mass flows were determined through energy balances. Subsequently, thermodynamic analysis allowed establishing that the proposed system's efficiency is 24,4%. Regarding the effect of co-combustion in the process, it was found that increasing the fraction of rice husk in the mixture led to a reduction in net power production and an increase in cost. Finally, it was estimated that to achieve economic feasibility, a plant with a minimum of 20 MW and a generation cost of 0,172 USD/kWh is required.