Biomass–plastic co-pyrolysis is a promising route for sustainable fuel production; however, predictive modeling is limited by the inability of conventional kinetics to capture composition-dependent interactions and by thermodynamic inconsistencies in purely data-driven models. This study develops a physics-informed neural network (PINN) that integrates composition-dependent Arrhenius kinetics with global mass and elemental (C, H, O) conservation through a multi-objective loss formulation. The model was trained on 106 experimental datasets and achieved high predictive accuracy on unseen data (R2 = 0.988, RMSE = 1.838 wt
This review focuses on invasive aquatic and wetland plants, such as cattail (Typha latifolia) L., common reed (Phragmites australis (Cav.) Trin. ex Steud.), and water hyacinth (Eichhornia crassipes (Mart.) Solms), as feedstocks for microbial production of organic acids used in reductive bioleaching of manganese, iron, and nickel. These species are abundant, fast-growing, low in lignin relative to woody biomass, and often available at zero or negative acquisition cost as products of environmental mitigation, making them attractive alternatives to feedstocks that compete with food or established markets. As high-grade ore reserves decline, sustainable and low-cost alternatives for metal recovery have become vital, and organic acids such as citric, oxalic, and acetic acid derived from biomass fermentation offer a promising alternative to synthetic inorganic acids. This paper synthesizes current literature on the compositional characterization of these aquatic and wetland feedstocks, the low-input pretreatment strategies suited to their low-lignin structure (including brief physical pre-conditioning via microwave or ultrasonic exposure alongside biological pretreatment), and the microbial fermentation pathways that convert their carbohydrate content into organic acids for reductive bioleaching. Key research gaps specific to bioconversion of these underexplored feedstocks are highlighted to guide the development of an integrated, scalable bioprocess for sustainable metal recovery.
The production of renewable chemicals and plastics has been extensively investigated in recent decades, with the purpose of reducing the global dependence on fossil resources. In this review, the main routes to produce chemicals from biomass are reviewed and a critical discussion on the prospects and techno-economic viability of these technologies is presented. As these topics are often considered as independent from each other, the aim of this work is to provide an unified and interdisciplinary perspective of main possible production routes and their development status for experts and non-experts. The main processes of biomass concentration were reviewed and two main approaches for obtaining renewable chemicals were considered: (i) the production of compounds chemically identical to petroleum derivatives, and (ii) the production of conventional and new oxygenated chemicals. The literature shows that there are sustainable technological alternatives to the substitution of many petroleum derived chemicals, but the complexity of the production processes should not be simplistically evaluated. Solutions and technologies must be carefully evaluated, both from the point of view of their technoeconomic viability and their sustainability.
High-ash biogas residue exhibits low reactivity and yields mineral-rich char with limited fuel quality under mono-pyrolysis. This study investigated the macro-isothermal co-pyrolysis of swine digestate (SD) with spent coffee grounds (SCG) or rice husk (RH) at a fixed 50:50 mass ratio using a custom thermogravimetric system with approximately 5 g samples, providing a controlled framework closer to abrupt external heating in a preheated reaction zone than conventional micro-scale TGA. Isothermal experiments at 500–800 °C were analyzed using a first-order model, and the resulting biochars were characterized by elemental analysis, N₂ adsorption, and higher heating value measurements. The first-order model described the main conversion range well (R² > 0.98). The blends showed lower apparent activation energies (21.47–22.06 kJ mol⁻¹) than the corresponding theoretical additive values, indicating positive kinetic synergy under macro-isothermal conditions. Co-pyrolysis also improved char properties relative to digestate mono-pyrolysis. The SD-RH biochar exhibited the highest BET surface area (82.48 m² g⁻¹), while biochar HHV increased from 4.67 MJ kg⁻¹ for SD to 9.75–13.03 MJ kg⁻¹ for the blends. In addition, the blended chars showed low H/Corg and O/Corg ratios (0.34–0.40 and 0.15–0.17), consistent with European Biochar Certificate (EBC) stability thresholds. These results suggest that co-pyrolysis with lignocellulosic biomass can improve the apparent reactivity and quality of digestate-derived biochar, while macro-isothermal testing offers a useful intermediate approach for studying conversion behavior under abrupt external heating.
In this investigation, we analysed the impact of ten chemical additives – galactose (Gal), arabinose (Ara), trehalose (Tre), urea (U), gum arabic (GA), ammonium sulphate (AS), sodium pyrophosphate (SPP), sodium thiosulphate (STS), sodium malonate (SM), and sodium sulphate (SS) – administered at four distinct concentrations, on the astaxanthin production of H. lacustris in nitrogen-deficient settings. Furthermore, the impact of the supplements on the growth, biomass, chlorophyll (chl) a, chl b, and total carotenoid levels of H. lacustris was documented. The most potent supplements, SPP, SM, and U, had remarkable outcomes. On day 15, the H. lacustris culture reached its maximal biomass (2.00 times relative to the control) when U-0.1 g/L (1.66 mM/L) was added. Similarly, adding SPP (0.01 g/L or 0.04 mM/L) was the most effective way to raise the astaxanthin concentration (55.94 ± 0.35 mg/g, a 4.24-fold increase from the control). Similarly, the maximum astaxanthin percentage of biomass (5.59 ± 0.04)
Microbial fuel cell (MFC) technology is a novel and promising bio-electrochemical process that integrates wastewater treatment, resource recovery, and electricity generation, offering substantial potential for sustainable energy production. The present study employs a bibliometric insight, technological readiness assessment, and techno-economic evaluation to illustrate the developments and future opportunities of MFC technology research, focusing on SDGs, such as clean water and sanitation, affordable and clean energy, sustainable cities and communities, and climate action. A bibliometric assessment shows fast-growing MFC research with the main emphasis on the advancement of electrodes, the valorization of wastewater, scaling-up, and hybrid processes. Despite substantial progress achieved in laboratory experiments, most MFC devices are still at the low or medium technology readiness levels (TRLs) because of their low energy density, instability, high cost, and poor scalability. The use of MFC-based hybrid systems with anaerobic digestion, microbial electrolysis, desalination, and energy storage provides higher efficiency and more opportunities for industrial deployment. In summary, the present investigation explores key challenges and opportunities while providing a comprehensive framework to guide efforts toward establishing MFCs as a viable, sustainable energy solution.
Hydrothermal carbonization (HTC) represents an efficient thermochemical pathway for the valorization of wet biomass residues into functional carbon-rich materials. This study employs a statistically supported experimental design to investigate how HTC operating conditions influence the physicochemical, energetic, and functional properties of non-activated hydrochars derived from apple peel waste. Apple peel waste was converted into hydrochars via HTC, systematically evaluating the effects of temperature (180–220 °C) and reaction time (4–8 h) using a full factorial design and response surface methodology. Solid yields ranged from 29.9 ± 3.3
Biochemical methane potential (BMP) assays are widely used to evaluate feedstocks for anaerobic digestion, but they are slow and resource-intensive. This study evaluated whether explainable machine learning can support transparent screening and hypothesis generation from compositional feedstock data. A Random Forest model was trained on 127 solid and semi-solid feedstocks from a public dataset (Dry Matter, DM ≥ 15
Biochar has emerged as a promising material for soil amendment, carbon sequestration, and renewable energy applications. Its physicochemical properties are strongly influenced by feedstock characteristics and pyrolysis operating conditions. In this study, sugarcane bagasse biochar was produced at three pyrolysis temperatures (400, 500, and 600 °C) using feedstock particle sizes of 0.40 and 1.0 mm. The produced biochars were systematically characterized for their agronomic, surface, thermal, and energetic properties. The results demonstrated that pyrolysis temperature was the dominant factor governing biochar characteristics. Increasing pyrolysis temperature enhanced biochar pH, aromaticity, thermal stability, recalcitrance, and higher heating value (HHV), indicating improved suitability for long-term carbon sequestration and energy applications. In contrast, low-temperature pyrolysis (400 °C) resulted in higher biochar yield, greater volatile matter content, a broader range of surface functional groups, and higher cation exchange capacity, all of which are beneficial for soil amendment applications. The BET surface area increased significantly with increasing pyrolysis temperature from 12 to 337 m²/g for 1 mm particles and from 29 to 555 m²/g for 0.40 mm particles. Additionally, finer particle sizes (0.40 mm) enhanced pore development, surface area, and ion release behavior by improving heat transfer and exposing internal pore structures. The study concludes that pyrolysis temperature and particle size can be effectively tuned to produce biochar with targeted properties for specific agricultural, environmental, and energy-related applications.
The accelerating global commitment to decarbonisation has intensified the search for sustainable, high-performance feedstocks capable of supporting the growing biofuel and Sustainable Aviation Fuel (SAF) sectors. Although conventional oilseed crops such as rapeseed, soybean, sunflower, and palm oil currently dominate biodiesel production, their long-term viability is constrained by issues including yield plateaus, competition with food-grade agriculture, extensive land requirements, and persistent sustainability concerns. These limitations underscore the need to explore alternative, climate-resilient crops with higher productivity and reduced environmental impact. In this context, high-oil-producing Moringa oleifera Lam. (drumstick tree) seed lines present a compelling opportunity. M. Oleifera combines strong agronomic resilience with favourable oil properties and significant potential for genetic enhancement, positioning it as a promising next-generation feedstock. This article evaluates the competitive position of M. Oleifera relative to established oilseeds through the application of Porter’s Five Forces, SWOT analysis, and the Total Product Concept. The analysis suggests that M. Oleifera oil holds considerable commercial and strategic potential for both biodiesel and SAF markets but also highlights the importance of targeted investment in breeding programmes, supp-chain development, and regulatory alignment to support successful large-scale adoption.
Water hyacinth (Eichhornia crassipes) is an invasive aquatic weed that presents environmental challenges all around the globe due to its fast growth rate. This water hyacinth can be a potential feedstock for renewable energy, but due to its complex lignocellulosic nature, it inhibits anaerobic digestion (AD). Therefore, this study used juice from this water hyacinth to extract the easily degradable organic matter for biogas production. This study evaluates a crushing–compressing–upflow anaerobic sludge blanket (UASB) approach for the high-rate digestion of water hyacinth juice (WHJ) under carrier-free conditions. The WHJ had a low average pH of around 5.7 with a high concentration of total solids (TS) ranging from 17.4 to 31.6 g·L-1 and total organic carbon (TOC) ranging from 3.9 to 7.9 g·L-1. A laboratory UASB of working volume 6.5 L was operated over 120 days with systematic hydraulic retention time (HRT) reduction from 5, 4, 3 to 2 days and a fed organic loading rate (OLR) ranging from 1.88 to 4.87 g-VSS·L-1·d-1 (0.96 to 3.02 g-TOC·L-1·d-1). With influent (WHJ)pH adjustment and a stepwise acclimation strategy, stable operation and high treatment efficiency was achieved at HRT of 2 days. The process attained TOC and dissolved organic carbon (DOC) removals of up to 95
Torrefaction is economically viable for bioethanol production if the supply chain benefits outweigh the yield loss. To evaluate this trade-off, technoeconomic models were developed for two ethanol production pathways from wheat straw: one using raw and alkaline-pretreated biomass (R-AP) and the other using torrefied and alkaline-pretreated biomass (T-AP). These models accounted for biomass transportation from the farm gate to the biorefinery gate. Additionally, decentralized commercial torrefaction facilities near the farms were simulated to estimate the production cost of torrefied biomass. For the scenarios modeled, the cost of torrefied biomass is 49
This study provides an original assessment of Nauphoeta cinerea residues, an unconventional and largely unexplored biomass, as feedstocks for biocoal production via torrefaction. By addressing a novel insect-derived resource, the work advances waste-to-energy strategies beyond traditional lignocellulosic and agro-industrial residues. Raw cockroach (RC) and defatted cockroach (DC) biomasses were processed under a Central Composite Design, comprising 26 experiments within 155–325 °C and 12–68 min. Response Surface Methodology was applied to optimize solid yield (SY), energy yield (EY), higher heating value (HHV), and atomic ratios (H/C, O/C). RC achieved superior performance, with SY of 63.66–99.33
This study aimed to employ elephant grass (Pennisetum purpureum) as a lignocellulosic support for lipase immobilization, with the goal of developing a sustainable biocatalyst for biodiesel synthesis. Initially, the material in its in natura form was washed with distilled water to remove impurities, dried in an oven at 60 °C, ground in a knife mill, sieved to the desired particle size (42–80 mesh), and chemically characterized regarding cellulose, hemicellulose, lignin, and ash content. Subsequently, Burkholderia cepacia lipase (BCL) was immobilized by physical adsorption, and the resulting biocatalyst was characterized in terms of biochemical properties (pH and temperature), kinetic parameters (Km and Vmax), thermal stability (45 °C), and morphology. Morphological analyses revealed a rough structure of the support and the adhesion of the enzyme to its surface. Biochemical evaluations indicated maximum hydrolytic activity at pH 7.5 and temperatures between 45–60 °C. The kinetic parameters Km and Vmax were 1689.71 ± 261.42 mM and 4641.50 ± 333.24U g-1, respectively, and thermal stability was evaluated at 45 °C, resulting in a half-life of 40.1 h. The catalytic performance was evaluated in the transesterification reaction of babassu oil with ethanol (molar ratio 1:12, 170 rpm, 45 °C, 72 h), resulting in 100
Recent studies have highlighted the potential of agricultural and food industry waste as substrates for biohydrogen production through dark fermentation. Among these wastes, orange waste is particularly promising due to its high water and organic matter content. It is produced in large quantities and lacks a standardized final disposal method, making it suitable for recovery. However, limonene has been reported as a limiting component in biological processes due to its inhibitory effect. The objective of this study was to determine the optimal substrate concentration and initial pH for hydrogen production from orange peels using a central composite design (22) with 13 runs. Batch experiments were conducted under mesophilic conditions (37 °C) with varying initial pH and substrate concentration, using granular anaerobic sludge as the inoculum and maintaining a substrate-to-inoculum ratio of 2.7. Additionally, metabolite production, kinetic parameters, limonene content, and microbial community composition were analyzed. The results indicated that the optimal initial pH and substrate concentration are 7.1 and 29.8 g VS/L, respectively, with a predicted cumulative hydrogen volume of 307.9 mL H2. Limonene at 402 mg/L had no effect on hydrogen production, and no inhibition was observed. Lactic acid was one of the main metabolites in runs with substrate concentrations above 30 g VS/L; however, the high lactic acid content did not correlate with decreased hydrogen production under certain conditions. The test that obtained the highest hydrogen production showed greater dominance of Citrobacter, Clostridium sensu stricto 1, Lacticaseibacillus, Levitactobacillus, and Lactiplantibacillus.
The present research work was focused on the biodiesel production from marine macroalgae Ulva intestinalis biooil using the synthesized catalyst from the de-oiled macroalgal biomass. The process optimization studies resulted in highest biodiesel yield of 93.1
Hybrid renewable energy systems are an alternative to provide electricity in off-grid regions worldwide. This research seeks to compare the techno-economic performance of several HRES scenarios for supplying a load of 720 kWh/day in an off-grid region in Colombia. Then, several steps were involved: (i) zone characterization and electricity demand setting, (ii) proposal of HRES configurations, (iii) experimental biogas production, (iv) simulation and techno-economic assessment of the biogas production process using the Aspen Plus v 14.0 and Aspen Process Economic Analyzer v14.0 software, (v) economic data acquisition of HRES components based on simulation tools or literature, and (vi) simultaneous analysis of all HRES configurations using the HOMER PRO software. The results elucidated the biogas production and combustion as a non-feasible process at lower scales since the raw material availability and biogas yield were the most important constraints. Solar-PV energy was not able to supply the required load due to the low sun radiation and clearness level. The best scenario was the combination of diesel generation with solar-PV energy since the net present cost and levelized cost of energy were 0.89 M.USD and 0.39 USD/kWh. This result was competitive with the current electricity price in off-grid regions (0.33 USD/kWh). As a conclusion, energy transition is not possible using only biogas since the amount of raw materials needed is excessive compared to the waste biomass production of a rural community. Solar energy is postulated as the most promising and fastest option to boost decentralized energy production based on low electricity production costs.
Despite their abundance and low cost, acid oils remain underutilized in large-scale biodiesel production using process intensification technique due to their very high free fatty acid (FFA) content, which poses significant challenges for efficient conversion. This study investigates the conversion of high FFA feedstocks-soya acid oil, rice bran acid oil, groundnut acid oil, and mixed acid oil (FFA: 65–92
India is prioritizing transition to renewable energy sources aiming to address the impacts of energy crisis and climate change. To support India’s 2030 renewable energy and land degradation neutrality targets, this study evaluates Calotropis procera, a resilient hyperaccumulator, as a sustainable biofuel source cultivated on heavy metal (HM) contaminated abandoned waste sites. The plant parts of C. procera were systematically processed to obtain crude oil, followed by transesterification to convert the extracted oil into fatty acid methyl esters (FAME) for biofuel production. Remarkably, the plant outperformed typical growth benchmarks under metal stress, yielding 54.20 ± 1.9 g of seeds per plant and path-breaking crude oil content of 32.75 Calotropis procera has been analysed overall biomass yield, GCV per unit plant on pre-, post-oil extraction and biodiesel. This research unveils unprecedented high-oleic ( 45
Biohydrogen production through dark fermentation (DF) is a promising process that attracts increasing attention in the context of energy transition. However, a deeper understanding is necessary to enable its upscale to industrial applications. This study investigated DF using three inocula sources - anaerobic UASB sludge (PS), activated sludge (AS), and cow manure (CM) – all subjected to acid (APT) and thermal pretreatments (TPT). To assess microbial dynamics, three substrates were tested: a simple sugar (glucose); sugarcane vinasse with filter cake (in natura), and sugarcane vinasse with filter cake enzymatically hydrolysed. The process was evaluated from the metabolic and microbiological perspectives, based on electron balance, volatile fatty acids (VFA) profiles and 16S rRNA sequencing. With glucose, thermally pretreated inocula showed stronger acidogenic activity, and electron balance calculations revealed distinct metabolic pathways for each microbial community, even with similar hydrogen yields (HY). Using vinasse and filter cake - both in natura and pretreated - AS achieved higher HY, followed by PS and then CM. Hydrolysis improved HY until 262
