Search Results (3,125)

Circular economy is today a key driver of every transformation process aimed at reducing and optimizing the use of energy and materials. The production of solid biofuel from waste is a typical route to lower the potential impact of greenhouse-gas emissions. In this context, olive pomace is a relevant feedstock, as 4 million tonnes are generated worldwide each year alongside olive oil production. However, only a small fraction of olive pomace is currently valorized. Fresh olive pomace must first be quickly dried to a low, controlled moisture. This step is performed poorly and at a high energy cost. This paper presents an automation-based approach to enhance biomass production from olive pomace, thereby advancing circular-economy practices in olive oil production. The work is focused on four aspects. In the first part, a review of the state of automation in agricultural engineering with a focus on biomass and olive pomace is proposed. Then, the design and construction of an innovative drying system that integrates an infrared solution directly into the transporting screw conveyor is described, integrating real-time online microwave moisture sensing and PLC control. After that, a cloud-based service is presented for remote monitoring, data analysis, and optimization. The innovative and automated drying system was validated during a preliminary field campaign at an olive mill. After about sixteen hours of continuous, cloud-monitored operation, the resulting olive pomace moisture fell below the 5% threshold across a wide range of inlet-moisture conditions, with a stable electrical power demand of approximately 1.85 kW. Finally, an environmental analysis is provided to evaluate the environmental aspects related to the proposed system. The preliminary analysis confirms a significant avoided-carbon potential if the resulting olive pomace is reused as biomass for energy production. The impact associated with 1 kWh_-eq produced from olive pomace is in the range of 0.006–0.033 kg CO_2-eq. Full article

Weather variability and CO₂ supply costs remain key barriers to the commercial viability of algal biofuel production. Recent experimental work has demonstrated that the algae Chlorella sp. strain SLA-04 achieves high productivity in extreme alkaline growth media (pH > 10), where the solution chemistry enables direct capture of atmospheric CO₂, eliminating the need for costly CO₂ sparging. Despite these promising results, the commercial-scale economic and environmental implications of this cultivation approach have not yet been assessed. Here, we present the first integrated Techno-Economic Analysis (TEA)/Life-Cycle Analysis (LCA) of high-pH–high-alkalinity production. We compare four SLA-04 cultivation scenarios with a baseline strain cultivation scenario with Nannochloropsis oceanica. These scenarios also include the first incorporation of Trona, a naturally occurring carbonate mineral and the primary domestic source of bicarbonate in the United States, into our TEA/LCA framework as a low-cost alternative to commercial NaHCO₃ for establishing the high-alkalinity growth medium. Our results indicate that the SLA-04-Trona scenario reduces carbon intensity and present value of lifetime expenses by 40% and 55% on a per-gallon basis, while simultaneously exhibiting lower production variability across all seasons. Quarterly revenues reflected an improvement of $6 million over the baseline strain revenue over 40,000 simulations. Modeled productivity was lower than what was observed experimentally and resulted in a MBSP of $705/ton. These findings provide the first quantitative evidence that high-pH–high-alkalinity cultivation can substantially improve both the economics and environmental footprint of commercial-scale algal biofuel production. Full article

Global land degradation affects approximately 2 billion hectares, threatening food security, biodiversity, and climate stability while undermining the United Nations Sustainable Development Goals (SDGs). The concurrent urgency to decarbonize the energy system and mobilize green finance for sustainable transitions has created a rare policy window in which AI-optimized biofuel production on degraded lands can simultaneously serve multiple imperatives. This study presents a comprehensive secondary data analysis of AI-based optimization frameworks for deploying biofuel production systems on degraded lands, integrating an explicit green finance dimension that has been largely absent from prior synthesis literature. Drawing on 152 peer-reviewed studies and authoritative datasets from FAO, IEA, IRENA, UNCCD, the Green Climate Fund (GCF), and the World Bank, we analyze machine learning, deep learning, reinforcement learning, and hybrid AI architectures applied to feedstock selection, soil remediation, yield prediction, supply-chain logistics, and green finance risk-return optimization. Based on evidence synthesized from 152 studies and supporting geospatial and scenario analyses, results indicate that AI-optimized systems can recover 75–94% of prime-land yields, achieve carbon sequestration rates of 2.1–6.8 t CO₂e ha⁻¹ yr⁻¹, central estimate ≈ 7–9 Gt CO₂e yr⁻¹ at 35% adoption with moderate exclusions, and generate projected internal rates of return ranging from 8–22%, depending on feedstock type, regional conditions, and financing assumptions. Yield-recovery and carbon-sequestration ranges are drawn from synthesis of the reviewed literature; IRR, financial-leverage, and market-expansion figures are author-constructed scenario projections based on this evidence, not independently observed outcomes. Green bonds, Article 6 carbon credits, GCF concessional finance, and blended finance structures are identified as the most impactful instruments, collectively projected, under scenario-based modeling, to reduce composite project risk scores by 30–45% and expand the investable universe of degraded-land biofuel projects by an estimated 340% relative to a no-AI, no-green-finance baseline; these figures represent author-constructed scenario estimates rather than direct empirical findings. We develop the AI-Biofuel-Land Restoration-Green Finance (ABLR-GF) conceptual framework (not yet empirically validated through field pilots or simulation) with explicit green finance routing pathways and identify critical policy enablers for global deployment. This study advances the evidence base for policy-makers, investors, researchers, and development practitioners working at the intersection of artificial intelligence, bioenergy, green finance, and sustainable land management. Full article

Biomass, particularly agricultural waste, has emerged as a highly attractive alternative fuel source for domestic and industrial applications. This study investigates the suitability and potential of plantain peel biomass (PPB) as a viable feedstock for bioenergy production. The PPB was comprehensively characterized using proximate and ultimate analyses, thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Experimental results indicate that the weight ratio of plantain peel (skin) to unpeeled plantains ranges from 27% to 47%. Proximate analysis of the PPB yielded volatile matter (VM) of 65.8% and fixed carbon (FC) of 14.5%, suggesting substantial energy potential. The ultimate analysis results, conducted on a dry, ash-free basis, were used to determine the biomass higher heating value (HHV), which ranged from 13.93 to 16.35 MJ/kg. TGA showed that the thermal decomposition of PPB is typical of lignocellulosic biomass, occurring in three distinct stages over a temperature range of 25 to 1000 °C. FTIR spectroscopy identified O-H and C-H as key functional groups present in the PPB, further supporting its viability for biofuel production. Furthermore, SEM micrographs revealed a porous surface texture with heterogeneous particle sizes and shapes. At the same time, EDS confirmed carbon (C), potassium (K), and oxygen (O) as the dominant elements, alongside trace amounts of magnesium (Mg), silicon (Si), phosphorus (P), chlorine (Cl), and iron (Fe). In conclusion, PPB represents a promising and sustainable feedstock for biofuel production in both domestic and industrial sectors. Full article

The European Commission’s decision to establish a 10% v/v volumetric ethanol cap in gasoline (E10) under Renewable Energy Directive II (RED II), further reinforced by the stricter sustainability criteria introduced in RED III, marks a critical turning point for the global ethanol industry. By 2023, worldwide ethanol production reached approximately 116–118 bn liters annually, with the United States dominating at 52% and Brazil contributing about 28%. First-generation (1G) ethanol is increasingly constrained in its expansion within the road transport sector, necessitating the identification of alternative markets to absorb surplus volumes. RED III emphasizes the deployment of advanced biofuels and renewable fuels of non-biological origin (RFNBOs), mandating either a 14.5% reduction in greenhouse gas emissions or a 29% renewable energy share by 2030, thereby encouraging sectoral diversification. The maritime sector emerges as a promising outlet to accommodate surplus ethanol. However, regulatory inconsistencies persist: ReFuel EU excludes crop-based biofuels, while Fuel EU Maritime permits certified options. Aviation remains limited to advanced biofuels. Meanwhile, IMO policies, including MEPC 83 and 84, introduce emissions pricing and lifecycle assessment frameworks, promoting low-emission fuels without clearly recognizing ethanol’s competitiveness. This study evaluates ethanol utilization in marine engines under these constraints. Full article

Conventional anaerobic digestion (AD), despite its proven efficiency in wastewater treatment, faces limitations due to energy requirements and extended hydraulic retention times, with methane yields from waste-activated sludge rarely exceeding 50% of the stoichiometric maximum at retention times of 20 days or more and with the resulting biogas containing 50–75% methane. It also has a constrained capacity for high-grade resource valorization except energy in the form of methane-enriched biogas. This review focuses on bioelectrochemical systems (BES) and hybrid configurations as promising alternatives for sustainable wastewater management. BES mechanisms, including microbial fuel cells (MFC), microbial electrolysis cells (MEC), and microbial electrosynthesis (MES), are analyzed in detail, with emphasis on their capacity to directly convert organic pollutants into electricity or high-value chemicals (hydrogen, acetate) with minimal external energy input. Key advantages include potential electrical energy production, significantly reduced excess sludge production, and high level of waste mineralization. Reported performance reaches power densities of 2203 and 4990 mW/m² for sludge-fed microbial fuel cells and up to 26,680 mW/m² in algae-assisted configurations, chemical oxygen demand (COD) removal of up to 92%, and excess sludge production of 0.09 g/g COD against 0.159 g/g COD for anaerobic digestion treating the same stream. Limitations in terms of scalability and capital costs remain barriers to industrial implementation. Special attention is given to hybrid configurations integrating BES with AD through direct interspecies electron transfer (DIET), which accelerates biodegradation kinetics and enhances resource recovery pathways; compiled MEC-AD data report methane increases of about 3–228% over unpolarized controls, and in a 1.7 L reactor treating alkaline-thermally pretreated waste-activated sludge, the optimum of 0.6 V raised the methane yield from 213.2 ± 9.5 to 308.7 ± 5.9 mL CH₄/g COD removed. These integrated approaches close material and energy cycles, enabling the simultaneous recovery of energy, nutrients (N, P), and bio-chemicals, transforming wastewater treatment plants into zero-waste biorefineries aligned with circular economy principles. Full article

Agricultural residues represent an abundant lignocellulosic resource for the production of renewable fuels and value-added products through thermochemical conversion. In this study, the influence of bran and peat as organic and mineral-rich binder components on the pyrolysis behaviour and product distribution of biomass pellets was investigated. Wheat straw, barley straw, and oat husks were pelletized using barley bran or peat as binders and analysed by thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR). The thermal degradation behaviour, product yields, evolution profiles of non-condensable gases, and composition of condensable products were evaluated during pyrolysis at 700 °C. The results indicated that pelletization modified the thermal degradation pathways and product distribution through interactions between biomass and binder components. Bran-bonded pellets promoted the formation of bio-oil and oxygen-containing condensable compounds, with bio-oil yields reaching up to 45.2%, whereas peat-bonded pellets showed increased formation of non-condensable gases and solid residue. CO₂ and CO were the dominant gaseous products, while CH₄ formation mainly occurred at elevated temperatures in the passive pyrolysis region. The results indicate that binder composition plays an important role in controlling pyrolysis pathways and product distribution, providing opportunities for the optimization of agricultural residue-based pellets for bioenergy and circular bioeconomy applications. Full article

Microalgae are promising platforms for biomass production, carbon capture, biofuels, and high-value bioproducts. However, despite significant advances in cultivation technologies, reactor engineering, and metabolic engineering, industrial implementation remains limited. This gap suggests that the main challenge of microalgae biotechnology lies not in the availability of productive strains or cultivation systems, but in managing the environmental and physiological heterogeneity that emerges during scale-up. This structured narrative review selected literature using predefined descriptors and relevance-based inclusion criteria and organized the evidence into five thematic domains encompassing cultivation-scale constraints, cellular physiology, bioengineering, precision technologies, and industrial translation. This review examines macrospatial bottlenecks related to light distribution, gas transfer, hydrodynamics, and reactor operation, alongside microspatial constraints involving cell cycle regulation, carbon allocation, metabolic adaptation, and stress responses. Recent advances in adaptive cultivation, real-time monitoring, artificial intelligence, digital twins, computational modeling, and bioengineering are discussed as tools to transform biological and environmental variability into actionable information. Based on concepts established in precision agriculture, this review proposes precision microalgae as a conceptual framework that integrates reactor engineering and cell physiology with three operational pillars: real-time monitoring, predictive modeling, and adaptive control. Its specific contribution is to connect currently fragmented technological and biological advances within a common framework for managing multiscale heterogeneity during cultivation and scale-up. Overall, the available evidence supports the operational logic of this framework, although its generalized effectiveness under industrial conditions remains to be demonstrated. Full article

Bio-asphalt–rubber (BAR) binders combine plant-based bio-oil, end-of-life tire crumb rubber, and petroleum asphalt binder, but their climate advantage remains uncertain because bio-oil supply chains, asphalt-binder inventories, and tire-rubber allocation choices can substantially change cradle-to-gate results. This study develops a probabilistic cradle-to-gate life-cycle assessment for one metric ton of binder at plant gate. Eight alternatives were evaluated: a neat petroleum binder, a rubberized binder, a bio-oil modified binder, and five BAR binders with crumb rubber contents of 20–30% and bio-oil contents of 5–15%, expressed relative to neat asphalt mass. The model includes A1 material production, A2 inbound transport, and A3 binder blending energy. Plant-based bio-oil was represented using a literature-derived inventory, while crumb rubber was evaluated under cut-off, avoided-burden, and clinker-fuel system-expansion scenarios. A 10,000-iteration Monte Carlo simulation propagated inventory, transport, energy, and allocation uncertainty. Under cut-off allocation, mean GWP decreased from 496 kg CO2e/t for the neat binder to 446–471 kg CO2e/t for BAR binders, with BAR_30CR_15BIO showing the lowest mean impact and a 98.8% probability of outperforming the control. Avoided-burden allocation strengthened the apparent benefit, whereas system expansion against clinker fuel reversed the conclusion for rubber-containing alternatives. Results show that BAR can reduce binder-level GWP, but the conclusion is not inherent to the material; it depends strongly on tire-rubber counterfactuals and asphalt-binder inventory assumptions. Full article

This work investigates the potential benefits of using bio-briquettes made from organic waste as an alternative source of fuel in sub-Saharan Africa. Over 80 million tons of organic waste are generated annually in the region. Our pilot case study in Zimbabwe processed mixed feedstocks sawdust, rice husks, groundnut shells, and bagasse using optimized parameters: drying at 105 °C to <8% moisture, particle size reduction to <5 mm, slow pyrolysis at 400 °C, 10% molasses binder, and 200 MPa compaction pressure. This process demonstrated an 85% mass conversion efficiency from raw feedstock to final bio-briquettes. The produced bio-briquettes exhibited calorific values of 20–25 MJ/kg, moisture content of <8%, an ash content of 2–4%, a bulk density of 600–800 kg/m³, and a sulfur content of <0.1%, as determined through standard proximate and ultimate analyses (ASTM standards). Techno-economic analysis revealed a production cost of US $45 per ton. Compared to traditional coal and charcoal, these bio-briquettes reduce sulfur emissions by over 60%, and ash waste by up to 80% and mitigate 2.5 tons of carbon dioxide equivalent (tCO₂e) per ton of fuel displaced, while maintaining a near carbon-neutral lifecycle. This study confirms that valorizing organic waste into bio-briquettes provides a cleaner, economically viable alternative to fossil fuels, contributing to climate change mitigation, improved waste management, and sustainable development across the region. Full article

The ReFuelEU Aviation Regulation introduces mandatory targets for sustainable aviation fuels (SAF) from 2025 to 2050. However, hydrotreated esters and fatty acids (HEFA) technology based on waste oils alone is insufficient to meet targets beyond 2030, highlighting the need for alternative biocrude feedstocks to increase SAF production in the EU. Microalgae are promising feedstocks due to their biochemical composition and CO₂-utilization potential, although their high moisture content and nitrogen and oxygen levels require energy-efficient conversion technologies. Hydrothermal liquefaction (HTL) is a suitable process for converting wet microalgal biomass into biocrude, with an optimal temperature window of approximately 300–330 °C and typical biocrude yields ranging from 20 to 70 wt%, depending on feedstock composition and operating conditions. However, microalgal HTL remains at TRL 5–7 and faces challenges related to the high heteroatom content of the resulting biocrude. Hydrodeoxygenation (HDO) is a key upgrading step for converting biocrude into drop-in aviation fuels and commonly operates at approximately 250–400 °C and 10–30 MPa H₂ pressure. Nevertheless, few studies have addressed the HDO of microalgae-derived biocrude. This review examines microalgal HTL, pilot and demonstration facilities, biocrude yields and quality, and upgrading strategies for producing synthetic drop-in aviation biofuels. Full article

Carbon capture is more and more often seen as a component of an integrated carbon-management system than as a stand-alone separation phase. The practical utility of capture technology depends on the chemical state in which the carbon dioxide is held, the energy and material needs for regeneration, the compatibility of the caught species with downstream catalysis and the lifetime of the resulting carbon-containing product. This paper offers an in-depth framework for integrated CO₂ capture and circular carbon use, including catalytic conversion, bio-integrated processes, biomass-derived materials and fuels, hydrogen-enabled routes, mineralization, and artificial intelligence-assisted process design. Reactive capture techniques that convert carbonate, bicarbonate, carbamate, dissolved CO₂ or surface-bound intermediates without first generating a purified gas stream are contrasted with sequential capture, purification, compression, transport and conversion. The thermocatalytic, electrochemical, photoelectrochemical and biological conversion pathways are compared against common parameters such as working capacity, conversion rate, selectivity, carbon efficiency, regeneration energy, stability and life-cycle greenhouse gas performance. Special emphasis is given on dual-functional materials, interfacial reactors, bio-integrated methanation, carbon mineralization in construction materials and coupling with renewable hydrogen. The review also discusses how machine learning, molecular screening, process simulation, graph-based data architecture, and digital monitoring could speed up material selection and system optimization. Across all pathways, the central design requirement is not maximum capture capacity alone, but a balanced match among binding strength, transport, catalytic reactivity, product separation, durability, and carbon permanence. A reporting framework and research agenda are proposed to guide credible scale-up and comparison of integrated carbon-management technologies. Full article

Global population growth, climatic extremes and rising resource pressures necessitate innovative agricultural methods to boost food, feed, fibre and fuel production sustainably. Seed enhancement technologies (SETs), such as seed coating and priming, have emerged as effective strategies to improve seed viability and vigour, seedling establishment and overall crop yield. Conventional seed treatments include seed coating (film coating, encrusting, pelleting) and seed priming (hydro-, osmo-, halo- bio-, nutri-, hormonal-, chemical- and solid matrix priming). They offer advantages such as improved seed handling, uniform germination and promotion of early growth. However, they also have significant drawbacks, including on soil health and off-target pollution from synthetic polymers and pesticides, seed longevity issues from re-drying and outcomes that can vary among different crops, soils and environments. To tackle these issues, new non-traditional SETs are being investigated, including nanotechnology, novel biodegradable coatings and agrichemical-free biostimulants, such as plant growth promoting microorganisms. These innovative methods demonstrate great promise in enhancing active and crop performance while minimising environmental impacts by providing alternatives to materials derived from fossil fuels and that contribute to waste and pollution. This review critically examines both conventional and novel SETs, discusses their pros and cons and outlines strategic research and industry directions to enhance agricultural sustainability and productivity in light of global food and resource security challenges. Full article

In response to rising global energy demand and sustainability targets, assessing the energy-related efficiency of agricultural products has become a critical issue. Sweet sorghum is widely recognized as a promising energy crop for sustainable biofuel production, thanks to its low water requirements and high biomass productivity. To the best of the authors’ knowledge, this study provides the first comprehensive cumulative exergy-based evaluation of sweet sorghum production by simultaneously assessing its energy, exergy, and environmental performance using five key indicators: Cumulative Energy Consumption (CEnC, 718.48 MJ/ton), Cumulative Exergy Consumption (CExC, 2031.42 MJ/ton), Cumulative CO₂ Emission (CCO₂E, 124.01 kg CO₂/ton), Cumulative Degree of Perfection (CDP, 2.8) and Renewability Index (RI, 0.64), based on field level data for the production of one ton of sweet sorghum. Input-based analysis revealed that electricity consumption accounted for the largest share of both energy and exergy use, amounting to 334.85 MJ/ton and 1396.32 MJ/ton, respectively. At the same time, irrigation water was identified as a major contributor to carbon emissions. The integration of renewable electricity sources substantially improved system performance, increasing the CDP to 6.32 and the RI to 0.84, corresponding to more than a twofold increase in exergy efficiency and a shift toward a predominantly renewable production system. Overall, the findings highlight the strong potential of sweet sorghum as a sustainable biofuel feedstock and underline the importance of integrated policy and management approaches that simultaneously address energy quality, exergy losses, and carbon emissions in agricultural energy systems. Full article

The degradation formed during the gas-phase reaction of amyl acetate, CH₃COO(CH₂)₄CH₃, initiated by chlorine atoms (^●Cl), was investigated under atmospheric conditions using gas chromatography–mass spectrometry. The main products identified were acetic acid, formaldehyde, acetaldehyde, butyraldehyde, and propionaldehyde. Calibration curves were established for each identified product at different concentrations to enable their quantification by gas chromatography coupled with flame ionization detection. Product yields were subsequently determined from the calibration data, allowing a quantitative evaluation of the formation of the major oxidation products. The results obtained contribute to a better understanding of the atmospheric degradation pathways of amyl acetate and related ester compounds, providing useful information for assessing the atmospheric processing of ester-containing emissions, including those associated with biofuel applications. Full article