BioEnergy Research最新文献

Global energy consumption is increasing, and there is a growing demand for renewable energy systems that replace fossil fuels with clean alternatives. Low-cost organic material, including organic wastes, can produce clean energy while reducing environmental soil, water, and air emissions. Anaerobic digesters (AD) can convert multiple streams of organic materials to renewable natural gas (RNG) and electricity, but they require optimal operation to minimize costs. This study employs a dynamic mixed-integer linear programming model (MILP) to optimize the collection, allocation, conversion, and dispatch of energy resources. The model optimizes the location of AD facilities producing RNG and power from combined streams that include agricultural biomass, manure, and municipal solid waste. It also optimizes the hourly dispatch of RNG and electricity based on urban residential, industrial, and commercial energy demand. The analysis shows that AD systems could generate RNG with a levelized cost of $0.011/kWh, electricity at a levelized cost of $0.025 to $0.039/kWh, and fertilizer at a cost ranging from $0.035 to $0.055/kWh. Scenario analysis indicates that RNG production is a viable alternative to renewable electricity. These cost estimates vary by location. Larger municipalities could lower costs by leveraging economies-of-scale to reduce capital costs and infrastructure optimizations to minimize waste. Furthermore, optimized AD systems could provide dispatchable heat and power to alleviate energy demand spikes in constrained municipalities. Future studies could evaluate the feasibility of these use cases.

Pretreatment is one of the bottlenecks in the cost and energy-efficient biomass valorization. Deep eutectic solvents are potential candidates for being used to address these challenges. In this work, the deep eutectic solvent composed of choline chloride, and acetic acid was studied for its use in wheat straw fractionation. The pretreated biomass was assessed concerning the lignin and glucan content. Under optimized time and temperature conditions, defined using Doehlert matrix chemometric tool, of 3 h 47 min and 139.6 °C, the processed wheat straw contained as much as 42.5 ± 0.42 wt.% and 38.59 ± 1.26 wt.% of glucan and lignin contents, respectively. The need for biomass washing after the pretreatment with deep eutectic solvents and before the enzymatic hydrolysis step was also evaluated. The obtained enzymatic hydrolysis results, i.e., glucan to glucose yield of 27.13 ± 0.25 vs. 25.73 ± 0.08 for washed or unwashed biomass correspondingly, are equally good substrates. Fractal kinetic analysis of the data showed similar values of k and h for both glucose and xylose reactions between washed and unwashed biomass. This confirmed that biomass washing is an unnecessary step, which in turn opens room for biomass processing intensification.

This study investigates the correlation between both the chemical compositions and physicochemical properties of pretreated oil palm empty fruit bunch (OPEFB) fibre and their enzymatic saccharification/total glucose yield (TGY). Twenty OPEFB samples, pretreated with various aqueous pretreatments, with diverse cellulose (25.63–44.23%), hemicellulose (0.01–42.49%), and lignin (3.7–47.1%) levels, were examined for their correlation with TGY (8.5–40%). The quadratic regression model was verified significant (p-value = 0.0006, R² = 0.8006). It was found that the pre-refined OPEFB experienced greater cellulose loss (35%) compared to unrefined ones (9%), adversely affecting TGY. Among physicochemical properties analysed using SEM, FTIR, XRD, Py-GCMS, and XPS, only crystallinity index (CrI) was significantly correlated with TGY based on theoretical glucose concentration (TGC) (R² = 0.77, 0.91). Other characteristics (morphology, functional groups, crystallite size, S/G ratio, and O/C ratio) exhibited no significant correlation to saccharification efficiency, exhibiting random trends (R² < 0.5). OPEFB fibres with CrI of 30–40 could achieve 100% TGY based on TGC. In conclusion, regardless of pretreatments, chemical compositions predominantly affected TGY in the enzymatic saccharification of biomass. Among commonly used physicochemical analytical methods, CrI is most significant in this evaluation and OPEFB should be unrefined before treatment to avoid cellulose loss.

Graphical Abstract

The yield of green energy from solid-state anaerobic co-digestion (SSAD) has recently been enhanced by incorporating innovative pretreatment methods and nanoparticles. However, the environmental consequences of employing new processes have not been fully examined. In this study, the environmental impacts of three high-methane-yielding scenarios including SSAD of corn stover blended with dairy manure (DM) denoted as (SYM1), calcium hydroxide-pretreated corn stover (CpCS) blended with DM (SYM2), and the CpCS blended with DM and nanoparticles (SYM3) were assessed and compared the baselines of solid-state and semi-solid-state anaerobic digestion using a life cycle assessment (LCA) approach. The approach investigated the best management practices that would result in high methane yield and low environmental impact. Results of the life cycle assessment indicate the inclusion of calcium hydroxide and nanoparticle has minimal negative environmental impact. There was an environmental gain in GWP when corn stover was co-digestion with DM (SYM1) relative to DM mono-digestions (baselines) and the carbon footprint of SYM1 was less by more than 85% compared to SYM2 and SYM3. However, the large volume of untreated corn stover harnessed for SYM1 scenario resulted in over 75% fossil fuel depletion compared to the other scenarios. The surplus methane from the SYM3 (at least twofold of other scenarios and baselines) in conjunction with being the least with the environmental implication makes the scenario the most attractive option for on-farm practice capable of harnessing the growing organic waste volume. These outcomes can guide trade-off between pretreatment and nanoparticle application to reduce solid-state anaerobic digestion’s negative environmental impact.

Levulinic acid is acknowledged as a significant high-value product derived from lignocellulosic biomass. Its acquisition involves acid hydrolysis, resulting in a challenging separation and purification process due to the formation of a dilute azeotropic mixture. This complexity renders separation costly and presents a hurdle for large-scale production. Various purification methods, including hybrid and intensified systems, have been proposed to address this issue. However, a systematic synthesis methodology incorporating multi-objective optimization considering economic and environmental factors has yet to be applied to this mixture. Hence, this study employs such a methodology to derive sustainable and thermodynamically feasible intensified designs. The optimization algorithm employed is differential evolution with a tabu list. Two objectives are considered: total annual cost as the economic criterion and the eco-indicator 99 as the environmental index. The intensified design, incorporating thermal coupling, presents the best results of the designs studied, with a total annual cost value of $13.9 million and 4.21 × 10⁹ environmental points per year. This represents an economic saving of $4.6 million per year and reduces environmental impact by 1.15 × 10⁹ points compared to the reference design, providing a sustainable alternative for purifying levulinic acid at a cost of $0.261 per kilogram.

This study reports results from a stochastic techno-economic analysis (TEA) model that assessed the financial feasibility of forest biomass harvest for low-carbon bioenergy feedstocks in the hardwood region of the Northeast United States. It analyzed three 24-year scenarios based on primary data collected from the mixed product harvest with whole tree harvesting systems that primarily produce clean chips, dirty chips, or pulpwood and dirty chips. Using a joint product costing approach, proportional costs of shared processes were allocated to different products on a mass basis. Uncertainty associated with key stochastic variables was incorporated into the model to generate net present values (NPV), benefit–cost ratios (BCR), and minimum selling prices (MSP) via Monte Carlo simulation. The clean chip scenario produced an NPV of $1.36 million and a BCR of 1.03, while the pulpwood scenario’s NPV and BCR ($0.06 million and 1.02) were lower, and the dirty chip scenario generated negative NPV (− $0.02 million) and a BCR of 0.99. The probabilities of achieving positive NPVs for all three scenarios fell between 47 and 56%. The mean MSP for one clean chip scenario was $94.03/dry Mg, while the mean MSPs for two dirty chip scenarios were $74.79/dry Mg and $75.93/dry Mg. NPV results were most sensitive to forest biomass feedstock harvesting production levels, transportation distances, and delivered prices, followed by diesel fuel consumption for in-wood harvest and diesel fuel price.

Technologies for producing renewable fuels and chemicals rely on the production of stable intermediates. For thermochemical technologies, pyrolysis of biomass produces oils that must compromise between carbon yield and oil quality. Bio-oil extraction has largely focused on regular bio-oils (~ 33 wt% O) and partially deoxygenated oils (< 12 wt% O). Furthermore, it is desired to extract phenolics without direct distillation of bio-oils, which would enable extraction from the heaviest portion of bio-oil. Mid-level oxygen (MLO) bio-oils (16–25 wt% O) produced from switchgrass were characterized for their ability to separate into phenolic-rich fractions. Toluene-soluble portions of the oils underwent NaOH extraction to extract one-ring phenolics, while toluene-insoluble portions were fractionated with iso-propyl alcohol (IPA). While phenolic extraction proceeded without distillation (having been a prerequisite for partially deoxygenated bio-oils), the efficiency of extraction was less than optimal, owing to the presence of other oxygenated compounds in the hydrocarbon-rich fraction. Both IPA-insoluble and IPA-soluble fractions underwent solvent liquefaction reactions with base additives. While using water as a reaction medium produced greater concentrations of phenols than when using methanol, addition of sodium carbonate produced narrower product distributions of phenols and inhibited formation of benzenediols.

In the process of poplar fermentation for ethanol, different methods are adopted to achieve efficient treatment and resource utilization of fermentation residues, which meets the current demand for green energy and carbon neutrality. Therefore, this work aims to establish an evaluation method on energy consumption, pollutant emissions, and cost expenditures in the production process for biofuels from poplar wood and residue. The process was simulated with commercial software (Aspen Plus for chemical production simulation and cost estimation and eBalance for LCA). Results showed that compared to FCE, it made a higher conversion efficiency of CFG because of the biojet fuel and gasoline from the gasification and conversion of residual lignin. And the flash evaporator, hydrolysis reactor, and fermentation reactor were components with the highest exergy loss. The economic cost of CFG was 9.63% less than that of FCE, and cellulase enzymes and poplar wood in variable costs were main factors in the total cost. Comparing environmental impacts from four perspectives, it was found that the total comprehensive impact of FCE was higher than that of CFG under each weight. The degree of influence of the first level indicator layer was energy consumption, environmental impact, and economic cost in descending order.

Graphical Abstract

Nowadays, in the bioethanol production process, improving the simplicity and yield of cell wall saccharification procedure represent the main technical hurdles to overcome. This work evaluated the application of a rapid and cost-effective technology such as near -infrared spectroscopy (NIRS) for easily predict saccharification efficiency from corn stover biomass. Calibration process focussing on the number of samples and the genetic background of the maize inbred lines were tested; while Modified Partial Least Squares Regression (MPLS) and Multiple Linear Regression (MLR) were assessed in predictions. The predictive capacity of the NIRS models was mainly determined by the coefficient of determination (r²ev) and the index of prediction to deviation (RPDev) in external validation. Overall, we could check a better efficiency of the NIRS calibration process for saccharification using larger number of observations (1500 sample set) and genetic backgrounds; while MPLS regression provided better prediction statistics (r²ev = 0.80; RPDev = 2.21) compared to MLR (r²ev = 0.68; RPDev = 1.75). These results indicate that NIRS could be successfully implemented as a large-phenotyping tool in order to test the saccharification potential of corn biomass.

Fish waste is a major environmental pollution problem and requires costly treatment prior to disposal. Conversion of fish waste to economically important and eco-friendly products will make fishing and fish processing more valuable and sustainable. This study evaluated waste residues from fish processing waste subjected to conventional physical extraction of fish oil for single-cell oil production using oleaginous yeast. Potential application of the single-cell oil to produce biodiesel was evaluated. The treatment containing fish waste residue (5%, w/v) and glucose (20 g/L, w/v) displayed the highest rate (14%) of total lipid generation. The fish waste residue proved to be a good nitrogen source for the oleaginous yeast, Rhodotorula sp. R1. At 15% (w/v) fish waste residue and 20% (w/v) glucose amendment of the medium, the highest biomass production was observed. The yeast bio-oil has a lipid profile like vegetable oils and consists of mainly long-chain fatty acids (between C14 and C24) which are suitable for biodiesel production. The most abundant fatty acids were palmitic acid (C16:0), elaidic acid (C18:1n-9t), and stearic acid (C18:0). FTIR analysis of the transesterification reaction product using the yeast oil confirmed its conversion to biodiesel. Although glucose amendment of medium supported lipid accumulation, it can be replaced with wastes rich in sugars to decrease the cost of single-cell bio-oil production. Results indicate the potential secondary value of fish processing waste in the cultivation of oleaginous yeast for bio-oil and biodiesel production.