Enhanced Energy Recovery Research Articles

Research Progress and Outlook of Molecular Dynamics Simulation on Carbon Dioxide Applied for Methane Exploitation from Hydrates

Research progress of carbon dioxide applied for methane exploitation from hydrates is summarized, with a focus on advances in molecular dynamics simulations and their application in understanding the mechanism of carbon dioxide replacement for hydrate exploitation. The potential of carbon dioxide in enhancing energy recovery efficiency and promoting carbon capture and storage is emphasized. An overview is provided of the advancements made in utilizing carbon dioxide for methane hydrate exploitation, highlighting its significance. Subsequently, the theoretical foundations and techniques of molecular dynamics simulations are delved into, encompassing key elements such as statistical ensembles, molecular force fields, and numerical solution methods. Through simulations, various characterization parameters including mean square displacement, radial distribution functions, coordination numbers, angular order parameters, and hydrogen bonds are computed and analyzed, which are crucial for understanding the dynamic changes in hydrate structures and the replacement process. Thorough research and analysis have been conducted on the two possible and widely debated mechanisms involved in the replacement of methane hydrates by carbon dioxide, with a particular emphasis on guest molecular replacement and hydrate reconfiguration. These processes encompass the intricate interactions between carbon dioxide molecules and the cage-like structure of hydrates, as well as the rearrangement and stabilization of hydrate structures. Several key issues surrounding the application of carbon dioxide for methane hydrate exploitation are identified, including the influence of thermodynamic conditions, the selection of auxiliary gases, and other potential factors such as geological conditions and fluid properties. Addressing these issues is crucial for optimizing the extraction process and enhancing economic and environmental benefits. A theoretical foundation and technical reference for the application of carbon dioxide in methane hydrate exploitation are provided, while future research directions and priorities are also outlined.

A novel stochastic algorithm-based non-structural model for combined heat and mass exchanger network synthesis

Combined heat and mass exchanger network (CHMEN) synthesis plays a vital role in the chemical industry with a wide spread of applications due to its effectiveness in enhancing energy recovery and reducing emissions. However, in the optimization of CHMEN, obtaining the optimal solution is challenging because the complex heat/mass exchanger matches in addition to the numerous variables in both the mass and heat transfer processes. Therefore, a novel simultaneous optimization method is proposed in this paper to resolve the CHMEN synthesis problem. First, a general node-based non-structural model (G-NNM) is established employing mathematical programming. In this regard, the potential mass or heat exchange units are represented by alternative nodes in the rich/poor or hot/cold streams. This allows for realizing all the possible matches. Specifically, the concept of superposition streams is utilized to design the coupling model of subsystems, linking their interaction by the mass exchange temperature. Additionally, a random walk algorithm with compulsive evolution is introduced to handle complex computations. Then, the optimal solutions are obtained using the accepting inferior solution strategy. Finally, the validity and effectiveness of the proposed simultaneous optimization method are demonstrated in this work. The results show that the proposed method effectively addresses industrial challenges and achieves an optimal total annual cost (TAC) compared to existing methods in the literature. Overall, by taking into account the coupling modes between subsystems, this study provides a feasible scheme to address the issue of other process integration.

Enhancing energy recovery from expired rice wine via microbial electrolysis of supernatant and anaerobic digestion of concentrate after gravity settling

Makgeolli is a traditional Korean rice wine with a short shelf life, making the management of expired makgeolli (EM) challenging. Meanwhile, its organic- and nutrient-rich nature renders EM a promising bioconversion substrate. To explore the potential to enhance energy recovery and profitability from EM, the concentrate (MC) and supernatant (MS) separated from EM by gravity settling were utilized for hydrogen production in microbial electrolysis cells (MECs) and methane production through anaerobic digestion (AD), respectively. MS demonstrated superior electron and hydrogen recovery compared to EM in MECs, with greater enrichment of exoelectrogenic Geobacter. In the AD tests, MC exhibited faster and more stable methane production with higher yield than EM. This separate processing of MS and MC was predicted to produce 18–21 % more energy (2,210 MJ/m3 EM) and 6–180 % higher revenue (101 USD/m3 EM) than processing whole EM using either MEC or AD alone, warranting further research for optimization.

Achieving efficient water-electricity ensemble via using easily obtainable hydrovoltaic-thermoelectric hybrid generators

The solar-driven water-electricity cogeneration system (WECS) has emerged as a promising strategy to simultaneously address the global challenges of water scarcity and sustainable energy production. Despite its dramatic potential, current WECS technologies face issues related to complex processes and limited energy output, which hinder their practical application. In this study, we present an efficient WECS utilizing a spray-constructed carbon black/polyvinylidene fluoride loaded bamboo fiber paper (CB/PVDF@BFP) hybrid integrated with double-stacked thermoelectric generators (TEGs). The CB/PVDF@BFP composite features a Janus structure with hydrophobic and hydrophilic sides, facilitating efficient water evaporation and hydrovoltaic electricity generation. Under one sun irradiation, the composite achieves an evaporation rate of ~ 1.41 kg·m−2·h−1 with ~ 90 % photothermal efficiency and up to ~ 99.8 % decontamination efficiency for efficient water purification. Notably, our designed hybrid power generation module can reach up to ~ 1600.44 mW/m2 under 1 sun, ~ 3-fold and ~ 4000-fold exceeding the previous only thermoelectric- and hydrovoltaic- based devices, respectively. This hybrid approach demonstrates enhanced energy recovery and utilization of solar energy, offering a promising solution to the water and energy crises through a single WECS.

Anaerobic co-digestion of winery wastewater with sewage sludge for methane production: Complementary feedstocks and potential direct interspecies electron transfer

Combining winery wastewater (WW) with sewage sludge (SS) in anaerobic co-digestion (AcoD) presents a promising approach for effective waste management and enhanced energy recovery. This study aimed to evaluate the efficiency and changes in microbial communities during the AcoD of WW with SS at 35 °C, using a mix of batch and semi-continuous testing methods. In the batch experiments, the highest hydrolysis rate (0.19 day−1) and methane production (285.61 ± 4.83 mL/g VS) were achieved at a WW:SS ratio of 3:2, exceeding those of SS mono-digestion by 126 % and 113 %, respectively. Furthermore, the semi-continuous experiments revealed a significant 30.0 % boost in the electron transport system activity and a notable 25.8 % increase in coenzyme F420 activity within the AcoD of WW with SS. Microbial analysis illustrated that AcoD of WW with SS significantly enriched the prevalence of potential genera associated with direct interspecies electron transfer (DIET), such as Longilinea, Bellilinea (genus of Chloroflexi), Syntrophomonas, Pseudomonas, Methanosarcina, and Methanobacterium species. Additionally, semi-continuous experiments demonstrated that AcoD facilitated interspecies hydrogen transfer between syntrophic bacteria and hydrogenotrophic methanogens, resulting in increased methane yield. Co-digestion of WW with SS is a more economical strategy that significantly enhances the stability of microbial communities through the use of complementary feedstocks. These results may offer valuable guidance for the efficient resource utilization of co-digestion processes involving WW and SS.

Effects of extended pin fins on the hydrothermal performance of double pipe heat exchanger

Double pipe heat exchangers (DPHEs) are crucial for effective heat transfer between two fluids in industrial processes, enhancing energy recovery and optimizing thermal performance. This study aims to enhance the efficiency of DPHEs by incorporating extended pin fins. DPHEs are vital in industrial applications for their efficient heat transfer, but optimizing their performance remains challenging. Extended pin fins, which are minor protrusions added to the heat exchanger’s surface, increase the surface area for heat transfer. A numerical study on DPHEs with pin fins of varying length ratios (R=1, 2, 3, and 4) is conducted, validating our model by comparing results with prior experimental data. Parameters such as Nusselt number (Nu), friction factor, thermal–hydraulic performance factor (TPF), and exergy efficiency across Reynolds numbers from 4400 to 9400 are calculated. The results indicate that pin fins significantly enhance heat transfer. The Nu increases by 163 %-242 % for different length ratios, while the friction factor decreases, showing reductions of 161 %-290 %. Exergy efficiency improves by 216 % with an R=4 design compared to a standard DTHE, and the TPF increases by 152 % with the R=4 configuration. These findings demonstrate the substantial benefits of using extended pin fins in improving the thermal performance of DPHEs.

Investigation of biochars derived from waste lignocellulosic biomass and insulation electric cables: A comprehensive TGA and Macro-TGA analysis

This study investigates the thermochemical decomposition and gasification performance of biochars produced from blends of waste lignocellulosic biomass and waste insulation electrical cables at varying temperatures. Characterization tests revealed changes, particularly in ash content (27.5 %–34 %) and elemental composition, with nitrogen content increasing notably in biochar samples compared to the original feedstock. Van Krevelen diagrams demonstrated a reduction in O/C and H/C ratios with increasing production temperature, resembling fossil fuels more closely. The thermogravimetric and the derived thermogravimetric profiles illustrated distinct degradation stages influenced by heating rates and production temperature. Macro-TGA tests provided insights into biomass residue behavior under gasification conditions, indicating higher reaction rates at elevated temperatures. Syngas analysis highlighted the impact of temperature and equivalence ratio on syngas composition, with higher temperatures favoring hydrogen-rich gas production. The observed trends in cold gas efficiency (42.61 %–50.40 %) and carbon conversion efficiency (45.83 %–50.40 %) underscore the significance of temperature control in maximizing gasification performance. Biochars produced at higher temperatures demonstrated superior gasification performance, suggesting potential for optimizing biochar production processes to enhance energy recovery and waste valorization.

Analysis on a five-spot well for enhancing energy recovery from silty natural gas hydrate deposits in the South China Sea

The five-spot well is a promising technique for enhancing the inherent low gas production rate from silty natural gas hydrate (NGH) reservoirs with low permeability in the South China Sea (SCS). However, the production characteristics and the responses to key geological and engineering factors are still unclear and warrants investigation. Herein, we first establish a three-dimensional reservoir model based on the SH2 NGH deposits at SCS with the implementation of a five-spot well. We systematically examine the gas production enhancement effect and the unexpected well-to-well interaction induced by long-term depressurization. A sensitivity analysis on the effects of bottomhole pressure (Pbtm), permeability (k) and hydrate saturation (SH) is conducted to elucidate the key factors controlling the gas production enhancement. Our results reveal that the five-spot well significantly improves the gas productivity with cumulative gas production increased to 4.12 times that of a single well over 10 years. The well interference on gas production is not significant in the early stage but becomes more significant as depressurization sustains. Due to the relatively slow pressure propagation at the inner well, contribution to gas production from the inner well decreases over time while the outer wells increase. Based on the sensitivity analysis, gas production increases with decreasing Pbtm, increasing k, and decreasing SH with Pbtm and k as the key controlling factors. The findings provide valuable design basis for the adoption of a multi-well system in enhancing gas production for targeted NGH reservoirs in the next field production trial at SCS.

Sewage sludge management and enhanced energy recovery using anaerobic digestion: an insight.

Sewage sludge (SS) is a potential source of bioenergy, yet its management is a global concern. Anaerobic digestion (AD) is applied to effectively valorize SS by reclaiming energy in the form of methane. However, the complex floc structure of SS hinders hydrolysis during AD process, thus resulting in lower process efficiency. To overcome the rate-limiting hydrolysis, various pre-treatment methods have been developed to enhance AD efficiency. This review aims to provide insights into recent advancements in pre-treatment technologies, including mechanical, chemical, thermal, and biological methods. Each technology was critically evaluated and compared, and its relative worth was summarized based on full-scale applicability, along with economic benefits, AD performance improvements, and impact on digested sludge. The paper illuminates the readers about existing research gaps, and the future research needed for successful implementation of these approaches at full scale.

Production of combustible gas via incorporating CO2 to pyrolysis of medicinal herbal waste

With the recent increase in the utilization of medicinal herbs, the generation of medicinal herbal waste has increased. However, conventional protocols for solid waste management (landfill and incineration) present environmental threats considering the complex chemical composition of medicinal herbal waste. Thus, this study introduces a thermochemical approach for managing medicinal herbal waste, focusing on conversion of red ginseng marc (RGM) into energy resource. This study explores an innovative strategy to maximize the production of pyrogenic gases using CO2 form improved syngas generation. The experimental results revealed an enhancement in CO from the pyrolysis of RGM under the CO2 condition in reference with the N2 condition, which was ascribed to gas-phased homogeneous reaction of CO2 with volatile matters liberated from RGM. Moreover, gas-phase reactions have proven to be effective in decreasing the benzene analogs, especially polycyclic aromatic hydrocarbons (PAHs), in pyrogenic liquids. To accelerate the gas-phase reaction rate, a nickel (Ni)-based catalyst was employed for the RGM pyrolysis. The introduction of Ni catalyst to the gas-phase reaction led to an CO enhancement (272 %) from the RGM pyrolysis in the presence of CO2. All experimental observations highlight the potential of incorporating CO2 in thermochemical conversion of RGM as an innovative way to enhance energy recovery.

Performance comparison of sCO[formula omitted] and steam cycles for waste heat recovery based on annual semi-transient modeling under complex industrial constraints

The increasing demand for energy efficiency is compelling industries to seek ways to save energy. Waste heat recovery plays a crucial role by optimizing fuel usage through combined heat and power generation. In recent decades, sCO2 technologies have emerged as potential contenders to traditional steam cycles. However, there is a noticeable gap in literature regarding case studies on integrating off-design behaviors of components in complex industrial environments. To address this gap, this study focuses on a specific scenario involving a waste incinerator already linked to a steam generator within a cogeneration setup, alongside a flue gas cleaning unit. The conventional steam bottoming cycle is innovatively replaced with an sCO2 cycle, and a comparison between the performance of the existing steam technology and a numerical sCO2 model is conducted. This comparison involves modeling the off-design behaviors of each component run hourly over a one-year period. Results show that the sCO2 setup increases the electric power generation by 25% with the global efficiency around 43%, compared to the initial 37.3%. These outcomes answer a need in literature by showing that, even in off-design, the higher exergy efficiency of the sCO2 setup is more advantageous. Unlike steam evaporation at constant temperature, sCO2 is less constrained by temperature limitations in the heater and allows for higher turbine inlet temperatures. Additionally, an economic assessment reveals a levelized cost of electricity between 8.5 and 16.7 $/MWhe. However, further advancements in component modeling and enhanced energy recovery from cooler/exhaust gases are identified as areas for future research.

Benefits from co-pyrolysis of biomass and refuse derived fuel for biofuels production: Experimental investigations

The application of renewable fuels and waste for energy production is crucial environmentally and economically. Co-pyrolysis of biomass and refuse derived fuel (RDF) offers a promising pathway for valuable products that combine various benefits including enhanced energy recovery, waste valorisation, improved product quality, and environmental sustainability. Consideration of specific feedstocks and optimization of process parameters are necessary to maximise the efficiency and effectiveness of the co-pyrolysis process. This work presents investigations of the co-pyrolysis process of lignocellulosic biomass wastes (rye straw and agriculture grass) and RDF. These biomasses ensure efficient decomposition. The RDF, high in carbon (78.5 %) and hydrogen (11.8 %), was predominantly plastic based. Based on Py-GC-MS studies at 600 °C, it was observed that the addition of RDF to biomass caused a significant decrease in the share of organic oxygen compounds among the released decomposition products. Laboratory tests were performed in a fixed-bed reactor for raw biomass and RDF and 1:1 and 3:1 biomass to RDF mass ratio. The results demonstrated that the yield of char production decreased with the addition of RDF, which promoted the bio-oil yield. Despite, RDF pyrolysis meets problems, it was proved that co-pyrolysis of biomass and RDF is a good solution for their utilization.

Enhancing energy recovery from aquaculture residual materials: a focus on anaerobic digestion of African catfish (Clarias gariepinus) sediment sludge

In Germany, warm water Recirculating Aquaculture Systems (RAS) are generally integrated with biogas plants. The process sludge produced in aquaculture could be utilized to generate energy. This study investigates the potential of process sludge from commercial African catfish (Clarias gariepinus) warm water RAS, alongside associated plant production residues (whole plants and pruning residues) for energy generation through anaerobic digestion. Biogas tests, including batch, semi-Continuous Stirred Tank Reactor (CSTR), and Upflow Anaerobic Sludge Blanket Reactor (UASB) were conducted. In batch, methane yields were 229 L(N) / kg VS from the sludge and 173–184 L(N) / kg VS from the various plant substrates (cucumber, paprika, and tomato plants). During CSTR operation, mono-fermentation of sludge produced a methane yield of 265 L(N) / kg VS. Co-fermentation with 25% cucumber residues, based on VS, increased this value to 381 L(N) / kg VS. Mono-fermentation of sludge in the UASB reactor yielded a maximum of 329 L(N) /kg VS. The relatively low TS content and unfavorable C/N ratio in C. gariepinus sludge, along with the low energy density and occasional high sulfur content in the investigated plant substrates, present challenges for CSTR biogas production. These challenges can be partially mitigated through substrate combination. For mono-fermentation of African catfish RAS sludge, the UASB reactor is recommended. Improved solids separation, extraction, and concentration techniques at aquaculture operations are essential for the efficient utilization of aquaculture sludge, especially from African catfish, in biogas plants.

Energy Efficiency Analysis of Waste-to-Energy Plants in Poland

The issue of enhancing energy recovery efficiency is a key concern within the European Union’s climate protection efforts. In particular, it applies to all processes and plants for the harvesting, gathering, and conversion of energy. The abandonment of fossil fuels in favour of alternative energy sources, and the increasing of energy efficiency and its recovery, is now a widely accepted direction of energy development. This study focuses on facilities that recover and process energy from municipal waste left after recycling processes, known as waste-to-energy (WtE) plants. These plants’ energy recovery efficiency is governed by the R1 Formula in EU countries. This report is based on an analysis of four years of operational data from selected Polish municipal waste incinerators, supplemented by a discussion of various studies on energy recovery efficiency. The primary objective of this report is to evaluate the effectiveness of these plants in contributing to sustainable waste management and energy recovery. The main effect of the developed report is the set of results of the energy recovery efficiency factor values, determined based on the R1 formula valid in the EU legislation, tabulated and graphically illustrated, and calculated for five selected Polish waste-to-energy plants. The presented results, with their graphical interpretation, discussion, and conclusions, provide insights into several factors influencing the value of the R1 efficiency factor. They can be a valuable contribution to operators of waste-to-energy plants, especially those operating in countries outside the EU.

Enhancing energy recovery in automotive suspension systems by utilizing time-delay

This study introduces time-delay active control technology to with the aim of enhancing the system's energy harvesting potential and ride smoothness. The time-delay active suspension represents a nonlinear, multivariable system, and stability analysis in this context is intricate. The mainly challenge lies in effectively leveraging time delay to augment the system's energy collection potential while harmonizing the vehicle's ride comfort and energy efficiency. Addressing this issue, our study proposes enhancing the suspension's energy recovery capability through time-delay control. Initially, the impact of time-delay control parameters on energy collection ability under various operational conditions was analyzed, establishing that appropriate time-delay parameters can enhance energy harvesting capacity. Subsequently, to balance the relationship between vehicle comfort and energy efficiency, the research introduces a method for constructing an optimized objective function based on linear equivalent excitation, thereby quantifying the relationship between system time-domain vibrational response, time-delay control parameters, and external excitations. This approach enables the comprehensive optimization of the suspension system's comfort, safety, and energy efficiency. The control system's stability was analyzed using cluster treatment of characteristic roots method. Finally, simulations and experiments were conducted to evaluate the effectiveness of time-delay active across different scenarios, confirming the efficacy of the proposed control methodology.

Research on regenerative braking control of electric vehicles based on game theory optimization.

The energy-efficient, clean, and quiet attributes of electric vehicles offer solutions to conventional challenges related to resource scarcity and environmental pollution. Consequently, thorough research into harmonizing energy recuperation during braking, enhancing vehicle stability, and ensuring occupant comfort in electric vehicles is imperative for their effective advancement. The study introduces a regenerative braking control strategy for electric vehicles founded on game theory optimization to enhance braking performance and optimize braking energy utilization. Develop a regenerative braking control approach based on the dynamic model of an electric vehicle equipped with hub motors. Employing game theory, we establish participants, control variables, strategy sets, benefit functions, and constraints to optimize the coefficient K for regenerative braking. The efficacy and superiority of the control strategy model are validated through joint simulations using Matlab/Simulink and AVL Cruise. Research findings indicate: (1) Speed tracking error remains below 3% in both NEDC and CLTC-P simulations, underscoring the effectiveness of the dynamic model and control strategy devised in this study. (2) The energy recovery rate achieved by the game theory-based optimization strategy surpasses that of the Cruise self-contained strategy and fuzzy control strategy by 18.06% and 4.5% in the NEDC simulation, and by 13.48% and 3.85% in the CLTC-P simulation, respectively. The adhesion coefficient curves implemented on the front and rear axles, derived from the game theory optimization control strategy, closely approximate the ideal adhesion coefficient curve, leading to a substantial enhancement in the car's braking stability. The degree of jerk magnitude regulated by the game theory optimization strategy consistently falls within the ±3 m/s³ threshold, resulting in a considerable enhancement in the comfort of vehicle occupants. These outcomes underscore the efficacy of the game theory-based optimized control strategy in enhancing energy recovery, braking stability, and comfort throughout the braking process of the vehicle.

Enhancing energy recovery from Wastewater Treatment Plant sludge through carbonization

The Wastewater Treatment Plant (WWTP) uses a dewatering machine to separate sludge from water. The resulting sludge is used as raw material for Refuse Derived Fuel (RDF), while the separated water is treated in the subsequent WWTP unit. However, the sludge from the WWTP is currently only processed into briquettes as per policy and then disposed of in landfills. Our investigation centers on the effects of carbonization temperature on sludge characteristics in a dewatering unit. Initial analysis revealed that 1-day-old sludge possesses a high moisture content (87.72 %) and a low calorific value (3.44 MJ/kg). Carbonization at 300 °C significantly enhanced the sludge's calorific value to 12,504 MJ/kg, reduced its moisture content to 60.72 %, and increased its carbon percentage to 22.76 %, indicating a direct correlation between carbonization temperature and both energy recovery and carbon content. Comparative analysis showed sludge carbonized at lower temperatures (200 °C and 100 °C) yielded lower carbon percentages (22.23 % and 21.66 %, respectively) and energy values, underscoring the efficiency of higher temperature carbonization in optimizing energy recovery.. This research contributes to developing sustainable organic waste recycling practices and supports achieving Sustainable Development Goals 11 and 12 targets. This research promotes sustainable development by improving sludge utilization from WWTPs as a raw material for energy production rather than being directly disposed of in landfills. This study provides insight into the potential for energy recovery from organic waste, technology, and policy's role in achieving a circular economy.

Impact of food waste addition in energy efficient municipal wastewater treatment by aerobic granular sludge process

Recently, one of the main purposes of wastewater treatment plants is to achieve a neutral or positive energy balance while meeting the discharge criteria. Aerobic granular sludge (AGS) technology is a promising technology that has low energy and footprint requirements as well as high treatment performance. The effect of co-treatment of municipal wastewater and food waste (FW) on the treatment performance, granule morphology, and settling behavior of the granules was investigated in the study. A biochemical methane potential (BMP) test was also performed to assess the methane potential of mono- and co-digestion of the excess sludge from the AGS process. The addition of FW into wastewater enhanced the nutrient treatment efficiency in the AGS process. BMP of the excess sludge from the AGS process fed with the mixture of wastewater and FW (195 ± 17 mL CH4/g VS) was slightly higher than BMP of excess sludge from the AGS process fed with solely wastewater (173 ± 16 mL CH4/g VS). The highest methane yield was observed for co-digestion of excess sludge from the AGS process and FW, which was 312 ± 8 mL CH4/g VS. Integration of FW as a co-substrate in the AGS process would potentially enhance energy recovery and the quality of effluent in municipal wastewater treatment.Graphical abstract

Anaerobic digestion of wastewater from hydrothermal liquefaction of sewage sludge and combined wheat straw-manure

Hydrothermal liquefaction (HTL) shows promise for converting wet biomass waste into biofuel, but the resulting high-strength process water (PW) requires treatment. This study explored enhancing energy recovery by anaerobic digestion using semi-batch reactors. Co-digesting manure with HTL-PW from wheat straw-manure co-HTL yielded methane (43–49% of the chemical oxygen demand, COD) at concentrations up to 17.8 gCOD·L-1, whereas HTL-PW from sewage sludge yielded methane (43% of the COD) up to only 12.8 gCOD·L-1 and complete inhibition occurred at 17 gCOD·L-1. Microbial community shifts confirmed inhibition of methanogenic archaea, while hydrolytic-fermentative bacteria were resilient. Differences in chemical composition, particularly higher levels of N-containing heterocyclic compounds in PW of sewage sludge, likely caused the microbial inhibition. The considerable potential of combining HTL with anaerobic digestion for enhanced energy recovery from straw-manure in an agricultural context is demonstrated, yet sewage sludge HTL-PW requires more advanced approaches to deal with methanogenesis inhibitors.

Insights into anaerobic digestion of microalgal biomass for enhanced energy recovery

This review paper delves into the intricate challenge of transforming microalgal biomass into biofuel through anaerobic digestion, elucidating its significance for sustainable energy production and waste management. Despite the promise anaerobic digestion holds, obstacles like inhibitory substances, process stability issues, and residue management complexities persist. Microalgal biomass, characterized by high biogas yields and carbon sequestration potential, emerges as a viable solution to enhance anaerobic digestion efficiency. Employing a comprehensive literature selection process, the review synthesizes recent studies to shed light on breakthroughs and pinpoint areas for future investigation. Key findings underscore advancements in microalgal biomass utilization, with strategic strain selection and innovative pretreatment methods resulting up to 25% increase in biogas production. Additionally, the assimilation of co-digestion techniques yields enhanced overall process efficiency. Microalgal biomass demonstrates remarkable carbon sequestration capabilities, sequestering up to 60% of CO2 during the anaerobic digestion process. Furthermore, the analysis reveals that despite inhibitory substances posing challenges, innovative approaches have reduced inhibition by 15%, promoting more stable and efficient digestion. Implications of the review findings stress the need to scale laboratory successes to industrial applications while maintaining environmental sustainability. Identified gaps include challenges in inhibitory substance management and process stability, with future research directions advocating for multidisciplinary approaches to unlock the full potential of microalgal biomass in anaerobic digestion. In conclusion, the review contributes significantly to understanding the intricate relationship between microalgal biomass and anaerobic digestion, highlighting the importance of continued research and development to address existing challenges and advance towards a more regenerative bioeconomy.