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Using waste biomass as feedstock to obtain high value-added chemicals has attracted increasingly more attention from the viewpoint of sustainable development. A novel renewable bio-based solid acid (LFuS) was prepared by a two-step sulfonation of the phenol-formaldehyde condensation product of sodium lignosulfonate (LS-Na) and furfural derived from industrial and agricultural organic wastes. LFuS was then firstly employed as a catalyst for the selective esterification of glycerol (GL) with acetic acid (HOAc) to produce a fuel bio-additive, a mixture of glycerol diacetates (DAG) and glycerol triacetate (TAG). Using LFuS achieved a 98.0% conversion of GL with the selectivity to DAG + TAG of 94.1% under milder conditions. Additionally, the obtained LFuS also exhibited an excellent reusability in this reaction, and no loss in glycerol conversion was observed after five cycles, with the corresponding selectivity to DAG + TAG only decreasing from 94.1% to 90.0% after five cycles. The high concentration of acid sites and the polyphenolic structure of LFuS are responsible for its excellent catalytic performance and reusability in selective esterification of glycerol reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, we have investigated the effect of water co-feeds on products distribution and coking behavior of a new composite catalyst in the MTG process. A novel ZSM-5/Beta bi-phase composite catalysts were synthesized via a hydrothermal crystallization method. Catalysts were all characterized by considering their crystallinity (XRD analysis), morphology (FE-SEM analysis), surface area, pore volume (N 2 adsorption/desorption technique), and acidity (NH 3 -TPD analysis). The catalytic performance of the synthesized catalysts was tested by the MTG reaction in WHSV of 20 h−1, the temperature of 400 °C, atmospheric pressure, and water content of 0, 10, and 20%. Over the ZSM-5/Beta composite catalyst, the methanol diluted with 10% water resulted in a 29% yield of gasoline compared with 21% over ZSM-5 and 66% selectivity to alkylated aromatics compared with 45% over ZSM-5. Adding water to the methanol had a key role in improving catalysts lifetime so that by using the feed with 10 wt% water, a lifetime about two times longer than pure methanol was observed. The higher activity over the ZSM-5/Beta sample co-feed with 10% water, was ascribed to overcoming the diffusion limitations and retarding catalyst deactivation in the presence of water. [ABSTRACT FROM AUTHOR]

Green hydrogen production technology based on photovoltaic (PV), battery energy storage system (BESS) and proton exchange membrane (PEM) water electrolysis plays a crucial part in the transition process of energy to zero carbon technology. But few studies have focused on achieving all-day continuous hydrogen production, which is the key to large-scale hydrogen utilization. In this study, we developed an off-grid PV-BESS-PEM system for hydrogen and oxygen production. Firstly, the PV, BESS and PEM water electrolysis components were modeled and model validation was performed. Secondly, an energy management strategy (EMS) is proposed to achieve the goal of continuous and stable hydrogen production. Then, a surrogate model between design variables and optimization objectives is established based on machine learning methods, and a multi-objective optimization algorithm is used to drive the optimization process. Finally, a case study of the PV-BESS-PEM system is presented based on solar irradiation data in Lhasa, where there is sufficient solar resources and oxygen demand. The results demonstrate that the EMS can satisfy the purpose of all-day continuous and stable hydrogen production. The number of cells in the electrolyzer and the water temperature have a significant effect on the hydrogen production and the electrolysis efficiency. And the optimal system has increased the hydrogen production by 16.80 % and the electrolysis efficiency of PEM by 12.08 %, respectively. Herein, the methodological framework is expected to provide theoretical guidance for large-scale water electrolysis hydrogen production applications based on solar energy. [Display omitted] [ABSTRACT FROM AUTHOR]

The need to reduce the carbon footprint of conventional energy sources has made green hydrogen a promising solution for the energy transition. The most environmentally friendly way to produce hydrogen is through water-based production using renewable energy. However, the availability of fresh water is limited, so switching to wastewater instead of fresh water is the key solution to this problem. In response to this issue, the present review reports the main findings of the research studies dealing with the feasibility of hydrogen production from wastewater using various technologies, including biological, electrochemical, and advanced oxidation routes. These methods have been studied in a large number of experiments with the aim of investigating and improving the potential of each method. On the other hand, the maturity of solar energy technologies has led researchers to focus on the possibility of harnessing this source and combining it with wastewater treatment techniques for the production of green hydrogen. Therefore, the present review pays special attention to solar driven hydrogen production from wastewater, by highlighting the potential of several technologies for simultaneous water treatment and green hydrogen production from wastewater. Recent results, limitations, challenges, possible improvements and techno-economic assessments reported by several authors, as well as future directions of research and industrial implementation in this field are reported. • The state of the art and recent findings on wastewater treatment and hydrogen production techniques are extensively reviewed. • Positive results confirming the sustainable efficiency of solar-driven techniques for hydrogen production are reported. • Techno-economic assessments of the potential of technologies for wastewater treatment and hydrogen production are addressed. • Limitations and challenges of scale-up for industrialization are reported in this review. [ABSTRACT FROM AUTHOR]

Green ammonia, a promising zero-carbon energy storage vector, has never been produced using solely tidal stream energy despite its predictable characteristics. Combining tidal stream sites with a phase difference (tidal phasing) facilitates anticorrelation between these sites' power profiles, enabling a more consistent power output. Green ammonia production benefits from a steady and predictable power input. The objective of this paper is to determine if nearby tidal sites have a large enough phase difference (anticorrelation) to reduce the cost of ammonia production. Moreover, producing green ammonia from underutilized or unutilized remote and grid-constrained tidal stream sites may enable viability of these sites. This paper is the first analysis of green ammonia production using solely tidal stream energy and the first analysis of tidal phasing for green fuel production. Two UK case studies are presented in i) the North Channel of the Irish Sea and ii) Orkney. There are tidal sites in each which have a phase difference (e.g. the Mull of Kintyre/Sound of Islay, and Graemsay/North Ronaldsay with correlation coefficients of 0.17 and −0.02 respectively), utilising this phase difference reduces the levelized cost of ammonia by 8% in the Irish Sea and by 12% in Orkney. [ABSTRACT FROM AUTHOR]

The hydrogen compressor is a key component in the refuelling station. As one type of hydrogen compressor, the ionic compressor applied in the refuelling station is essentially a liquid piston compressor. The structure and operating condition would significantly influence the system efficiency of the liquid piston compressor. This paper investigated the impact of three key operating factors on the compressor performance of a novel embedded two-piston compressor, based on which the optimal operating values were identified by the Taguchi method when the hydrogen was compressed from 12 to 45 MPa. It was revealed that the movement time ratio of Piston A was the dominating factor for the power consumption and specific consumption while the upward time ratio of Piston B was the most influential parameter for the mass delivered. The optimal combination was 0.4 for the movement time ratio of Piston A, 0.45 for the upward time ratio of Piston A and 0.5 for the upward time ratio of Piston B. Under the predicted optimal operating conditions, the lowest specific energy consumption was obtained as 2733.75 kJ/kg. [ABSTRACT FROM AUTHOR]

An innovative tandem photoelectrochemical cell with a scaled-up active area from 0.25 to 25 cm2 based on low-cost and non-critical raw materials was employed to produce green hydrogen by water splitting. It uses a photoanode/membrane/photocathode tandem cell configuration in which a hematite-based photoanode is layered on a fluorine-doped tin oxide glass for the oxygen evolution reaction, CuO is deposited on a hydrophobic gas diffusion layer as the photocathode for the hydrogen evolution reaction and an anion exchange membrane is used as the electrolyte and gas separator. The solid membrane's low hydrogen and oxygen crossover guarantees the operational stability of the tandem photoelectrochemical cell and the efficient separation of water-splitting products. Significant efforts have been focused on scaling up the cell. It has allowed obtaining, for the first time, a 25 cm2 unit cell prototype. Appropriate design approaches have been considered to optimise water/gas management, current collection, gas-tightness and clamping. The adopted architecture allowed for the reduction of the bias-potential from −1.23 V, generally employed to investigate PEC cells, up to −0.6/-0.4 V 20 h-durability tests demonstrated good resistance to corrosion, showing a constant photocurrent. Efficiency at −0.6 V was about 0.2%. Selective hydrogen production was demonstrated by mass spectrometric analysis. [ABSTRACT FROM AUTHOR]

This work is focused on analyzing the efficiency of using "green" hydrogen as a fuel for power generation systems. Three main stages of the process were considered: hydrogen production through electrolysis, hydrogen compression for transportation, and hydrogen utilization as a fuel in a combined cycle power plant. It was established that LHV efficiency of alkaline water and proton-membrane electrolysis is up to 70% and 85%, respectively. The thermodynamic analysis of hydrogen compression showed that the energy consumption per 1 kg of hydrogen to compress from 20 bar to 600 bar is 1.51 kWh with the utilization of waste-heat in an Organic Rankine Cycle (ORC), and 1.77 kWh without ORC. This energy consumption corresponds to losses of 4.5% and 5.3% of hydrogen LHV, respectively. The energy analysis of using hydrogen as a fuel was performed for pure hydrogen and hydrogen-methane blends of different compositions. An increase in the hydrogen volume fraction in the fuel increases LHV efficiency and decreases HHV efficiency. When fuel with 100% H 2 is used, HHV and LHV efficiency are 48.7% and 57.5%, respectively. The real efficiency of transforming renewable energy via hydrogen as an energy carrier into electricity in combined cycle power plants is about 38%. • Considering and comparing the green hydrogen production systems. • Industrially achieved level of green hydrogen production efficiency is up to 85%. • Hydrogen compression to 600 bar takes up to 5% of hydrogen LHV. • Efficiency of hydrogen utilization as a fuel for power generation is up to 60%. • Energy efficiency of system "green hydrogen production, compression, and utilization as a fuel" is about 40%. [ABSTRACT FROM AUTHOR]

While geothermal energy is typically associated with beneficial environmental effects, it is crucial to acknowledge that it can lead to greenhouse gas emissions. Therefore, the implementation of geothermal systems should include an environmental assessment. This study presents and evaluates an innovative geothermal-powered bi-evaporator poly-generation system from seven perspectives: thermodynamic, extended-environmental, exergoenvironmental, exergoeconomic, net present value, and bi-objective optimization. The designed ploy-generation system comprises a desalination unit, a unit for extracting hydrogen, and a modified organic flash cycle, all integrated with a single geothermal flash cycle. These subsystems work in unison to create a comprehensive and integrated system for simultaneously generating purified water, green hydrogen, electricity, and meeting refrigeration load requirements. Regarding the findings at the base mode, the designed system is able to generate net power, refrigeration load, distilled water, and H 2 production rates of 244.9 kW, 741.4 kW, 0.4443 kg/s, and 1.062 kg/h, respectively. By employing NSGA-II optimization, the values of commodities are substantially increased, which enhanced the poly-generation system product cost and energetic efficiency by 7.13 % and 30.48 %. Also, the net electricity selling price significantly affects NPV, so the payback period reduces to 8.56 years. • Introducing a Bi-Evaporator Poly-Generation System (BEPGS) powered by geothermal energy. • Using extended- and exergo-environmental aspects is an innovative method first applied to BEPGS. • Selling price of the net electricity has a significant effect on the net present value (NPV). • With increasing booster pressure ratio, cooling capacity enhances by 195.40%. • The optimum value for the Cost of Poly-Generation System (CPGS) was 48.84 $/GJ. [ABSTRACT FROM AUTHOR]

Geothermal energy is one of the largest renewable energy sources available in Mexico and is the most important non-conventional renewable energy source utilised in this country. It is estimated that Mexico has geothermal reserves of approximately 8000 MWe, which can be implemented for the generation of green hydrogen. The paper focuses on the geothermal energy potential of high-enthalpy resources dominantly found South and Southeast Mexico, through investigations of 12 hot springs, with temperature depths as high as 400 °C in some areas. The utilization of suitable power production equations is further refined using the Monte Carlo Method to optimize the numerical findings of the power potential. Therefore, the Visual Basic Application (VBA) in Microsoft Excel is used through the Visual Basic Editor (VBE) function to code the Volumetric Method Equations. Furthermore, 20,000 iterations are then simulated to produce the minimum and maximum power potential/capacity (MWe), from which 10 % and 90 % confidence intervals are then determined. The study calculates that, considering a production lifetime range of 25 years, a total of 147.57 MWe of geothermal power capacity could be generated across all 12 hot springs in Mexico. [ABSTRACT FROM AUTHOR]

This research focused on utilizing photoautotrophically-cultivated microalgae as efficient converters of CO 2 into high-quality renewable biodiesel. This study investigated the feasibility of capturing CO 2 from the atmosphere (0.04 % CO 2) and simulating industrial sources (20–40 % CO 2) for utilization as a simulated waste carbon source for the growth and biodiesel feedstock accumulation of three photoautotrophically-cultivated microalgae species, including Chlorella sp. AARL G049, Tetradesmus obliquus AARL G090, and Desmodesmus opoliensis AARL G085. The results demonstrated that all the tested microalgae are promising CO 2 -to-fuel converters due to their ability to efficiently convert CO 2 into lipid-rich biomass, which can subsequently be processed into biodiesel. All three strains of microalgae displayed remarkable CO 2 capture capabilities as well as significant biomass production and lipid accumulation, with the highest performance observed under a 20 % CO 2 concentration. The microalgae demonstrated CO 2 fixation rates ranging from 0.020 to 0.072 g-CO 2 /L/day, leading to significant improvements in both biomass productivity, which ranged from 0.011 to 0.040 g/L/day, and lipid accumulation, which ranged from 0.22 to 3.39 mg/L/day. Additionally, the lipid content varied between 5.04 % and 14.75 %. Interestingly, changes in CO 2 concentration, ranging from 0.04 % to 40 %, significantly influenced the composition of fatty acids, leading to elevated levels of C16–C18 fatty acids. Nevertheless, these alterations had a minimal impact on the overall quality of biodiesel. The estimated fuel characteristics of the produced biodiesel complied with global specifications for biodiesel, providing better oxidative stability (≥6 h), high heating value (≥39 MJ/kg), and cetane number (≥47). Therefore, this study emphasizes sustainable CO 2 capture and the potential of microalgae as a renewable source of economically viable biodiesel. [ABSTRACT FROM AUTHOR]

In response to the demand for clean, renewable energy sources and storage technologies, innovative materials and combinations have been developed at reasonable prices as effective electrode materials. Current research and development of carbon-based metal-free catalysts have opened up new research areas for bifunctional electrocatalysts for overall water splitting. Herein, we developed N-self-doped defect-rich porous carbon nanosheets derived from platycladus orientalis tree-cone biomass for overall water splitting. The developed N-self-doped defect-rich porous carbon nanosheets have large surface areas (3369 m2/g), high pore volumes (2.1 cm3 g−1), and high electrical conductivities (12.69 S/cm). N-self-doped defect-rich porous carbon nanosheet framework was employed in water splitting as a dual function in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Electrodes fabricated from the KOH-II ABC nanosheets show excellent OER and HER performances in the 0.5 M H 2 SO 4 solution. The current density of 10 mA cm−2 is reached at a low overpotential of 90 mV for OER and 188 mV for HER. In addition, KOH-II ABC nanosheets also show a remarkable performance on overall water splitting, which only required a cell voltage of 1.49 V to reach current densities of 10 mA cm−2 in 0.5 M H 2 SO 4 solution. The presence of defects in the carbon nanosheets, higher specific surface area, excellent electrochemical active surface area and N doping effectively enhance the reaction kinetics for attaining efficient OER and HER performances. This facile approach to preparing biomass-derived N-doped defect-rich porous carbon materials empowers next-generation green fuel conversion technologies for carbon neutrality. [Display omitted] [ABSTRACT FROM AUTHOR]

This research focused on utilizing photoautotrophically-cultivated microalgae as efficient converters of CO 2 into high-quality renewable biodiesel. This study investigated the feasibility of capturing CO 2 from the atmosphere (0.04 % CO 2) and simulating industrial sources (20–40 % CO 2) for utilization as a simulated waste carbon source for the growth and biodiesel feedstock accumulation of three photoautotrophically-cultivated microalgae species, including Chlorella sp. AARL G049, Tetradesmus obliquus AARL G090, and Desmodesmus opoliensis AARL G085. The results demonstrated that all the tested microalgae are promising CO 2 -to-fuel converters due to their ability to efficiently convert CO 2 into lipid-rich biomass, which can subsequently be processed into biodiesel. All three strains of microalgae displayed remarkable CO 2 capture capabilities as well as significant biomass production and lipid accumulation, with the highest performance observed under a 20 % CO 2 concentration. The microalgae demonstrated CO 2 fixation rates ranging from 0.020 to 0.072 g-CO 2 /L/day, leading to significant improvements in both biomass productivity, which ranged from 0.011 to 0.040 g/L/day, and lipid accumulation, which ranged from 0.22 to 3.39 mg/L/day. Additionally, the lipid content varied between 5.04 % and 14.75 %. Interestingly, changes in CO 2 concentration, ranging from 0.04 % to 40 %, significantly influenced the composition of fatty acids, leading to elevated levels of C16–C18 fatty acids. Nevertheless, these alterations had a minimal impact on the overall quality of biodiesel. The estimated fuel characteristics of the produced biodiesel complied with global specifications for biodiesel, providing better oxidative stability (≥6 h), high heating value (≥39 MJ/kg), and cetane number (≥47). Therefore, this study emphasizes sustainable CO 2 capture and the potential of microalgae as a renewable source of economically viable biodiesel. [ABSTRACT FROM AUTHOR]

In response to the demand for clean, renewable energy sources and storage technologies, innovative materials and combinations have been developed at reasonable prices as effective electrode materials. Current research and development of carbon-based metal-free catalysts have opened up new research areas for bifunctional electrocatalysts for overall water splitting. Herein, we developed N-self-doped defect-rich porous carbon nanosheets derived from platycladus orientalis tree-cone biomass for overall water splitting. The developed N-self-doped defect-rich porous carbon nanosheets have large surface areas (3369 m2/g), high pore volumes (2.1 cm3 g−1), and high electrical conductivities (12.69 S/cm). N-self-doped defect-rich porous carbon nanosheet framework was employed in water splitting as a dual function in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Electrodes fabricated from the KOH-II ABC nanosheets show excellent OER and HER performances in the 0.5 M H 2 SO 4 solution. The current density of 10 mA cm−2 is reached at a low overpotential of 90 mV for OER and 188 mV for HER. In addition, KOH-II ABC nanosheets also show a remarkable performance on overall water splitting, which only required a cell voltage of 1.49 V to reach current densities of 10 mA cm−2 in 0.5 M H 2 SO 4 solution. The presence of defects in the carbon nanosheets, higher specific surface area, excellent electrochemical active surface area and N doping effectively enhance the reaction kinetics for attaining efficient OER and HER performances. This facile approach to preparing biomass-derived N-doped defect-rich porous carbon materials empowers next-generation green fuel conversion technologies for carbon neutrality. [Display omitted] [ABSTRACT FROM AUTHOR]

Recent advances in biohydrogen production using plasma processes have brought opportunities to replace fossil fuels with a sustainable and green source of energy from biomass. This work provides a comprehensive elucidation regarding the principal concepts, procedures, benefits, and drawbacks of plasma-based biomass conversion processes to produce hydrogen (H 2) including pyrolysis, reforming, and gasification. In the past, plasma was considered as alternative process for H 2 production, and this paper surveys the impact of process variations and catalysts reported in recent research to foster the performance of possible plasma-based H 2 production processes, including both non-thermal plasma (NTP) and thermal plasma (TP). Recent research has opened new, multifacetted directions for plasma applications of biomass. This includes biogas conversions to syngas and other gases, NTP for biomass-derived tar compound conversion, combination of biomass gasification and NTP reforming employing a two-stage reactor, and biomass thermal pretreatment. Several approaches are introduced, including the advancement of catalysts within plasma conversion processes, along with novel strategies to enhance the efficiency of plasma-based H 2 production and productivity, which are thoroughly examined and deliberated upon. This review aims to answer three questions: Can plasma be applied to convert various kinds of biomass into H 2 with sustainability? For which of the process steps from biomass to H 2 involved does plasma suit? When is NTP needed, when TP? • Plasma technology has potential to assist the conversion of biomass to generate H 2. • Plasma can be applied to convert various kinds of biomass into H 2 with sustainability. • The applicability of thermal plasma and non-thermal plasma is clarified. • Drawbacks to overcome have also been outlined. • Several approaches are required to render plasma catalysis as a sustainable and economical technology. [ABSTRACT FROM AUTHOR]

In the present study, we report an efficient vapor-phase catalytic process operating on a hierarchically porous non-noble metal decorated HZSM-5 catalyst to produce high octane aromatics-rich hydrocarbon-stock and valuable fuel gases from crude-glycerol in the presence of methanol. A novel hierarchically porous HZSM-5 catalyst (synthesized by 0.2 M alkali solution followed by 1 wt% Zn loading) exhibited 100% carbon conversion of glycerol-methanol with superior aromatics selectivity >80% with a prolonged catalyst lifetime. Here, the combination of well-preserved micropores and optimum Lewis acidity observed in the synthesized catalyst are collectively responsible for enhanced aromatics selectivity, while mesopores of the catalyst help in the ease of diffusion of bulky product molecules (including coke precursor) to facilitate improved catalyst lifetime. The liquid stock possessing aromatics-rich hydrocarbons with high octane rating (RON 92) is suitable for gasoline blending applications. The C 3 –C 4 and H 2 gases formed as byproducts also attract LPG and green fuel applications. Overall study indicates that the co-processing of glycerol with methanol facilitated higher carbon atomic efficiency for the production of gasoline stocks. The reaction environment with a higher H/C eff also contributed to the improved product quality and catalyst life that attracts sustainable features of the process. The present study reports the efficient production of gasoline range aromatics-rich hydrocarbons and H 2 enriched LPG gas from bio-diesel derived crude glycerol over a hierarchically porous 1Zn/HZSM-5(0.2) catalyst, suitable for sustainable fuel applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMWW) management is recognized as the major defy that olive oil industry is facing. Recently, we have established an eco-friendly strategy for the OMWW conversion into irrigation water sources, green biofuels and biofertilizers. This work is a part of a series of papers detailing the different steps established in this environmental friendly strategy for OMWW management. It deals with the bio-oil production and characterization during the pyrolysis of OMWW impregnated on olive pomace (OP) in a pyrolyzer pilot. Results show a bio-oil production yield of 36 wt% during the pyrolysis test. This yield could be attributed to the recovery of organic compounds from OMWW through OP impregnation and their conversion to bio-oil. The bio-oil properties show that viscosity and flash point values could reach the European standards. However, the lower heating values (26 MJ/kg) and the acidic character limit its direct use. These values are attributed to the higher water and oxygen contents. The GC/MS analysis confirms these properties showing the presence of phenolic molecules and long chain organic acids. Therefore, OMWW impregnation on OP and pyrolysis could be considered as a promising issue for bio-oil production. However, this bio-oil requires an upgrading step for a better valorization. • A strategy for olive mill wastes recovery is established using pyrolysis technique. • A bio-oil production yield of 36% confirms the OMWW organic matter valorization. • Bio-oil viscosity and flash point properties could reach biofuels Standards. • Bio-oil contains many components as phenolic molecules and long chain organic acids. • Oxygen and water contents, acidic pH require improvement before bio-oil direct use. [ABSTRACT FROM AUTHOR]