Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties with many promising application prospects, such as photoelectric detectors, nonlinear optics, ...infrared photoelectric devices, and ultrafast photonics. Among them, ultrafast photonics has attracted much attention due to its enormous advantages; for instance, extremely fast pulse, strong peak power, and narrow bandwidth. In this work, SnSe2 nanosheets are fabricated by using solvothermal treatment, and the characteristics of SnSe2 are systemically investigated. In addition, the solution of SnSe2 nanosheets is successfully prepared as a fiber‐based saturable absorber by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode locking is generated in an Er‐doped fiber laser, corresponding to the maximum repetition rate of 257.3 MHz and pulse duration of 887 fs. The results show that SnSe2 can be used as an excellent nonlinear photonic device in many fields, such as frequency comb, lasers, photodetectors, etc.
Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties. SnSe2 nanosheets fabricated by using solvothermal treatment are successfully prepared as fiber‐based saturable absorbers by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode‐locking is generated, corresponding to 257.3 MHz repetition rate.
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•Precooling is an energy–intensive section due to large temperature difference.•Process enhancement using two precooling cycles with addition of HFO in 1st cycle.•Energy consumption ...of precooling section reduced from 4.197 to 2.83 kWh/kgLH2.•Specific energy consumption of process is 4.55 kWh/kgLH2 with 67% exergy efficiency.•Annual cost of proposed process is $1.89 × 106/y and $5.18/kg LH2 at 1TPD.
Hydrogen liquefaction can be one of the effective and viable solutions to enhance its energy contents for storage and transportation purposes. However, liquefaction of H2 is highly energy intensive where precooling is the most significant energy consumption section (∼50% of overall process) due to huge reduction in temperature (25 to −159.4 °C). In this context, in proposed study the precooling cycle is split into two cycles for reducing the energy consumption, 1) Hydrofluoroolefin–based mixed refrigerant stream which reduces the H2 temperature to −30 °C and 2) Mixed refrigerant stream which tends to reduce the H2 temperature up to −159.4 °C. This is the first study which utilizes the four refrigeration cycles with unique selection of HFO–based mixed refrigerants in precooling section to reduce the gaseous H2 temperature. Results of proposed study reveal that the specific energy consumption of proposed process was reduced by 55.2 % and 29.5%, as compared to base case–I (10.15 kWh/kgLH2) and base case–II (6.45 kWh/kgLH2), respectively. The exergy efficiency of the proposed process was increased by 67%. In addition, results of economic evaluation depicted that the total annualized cost of proposed process was obtained as $1.89 × 106 /y where the CAPEX has share of ∼ 71.7% in total cost of project. The estimated unit production cost was recorded as $5.18/kg of LH2 at the capacity of 1TPD. The simplicity and less energy consumption of proposed model built a basis for its development to commercial scale adoption.
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•ILs have high CO2 uptake, high thermal stability, and negligible vapor pressure.•Process systems engineering aspects of ILs for biogas upgrading were evaluated.•High cost, ...operational, and technical issues are major hurdles in commercialization.•LCA a is crucial for ILs to quantify the relevant emissions compared to amines.•Wide range of solubility data is required to assess the process design feasibility.
Biogas has emerged as an alternative renewable fuel to natural gas. However, the presence of trace contaminants and large quantities of CO2 in biogas necessitates its purification and upgrading to increase its calorific value. Different technologies have been developed to upgrade biogas to biomethane. Among these, chemical absorption is commonly employed due to its high process efficiency and less solvent requirement due to high selectivity compared to physical absorption. However, the chemical decomposition of amine-based solvents, toxicological impact, high plant maintenance costs, high enthalpy of reaction, and corrosivity associated with chemical absorption limit its large-scale application. Recently, ionic liquids (ILs) have garnered attention as alternative absorption media to conventional solvents. ILs have a high CO2 uptake, thermal stability, and negligible vapor pressure. Recent process simulation studies featuring ILs as solvents for biogas upgrading reveal the suitability of these approaches as alternatives to laborious experimental work to assess the practical, technical, and economic viability of ILs. As per the authors' knowledge, this is the first review comparing biogas upgrading technologies from a technical, environmental, and economic perspective. Primarily, studies relating to IL-based biogas upgrading are considered, and challenges associated with the large-scale adoption of ILs as absorption media are discussed. Process simulations and techno-economic assessments of IL-based biogas upgrading techniques are presented. A conceptual design approach is proposed for the successful scale-up of IL-based biogas upgrading. Based on results, deep eutectic solvents are recommended as next-generation solvents for absorption as technical and economic aspects are found superior to conventional amines and ionic liquids.
Two-dimensional (2D) transition metal dichalcogenide materials have attracted much attention in recent years due to their excellent electro-optical properties. FeS
, the ideal composition of iron ...pyrite, is a 2D transition metal dichalcogenide which has been potentially used in the electronic, optical, and chemical fields. On the other hand, the narrow band gap of FeS
(≈0.96 eV) makes it very suitable and promising for the ultrafast application in near-infrared regimes. However, the potential application of FeS
in laser technology has not been explored till now. Ultrashort pulse lasers have great applications in industry and science because of its stability, ease of operation, and portability. Passively mode-locked fiber lasers using 2D materials (such as MoS
, CuS
, and WS
) as saturable absorber are intensively investigated. Here, layered FeS
has been characterized systematically. It is successfully applied in ultrafast photonics and plays a key component in the passively mode-locked laser for the first time. The single pulse can be obtained with 1.7-ps pulse duration, 1.89-nm spectral width, and fundamental repetition of 6.4 MHz at 1563 nm central wavelength. Through controlling the pump power, the evolution of the pulse train can be observed, which can be transformed from single pulse to bound states. Also, the harmonic mode-locked fiber laser is observed with the pump power high enough.
•An integrated energy system of SNG production is proposed with net zero CO2 outflow.•SOEC–based water electrolysis was used which accounts specific power 35.56 kW/kgH2.•Heat recovery from SNG ...production was achieved by Rankine cycles with 1.8 MW power.•Efficiency of proposed integrated system for PtM technology was obtained as 77.3%•SNG unit production price was calculated as 0.223 $/kWh.
Integrated energy systems are getting high attention due to their synergistic effects on both the energy efficiency and process economy. This study demonstrates the similar effect of coupling four processes such as solid oxide electrolyzer cell (SOEC)-based hydrogen production from renewable energy, synthetic natural gas (SNG) production, steam Rankine cycle (SRC) for energy recovery, and amine-based SNG upgrading. Integration of two SRCs with SNG produces 1.8 MW of power that is assumed to reduce the load on SOEC. In addition, monoethanol amine (MEA)-based chemical absorption provides two benefits comprising SNG upgrading and capture of unreacted CO2. The proposed process integration claims the net zero output of CO2 in purified SNG stream as the captured CO2 is recycled back to the SNG reaction system for process enhancement. Conclusively, proposed integrated process synergistically enhances the SNG production efficiency by up to 86 % while the whole integrated process efficiency is calculated at 77.3 %. Corresponding to process economy, unit production price of SNG is observed to be 0.223 $/kWh, which is comparable to other existing processes. Moreover, methane parity analysis and future predictions are made with expected natural gas price to estimate the possible reliance on SNG in coming decades.
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•Straw-based black liquor was employed to generate H2 via biological dark-fermentation.•Anaerobes immobilised on magnetite nanoparticles improved HY by 2.3-folds.•Digestate-derived ...biochar enjoyed carbonization properties for using as soil amendment.•Study outcomes are linked to paper industry; crops cultivation; bio-energy production.•H2/biochar promotes sustainable development goals: environmental; economic; social.
Black liquor (BL) rich phenolic and complex compounds is generated from pulp and paper mill manufacturing processes which should be treated before reaching the environment. The potential of achieving several sustainable development goals (SDGs) by recovering energy and valuable by-products from BL was extensively investigated. Results revealed that under a dark-fermentation process, the organic content in BL was effectively bio-degraded by anaerobes to achieve a hydrogen yield (HY) of 0.62 ± 0.04 mol/molglucose. Fortunately, the HY was significantly increased up to 1.41 ± 0.13 mol/molglucose by immobilizing the anaerobes onto magnetite nanoparticles (MN). α-amylase, xylanase, CM-cellulase, polygalacturinase, and protease enzymes activities were increased by 2.3, 23.7, 2.7, 26.8, and 31.1 folds with supplementation of MN. Moreover, the conversion efficiencies of protein and carbohydrate were improved by values of 36 and 113.3% and total phenolic compounds (TPC) were enhanced by 23.5% compared with the control test. Electron-equivalent and COD mass balances were estimated to comprehensively describe the effect of Mn supplementation on the HY performance and fermentation pathways. Digestate generated from the fermentation process was utilized to produce biochar, having C (58.2%), O (32.4%), Na (4.7%), and P (1.1%). The study outputs were interlinked to bio-energy generation, pollution minimization, biochar as a soil amendment, nanoparticles and paper manufacturing industrialization, meeting environmental, economic, and social related SDGs.
Solubility prediction, process design, and energy analysis of mixed gases in deep eutectic solvent to mitigate energy and climatic concerns.
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•A novel ML–based LSTM autoencoder model ...for predicting solubilities of gases in DES.•Predicted solubilities are used in process modelling.•≥90% recovery and ≥99% purity of H2 is obtained from complex gas mixture.•Specific power consumption is calculated as 6.03 kWh/kg H2.•Regeneration energy is 3.02 MJ/kg CO2 with ≥99% removal of CO2 from the system.
Deep eutectic solvents (DES) are used as a green sustainable alternative to room temperature ionic liquids (RTILs), given their low cost and environmentally friendly nature. In this work, solubilities of CO2, CO, CH4, H2 and N2 gases in choline chloride/urea (ChCl/Urea) based DES is investigated. Experimental solubility data from literature is used to train machine learning models to predict the solubilities of different gases in ChCl/Urea at temperatures ranging from 298.15 K to 372.15 K and pressure ranging from 0.01 to 5 MPa. In this context, a Support Vector Machine and Long Short-term Memory Auto Encoder–based hybrid machine learning model is proposed. The hybrid model exhibited excellent prediction accuracy with low root mean square error values of 0.000985, 0.00055, 0.00037, 0.000583 and 0.000164 for CO2, CO, CH4, H2 and N2, respectively. The predicted solubility data is regressed in commercial software Aspen Plus V11 for process design of H2 separation from gaseous feed mixture. Complex feed mixture consisting of CO2, CH4, H2, CO, and N2 is absorbed in ChCl/Urea. As a result, hydrogen is recovered and purified from complex feed mixture at specific energy consumption of 6.03 kWh/kgH2. Furthermore, carbon removal is observed as > 99% from feed gas at the expense of 3.02 MJ/kgCO2.
Sustainable scale-up of biomethane to overcome the dependency on fossil energy sources is still not matured, fundamentally owing to its production and availability at a lower pressure (i.e., ...atmospheric) compared with the conventional natural gas. This is a fundamental assessment that specifically aims to overview the biogas production, cleaning technologies, upgrading technologies, and possible biomethane liquefaction technologies. The digestion technologies for biogas production are analyzed in terms of their important operating and performance parameters corresponding to optimum digester operation. The cleaning and upgrading technologies are assessed corresponding to their competitive factors, merits, and associated challenges. Cryogenic separation relies on different technologies that are based on different mechanisms (anti-sublimation, distillation, etc.). These technologies have been recently studied for CO2 removal from high CO2-content natural gas, showing promising results for application to biogas upgrading, in particular if the final goal is liquefaction. Since liquefaction itself is an energy- and cost-intensive process, cryogenic separation is synergistic in obtaining upgraded and liquefied biomethane in a single process unit, instead of integrating liquefaction with other upgrading technologies. Among all available liquefaction technologies, the nitrogen expander-based liquefaction processes are most promising candidates to produce liquified biomethane (LBM), mainly due to small investment costs, simple operation, and compact design. This study suggests that there is a need to design energy-efficient small-scale biomethane liquefaction processes following biogas upgrading. Thus, incorporating biogas in the energy mix would result in economic, environmental, and climate benefits, globally.
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•An assessment of liquefied biomethane supply chain is presented.•Biogas digestion systems along with their performance parameters are analyzed.•A comparative features of typical approaches to upgrade biogas to biomethane.•Liquefaction is suggested for the feasible and economic transportation of biomethane.•Challenges and future research directions of biogas industry are identified.
Fe3O4 nanoparticles (FONPs) are magnetic materials with a small band gap and have well-demonstrated applications in ultrafast photonics, medical science, magnetic detection, and electronics. Very ...recently, FONPs were proposed as an ideal candidate for pulse generation in fiber-based oscillators. However, the pulses obtained to date are on the order of microseconds, which is too long for real application in communication. Here, we report the use of FONPs synthesized by a sol–hydrothermal method and used as a saturable absorber (SA) to achieve nanosecond pulses in an erbium-doped fiber laser (EDFL) for the first time. The proposed fiber laser is demonstrated to have a narrow spectral width of around 0.8 nm and a fixed fundamental repetition rate (RPR) of 4.63 MHz, whose spectra and pulse dynamics are different from the mode-locked lasers reported previously. It is demonstrated that the proposed fiber laser based on a FONP SA operates in the giant-chirp mode-locked regime. The most important result is the demonstration of a pulse duration of 55 ns at an output power of 16.2 mW, which is the shortest pulse based on FONPs for EDFLs reported to date. Our results demonstrate that the FONP dispersion allows for an excellent photonic material for application in ultrafast photonics devices, photoconductive detectors, and optical modulators.
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