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With possible food crises looming in the near future, urban farming, including small-scale community and home gardens for home consumption, presents a promising option to improve food security in cities. These small-scale farms and gardens often use planter boxes and raised beds filled with lightweight soil or potting mixes. While previous studies on biochar focused on its application on large-scale contiguous farmlands, this study aimed to evaluate the suitability of biochar as a partial soil substitute to produce a durable and lightweight soil-biochar mix for small-scale urban farms. The effects of biochar on the chemical properties of the soil-biochar mix, crop yield and, particularly, crop nutrients and metabolic content were assessed. A germination test using pak choi seeds (Brassica rapa L. cultivar group Pak choi, Green-Petioled Form) showed that the biochar contained phytostimulants. Through a nursery pot experiment over four growth cycles, biochar treatments performed better than pure soil at retaining water-soluble NO3- and K+ ions, but were worse at retaining PO43- ions. Nonetheless, despite its positive effect on soil NO3- retention, biochar application did not improve crop yield significantly when the application rate varied from 0% to 60% (v/v). Untargeted metabolomic analyses showed that biochar application may increase the production of carbohydrates and certain flavonoids and glucosinolates. The results of this study showed that biochar can potentially be used to improve pak choi nutritional values and applied in large quantity to obtain a lightweight soil mix for urban farming.

Chemical reaction induced particle collision and aggregations in gas-solid phase reaction were presented in this work. The characteristics of particle collision and aggregations in non-catalytic gas-solid phase reaction- petcoke particles combustion process in air was experimentally analyzed. The reason for the formation of different aggregation structures is the reactant concentration distribution and particle position. Different spatial positions of solid particles caused the non-uniform concentration distribution of gaseous reactant and product around particle surface. The non-uniform distribution of gaseous reactant results in cohesive force, which lead to particle collision and aggregations. The aggregates of multi-particles tend to show “I” and “L” structure with the effect of cohesive force and drag force. Simulation work also were conducted to analyze the reactant and product concentrations, release velocity of product and bearing force of solid particles. The mechanisms of different particle aggregation patterns were demonstrated.

To manage the mixture of food waste and plastic waste, a hybrid biological and thermal system was investigated for converting plastic-containing food waste (PCFW) into renewable energy, focusing on performance evaluation, microbial community analysis, and energy balance assessment. The results showed that anaerobic digestion (AD) of food waste, polyethylene (PE)-containing food waste, polystyrene (PS)-containing food waste, and polypropylene (PP)-containing food waste generated a methane yield of 520.8, 395.6, 504.2, and 479.8 mL CH

Pressurized oxy-fuel combustion (POFC) of solid fuels in fluidized beds possess the potential for CO2 capture at low cost. However, the practical experience of oxy-coal combustion in pressurized fluidized beds (PFB) is still very limited, and there is a lack of attempts on the co-firing of coal and other fuels. In this study, the co-firing of coal and biomass in a POFC mode at a 10 kWth PFB was tested. The dynamic behaviors of the start-up process and combustion mode switching were investigated. The effects of key operating parameters, including combustion pressure (P), biomass blending ratio (Mb), and excess oxygen coefficient (α), on the temperature distributions, CO2 enrichment and conversion, pollutant emissions (CO, NOX, SO2), and solid residues were methodically studied. The results show that the stable, pressurized, and oxy-fuel combustion mode with coal and biomass mixtures as fuels can be successfully realized in a fluidized bed. Increasing P and Mb not only conduces to better temperature distribution, more CO2 enrichment in flue gas, and higher combustion efficiency but also has the advantage of reducing NOx and SO2 emissions by over 30%. In the oxy-fuel PFB, the positive effect of α on the combustion performance is more significant than that under atmospheric conditions. As P increases, the fly ash surface is more cracked, and the particle size distribution of fly ash decreases, while the bottom slag surface is smoother. Besides, the increase in P results in a decreased specific surface area and cumulative pore volume but an increased average pore diameter in fly ash.

This study addressed the production of high-quality bio-oil and carbonaceous materials from in-situ co-pyrolysis of chicken manure (CM), algal bloom (AB) and woodchip (WC). The effects of biowaste-derived catalyst and AB-based NH3 on improving the quality of bio-oil, tar and carbonaceous materials were investigated, respectively. The major presence of Ca-Mg-P in CM resulted in a higher quality of bio-oil with a cetane number of 40 and HHVs of 38.62 MJ/kg. The loading of Ni2P further enhanced the catalytic performance of CM-derived catalyst and contributed to the produced bio-oil with a cetane number of 50 and HHVs of 40.85 MJ/kg. The major presence of K-Cl-Fe in AB and AB-based NH3 activation contributed to a larger specific surface area of carbonaceous materials as high as 567 m2/g. Furthermore, the catalytic activity, electrochemical activity and potential market value of biowaste-derived carbonaceous materials were explored in this study. To facilitate the investment decision-making in industrial applications, techno-economic analysis was conducted for the deployment of co-pyrolysis system in a hen layer farm for its daily treatment of 20-ton CM. The technological approach and techno-economic analysis can be generalized to the other types of bioresources. This work provides a novel and effective approach to convert and manage biowaste resources for environmental sustainability and carbon neutrality.

Fluidized-bed based solar reactors for the gasification of biomass have been widely recognized as a promising approach to produce high-quality syngas due to the merits, e.g. continuous operation and superior heat and mass transport. In this work, a novel high-temperature solar reactor with a clapboard-type internally circulating configuration that can efficiently mitigate the overheating of the bed wall affected by non-uniform solar radiation, is designed, constructed, and experimentally investigated under Singapore’s first 28 kWe high-flux solar simulator. To investigate the flow dynamics in the high-temperature solar reactor, a transient 3D computational fluid dynamics multi-phase model is developed accordingly and validated by the experimental data. The simulated results can well clarify the flow and thermal behaviours in experiments. The effects of the gas flow rate and bed mass on the thermal performances of different Group-B particle materials are studied through experiments and simulation. The results indicate that increasing the bed mass in the solar reactor is capable of mitigating the overheating of the absorber surface caused by hot spots. The gas flow rate is dependent on the particle thermo-physical properties and shape as well as the clapboard geometric parameters. The highest solar-to-thermal conversion efficiency (defined as the ratio of the accumulated sensible heat of the particles to the solar power input) of 10.7 ± 0.4% is achieved by SiC due to its superior thermal conductivity.

Syngas and biochar production are mainly influenced by temperature, feedstock properties, gasifying agent, pressure, and the mass ratio between gasifying agent and feedstock with temperature being the most significant factor. Increasing temperature generally promotes syngas production while suppressing biochar production. The selection of gasifiers (fixed bed, fluidized bed, and entrained flow) is highly dependent on scale requirement (e.g., volume of feedstock and energy demand), feedstock characteristics (e.g., moisture and ash content), and the quality of syngas and biochar. Updraft fixed bed gasifiers are suitable for the feedstocks with a moisture content up to 50 wt.%. High ash feedstocks such as Indian coal, dried sewage sludge, and municipal solid waste that are not suitable for fixed bed gasifiers, have been successfully gasified in bubbling fluidized bed reactors. Woody biomass is not suitable for entrained flow gasifiers unless specialized feeding methods are employed such as wood torre...

The increasing challenge in waste disposal and high dependency on imported fossil fuel has compelled Singapore to make continuous efforts in advancing waste to energy (WTE) technology, which could ensure sustainable development on one hand and energy resilience on the other hand. This paper summarizes the current WTE practices and research trends in Singapore, covering anaerobic digestion (AD), gasification, combustion-based biomass combined heat and power (CHP) production, and incineration, with the aim to define future perspectives of Singapore WTE application. Among the different aspects assessed, source-separated food waste (FW) and brown water present the biggest energy potential if AD is adopted instead of incineration. Given that the purity of source separated waste determines the extent of recovered energy, suggestions are made to increase the participating rate in source separation among Singapore residents, such as environmental education through social media and phone apps and proper facilities installation at household and community. Moreover, additional benefits can be credited to WTE system if the waste to material practice is also conducted on top of energy production.

Disposal of nitrogen-containing sewage sludge (SS) via gasification leads to the formation of NOx precursors and NOx and ammonia emissions. Pretreatment of SS via hydrothermal carbonization (HTC) was shown to improve coalification, desulfurization, and deamination. In this study, we propose a combined hydrothermal pretreatment and CO2 gasification process for removal of nitrogen from SS and production of energy via the gasification of the pretreated SS. In the HTC process, around 50% of nitrogen contained in the sludge was removed. The derived hydrochar (HC) was subsequently fed for gasification using CO2 as a gasifying agent, which was characterized by the expected reduction in the formation of ammonia. We further improved the process by establishing cogasification of hydrochar with waste leaves. The improvement is believed to be due to the catalytic effect of Ca, present in plant leaves, on the gasification. Cold gas efficiency of the cogasification process of a 1/1 hydrochar/leaves blend by mass was en...

Gasification and pyrolysis technologies have been widely employed to produce fuels and chemicals from solid wastes. Rare studies have been conducted to compare the particulate emissions from gasification and pyrolysis, and relevant inhalation exposure assessment is still lacking. In this work, we characterized the particles emitted from the gasification and pyrolysis experiments under different temperatures (500, 600, and 700 °C). The collection efficiencies of existing cyclones were compared based on particle respiratory deposition. Sensitivity analysis was conducted to identify the most effective design parameters. The particles emitted from both gasification and pyrolysis process are mainly in the size range 0.25–1.0 μm and 1.0–2.5 μm. Particle respiratory deposition modelling showed that most particles penetrate deeply into the last stage of the respiratory system. At the nasal breathing mode, particles with sizes ranging from 0.25 to 1.0 μm account for around 91%, 74%, 76%, 90%, 84%, and 79% of the total number of particles that deposit onto the last stage in the cases of 500 °C gasification, 600 °C gasification, 700 °C gasification, 500 °C pyrolysis, 600 °C pyrolysis, and 700 °C pyrolysis, respectively. At the oral breathing mode, particles with sizes ranging from 0.25 to 1.0 μm account for around 92%, 77%, 79%, 91%, 86%, and 81% of the total number of particles that deposit onto the last stage in the six cases, respectively. Sensitivity analysis showed that the particle removal efficiency was found to be most sensitive to the cyclone vortex finder diameter (D0). This work could potentially serve as the basis for proposing health protective measures against the particulate pollution from gasification and pyrolysis technologies.

This study is a comparison of the effect of biochar produced by bioenergy systems, via the pyrolysis and gasification processes, on the immobilization of metals/metalloids in soil. Because the processes for these two techniques vary, the feedstocks undergo different heating regimens and, as a result, their respective char products exhibit different physico-chemical properties. Therefore, this study focuses on (1) the characterization of derivative biochar from the bioenergy system to understand their features and (2) an exploration of various biochar impacts on the mobility of As and Pb in contaminated soil. The results showed bioenergy biochars (BBCs) performed well in mitigating Pb extractability (1 M ammonium acetate) with a Pb immobilization >80%, but unfavorably mobilized the bioavailable As, likely because of electrostatic repulsion and ion exchange competition. The BBC surface functional group would chemically bond with the As and remain stable against the pH change. An increment in aromatic carbon would effectively enhance cation-π interaction for Pb immobilization. Nevertheless, an amendment with richer condensed structure and higher inorganic minerals (Ca2+, K+, Mg2+, and Na+) can lead to better performance in retaining Pb.

A life cycle assessment (LCA) was conducted to determine the best solution for dealing with the food waste (FW) generated in Singapore eateries. Since the representativeness of the life cycle inventory (LCI) data determined the overall quality of the LCA, this study made a significant endeavor to capture the local specificities, such as waste composition, water supply and treatment plant operation. Characterization data showed that eatery FW from Singapore contained 16% non-biodegradable impurities (such as plastic and metal) and a higher methane generation potential was found in FW from the dining table than in FW from the kitchen. Based on the FW chemical element composition, mass balances were established for the four examined scenarios, including incineration (Inci), anaerobic digestion (AD) followed by composting (ADcom), AD followed by incineration (ADinci) and AD followed by gasification (ADgas). Because of the environmental benefits from compost production in addition to electricity generation, ADcom outperformed other scenarios in all impact categories except Eutro (eutrophication), GW (global warming) and POC (photochemical ozone creation). The best score of GW was observed in ADgas, mainly ascribed to the highest electricity output and the carbon sequestration of biochar. The disadvantages of the AD scenarios in Eutro and POC were associated with NOx and CO emissions from the biogas engine. Finally, the sensitivity analysis demonstrated that better environmental profiles could be achieved if improvements can be made by minimizing water usage, mitigating gas engine pollution, and diverting as much FW as possible from incineration plants to AD plants. However, based on the local context, source separation was not an urgent issue for improving the sustainability of eatery FW management.

Phytoremediation is increasingly recognized as a cost-effective approach for remediation of heavy metal (HM) contaminated soils, whereas the derived HM-enriched hyperaccumulators must be properly harvested and disposed. In this study, gasification of Sedum alfredii was performed at a temperature series (300–900 °C) with different gasifying agents (N2, CO2 and air), then the transfer behaviors of zinc (Zn), cadmium (Cd), and lead (Pb) and the characteristics of the derived biochar and syngas were investigated. The high gasification temperatures and reducing atmosphere (N2) effectively enhanced the volatilization of Zn, Cd, and Pb, and the results from toxicity characteristic leaching process indicate that gasification greatly enhanced the stability and reduced the availability of HMs in S. alfredii. The CO2-derived biochars had moderate pH and greater stability, while the N2-derived biochars showed better energy density. The evolution of functional groups and crystalline phases in biochars were both influenced by the temperature, and the role of atmosphere was increasingly obvious at temperatures above 600 °C. As expected, biochars derived under N2 and CO2 both showed considerable sorption capacity for Pb (134.2–198.8 mg g−1) and Cd (38.1–186.8 mg g−1). CO2 atmosphere greatly enhanced the production of CO at higher temperatures (>700 °C), while N2 atmosphere favored the yield of H2 and CH4. These results imply that gasification could be a promising technique to achieve the separation of HMs from hyperaccumulator as well as the production of energy and multifunctional material, and this process is greatly affected by the gasification temperature and atmosphere.

With the advancement in medical science and understanding the importance of biodistribution and pharmacokinetics of therapeutic agents, modern drug delivery research strives to utilize novel materials and fabrication technologies for the preparation of robust drug delivery systems to combat acute and chronic diseases. Compared to traditional drug carriers, which could only control the release of the agents in a monotonic manner, the new drug carriers are able to provide a precise control over the release time and the quantity of drug introduced into the patient's body. To achieve this goal, scientists have introduced "programmed" and "on-demand" approaches. The former provides delivery systems with a sophisticated architecture to precisely tune the release rate for a definite time period, while the latter includes systems directly controlled by an operator/practitioner, perhaps with a remote device triggering/affecting the implanted or injected drug carrier. Ideally, such devices can determine flexible release pattern and intensify the efficacy of a therapy via controlling time, duration, dosage, and location of drug release in a predictable, repeatable, and reliable manner. This review sheds light on the past and current techniques available for fabricating and remotely controlling drug delivery systems and addresses the application of new technologies (e.g. 3D printing) in this field.

Bioprinted skin tissue has the potential for aiding drug screening, formulation development, clinical transplantation, chemical and cosmetic testing, as well as basic research. Limitations of conventional skin tissue engineering approaches have driven the development of biomimetic skin equivalent via 3D bioprinting. A key hope for bioprinting skin is the improved tissue authenticity over conventional skin equivalent construction, enabling the precise localization of multiple cell types and appendages within a construct. The printing of skin faces challenges broadly associated with general 3D bioprinting, including the selection of cell types and biomaterials, and additionally requires in vitro culture formats that allow for growth at an air-liquid interface. This paper provides a thorough review of current 3D bioprinting technologies used to engineer human skin constructs and presents the overall pipelines of designing a biomimetic artificial skin via 3D bioprinting from the design phase (i.e. pre-processing phase) through the tissue maturation phase (i.e. post-processing) and into final product evaluation for drug screening, development, and drug delivery applications.

In this work, the small-scale downdraft gasification system was integrated with a set of internal combustion engine power generation and successfully used for converting biomass waste into energy in the forms of electricity and heat. The performance of integrated system was investigated by using redwood pellets with a lower heating value of 17 MJ/kg as a feedstock. Experimental results show that the maximum syngas yield of 33.6 Nm3/h can be achieved from the gasifier. From thermodynamics analysis, the maximum energy and exergy efficiencies of the whole integrated system were found to be 31.9% and 15.6%, respectively, considering both electricity and heat generated. Apart from syngas, gasification system also generates significant amount of bottom ash that can be harmful to the environment and public health if it is not treated properly. Therefore, this work also focused on the reutilization of bottom ash in order to reduce the environment and health concerns associated with its disposal, making the overall process more environmentally friendly. From elemental analysis, bottom ash produced from redwood pellets gasification contains significant amount of silica, making it become a highly potential source for synthesizing silica-containing compounds. In this work, alkali hydrothermal reaction has been successfully used to convert this bottom ash into zeolite (or aluminosilicate compound) which can be potentially used as an adsorbent material.

Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

A two-step fabrication process combining emulsification-solvent evaporation method for encapsulation of drug in PLGA microparticles followed by supercritical gas foaming was developed to produce drug-releasing biodegradable micro-porous foams. The encapsulation and release of model hydrophobic drug (Curcumin) and of model hydrophilic drug (Gentamicin) were investigated in this work. By utilizing a two-step fabrication process, a uniform dispersion of the drug in PLGA polymer matrix can be achieved and the method can be further adapted for the encapsulation of a wide range of active ingredient (both hydrophobic and hydrophilic) in biodegradable micro-porous scaffold. The in vitro release profile of the drug-encapsulated PLGA foam was studied over a period of 2 weeks and it was observed that the drug release profile can be engineered by the selection of different PLGA polymer blend, varying lactic to glycolic ratio and molecular chain length of the polymer, and by addition of compatible biodegradable polymer such as Polyethylene Glycol (PEG) to the polymer matrix.

In this study, three-phase flow model together with a thermal-equilibrium model was developed to study the operation of downdraft biomass gasifiers. Gasification experiments were conducted to obtain pyrolysis kinetics and validate the models. A good agreement was found between experiment data and model predictions, in terms of syngas composition and temperature, respectively. Kinetics based on experimental study improves the accuracy of simulation. The thermal-equilibrium model was applied to study the effects of air to biomass ratio on gas composition, LHV (lower heating value), and temperature. The 3D multiphase flow model was applied to investigate the spatial distributions of various parameters (i.e. pressure, gas velocity, temperature, and gas composition) inside the gasifier that are critical to the design of gasifier. A rough division of four gasification zones was determined based on temperature profile. It was also found that the cold gas efficiency was around 63% based on CFD (computational fluid dynamic) simulation. The temperature distributions could be used to guide the application of heat resistant materials inside the gasifier. In addition, the simulation results indicated that blockage of the gasifier has a high chance to occur at the top of reduction bell when using feedstock of high metal contents. Effects of reduction bell dimension and operation conditions on the temperature distribution and syngas production were also investigated by the 3D CFD model, which sheds light on the improvement of the design and operation of reactor. The syngas production could be enhanced by varying the size of reduction bell.

A combined cooling, heating, and power system based on biomass gasification is modeled via experiment and its performance is evaluated. The system operation is simulated using load data of small offices located in different climate zones in the U.S. The operation strategy comprises following the electric load (FEL) and following the thermal load (FTL). Based on the operation data, energetic, economic, environmental, and overall performances of the system are evaluated. Results show that the annual integrated performance (Swhole) of the system ranges from 0.229 to 0.473 in FEL mode and from 0.067 to 0.457 in FTL mode, in different regions. The system has a better performance in FEL mode, and is more attractive to install in the regions with more thermal load. Furthermore, the match degree of heat to power ratio between load and output also has an effect on the system performance. Sensitivity analysis shows that the system performance is more sensitive to the cost of biomass, cost of grid electricity and CO2 emission rate of the grid in both modes, and COP of thermally activated chiller in FTL mode. By changing the above-mentioned parameters, Swhole can be improved by up to 13.7%, 8.2%, 11.0%, and 19.7% respectively.

In this study, microwave-assisted alkali pretreatment for brewers’ spent grain (BSG) waste was comprehensively investigated using Box-Behnken design under varying operating parameters, i.e. microwave power, pretreatment time and alkali/biomass (A/B) ratio. Both quantitative and qualitative characterization analysis such as crystallinity index (CrI), specific surface area (SSA), morphology and compositional analyses were conducted on pretreated samples. Standard biomethane potential (BMP) tests were performed for each pretreated sample to observe the biomethane enhancement after pretreatment. Under optimized conditions, it was observed that the pretreatment technique has facilitated removal of 46% of lignin and 38% of hemicellulose and improved the SSA of samples from 9.55 to 161.98 m2/g, contributing to 52% increase in BMP value. Meanwhile, mathematical models with correlation coefficients of 97.9% and 98.2% respectively were built to predict both the soluble chemical oxygen demand (COD) yield and BMP after pretreatment. Furthermore, a simplified concept of overall evaluation mechanism for pretreatment has been introduced, taking into account waste-removal, energetic and economic indices. Under the proposed evaluation mechanism, the caustic soda price was found to play a more important role than the prices of industry electricity and wholesale natural gas.

Syngas and biogas are two typical biofuels generated from biomass wastes through gasification and anaerobic digestion processes, which are considered to be the future fuels for IC engines. In this work, the utilization of biogas and syngas produced from horticultural waste in a premixed spark ignition engine was investigated. An experimentally validated KIVA4-based CFD simulation integrated with CHEMKIN was performed to evaluate engine performance fuelled by syngas and biogas under both single and blended-fuel modes. Effects of ignition timing, hydrogen content in syngas and methane content in biogas on both energetic and environmental performance have been studied. The indicated thermal efficiency (ITE) of syngas fueled engine at wide open throttle (WOT) condition under maximum brake torque (MBT) operation was found to be higher than that of biogas fueled engine, meanwhile, with much lower NOx emission. In addition, a comparison of the engine performance between the single and blended-fuel modes under different syngas mixing ratios was conducted in terms of ITE and NO X emission. The results suggest that the utilization of syngas and biogas under blended-fuel mode can not only maintain the MBT energetic performance under single-fuel mode, but also show its potential in reducing NOx emission and lessening the tendency of knock onset.

Convection enhanced delivery (CED) of chemotherapeutic drugs can successfully bypass the blood-brain barrier (BBB). However, the treatment efficacy is significantly variable in clinic owing to the absence of proper drugs and the lack of understanding on the local drug transport. In this study, mathematical modelling is employed to investigate the suitability of six chemotherapeutic drugs from the perspective of intratumoural transport, including fluorouracil, carmustine, cisplatin, methotrexate, doxorubicin and paclitaxel. The convection/diffusion/reaction model coupled with Darcy's law is applied to a 3-D realistic brain tumour model that is extracted from magnetic resonance (MR) images. The modelling demonstrates the advantages of CED in enhancing the convective flow of interstitial fluid and reducing the drug concentration dilution caused by the fluid loss from blood stream in the tumour region around the infusion site. The delivery outcomes of the drug in CED treatments are strongly dependent on its physicochemical properties. Convection is more effective in determining the transport of paclitaxel and methotrexate in brain tumour. Paclitaxel exhibits its superiority in drug penetration and accumulation, resulting in the largest effective delivery volume as compared to the other studied drugs. Nanocarrier and diagnostic ultrasound are able to enhance the drug penetration for achieving improved delivery outcomes. Results obtained in this study can serve as a guide for optimising CED treatment regimens.

Currently, industrial wastes are typically combusted at incineration plants, and the resulting ashes are sent to landfill. This practice raises issues, such as potential toxicity of the leachate to the environment, as well as the loss of valuable metals left in the waste. Therefore, from both economic and environmental standpoints, it is becoming increasingly important to recover valuable metals from industrial waste. In this work, a transformative recovery of vanadium (conversion nearly 100%) from leaching solutions of carbon black waste (metal leaching efficiency > 97%) which originates from oil refineries in Singapore, has been systematically studied. Interestingly, three distinctive alkaline earth vanadate nanomaterials were successfully synthesized from the leaching solutions by a facile hydrothermal process, that is, single-crystal calcium vanadate nanorods (Ca10V6O25) oriented along the [001] direction, strontium vanadate nanorods with ellipsoid-like assembly (Sr10V6O25), and barium vanadate polyhe...

The solar/autothermal hybrid gasifier (SAHG) is an attractive approach to provide continuous production of the syngas via coupling autothermal and solar gasification together, where the SAHG mainly includes fully solar, hybrid, and fully autothermal modes. An ICE CCHP system driven by the SAHG with an indirectly irradiative two-cavity reactor introduced conceptually and investigated thermodynamically. Considering the effects of solar flux inputs and various reactant ratios, a zero-dimensional steady-state model of the SAHG was established by using Gibbs free energy minimization, and was validated with the reported data. The optimal steam-to-feedstock and oxygen-to-feedstock ratios has been achieved based on the restrictions of temperature over 1000 K and minimization of steam input. The results of two consecutive days indicate mole flow rates of H 2 and CO were increased by over 38.8% and 11.8%, respectively, leading to an increment in LHV s by 51.7%. An increment in primary energy ratio by 11.5% can be achieved by using the SAHG-CCHP system. The yearly assessment of the SAHG-CCHP system shows that the yearly average increments in heat, power, and cooling for the SAHG system were reached by 19.5%, 23.8%, and 4.5%, respectively. A yearly average increment of 14.2% in primary energy ratio can be obtained under the solar radiation condition of Singapore.

Containment of oil spills in aquatic bodies and treatment of oily wastewater are necessary to mitigate oil pollution. Synthetic oil sorbents are commonly used for managing oil spills and while they are effective, their usage introduces a considerable amount of non-biodegradable plastic into the environment. In an effort to develop an inexpensive sorbent by reutilizing solid wastes for a sustainable future, this study investigates the fabrication of a composite oil sorbent from used polyethylene terephthalate bottles and waste carbonaceous residue from the gasification of oil refinery bottoms via an energy efficient phase inversion method. The composite sorbent demonstrated oil sorption capacity of ∼ 8 g/g, which is comparable to some commercially available adsorbents, and excellent retention capacity for mineral, paraffin and crude oils of different viscosities. Furthermore, the composite is able to remove oil from mineral or paraffin oil-in-water emulsions by sorption, with an efficacy of > 99.7 %, indicating its promising application in the treatment of industrial oily wastewater. Cost analysis shows that this waste-derived composite can be produced commercially at a competitive price.

A 7-kWth indirectly irradiated solar gasifier with a clapboard-type internally circulating fluidized bed was developed and conducted experimentations under concentrated solar radiation. The solar CO2 gasification of charcoal produced by low-temperature pyrolysis was examined under a 28-kWe high-flux solar simulator considering different operating conditions. The effects of CO2:C and feedstock mass on the key performance indicators e.g. the carbon conversion, energetic upgrade factor, and solar conversion efficiency were investigated by using alumina granules as an inert bed material. The first-hand, reproducible experimental data indicated the highest values of the average carbon conversion of 0.53 ± 0.04, energetic upgrade factor of 0.883 ± 0.03, solar conversion efficiency of 5.3 ± 0.6% were achieved under the operating conditions of 80 g charcoal, 1.5 kg alumina particles, and 2 L/min CO2. The feedstock mass significantly affected the solar conversion efficiency but no notable effect on the energetic upgrade factor was observed. The solar conversion efficiency can be significantly improved via fully replacing inert alumina particles by feedstock, adding a continuous feeder, and optimizing the superficial velocity to minimize particle entrainment.

This study focused on conversion of algal biomass to bio-oil through in-situ catalytic fast pyrolysis. In particular, novel Ni2P-loaded and unmodified (zeolite, activated carbon and chicken manure biochar) catalysts were evaluated to determine their effect on in-situ upgrading of algal pyrolysis products. Among the catalysts evaluated, Ni2P-loaded zeolite achieved the highest bio-oil hydrocarbon (34.97 %) and calorific value (32.66 MJ/kg), and the lowest O/C (0.075) and N/C (0.074) ratios. There was a 137 % increase of the aliphatic hydrocarbon fraction and a 72 % increase of the biochar specific surface area (SSA) with the loading of Ni2P to zeolite. Additionally, unfavourable major oxygen- and nitrogen-containing compound, phytol and tetradecanamide, decreased seven- and six-fold, respectively, compared to the non-catalytic baseline case. Ni2P-loaded biochar achieved a reduction in the bio-oil acidity from a pH of 4.52–6.78 and a 41 % decrease of the carboxylic acids content. Biochar produced from the zeolite formulations exhibited especially favourable sorbent quality with SSA greater than 500 m2/g. According to the proposed catalytic mechanism, the generation of n-heptadecane and hexadecanamide may be due to the decomposition of phytol and tetradecanamide, and the catalytic activity was correlated to the pore size of the catalyst (22.22 A). Direct addition reactions were the dominant pathway in the formation of liquid hydrocarbons. These results suggest that it is feasible to develop an in-situ multi-catalyst system to achieve high-quality bio-oil production. Thus, the development of novel Ni2P-loaded catalysts addressed a promising approach for biomass conversion into hydrocarbon-rich products with low risk to the environment.

In this work, an integrated biomass waste gasification combined heat and power (CHP) system is simulated and analyzed based on a multi-scale first-principles numerical model, which consists of a 1D fixed-bed gasifier model and a 1D hybrid peripheral fragmentation and shrinking-core biomass particle model. The simulations are based on a 15kW gasification CHP system and the numerical model is validated by two different groups of experimental data, and the maximum deviation is 2.56% in syngas H2 composition prediction. A multi-objective optimization framework of the integrated biomass waste gasification CHP system is formulated that considers 3 objectives: economic benefit, greenhouse gas emission, and potential health impact caused by PM emission. The best-compromised solution from the Pareto front leads to $142.8/day economic benefit, 694.3 kg CO2eq/day mitigation, and 57.67 Singapore Pollutant Standards Index score. The impacts of the three objectives on decision variables (i.e., feedstock flowrate, feedstock moisture content, and equivalent ratio) are analyzed by investigating 21 different weighted single-objective problems.

Phytoremediation is a green technology for heavy metal removal from contaminated soil, and its remediation efficiency and economic feasibility in field trial should be evaluated before large-scale application. However, there is still lacking relevant analysis, especially for phytoremediation with different cropping patterns. In the present study, we performed phytoremediation on slightly Cd-contaminated farmland soil via three cropping systems, i.e. Sedum alfredii monoculture, oilseed rape monoculture, and S. alfredii-oilseed rape intercropping. Dry weights of S. alfredii and oilseed rape were both enhanced under intercropping pattern, while the highest total Cd extraction amount (148 g ha−1) were observed under S. alfredii monoculture. Furtherly, a cost-benefit analysis via Monta Carlo simulation in a ten-year lifetime was conducted. The benefits of S. alfredii monoculture and intercropping schemes would offset the total costs in 6 and 8 years, respectively. S. alfredii monoculture achieved a higher net present value of 1.88 × 104 US$ as compared with intercropping (9.53 × 103 US$). These results indicate that S. alfredii monoculture scheme could be a promising phytoremediation strategy for slightly Cd-contaminated soil owing to better remediation efficiency and economic feasibility. Moreover, the enhancement in mechanization level and the reduction of seedling cost could further improve its economic viability.

In this study, Extended Exergy Accounting was adopted to develop an accounting model to evaluate the performance of a Municipal Solid Waste Management System. Furthermore, urban metabolism sustainability index for waste was also proposed to represent the unified society-economy-environment impacts of the MSWMS under the framework of a comprehensive sustainability evaluation. A detailed analysis of wood and horticultural waste treatment scenarios in Singapore was done as a case study. It was found that the gasification scenario theoretically performs significantly better than the incineration scenario, in terms of energy carrier consumption, emissions, thermodynamic efficiency and sustainability. Analysis results show that, if extrapolated to Singapore’s total wood and horticultural waste, gasification technology has potential to reduce energy consumption and increase electricity output. An uncertainty analysis was carried out and it was found that the main extended exergetic parameters of the two scenarios considered were in the range of 3–8%, thus confirming the reliability of the accounting results. A sensitivity analysis of the urban metabolism sustainability index for waste was conducted for the gasification scenario to identify key influencing factors and seek potential improvements; this was done by considering changes in four variables: transportation distance, electrical efficiency, working hour increment and gross capital cost per ton waste treated. It was found that, to ensure the feasibility and sustainability of gasification scenario, the following are required: keeping the electricity production efficiency greater than 21.33%; the transportation distance between the gasification power plant and source of wood and horticultural waste should be kept within 17.08 km; employment of per kton annual treatment capacity should be less than 0.14 workers; wood and horticultural waste source should control the waste collection frequency of no more than 3 times per day and the number of workers participating in the collection each time is less than 4 persons, totaling to 12 workers per day.

Biomass gasification-based cogeneration systems integrated with dehumidification of desiccant coated heat exchangers, covering the cogeneration system inclusive of sensible heat storage and internal heat recovery (SC-1), the cogeneration system inclusive of sensible heat storage (SC-2), and the cogeneration system exclusive of heat storage and internal heat recovery (SC-3), are introduced and comparatively investigated on the energetic and economic performances. The developed models of the cogeneration systems are embedded into a multi-criteria decision-making framework to find the optimal system configuration and parameters. The most favorable scheme (SC-1) – that reaches an overall energy efficiency of 0.963, net present value of 1,429,400 USD, levelized total cost of 646,835 USD/year, payback period of 3.7, heat storage tank of 7 m3, heat recovery tank of 2.1 m3, jacket heat rate of 290 kW, and nominal electric power of 629 kWe – is determined. The sensitivity analysis indicates that the net present value is most sensitive to the electricity tariffs, followed by the biomass feedstock price and the selling price of electricity to utility grid. The overall energy efficiency of 0.81–0.995, the net present value of −470,400–6,166,900 USD, and the payback period of 1.5–13.1 were achieved against the price variation range of ±80%.

Disposal of animal manure in an environmentally friendly way is a severe challenge for megacities. At the gasification temperature of chicken manure around 900 °C, the CO2 gasification product is abundant in hydrogen. The co-gasification of chicken manure with petcoke increased the hydrogen content in syngas. The catalytic effect of chicken manure ash on petcoke gasification was investigated individually. The yield of CO in ash catalyzed gasification product of petcoke was more than 5 times higher than that in pure petcoke gasification product, which demonstrated the strong catalytic effect of chicken manure ash on gasification reaction. The microstructure of partially gasified petcoke particles demonstrated the effect of chicken manure ash on pore development. Reaction surface areas of petcoke also would be blocked when adding excess ash in petcoke for gasification. The high content of calcium and potassium contributed to the dramatically catalytic effect of chicken manure ash. The combustion of petcoke supplied enough heat for co-gasification process. Synergistic effect was achieved during co-gasification process of chicken manure and petcoke. The chicken manure waste was sustainably disposed and also was used as catalyst for gasification reaction.

A food waste treating system was proposed in this study by combining biochar-assisted high-solid anaerobic digestion and subsequent steam gasification of the digestate. The effect of solid level, biochar dosage in anaerobic digestion on the properties of biogas, syngas, and final biochar products were investigated. Results showed that at a high total solid level and biochar dosage of 25 g/L and 50 g/L, the accumulative methane yield reached 110.3 mL CH4/g VS and 126.7 mL CH4/g VS, respectively. From steam gasification of different digestates under 850 °C for 15 min, a maximum of 34.92 mmol/g for the hydrogen yield and 11.44 MJ/m3 for the higher heating value could be obtained for the syngas. Furthermore, the by-product produced from steam gasification was a nutrient-enriched porous biochar, which was suitable to be used as compost. This study demonstrated a pathway for food waste treating to produce methane-enriched biogas, hydrogen-enriched syngas, and nutrient-enriched biochar.

This review lays great emphasis on production and characteristics of biochar through gasification. Specifically, the physicochemical properties and yield of biochar through the diverse gasification conditions associated with various types of biomass were extensively evaluated. In addition, potential application scenarios of biochar through gasification were explored and their environmental implications were discussed. To qualitatively evaluate biochar sustainability through the gasification process, all gasification products (i.e., syngas and biochar) were evaluated via life cycle assessment (LCA). A concept of balancing syngas and biochar production for an economically and environmentally feasible gasification system was proposed and relevant challenges and solutions were suggested in this review.

The fabrication of conductive carbon nanomaterial has attracted extensive research due to its promising potential in energy application. However, the conventional fabrication methods, e.g. chemical vapour deposition, are expensive due to high energy consumption, which makes it both economically and environmentally unsustainable. The concept of using carbonaceous waste as a precursor for growing carbon nanomaterial has recently been explored. By using carbonaceous waste, the fabrication of conductive carbon will be more sustainable. In this work, a carbonaceous waste has the potential to be a precursor for the fabrication of conductive carbon nanomaterial. Our previous characterisation work showed that the carbonaceous waste had a nano-particle size distribution and possessed conductive property. Due to its inherent nano-particle size, no further size reduction is required. However, the carbonaceous waste had to be leached to remove the toxic heavy metal. After leaching, the conductive property decreased slightly. This work explores the use of hydrothermal treatment of the leached sample at low temperature to modify the surface area and surface functional groups, so as to enhance the conductive property of the carbonaceous waste. The capacitance of the treated carbonaceous residue was also analysed.

In this study, the conversion of fat, oil and grease (FOG) into fatty acid methyl esters (FAMEs) without pre-treatment of FOG is investigated. A thermally induced process to accomplish simultaneous esterification of free fatty acids (FFAs) and transesterification of lipids is introduced. Despite high contents of impurities in FOG (∼14 wt%), the maximum achievable yield of FAMEs on feedstock mass basis was >86% for 10 s reaction time without removal of impurities prior to the reaction while conventional acid catalyzed reaction only produced

Biomass conversion to value-added chemicals and fuels over heterogeneous catalysts is one of the top issues in green chemistry. This review focuses on recent advances in the application of solid catalysts for producing three prominent bio-based chemicals, hydroxymethylfurfural (HMF), levulinic acid (LA) and fatty acid methyl ester (FAME) from biomass materials, respectively. Our work highlights the perspectives and challenges during the conversion of actual biomass, including the impact of complex constituents and impurities of biomass on the solid catalysts, mass transfer limitation in the reactions, and the stability and deactivation of the solid catalysts. Transformation of solid catalysts from research to industrialization necessitates future work on identification of interactions between the catalysts and actual biomass, and comprehensive evaluation of the suitability of the catalysts in the reaction systems.

Replacing a part of energy derived from fossil fuels with bioenergy derived from solid waste streams may be a promising method to tackle the dual crisis of increasing waste pile-up and global climate change. In this study we propose a decentralised sewage sludge and woody biomass co-gasification system for Singapore. We evaluate the greenhouse gas emission of the proposed system and compare it to the existing system through life cycle assessment. The proposed system is expected to provide a net annual emission reduction of 137.0–164.1 kilotonnes of CO 2 eq. Increase in electricity recovery, carbon sequestration in the biochar produced and the avoidance of the use of supplementary fuel for sewage sludge incineration are the major contributors for the emission reduction. The proposed system is able to increase the net electricity production from sewage sludge and woody biomass by 3–24%. This could lead to an annual increase in electricity recovery of 12.1–74.8 GWh. It is estimated that the proposed system can produce 34 kilotonnes of biochar annually. It is found that decentralisation helps to reduce the annual tonne-km driven by 4.23 million tonne-km which could decrease the number of on-road vehicles required for waste handling.

In this work, coal fly ash (CFA) – a byproduct of coal combustion, has been successfully converted into a value-added product— zeolite. This study focuses on the production of the Na-A zeolite phase via the fusion method. The effects of fusion reaction temperature, hydrothermal reaction temperature, reaction time, and the concentration of alkaline were investigated. The synthesized products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) and studied for their purity and yield. A fusion temperature of 550 °C, fusion duration of 1.5 h, and a subsequent hydrothermal temperature of 100 °C for a reaction of 12 h were found to be the optimal conditions. Based on the synthesis conditions found, an up-scale production process was designed and simulated with aid from the Aspen Plus program. It was found that zeolite production via the fusion method obtained high profitability. For a 5000 kg/h coal fly ash feed, a payback period of 7.1 years is feasible over a 20-year ope...

Electrostatic charge generation is a multivariable and complex issue whose working mechanism has never been fully understood. The objective of this paper is to investigate the effect of granule surface roughness on electrostatic charge generation. Two kinds of granule material, Polyvinyl chloride (PVC) and polypropylene (PP) were used with the granule size of 4 mm diameter, 2 mm height and the shape was cylinder or semi-cylinder. The working surfaces were grounded and roughness ranged from 0.140 to 8.600 μm. It was found that uneven surfaces tended to give rise to voids between two solids, where air stored in the voids was able to accelerate discharging. With the same roughness, PVC tended to generate more electrostatic charge than PP by one order of magnitude. For both materials, electrostatic charge generation first increased with surface roughness and then decreased. The maximum electrostatic charge generated was found to occur when the effects of interaction, contact area and voids discharging were at equilibrium. With the combined effect of humidity, surface roughness and contact area, highest electrostatics generation occurred near the mid-roughness tested in this work. Humidity had more effect on electrostatic charge generation as the granule working surface had lower roughness.

A single-step fabrication method, coaxial electrohydrodynamic atomization (CEHDA), was developed to synthesize drug-loaded microbubbles (MBs) for combination treatment of ischemic stroke. The bioactivity of therapeutic agent (tPA, tissue plasminogen activator) after preparation was evaluated, showing that CEHDA could be very promising method for producing MBs with therapeutic functions. The bubble performance and tPA release profiles were also examined by exposing the bubbles to 2 MHz ultrasound of various intensities. The results showed that the mean diameter of tPA-loaded MBs was found to fluctuate about its original diameter when exposed to ultrasound and higher intensity ultrasound was more effective in triggering the burst of CEHDA MBs. High ultrasound-triggered bubble disintegration effectiveness in a short period (first 5 min) fits well with the requirement of short ultrasound exposure time for human brain. Moreover, a numerical model was also applied to investigate the stability of the fabricated MBs in the bloodstream. It was found that MB dissolution time increased with initial radius, decreased with initial surface tension and increased with initial shell resistance but it was barely affected by the average excessive bloodstream pressure.

Background and Objective This study aimed to develop pH-responsive polylactide-glycolic acid co-polymer and chitosan (PLGA/chitosan) nanosphere as an inflammation-responsive vehicle and evaluate the potential of the nanosphere encapsulating metronidazole, an antibiotic, and N-phenacylthiazolium bromide (PTB), a host modulator, for treating periodontitis. Material and Methods PLGA/chitosan nanospheres were fabricated using oil-in-water emulsion method. Experimental periodontitis was induced on the rat maxillae, and the sites were randomly allocated to four treatment categories, including periodontitis alone (PR), periodontitis with nanospheres alone, nanospheres encapsulating metronidazole (MT) and nanospheres encapsulating PTB (PB). The ligature was retained until the animals were killed, and the treatment outcome was evaluated by the progression of periodontal bone loss (PPBL), inflammatory cell infiltration and collagen deposition. Results The encapsulated drug was released rapidly from the nanospheres without significant initial burst release at pH 5.5. Compared with group PR, PPBL was significantly reduced in groups MT and PB on day 4 (P

In this work, a double-nozzle coaxial electrohydrodynamic atomization (CEHDA) system was designed as an instructive case toward large-scale production of core-shell microspheres. The effect of nozzle-to-nozzle distance was investigated to reveal that the interference between neighboring nozzles significantly affect the product quality in terms of morphology and core-shell structure. Optimal spacing indicated that ∼3000 nozzle/m2 packing density may be achieved with minimum interference of electric field from neighboring nozzle by adjusting the nozzle-to-nozzle distance greater than 0.018 m. The proposed multi-scale model also showed that the X-component of electric field strength (Ex) at the region near side nozzles increases with increasing nozzle number, and the bending of jets/sprays at the side may be reduced by using dummy nozzle at the edge side. The model could guide the design of multi-nozzle CEHDA system for production of core-shell microparticles in large-scale. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5303–5319, 2017

Owing to the presence of multidrug resistance in tumor cells, conventional chemotherapy remains clinically intractable. To enhance the therapeutic efficacy of chemotherapeutic agents, targeting strategies based on magnetic polymeric nanoparticles modified with targeting ligands have gained significant attention in cancer therapy. In this study, we synthesized transferrin (Tf)-modified poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NPs) loaded with paclitaxel (PTX) and superparamagnetic nanoparticle (MNP) using a solid-in-oil-in-water solvent evaporation method, followed by Tf adsorption on the surface of NPs. The Tf-modified magnetic PLGA NPs were characterized in terms of particle morphology and size, magnetic properties, encapsulation efficiency and drug release. Furthermore, the cytotoxicity and cellular uptake of the drug-loaded magnetic PLGA NPs were evaluated in both MCF-7 breast cancer and U-87 glioma cells in vitro. We found that Tf-modified PTX-MNP-PLGA NPs showed the highest cytotoxicity effect and cellular uptake efficiency under Tf receptor mediation in both MCF-7 and U-87 cells compared to unmodified PLGA NPs and free PTX. The cellular uptake efficiency of Tf-modified magnetic PLGA NPs appeared to be facilitated by the applied magnetic field, but the difference did not reach statistical significance. This study illustrates that this proposed formulation can be used as one new alternative treatment for patients bearing inaccessible tumors.

There is a rapid growing interest in using biomass as an alternative source for clean and sustainable energy production. In this work, a hybrid system was developed to combine anaerobic digestion (AD) and gasification for energy recovery from yard waste and woody biomass. The feasibility of the proposed hybrid system was validated experimentally and numerically and the energy efficiency was maximized by varying energy input in the drying process. The experiments were performed in two stages. At the first stage, AD of yard waste was conducted by mixing with anaerobic sludge. At the second stage, co-gasification was added as post-treatment for the AD residue for syngas production. The co-gasification experiments of AD residue and woody biomass were conducted at varying mixing ratios and varying moisture contents of AD residue. Optimal energy efficiency was found to be 70.8% at mixing ratio of 20 wt% AD residue with 30 wt% moisture content. Two kinetic models were then adapted for prediction of biogas produced in AD process and syngas produced in gasification process, respectively. Both experimental and numerical results showed that full utilization of biomass could be realized to produce energy through the combination of these two technologies.

Convection enhanced delivery (CED) is a promising method of anticancer treatment to bypass the blood–brain barrier. This paper is aimed to study drug transport under different CED operating conditions. The convection enhanced delivery of chemotherapeutics to an intact and a remnant brain tumour after resection is investigated by means of mathematical modelling of the key physical and physiological processes of drug transport. Realistic models of brain tumour and its holding tissue are reconstructed from magnetic resonance images. Mathematical modelling is performed for the delivery of carmustine and paclitaxel with different infusion rates, solution concentrations and locations of infusion site. Modelling predications show that drug penetration can be improved by raising the infusion rate and the infusion solution concentration. The delivery of carmustine with CED is highly localised. High drug concentration only can be achieved around the infusion site. The transport of paclitaxel is more sensitive to CED-enhanced interstitial fluid as compared to carmustine, with deeper penetration into tumour interior. Infusing paclitaxel in the upstream of interstitial fluid flow leads to high spatial averaged concentration and relatively uniform distribution. Results obtained in this study can be used to guide the design and optimisation of CED treatment regimens.

The auto-regressive distributed lag (ARDL) bound testing approach was used to study the relationships between the monthly household electricity consumption and outdoor PM2.5 concentration with the consideration of ambient temperature and the number of rainy days for Singapore and Shanghai. It is shown that there are significant long-run relationships between the household electricity consumption and the regressors for both Singapore and Shanghai. For Singapore, a 20% increase in the PM2.5 concentration of a single month is in the long-run significantly related to a 0.8% increase in the household electricity consumption. This corresponds to an electricity overconsumption of 5.0 GWh, a total of 0.7–1.0 million USD in electricity cost, and 2.1 kilotons of CO2 emission associated with electricity generation. For Shanghai, a 20% decrease in the PM2.5 concentration of a single month is in the long-run significantly related to a 2.2% decrease in the household electricity consumption. This corresponds to a 35.0 GWh decrease in the overall household electricity consumption, 1.6–5.1 million USD decrease in electricity cost, and 17.5 kilotons of CO2 emission. The results suggest that the cost of electricity consumption should be included in the economic cost analysis of PM2.5 pollution in the future. A 1 °C increase in the monthly temperature is in the long-run significantly related to a 13.6% increase in the monthly electricity consumption for Singapore, while a 30 degree days increase in heating & cooling days (HCDD) is in the long-run significantly related to a 24.9% increase in the monthly electricity consumption for Shanghai. A 5-day increase in the number of rainy days per month is in the long-run significantly related to a 3.0% and 5.8% increase in the monthly electricity consumption for Singapore and Shanghai, respectively.