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Abstract The effective utilization of solar energy is a big challenge as global energy demand is increasing sharply. In this paper, we present the details of design of an extremely concentrated solar energy delivery system (ECoSEnDS) and its possible utilization in daylighting and sustainable wastewater treatment. The EcoSEnDS is made with double mirror based solar concentrator coupled with pure silica optical fiber bundle. This device is capable to deliver 96 suns concentrated sunlight in first stage of testing where efficiency of the primary mirror is 50%. This device can distribute light equivalent to 813 incandescent bulbs of 60 W or 149 LED bulbs of 15 W. Therefore, this device can be used as daylighting system in the building and underground car parking area. Using appropriate semiconductor nanophotocatalysts, this device can be used for sustainable rapid wastewater purification process. We have used BiVO4 nanoparticles for photocatalytic methylene blue degradation and the complete (100%) purification of methylene blue stained wastewater was achieved within one hour using only 7 suns concentrated sunlight. Therefore, the ECoSEnDS will open new technological aspects for sustainable fastest wastewater treatment process using solar energy.

Abstract Conventional jaggery making process utilizes the bagasse for boiling of sugar cane juice which releases pollutants into the atmosphere and high particulate matter from these emissions causes air pollution. In this article, solar powered jaggery industry with freeze pre-concentration is proposed with conventional and modified heating pans. The system performance, environmental impacts and economic feasibility were assessed by carrying out 4E (Energy-Exergy-Environment-Economic) analyses using the developed mathematical model. These systems were designed to produce 300 kg of jaggery per day when operated for 7.5 h in 3 batches with average solar direct normal irradation of 662 W/m2 and 343 °C. These systems are integrated with auxiliary heating for uninterrupted production in the absence of sunlight. These systems can mitigate nearly 2015.95 to 3062.15 tons of CO2 emission during its 25 years of lifespan under 300 clear days of operation each year. Jaggery produced by this technique is rich in its colour and completely safe for human consumption as no artificial clarificants are used. Amount invested in these systems can be recovered in a span of 12.03 to 13.45 years for jaggery selling price of USD.0.514/kg or INR.36/kg.

Abstract Microencapsulated n-octadecane with titanium dioxide (TiO2) shell was prepared by a sol–gel method in a nonaqueous oil-in-water (o/w) emulsion using a green solvent as the dispersion medium. The morphology, chemical structure, and crystalloid phase of the resultant microcapsules were determined by scanning electronic microscope (SEM), Fourier transformation infrared spectroscope (FT-IR), and X-ray diffractometer (XRD), respectively. The differential scanning calorimeter (DSC) and the thermogravimetric analyzer (TGA) were used to investigate the thermal properties and thermal stabilities of the samples. The resulting microcapsules presented spherical shape with average size of 2–5 μm. The results of FT-IR and XRD showed that n-octadecane was well microencapsulated in TiO2 shell. DSC and TGA results indicated that the samples exhibited good performance of storing and releasing the latent heat during phase-change cycles and high thermal reliability. The microencapsulation process in this study is simple, high-efficiency, and environmentally friendly. The microencapsulated n-octadecane with TiO2 shell will be a potential candidate material for thermal energy storage applied in the fields of solar energy storage, building energy conservation, air-conditioning systems, and waste heat recovery.

Abstract In this effort, 10 μm thick rear contact (RC) silicon–germanium (SiGe) based solar cell device has been discussed with SiC (20 nm)-based front surface passivation for the suppression of interface recombination as well as improvement of short circuit current density ( J SC ) and open-circuit voltage ( V OC ). The design principles presented here balance the electronic and photonic effects together and is a significant step to design highly efficient thin solar cells. Photo reflectance is significantly reduced in the UV/visible spectral region due to the presence of SiC. This results in external quantum efficiency (EQE) >90% in the spectrum range of 400–650 nm wavelength. Also, at wavelengths equivalent to 300 nm, SiC passivated device shows record EQE of 85%. The presence of SiC as a surface passivating layer shows enhanced surface characteristics in terms of reduced surface recombination and higher photon absorption rate. This results in 15.4% power conversion efficiency (PCE) under standard air mass 1.5 illuminations. Further, the proposed device has also been analyzed for concentrator photovoltaics (CPV) applications, resulting in 18.4% and 19.3% efficiencies at 1 W/cm 2 (10 suns, 27 °C) and 2 W/cm 2 (20 suns, 27 °C) respectively. Till date, the proposed design proves to be highly efficient in the sub 10 μm regime. All the simulations have been done using DEVEDIT and ATLAS device simulator

Abstract This article presents the experiences learned using micro-hydro power at the village level. Site evaluation procedure, financing methods, turbine fabrication, and site construction are discussed. Micro-hydro power provides a decentralized energy source for several of the energy-intensive tasks of villagers. Low-head, small volume hydro potential is common in the Zairian countryside. Often a potential site also serves as the village water source, hence it is located near potential beneficiaries of the power. Over the past three decades, a religous NGO in the Ubangi and Mongala Subregions of northwest Zaire has been developing this small hydro potential as part of its technology transfer and village development program. Local materials and knowledge are used as much as possible in construction. Experiences gained constructing a 370 kW hydro-electric site, as well as building water wheels for water pumping has led to the construction of micro-hydro sites using locally made cross-flow turbines. Four water wheel sites and six micro-hydro sites have been built. The hydropower is used to mill flour and hull coffee. One site also generates 220 V electricity, and two others have 12 V generation planned.

Abstract Owing to the superior optoelectronic properties of perovskite materials, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been increased dramatically within several years, but the poor thermal, humidity, and light stability of these PSC devices hinders the progress to their practical application. We obtained an inspiration from two-dimensional (2D) Ruddlesden–Popper perovskite solar cells with good photovoltaic performance and placed the organic-inorganic hybrid perovskite layer inside two fully-inorganic CsPbI3 perovskite layers in the cubic α phase. The middle layer has lower stability than the two outer ones, which protect the middle layer by impeding the organic ions of the organic-inorganic hybrid perovskite middle layer from diffusing outside and causing damage to neighbor CTLs. Water molecules from air are also obstructed from reaching the hybrid perovskite layer. We used 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) ionic liquid and 3-(decyldimethylammonio) propane-1-sulfonate (DDMAPS) and obtained phase-stable fully-inorganic α phase CsPbI3. The constructed PSCs have extremely high stabilities and high PCEs. After 1000 h of illumination under AM1.5 illumination in air at 60 °C (Humility: ~60%), PSCs with a sandwich structure of three perovskite layers maintain nearly all the original PCE of 21.32%, while those without that only remain 76.63%.

Abstract This paper explores a solar mixed-use community and its potential towards achieving net-zero energy status. This mixed-use community combines residential and commercial/institutional buildings. Energy performance of this neighbourhood is estimated in terms of energy consumption and generation potential by means of building integrated PV systems. A solar thermal collector system combined with a borehole thermal energy storage (BTES) is designed to investigate the impact on the overall performance of the neighbourhood. The design of solar thermal collectors and the sizing of short-term thermal energy storage is based on the analysis of the thermal loads for heating and domestic hot water in each district of the community. The results of the performance of the thermal collectors and BTES align with existing communities, which employ similar technologies. The results indicate that implementing energy efficiency measures together with PV systems, allows the neighbourhood to generate around 70% of its total energy consumption. The implementation of thermal collectors and seasonal storage, in this high-energy performance neighbourhood, leads to a net positive energy status.

Abstract Highly-efficient solar steam generator holds promise in seawater desalination and wastewater treatment with low energy consumption. The efficiency of generator highly depends on several factors including the kind of the absorber layer, the structure and the thickness of the generators. In this study, a model for calculating the optimal thickness was established based on the water transfer rate and thermal conduction loss. An optimal thickness of generator was determined by the calculation and experiment, taking carbonized wood based solar steam generator (CWSG) as an example. CWSG with optimal thickness about 22 mm performed a highest evaporation rate of 6.89 kg m−2 h−1, corresponding to efficiency of 87.7% under 5 sun. CWSG also served for seawater desalination and dye removal, which exhibited a stable performance even after 20 cycles. The results indicate that maximizing the efficiency of solar steam generator by thermal calculation could provide a new choice to design highly efficient solar steam generator for seawater desalination and dye removal.

Abstract To overcome the leakage of phase change materials (PCMs) above melting temperature, PCMs are commonly encapsuled by chemically crosslinked networks, which bring the issues of reparability, reprocess-ability and recyclability making for the environment pollution and resource waste. Herein, a reversible aromatic disulfide is adopted to form dynamic epoxy networks which not only encapsulate polyethylene glycol (PEG) as the shape-stabilized PCMs (SSPCMs) but also address the issues about the un-recyclability of traditional SSPCMs. The PEG was well encapsulated and uniformly dispersed in disulfide-based epoxy due to the elaborate molecular design. The obtained SSPCMs (named EXAP2) shows typical solid–solid phase transitions characteristic and thermal reliability with high latent heat value of 82.7 J/g. Besides, the EXAP2 exhibit dynamic performance and can be reprocessed by hot press via the disulfide bonds exchange reaction above topology freezing temperature (Tv). And the reprocessed EXAP2 exhibits close phase change properties with the original sample, implying the reprocessing does not affect the crystalline structure and encapsuling capability of disulfide crosslinked networks. This strategy prove a significant way for fabricating the novel SSPCM with recyclability, reprocessability and reliability.