Electricity has become a part and parcel of modern life. The world is constantly developing, and the electricity demand is inevitably increasing with it. It is a big challenge for the power generation organizations to cope up with this increasing demand. For a developing country like Bangladesh, this challenge is even bigger. Bangladesh has many remote areas which are deprived of grid connectivity. In this article, system design and performance evaluation are conducted on a solar battery‐based hybrid renewable energy system (HRES) with diesel backup for a school in a remote area located in the northern part of the country, where conventional power grid connectivity is not available. From field survey, a load demand of 10.468 kWh/day for a normal working day and a peak demand of 3.3 kW are considered in this work for the proposed site. For simulation purpose hybrid optimization model for electric renewable, very well‐known software is used. The solar radiation data required for the work are collected from NASA Surface meteorology and Solar Energy database. Analyzing the load requirements and metrological data a solar‐battery diesel generator‐based HRES is proposed for the school. From the analysis and simulation, the Net Present Cost (NPC) for the proposed system is found USD 6191 with a Cost of Energy (COE) of $0.125/kWh. Further, a comparative study is done and the proposed system can reduce the COE and Green House Gas (GHG) emission of about 29.85% and 69% respectively than the conventional power plants. Finally, a techno‐economic analysis is conducted with sensitivity analysis, time series analysis, and multiyear analysis to prove the rigidity of the proposed system.

Potentiometric redox sensing in solutions containing multiple redox molecules was evaluated using in-house constructed nanoporous gold (NPG)-platinum (Pt) and unmodified NPG electrodes. The NPG-Pt electrode was fabricated by electrodepositing Pt into the nanoporous framework of a chemically dealloyed NPG electrode. By varying the concentration of the Pt salt and the electrodeposition time, different amounts of Pt were introduced. Characterization by SEM shows the pore morphology doesn’t change with the addition of Pt and XPS indicates the electrodes contain ∼2.5–24 wt% Pt. Open-circuit potential (OCP) measurements in buffer and solutions containing ascorbic acid, cysteine, and/or uric acid show that the OCP shifts positive with the addition of Pt. These results are explained by an increase in the rate of the oxygen reduction reaction with the addition of Pt. The overall shape of the potentiometric titration curves generated from solutions containing one or more bioreagents is also highly dependent on the amount of Pt in the nanoporous electrode. Furthermore, the generation of OCP vs Log [bioreagent] from the results of the potentiometric experiments shows an ∼2-fold increase in sensitivity can result with the addition of Pt. These results indicate the promise that these electrodes have in potentiometric redox sensing.

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Potentiometric redox sensing is a relatively inexpensive and passive approach to evaluate the overall redox state of complex biological and environmental solutions. The ability to make such measurements in ultra-small volumes using high surface area, nanoporous electrodes is of particular importance as such electrodes can improve the rates of electron transfer and reduce the effects of biofouling on the electrochemical signal. This work focuses on the fabrication of miniaturized nanoporous gold (NPG) electrodes with a high surface area and a small footprint for the potentiometric redox sensing of three biologically relevant redox molecules (ascorbic acid, uric acid, and cysteine) in microliter volumes. The NPG electrodes were inexpensively made by attaching a nanoporous gold leaf prepared by dealloying 12K gold in nitric acid to a modified glass capillary (1.5 mm id) and establishing an electrode connection with copper tape. The surface area of the electrodes was ~1.5 cm2, providing a roughness factor of ~16 relative to the geometric area of 0.09 cm2. Scanning electron microscopy confirmed the nanoporous framework. A linear dependence between the open-circuit potential (OCP) and the logarithm of concentration (e.g., Nernstian-like behavior) was obtained for all three redox molecules in 100 μL buffered solutions. As a first step towards understanding a real system, the response associated with changing the concentration of one redox species in the presence of the other two was examined. These results show that at NPG, the redox potential of a solution containing biologically relevant concentrations of ascorbic acid, uric acid, and cysteine is strongly influenced by ascorbic acid. Such information is important for the measurement of redox potentials in complex biological solutions.