Journal of Renewable Energy and Environment
Volume:10 Issue: 2, Spring 2023

The present study aims to develop different strategies for better utilization of oxygenated Diethyl ether and ethanol as supplementary fuels by blending them with biodiesel as the base fuel in CI engines. The used biodiesel used was readily available Karanja Oil Methyl Ester (KOME), its scientific name being Pongamia Pinnata. Initially, 5 %, 10 %, 15 %, and 20 % amounts of ethanol (volume) were mixed with biodiesel. Further, the optimum selected blend BE15 was mixed with 5 %, 10 %, 15 %, and 20 % DEE by volume to make the ternary blend. This DEE-ethanol-biodiesel blend was tested on the same engine under the same conditions. The experimental results exhibited that the DEE-ethanol-biodiesel ternary blend, BE15DE10, mitigated BTE by 8.89 % and the smoke, NOx, and CO emissions by 15.66 %, 50.7 %, and 18.5 %, respectively, compared with neat biodiesel. The HC emission exhibited a slightly increasing trend. The results summarize the trade-off between smoke and NOx reduction using DEE and ethanol oxygenated fuels. The addition of ethanol by 15 % and DEE up to 10 % by volume to biodiesel could be considered the most favorable blend without any significant modifications in the CI engine.

The optimal combination of distributed generation units in recent years has been designed to improve the reliability of distributed generation systems as well as to reduce losses in electrical distribution systems. In this research, the improved Genetic Algorithm has been proposed as a powerful optimization algorithm for optimizing problem variables. The objective function of this paper includes power loss reduction, hybrid system reliability, voltage profile, optimal size of distributed generation unit, and finally improvement of the construction cost of combined wind and solar power plants. Therefore, the problem variables are subject to reliable load supply and the lowest possible cost during the optimization process. In order to achieve this goal in this study, the IEEE standard 30-bus network is examined. The results of the system simulation show the reduction of total system losses after DG installation compared to the state without DG and the improvement of other variable values in this network. This loss index after installing DG in the desired bus has a reduction of about 200 kWh during the year and has a value equal to 126.42 kWh per year.

In this research, the performance of an asphalt solar air collector was experimentally tested and the daily thermal and exergy efficiencies of the collector were analyzed. The sun's radiant energy is absorbed by asphalt and converted into thermal energy. Then, it is transmitted to aluminum pipes buried under the asphalt and, finally, to the air passing through the pipes. A suction fan induces the ambient air to the collector. The experimental results show that the daily thermal efficiencies at mass flow rates of 0.007 (kg/s) and 0.014 (kg/s) are 11.98 % and 24.10 % and daily exergy efficiencies are 0.34 % and 0.66 %, respectively, showing the increase in daily energy and exergy efficiencies with increasing the air mass flow rate. In addition, results show that as the flow rate increases, the outlet air temperature decreases. The presence of temperature difference between the inlet and outlet of the collector in the last hours of the day, when the sun's radiation islow, indicates that asphalt acts as a thermal energy storage medium.

In this study, a novel stochastic planning method is proposed for AC-DC hybrid distribution networks. The proposed approach is based on the graph theory, and the optimal AC-DC structure of the network is selected among the system spanning trees. The presented method is a Mixed Integer Nonlinear Programming (MINLP) problem, which is solved using genetic algorithm. The buses and lines of the network can be either AC or DC to minimize the system investment costs in the master optimization problem. The location and capacity of the Distributed Energy Resources (DERs) as well as the site and size of the Electric Vehicle (EV) charging stations  are optimized in the slave problem to minimize the network losses and system costs. The proposed model utilizes Monte Carlo simulation to deal with the stochastic variations of the renewable energy resources power and load demands. Besides, the converter efficiency curve in the proposed planning problem is modeled based on a function of its input current using PLECS software. The proposed approach for network design can be applied to different DG resources and AC-DC loads. The comparison between the simulation results of the proposed approach and the conventional AC planning method demonstrates the efficiency of the proposed model in reducing network losses and system costs

Anaerobic digestion is one of the most effective technologies for managing degradable waste, which produces renewable energy and digestate as the byproduct. In this study, sewage sludge (SS), poultry litter (PL), and food waste (FW) were co-digested at ratios (SS:PL:FW 2:1:1) with 8 % total solid content at ambient temperature (average 22 °C) and controlled temperature (35 °C) in summer. The synergistic effects of co-digesting substrates enhance the biogas production potential when digested at an optimized ratio. The maximum biogas yield was 688.7 L/kgVSa at the controlled temperature and 462.3 L/kgVSa at ambient temperature. The ambient reactor had a methane composition of 55 %, while the controlled temperature reactor had about 60 %. The results provide approaches to increase biogas production in the anaerobic digestion process through co-digestion and controlled mesophilic temperature. Biogas production from anaerobic co-digestion could significantly transform waste into energy in low-income countries to achieve the objective of clean energy production and environmental sustainability.

Thermal Energy Storage (TES) for solar thermal systems has attracted great attention because of the intermittent availability of solar energy. In the current paper, new combinations of several Phase Change Materials (PCMs) including a type of paraffin and some mineral compounds like ammonium nitrate and magnesium nitrate hexahydrate were exanimated and their thermo-physical properties were compared. This study targets solar heating systems at different temperature intervals for the TES. Another new approach of this study is to determine the effect of Multi-Wall Carbon Nanotubes (MWCNTs) with two diameters (D) of 8 and 10-20 nm on paraffin's thermophysical property to improve these properties. An innovative method was used to measure Electrical Conductivity (EC) as it is easier to measure than thermal conductivity (K) to study the effect of nanoparticles on PCM behavior. The results showed that the highest values of improvement over paraffin properties were related to 5% nanoparticle additive for both nanoparticle diameters among the percentages studied. The addition of 5 % nanoparticles with 10-20 nm and 8 nm to paraffin at 25 ° C increased heat conductivity by 142% and 156%, respectively. The addition of nanoparticles to paraffin improved EC several times such that a diameter of 8 nm made a 300% increase in EC compared to 10-20 nm.

Despite the falling costs of Renewable Energy (RE), RE adoption in Indian residential households is still attepid growth rates. With the onset of retail electricity market deregulation in India, the introduction of “greentariffs” for residential households can be effective in resolving the issue of low RE adoption. This studyinvestigates the willingness to pay for green tariffs/renewable energy-based electricity contracts using thecontingent valuation method. Data collected from 476 Indian residential households are analyzed by theDouble-Bounded Dichotomous Choice technique. The results of the conducted maximum LikelihoodEstimation (MLE) method reveal the mean willingness to pay 308.52 Rs per household/month for consumption of green power in a premium-paying setting. Results indicate that although households hold positive perception of renewable energy, the willingness to pay is not commensurately high, indicating an attitude-action gap. The study recommends green energy defaults in residential energy contracts, direct marketing of non-use value of RE use (altruistic and bequest) by power supplying utilities, and promoting RE use through RE opinion champions/influencers as measures to enhance RE adoption amongst Indian residential energy consumers.

This study was conducted in the Loka Abaya District of Sidama Region, Southern Ethiopia to assess the environmental impacts of biomass energy production with particular emphasis on charcoal and firewood. The data collection was undertaken using the questionnaire survey administered to 186 randomly selected households. This task was followed by key informant interviews and an analysis of the literature. The sampled households produced 208 432.9 kg firewood yr-1 for domestic consumption and 261 039.8 kg charcoal yr-1 for sale in town. 2.3 × 10-6 km2 of the forest is cleared to produce a single sack of charcoal. Charcoal and firewood production is totally responsible for the degradation of 39.4 ha of forest per year. The associated emissions of CO2, CO, N2O, CH4, and TNMHC (total non-methane hydrocarbon) during the production and consumption of firewood and charcoal were calculated based on the emission factors indicated by previous studies. The results demonstrated that the trace gases produced during charcoal making were higher than that of charcoal burning. Further, the amounts of greenhouse gases generated during firewood burning were higher than the onesgenerated during charcoal burning. In order to minimize the challenges of deforestation and greenhouse gas emissions caused by charcoal and firewood consumption, a strategy of promoting the utilization of alternative clean energy sources such as solar and biogas should be implemented in parallel to the effort of adoption of improved biomass energy-saving cook stoves.

The present study aims to explore the role of characterized hydrocarbons in thermally cracked shell liquid in determining its overall fuel properties and combustion characteristics in a CI engine. For this purpose, waste shell liquid was extracted from waste cashew nut shell by means of cold extraction technique using a simple electrically operated mechanical screw press, which reported maximum extractable oil content as 17.7 %. In addition, it was thermally cracked at 350-400 °C using conventional heating for both lab-scale and pilot-scale extraction. Based on its chemical composition, raw shell liquid contained anacardic acid and cardol, while thermally cracked shell liquid had cresol and methyl oleate as their dominant hydrocarbon compounds. Their composition was found to be 51.84 %, 33.68 %, 43.87 %, and 28.49 %, respectively. According to their contribution, both cyclic and aromatic as well as linear-chained hydrocarbons exhibited significant effect on the fuel properties of the cracked shell liquid, with carbon atoms contributing to its physical and thermal properties, whereas cyclic and aromatic hydrocarbons enhance its flow characteristics. Next, neat and blend samples of this cracked shell liquid with petro diesel reported higher peak in-cylinder pressure by 5.6 % (on average) due to the presence of fatty acid esters, which induced early ignition and provided sufficient time for combustion. Meanwhile, higher emission levels were attributed by both cyclic and aromatic and linear-chained hydrocarbons, citing aromaticity and unsaturation in their molecules, which also resulted in reduced thermal efficiencies by 12.5 % (on average), upon accounting for their inferior calorific content. In conclusion, it is evident that hydrocarbons in these treated shell liquids play a significant role in their fuel properties and engine characteristics.

In this study, energy management of grid-connected Multi-Microgrid (MMG) is performed through joint optimization of the energy and ancillary service market. The test system comprises the IEEE 30 bus system as the main grid and the 16-bus system as an MMG. The MMG is comprised of dispatchable and non-dispatchable generation and loads. The non-dispatchable generators are based on renewable energy sources (RES) such as solar and wind. The uncertainty modeling for wind and solar is performed by Weibull and beta probability distribution function. The strategic integration of RES helps MMG deliver both energy and ancillary services to the utility grid. This research aims to reduce the total energy cost while reducing reserve cost by maximizing the use of RES under normal operation and during contingency conditions. It is observed that if MMG is incorporated into the system, then the total generation cost, reserve cost, and power losses are reduced to 0.11 %, 0.325 %, and 1.201 %, respectively, in normal operating conditions. Under contingency, when Generator 5 is out of service and the main grid is operating alone, the total generation cost increased significantly from 22118.92 $ day-1 to 22435.68 $ day-1 and the real power loss increased from 233.35 MW day-1 to 245.11 MW day-1. However, by interconnecting MMG with the main grid, generation cost and power loss get reduced to 22375.60 $ day-1 and 243.35 MW day-1, respectively. It is analyzed that participation of MMG provides techno-economic benefits during normal operation and contingency conditions.

As one of the main consumers of electricity, industries account for in releasing a large amount of emission. Using renewable energies to feed factories is not an easy task and they should be economically viable to compete with fossil fuels. The goal of this study is to analyze the possibilities of using energy local area networks in off-grid and on-grid modes in an industrial project by considering and calculating all primary and deferrable loads in detail for the first time. The industrial project is sensitive and all possibilities should be considered closely to avoid economic losses. In this case, changes in electrical loads during the project, degradation of components, environmental risks, and economic risks of the investment (for each scenario) are considered and determined too. The results indicate that component degradation can cause 24,000 kWh drop in total electricity production at the end of the project and the total biogas consumption increases from 742 kg/yr to 9330 kg/yr. The results also show that the on-gird scenario (solar/battery) with the Net Present Cost of 200,000$ will be an easy and low-risk choice for investment, but has high environmental risks. On the other hand, the stand-alone scenario (solar/wind/bio/battery) with Net Present Cost of 598,000$ minimizes the environmental risks at the expense of high investment risk. A proper comparison between the multi-year and single-year modes at the end of the project ensures the high accuracy of techno-economic analysis in terms of optimum system types, emissions, and economics.

In this paper, an industrial dairy farm unit was taken as a case study to carry out the applicable technical assessment for the construction of a biogas plant using a combined heat and power (CHP) unit. A comprehensive sensitivity analysis was applied to examine the effectiveness of the operational parameters and feed composition in the purity and production rate of biogas. Aspen Plus was used to implement the anaerobic digestion process. The results showed that any increase in the digester’s operational performance and mass rate of feedstock water led to the modification of biomethane content, but dropped in biogas mass flow rate. Moreover, an increase in the mass rate of carbohydrates, protein, and organic load rate (OLR) of feedstock reduces methane composition. Besides, increasing the rate of lipids has raised the rate of methane production and its composition.