An optimum location of on-grid bifacial based photovoltaic system in Iraq

Bifacial photovoltaic (PV) module can gain 30% more energy compared to monofacial if a suitable location were chosen. Iraq (a Middle East country) has a variable irradiation level according to its geographic coordinates, thus, the performance of PV systems differs. This paper an array (17 series, 13 parallel) was chosen to produce 100 kWp for an on-grid PV system. It investigates the PV system in three cities in Iraq (Mosul, Baghdad, and Basrah). Effect of albedo factor, high and pitch of the bifacial module on energy yield have been studied using PVsyst (software). It has been found that the effect is less for a pitch greater than 6 m. The energy gained from bifacial and monofacial PV system module in these cities shows that Mosul is the most suitable for installing both PV systems followed by Baghdad and lastly Basrah. However, in Basrah, the bifacial gain is 12% higher in the energy than monofacial as irradiation there is higher than the other locations, especially for elevation above 1.5 m. Moreover, the cost of bifacial array is 7.23% higher than monofacial, but this additional cost is acceptable since the bifacial gain is about 11.3% higher energy compared to the monofacial.

Effects of Tillage and Cropping Sequences On Crop Production And Environmental Benefits in the North China Plain

The ever-increasing trend of greenhouse gas (GHGs) emissions is accelerating global warming and threatening food security. Environmental benefits and sustainable food production must be pursued locally and globally. Thus, a field experiment was conducted in 2015 to understand how to balance the trade-offs between agronomic productivity and environment quality in the North China Plain (NCP). Eight treatments consisted of two factors, i.e., (i) tillage practices: rotary tillage (RT) and no-till (NT), and (ii) cropping sequences (CS): maize-wheat-soybean-wheat (MWSW), soybean-wheat-maize-wheat (SWMW), soybean-wheat (SW), and maize-wheat (MW). The economic and environmental benefits were evaluated by multiple indicators including the carbon footprint (CF), maize equivalent economic yield (MEEY), energy yield (EY), carbon sustainability index (CSI), etc. Compared with NT, RT increased the EY and MEEY, but emitted 9.4% higher GHGs. Among different CSs, no significant reduction was observed in CF. The lowest (2.0 Mg CO2-eq ha-1 yr-1) and the highest (5.6 Mg CO2-eq ha-1 yr-1) CF values were observed under MW and SWMW, respectively. However, CSs with soybean enhanced MEEY and the net revenue due to its higher price compared to that of MW. Although the highest CSI was observed under RT-MW, soybean-based crop rotation could offset the decline in CSI under NT when compared to that for RT. These findings suggest that conservation agriculture (CA) could enhance the balance in trade-offs between economic and environmental benefits. Additional research is needed on how to achieve high crop production by establishing a highly efficient conservation agriculture system in the NCP.

Torrefaction of Palm Kernel Shell and Petcoke Blends for Various Mixing Ratios and Temperatures

In the present study, torrefaction of palm kernel shell (PKS) and petcoke blends was performed for the production of solid biofuels with high energy density. The torrefaction process was performed for mixtures with various mixing ratios (by weight) from 90:10 to 60:40 (PKS:petcoke). For torrefaction under various temperatures of 250℃ to 300℃, the mixing ratio of 60:40 was used. Meanwhile, residence time and nitrogen flow rate were fixed at 30 minutes and 1 l/min, respectively. In general, the fixed carbon and ash contents increased, while the moisture and volatile matter contents decreased after torrefaction. It has been elucidated that mass yield is a dominant factor that affects the energy yield of torrefied mixtures rather than the higher heating value (HHV) ratio. Based on the energy yield and ultimate analysis, it was found that a higher amount of petcoke and higher temperature give better performance, thus causing the torrefied mixture to become very close to coals region in Van Krevelen diagram. In this case, the mixture with a mixing ratio of 60:40 torrefied under the temperature of 300℃ gives the best performance. It was also found that this mixture is thermally stable than the mixture torrefied at 250℃.

Productivity of switchgrass (Panicum virgatum L.) agrophytocenoses for long-term use

Purpose. To determene the productivity of switchgrass (Panicum virgatum L.) agrophytocenoses under the long-term use. Methods. Field, statistical, calculation and comparative. Results. During long-term switchgrass cultivation, the lowest yield was obtained in the first vegetation year: 19.7 t/ha in the control treatment, 25.3 and 17.5 t/ha in the experimental treatments. The average raw biomass yield was as following: 30.3 t/ha in the control (variety ‘Cave-in-Rock’), 32.6 t/ha and 26.5 t/ha in the experimental treatments (varieties ‘Kanlow’ and ‘Morozko’, respectively). The yield of solid biofuel (17.3 t/ha) indicates the advantage of ‘Kanlow’ over the control (11.7 t/ha). The lowest yield (15.7 t/ha) was obtained from ‘Morozko’ variety. The energy yield over the treatments: 312.8 GJ/ha in the control, 397.5 and 367.2 GJ/ha in the experimental treatments, respectively. The cost of the grown production was as following: 416.03 UAH/t in the control (‘Cave-in-Rock’), 312.01 UAH/t in ‘Kanlow’, and 366.42 UAH/t in ‘Morozko’. The profitability of the control (‘Cave-in-Rock’) was 69.5%, ‘Kanlow’ – 101.4%, ‘Morozko’ – 66.8%. Economic evaluation of the productivity of switchgrass agrophytocenoses resulted in the following ranking: ‘Kanlow’, ‘Cave-in-Rock’, ‘Morozko’. When analyzing the energy equivalent of switchgrass biomass production and energy consumption, it was found that ‘Kanlow’ yielded 588.8 GJ/ha and the control – 468.3 GJ/ha, which is lower by 120.5 GJ/ha. Conclusions. The yield of switchgrass agrophytocenoses on average over the years of research (2014–2019) was 30.3 t/ha in ‘Cave-in-Rock’ (the control), 32.6 t/ha in ‘Kanlow’, and 26.5 t/ha in ‘Morozko’. The energy equivalent of the obtained yield was 468.3 GJ/ha in ‘Cave-in-Rock’ and 588.8 GJ/ha in ‘Kanlow’, which is by 120.5 GJ/ha higher than in the control.

Reliability Analysis of Bifacial PV Panel-Based Inverters Considering the Effect of Geographical Location

Recent trends in the photovoltaic (PV) technology industry are moving towards utilizing bifacial PV panels. Unlike traditional PV panels, bifacial PV panels can yield energy from both sides of the panel. Manufacturers specify that bifacial PV panels can harness up to 30% more energy than traditional PV panels. Hence, bifacial PV panels are becoming a common approach at low solar irradiance conditions to yield more energy. However, a bifacial PV panel increases PV inverter loading. The PV inverter is the most unreliable component in the entire PV system. This results in a negative impact on PV system reliability and cost. Hence, it is necessary to anticipate the inverter’s reliability when used in bifacial PV panels. This paper analyzes the reliability, i.e., lifetime, of PV inverters, considering both monofacial and bifacial PV panels for the analysis. Results showed that the increase in bifacial energy yield could significantly affect PV inverter reliability performance, especially in locations where the average mission profile is relatively high.

Biomimetically Generated Nanoparticles in Boosting the Performance of Microbial Fuel Cells

Studies are presented in the context of the past attempts at finding nanocatalysts that can boost the performance of microbial fuel cells (MFCs) ? in terms of waste treatment and energy generation. Given the great potential of biomimetically synthesized nanoparticles (BMNPs) in providing less expensive and more environmentally friendly alternatives to NPs synthesized by physical and chemical methods, as well as a near-total lack of previous work in this area, the current research was undertaken. Effect of gold and silver nanoparticles (NPs), synthesized biomimetically using five freely available weeds, was assessed as catalysts in the MFCs. In all cases, the nanoparticles were seen to enhance the coulombic efficiency (reflective of the reduction in the waste’s organic carbon load), maximum attainable power density, and overall energy yield of the MFCs by >200% relative to the uncatalyzed MFCs. Gold nanoparticles were more effective than silver nanoparticles by ? 20%. The results reveal that biomimetically synthesized NPs can be highly effective in reducing the operational costs as well as ecological footprints of MFCs and further work should be focused on NPs of non-precious metals.

Functional analysis of H + -pumping membrane-bound pyrophosphatase, ADP-glucose synthase, and pyruvate phosphate dikinase as pyrophosphate sources in Clostridium thermocellum

The atypical glycolysis of Clostridium thermocellum is characterized by the use of pyrophosphate (PP i ) as phosphoryl donor for phosphofructokinase (Pfk) and pyruvate phosphate dikinase (Ppdk) reactions. Previously, biosynthetic PP i was calculated to be stoichiometrically insufficient to drive glycolysis. This study investigates the role of a H + -pumping membrane-bound pyrophosphatase, glycogen cycling, a predicted Ppdk–malate shunt cycle and acetate cycling in generating PP i . Knockout studies and enzyme assays confirmed that clo1313_0823 encodes a membrane-bound pyrophosphatase. Additionally, clo1313_0717-0718 was confirmed to encode ADP-glucose synthase by knockouts, glycogen measurements in C. thermocellum and heterologous expression in E. coli . Unexpectedly, individually-targeted gene deletions of the four putative PP i sources did not have a significant phenotypic effect. Although combinatorial deletion of all four putative PP i sources reduced the growth rate by 22% (0.30±0.01 h −1 ) and the biomass yield by 38% (0.18±0.00 g biomass g substrate −1 ), this change was much smaller than what would be expected for stoichiometrically essential PP i -supplying mechanisms. Growth-arrested cells of the quadruple knockout readily fermented cellobiose indicating that the unknown PP i -supplying mechanisms are independent of biosynthesis. An alternative hypothesis that ATP-dependent Pfk activity circumvents a need for PP i altogether, was falsified by enzyme assays, heterologous expression of candidate genes and whole-genome sequencing. As a secondary outcome, enzymatic assays confirmed functional annotation of clo1313_1832 as ATP- and GTP-dependent fructokinase. These results indicate that the four investigated PP i sources individually and combined play no significant PP i -supplying role and the true source(s) of PP i , or alternative phosphorylating mechanisms, that drive glycolysis in C. thermocellum remain(s) elusive. IMPORTANCE Increased understanding of the central metabolism of C. thermocellum is important from a fundamental as well as from a sustainability and industrial perspective. In addition to showing that H + -pumping membrane-bound PPase, glycogen cycling, a Ppdk–malate shunt cycle, and acetate cycling are not significant sources of PP i supply, this study adds functional annotation of four genes and availability of an updated PP i stoichiometry from biosynthesis to the scientific domain. Together, this aids future metabolic engineering attempts aimed to improve C. thermocellum as a cell factory for sustainable and efficient production of ethanol from lignocellulosic material through consolidated bioprocessing with minimal pretreatment. Getting closer to elucidating the elusive source of PP i , or alternative phosphorylating mechanisms, for the atypical glycolysis is itself of fundamental importance. Additionally, the findings of this study directly contribute to investigations into trade-offs between thermodynamic driving force versus energy yield of PP i - and ATP-dependent glycolysis.