Net Generation Research Articles

The roadmap towards the efficiency limit for supercritical carbon dioxide coal fired power plant

The Chinese Government has issued a series of documents to explain China’s control over the carbon dioxide (CO2) emission. One of the major tasks is to develop higher efficiency coal fired power plant, compared with current running power plant. In this paper, we aim to explore the roadmap to reach the efficiency limit for coal fired power plant using supercritical carbon dioxide cycle (sCO2 cycle). Referenced to Carnot cycle, the proposed roadmap is to increase the cycle efficiency by elevating average heat absorption temperature (Tave,h) and lowering average heat release temperature (Tave,l). In contrast to recompression cycle (RC), tri-compression cycle (TC) is introduced. Due to the increased Tave,h, TC achieves the second largest contribution for efficiency increment, followed by the reheating technique. Then, TC, double reheating (DRH) and intercooling (IC) are integrated as TC + DRH + IC in the power plant. To completely absorb flue gas energy over entire temperature range of (1500 ∼ 120) °C. A top cycle and a bottom cycle are connected for cascade utilization of flue gas energy. Overlap energy utilization is further utilized to fill the efficiency gap between top and bottom cycles. The proposed cycle also integrates the module boiler design to suppress the pressure drop penalty, and the flue gas recirculation to keep the heater surface temperature in an accepted level. A numerical model is developed for the comprehensive sCO2 cycle. At the main vapor parameters of 35 MPa/630 °C, the sCO2 coal fired power plant reaches the net power generation efficiency of 51.03%, which is higher than 48.12% for a supercritical water-steam power plant at the same capacity. Such efficiency improvement saves 175.2 kilotons of coal and reduces 396.4 kilotons of CO2 emission for 1000 MW capacity in a fascial year. Our work provides the guideline for the design and operation of large scale sCO2 coal fired power plant.

Influence of porous plate position on thermoelectric generator

Thermoelectric generators can be used to utilize the waste heat from vehicle exhaust for power generation. Due to the poor heat transfer of the exhaust, the thermoelectric conversion efficiency of the generator is poor, thus strengthening the heat transfer in the exhaust heat exchanger (EHE) is crucial. However, the complex optimized structure also poses challenges for the processing of EHE. In this paper, the addition of porous plates in the exhaust channel is proposed to improve the thermoelectric conversion efficiency of exhaust waste heat, and a coupled heat-electric-flow model of the exhaust generator is constructed. The simulation results found that the addition of the porous plate has a greater impact on the rear side flow, which can cause a pronounced increase in the overall temperature of the channel. Moreover, optimal insertion position exists for maximum net power generation.

Multi objective short term hydro-thermal- CHP scheduling using social spider algorithm

Potential of cheap and emission free hydro electric generation and that of another non linear efficient distributed energy resource namely combined heat and power (CHP) are utilized in the present dissertation. Water discharge from cascaded multi-reservoir system, its net head and power generation from such a hydroelectric system bears a nonlinear relationship. Such a hydro system with water transport delay among reservoirs is considered here. Optimal utilization of these sources to serve demands over short term of 24 h of a day by scheduling their respective generations so as to achieve multi objectives of cost effective production, reduced emission and transmission loss have been studied using a bio-inspired social spider algorithm. Outcome of the first test system containing hydro-thermal units shows the efficacy of the utilized optimization method while compared to other existing optimization techniques. The second test system is designed for the first time to exhibit the usefulness of the used algorithm in hydro-chp scheduling concept. Provided Statistical analysis justifies the significance of the data of the test systems.

Complement C3 inhibition in severe COVID-19 using compstatin AMY-101.

Complement C3 activation contributes to COVID-19 pathology, and C3 targeting has emerged as a promising therapeutic strategy. We provide interim data from ITHACA, the first randomized trial evaluating a C3 inhibitor, AMY-101, in severe COVID-19 (PaO2/FiO2 ≤ 300 mmHg). Patients received AMY-101 (n = 16) or placebo (n = 15) in addition to standard of care. AMY-101 was safe and well tolerated. Compared to placebo (8 of 15, 53.3%), a higher, albeit nonsignificant, proportion of AMY-101–treated patients (13 of 16, 81.3%) were free of supplemental oxygen at day 14. Three nonresponders and two placebo-treated patients succumbed to disease-related complications. AMY-101 significantly reduced CRP and ferritin and restrained thrombin and NET generation. Complete and sustained C3 inhibition was observed in all responders. Residual C3 activity in the three nonresponders suggested the presence of a convertase-independent C3 activation pathway overriding the drug’s inhibitory activity. These findings support the design of larger trials exploring the potential of C3-based inhibition in COVID-19 or other complement-mediated diseases.

Absorption Chiller/Kalina Cycle Coupled System for Low-Grade Waste Heat Recovery in Hydrate-Based CO2 Capture Process: An Economic and Exergetic Study

This study investigates a coupled system combined by a LiBr/H2O absorption refrigeration cycle and a Kalina cycle, to recover waste heat from a hydrate-based CO2 capture process. The optimal system operation has been obtained. Payback time, Return on investment, Net present value and Discounted cash flow rate of return are selected as the evaluation indicators for a comprehensive economic analysis. Cash flow patterns are obtained for different discounted interest rates and electricity prices. Exergy analysis is conducted and the exergy loss of each component is calculated. Results show that in comparison with the individual Kalina cycle, the net electricity generation is increased by around 45%. The highest thermal efficiency of this coupled system is 16.78%. Payment balance can be achieved with a payback time of 6 years. The purchase price of heat exchanger occupies the largest capital investment. Exergy efficiency of this system is obtained as 36.89%. Major system irreversibility occurs in heat transfer processes of heat exchangers and the largest exergy loss is found in generators of both subcycles. Reducing the heat transfer irreversibility and the size of heat exchangers are greatly encouraged in future efforts.

Improvement of the subcooled boiling model using a new net vapor generation correlation inferred from artificial neural networks to predict the void fraction profiles in the vertical channel

In the one-dimensional thermal-hydraulic (TH) codes, a subcooled boiling model to predict the void fraction profiles in a vertical channel consists of wall heat flux partitioning, the vapor condensation rate, the bubbly-to-slug flow transition criterion, and drift-flux models. Model performance has been investigated in detail, and necessary refinements have been incorporated into the Safety and Performance Analysis Code (SPACE) developed by the Korean nuclear industry for the safety analysis of pressurized water reactors (PWRs). The necessary refinements to models related to pumping factor, net vapor generation (NVG), vapor condensation, and drift-flux velocity were investigated in this study. In particular, a new NVG empirical correlation was also developed using artificial neural network (ANN) techniques. Simulations of a series of subcooled flow boiling experiments at pressures ranging from 1 to 149.9 bar were performed with the refined SPACE code, and reasonable agreement with the experimental data for the void fraction in the vertical channel was obtained. From the root-mean-square (RMS) error analysis for the predicted void fraction in the subcooled boiling region, the results with the refined SPACE code produce the best predictions for the entire pressure range compared to those using the original SPACE and RELAP5 codes.

Optimization study of CO2 capture unit for subcritical coal-fired power generation unit based on Ebsilon and Aspen plus

CO2 emissions from coal-fired power generation account for 70% of the total carbon emissions from the global power industry, thus it is essential to install CO2 capture unit (CCU) to coal-fired power generation units (CPGU), but this will cause a decrease in the thermal economy of the unit. Based on this, this paper takes 220 MW subcritical CPGU as the research object. An optimized CCU with integrated rich solvent split (RSS) process and CO2 compression intercoolers heat recovery (CIHR) process is constructed by Aspen Plus. Furthermore, an absorption heat pump (AHP) system driven by superheat of extracted steam is proposed to recover the waste heat of CO2-removed flue gas, and finally a novel CO2 capture CPGU coupled with AHP and optimized CCU is built and the thermal economy of the unit is simulated by Ebsilon. The results show that when the CO2 capture capacity is 500,000 tons/year, the optimized CCU reduces the regeneration energy consumption by 19.02% compared with the conventional CCU. When the unit load is 127.55 MW, the net electric power output of the novel CO2 capture CPGU is increased by 7.45%, the net generation efficiency is increased by 2.18%, the heat consumption is reduced by 887.31 kJ/kWh, and the standard coal consumption is reduced by 30.32 g/kWh compared with the conventional CO2 capture CPGU. The novel CO2 capture CPGU proposed in this study can significantly improve the thermal economy of the units and provide guidance for thermal integration of the CCU with the subcritical CPGUs.

Environmental desulfurization of mine tailings using froth flotation: The case of Amaruq Mine (Nunavut, Canada)

This research examined the the desulfurization of tailings from the Amaruq mine at a laboratory scale using froth flotation. Optimization of the flotation process was carried out by testing the conventional potassium amyl-xanthate collector (PAX) and three alternative collectors from the mercaptobenzothiazole (MBT) and dithiophosphate (DTP) families. The main goal was to assess the efficiency of the desulfurization process as a sustainable tailings management approach to prevent contaminated mine drainage generation. Mineralogical characterization of the Amaruq tailings using automated scanning microscopy (QEMSCAN®) revealed that the total sulfide and carbonate contents were about 8 wt% and 3 wt%, respectively; 63.39 % of the sulfur occurred as pyrrhotite, 30.17 % as pyrite, 3.63 % as gersdorffite, and 2.61 % as arsenopyrite. To compare the collector flotation yields, response surface methodology (RSM) was used for statistical design, analysis, and modelling of froth flotation experiments using three key-parameters: pH, activator (CuSO4) dosage, and collector dosage. Four quadratic mathematical models were developed for each collector to calculate sulfide recovery. Variance analysis (ANOVA) revealed that the factors that most affected sulfide recovery were collector type/dosage and pH. Process optimization yielded a maximum sulfide recovery of 96.73 % using 300 g/t PAX and 300 g/t CuSO4 at pH 11. A similar recovery of 95.83 % was achieved using an MBT-MTP based collector under the same conditions. The maximum recovery obtained using MTP and MTP-DTP based collectors while operating at optimal conditions (alkaline pH and maximum collector dosage at 350 g/t) was 88.65 %. The desulfurization process succeeded in decreasing the sulfur content in the tailings to<0.11 wt%. The final tailings were not acid-forming, as confirmed by the acid-base accounting (ABA) and net acid generation (NAG) static tests, compared to the highly acid-forming feed samples. Kinetic testing on the benign desulfurized tailings was also performed to predict and validate their acid generating potential, as well as their contaminant release rates (particularly As, Ni, Cu, Fe, and Zn). The Amaruq desulfurized material did not present any significant risk of contaminated mine drainage generation, and the leached contaminants did not exceed the criteria set by Quebec provincial legislation.

Multiphase simulation and parametric study of direct vapor generation for a solar organic Rankine Cycle

Parabolic trough collectors coupled with Organic Rankine Cycles are an attractive option for decentralized power generation. This work is dedicated to the parametric study of a parabolic trough collector system filled with benzene under solar irradiation for use in an Organic Rankine Cycle; the Computational Fluid Dynamics software ANSYS FLUENT was used in the study. Different inlet temperatures (465, 475 and 485 K), mass fluxes (168, 336 and 504 kg/m2s), and solar-concentrated heat fluxes (15.1, 18.5 and 22.2 kW/m2) are used in the simulations. The numerical model is validated with experimental data to a good concordance (maximum measured error for outlet equilibrium vapor quality and temperature is about 6 % and 0.01 %, respectively). The results indicate that (1) the inlet temperature does not have an effect in the fluid boiling behavior, (2) increasing the mass flow rate decreases the fluid evaporation rate, (3) the fluid evaporation rate is directly affected by the solar heat flux and (4) the mass flux affects the point where evaporation begins occurring (tube lengths of 10, 15 and 25 m for mass fluxes of 168, 336 and 504 kg/m2s, to 15.1 kW/m2, respectively.) Results also show that an excessive heat flux can result in large thermal gradients inside the collector (hence, overheating), and an excessive mass flow will delay the net vapor generation point.

Thermoeconomic analysis of conventional and recuperative ORC for heat recovery of exothermic reactions

The possibility of using medium temperature (478–506 K) saturated steam from a reactor cooling system as heat source for generating electricity is evaluated in this work. Both usual Organic Rankine Cycle (ORC) and recuperative (RORC) configurations were modeled for 3 different boiler heat loads (Cases 1, 2 and 3) so that the electricity generation capacity effect on the economic performance could be evaluated. From the power cycle simulations, methanol and ethanol had shown the best performance in the ORC configuration with average First and Second Laws’ efficiencies of 16% and 44%, respectively. By adding a recuperator, most of the dry fluids have also shown similar performances. In the economic analysis, net power generation plays a major role. For Case 2 ( ≈ 250 kW net) and Case 3 ( ≈ 850 kW net), the power generation revenue was insufficient to cover the operational expenses, yielding unfeasible scenarios. However, for Case 1 ( ≈ 2.5 MW net), economic feasibility was achieved even for low operating pressures. The best power cycle thermoeconomic performance was found for methanol as working fluid. In the best scenario, an attractive internal rate of return of 14.5% was achieved for an specified electricity cost of US$ 0.0671 per kW h. • Heat from medium temperature latent heat source is recovered to power an ORC. • Optimal evaporation temperature for dry fluids in RORC configuration is defined. • Minimum temperature difference automatic adjustment during power cycle simulation. • Heat exchanger detailed design based on literature correlations. • Power cycle NPV and pay-back calculation.

Design and evaluation of a new solar-biomass based energy system for a small sustainable residential community

In this paper, an integrated energy system is developed and analyzed, which generates power, heating and freshwater while being supplied with two distinct renewable energies: biomass and solar thermal. The system combines a multi-staged steam Rankine cycle with the steam generator energized via heat transfer from hot biomass combustion gases and hot solar thermal oil. It also includes a multi-effect desalination unit energized with thermal energy recovered from hot flue gases. The biomass combustion rate is controlled so that steam is generated steadily and at constant parameters regardless of the fluctuation and intermittence of solar radiation. At the same time, no thermal storage is required for solar energy. The steam Rankine cycle is optimized to steam extraction fraction so that the net power generation is maximized. The optimum steam extraction fraction of a low-pressure turbine is 5.5% of the main steam flow rate, which is the steam ahead of the high-pressure turbine. Due to solar radiation, biomass consumption is reduced to about half. Considering the solar radiation for a typical day in the Kingdom of Saudi Arabia, biomass consumption decreases three times during noontime (when solar radiation is the maximum) with respect to the nighttime. Nevertheless, the studied system generates more heating by-products and more freshwater when the biomass combustion rate is higher. During daytime, the current study achieves freshwater and heating production almost three times higher than the nightime requirement. The study results show that the need for typical solar thermal storage can be eliminated, and so the economic competitiveness of the solar thermal energy resource substantially increased. The maximum energy efficiency is slightly over 50% due to cogeneration, whereas the maximum exergy efficiency is 47%. The Rankine cycle destroys three times more exergy than the combustion chamber, whereas the other subsystems destroy significantly less exergy than the Rankine cycle.

Environmental Geology of Barite Deposits in Nevada

Abstract Barite is an important industrial mineral used as a weighing agent in fluids during the drilling of oil and natural gas wells, with the majority of United States production originating from Nevada. This paper considers three barite properties at varying stages of development—Rossi, Heavy Spar, and Ann—all located within the northern Nevada barite belt. At all three sites, barite is hosted in the Roberts Mountains allochthon consisting of siliceous sedimentary rocks. Geochemical characterization of waste rock, ore, and process products has been undertaken as part of project development at each site, including 212 acid-base accounting (ABA) analysis and 19 humidity-cell tests operated for up to 114 weeks. This study demonstrates that the presence of barite greatly limits the application of using traditional Sobek-style ABA methods. Barite will undergo incomplete dissolution and extraction in the ABA tests that will result in an overprediction of acid generation for materials that contain barite (i.e., ore and jig by-products). Results indicate use of the net acid generation test to inform waste rock management represents a more reliable indicator of acid generation for these three deposits and potentially also other barite deposits. Potential barite mine sites should continue to be evaluated using the same geochemical testing tools as base metal mines but using those tools in a selective way to achieve balance between regulatory requirements and costs.

Sulfide Variation in the Coeur Rochester Silver Deposit: Use of Geologic Block Modeling in the Prediction and Management of Mine Waste

Abstract A critical issue in mine waste management is the management and mitigation of acid rock drainage and metal leaching particularly from waste rock. This requires good understanding and characterization of materials most likely to generate acid pH waters and generate leachable metals and metalloids, as well as the presence of minerals most likely to neutralize acidic pH such as carbonates and certain silicates. For low-sulfidation epithermal deposits in silica-rich volcanic rocks, neutralization minerals are rare. Consequently, determination of acid generation is almost entirely a function of sulfide content of the rocks. By understanding the distribution of sulfide minerals within such a deposit, an initial mine waste management plan can be developed. The Rochester mine currently exploits a low-sulfidation epithermal gold-silver deposit and is located on the southern flank of the Humboldt Range in west-central Nevada. The Rochester mine is a conventional open-pit mining operation with cyanide heap leaching and Merrill Crowe processing. Silver and lesser gold mineralization occur associated with sulfide minerals hosted in Permian-Triassic Koipato Group rhyolitic units with extensive quartz-sericite-pyrite alteration. Gangue mineralogy of the deposit is dominated by slow or unreactive silicate minerals with little or no carbonate. Silver-bearing mineralization was controlled by primary hypogene sulfides and secondary supergene oxidation processes, and most of the mineralized material mined to date has been fully or partially oxidized. Oxidation mobilizes and depletes all forms of sulfur from primary sulfide minerals. Due to the low sulfate content and low content of neutralizing gangue phases, the waste rock classification can be based on total sulfur content. Based on the analysis of pulp samples collected from within the mine area, a sulfur block model was developed and compared to the results of standard acid-base accounting and net acid generation tests. This comparison demonstrates the benefit of the block model in identifying zones of potentially acid-generating material in the mined waste. Application of this information to mine planning has allowed more efficient management of acid-generating mine waste by allowing the operator to develop areas of the waste rock facility to receive the waste in a timely fashion. Such an approach is based on good mine geologic and mineralogical characterization and the use of a representative and comprehensive geologic block model.

The potential of using alkaline gold mine tailing as a cover material to mitigate AMD formation from acidic gold mine tailing pile at Sabie-Pilgrim's Rest Goldfields, South Africa.

Acid mine drainage (AMD) caused by the oxidation of sulphide minerals found in mine waste is a global environmental concern, especially in water-restricted countries with heavy mining industries. Implementing AMD treatment and prevention programs can be extremely expensive, hence the need to identify environmentally sustainable treatment and preventative techniques to mitigate the potential of AMD formation. Soil covers and blends have been identified as an attractive approach. However, prior studies on the characteristics of the soils concerned and the acid-neutralisation rate should be carried out before considering the implementation of a soil cover or blending system to mitigate AMD formation. This study evaluated the acid generation capabilities of acidic gold mine tailings (AG), alkaline gold mine tailings (AN) and blends (MIX25, MIX50). Acid-base accounting (ABA), net acid generation (NAG) and acid-buffering characteristic curve (ABCC) test methods were used to evaluate the acid-generating and acid-neutralising capabilities of AG, AN, MIX25 and MIX50 samples. Leach column tests were conducted using alkaline gold mine tailings (AN) as the top pH neutralising cover (COV25) to determine the potential of the alkaline gold mine tailing to serve as a pH neutralising cover material to prevent and treat AMD generated by the acidic gold mine tailings. The ABA, NAG and ABCC results showed that AN has a high acid-neutralising capacity while AG has the potential to generate acid. The results further indicated that the AN to AG blend ratio of 1:3 by weight (MIX25) would neutralise the acid generated by AG. Leach column experiment (COV25) found that using AN as a pH neutralising cover would be a feasible option.

Neutrophil extracellular traps promote thrombogenicity in cerebral venous sinus thrombosis

BackgroundNeutrophil extracellular traps (NETs) contribute to the creation of a coagulation state in various diseases. Currently, it is not clear whether NETs are present in the thrombi and plasma of patients with cerebral venous sinus thrombosis (CVST). This study aimed to investigate the presence of NETs in thrombi and blood samples from CVST patients and the procoagulant activity (PCA) of NETs during the progression of CVST.ResultsThrombi obtained from CVST patients undergoing thrombectomy were examined by immunochemistry using neutrophil elastase (NE), CD66b and citrullinated histone H3(citH3). The presence of NET markers in samples from 37 CVST patients and 32 healthy people was evaluated by ELISA. NET-producing neutrophils and neutrophil-platelet (PLT) aggregates were examined in samples obtained from CVST patients and healthy people by flow cytometry. The TAT complex in plasma sample from each group was detected by ELISA to evaluate the procoagulant activity of NETs in CVST patients. Neutrophils from healthy subjects were treated with PLT-rich plasma in the presence of anti-PF4 antibodies or an autophagy inhibitor and analyzed by flow cytometry and confocal microscopy. After treatment with NETs, the expression of von Willebrand factor (VWF), tissue factor (TF) and CD31 in human brain microvascular endothelial cells (HBMECs) was measured by confocal microscopy and western blotting. Our results showed that NETs were abundant in the plasma and thrombi from CVST patients. Platelet factor 4 (PF4) from CVST PLTs induced NET generation through autophagy. NETs could induce PCA by modulating TF and phosphatidylserine (PS) in CVST. NETs also disrupted the endothelial barrier and transformed ECs into a procoagulant phenotype to exacerbate thrombogenicity.ConclusionsNET generation was mediated by PF4 from PLTs through autophagy and contribute to thrombosis in CVST patients.

Environmental justice and power plant emissions in the Regional Greenhouse Gas Initiative states.

Policies to reduce greenhouse gases associated with electricity generation have been a major focus of public policy in the United States, but their implications for achieving environmental justice among historically overburdened communities inappropriately remains a marginal issue. In this study we address research gaps in historical and current ambient air emissions burdens in environmental justice communities from power plants participating in the Regional Greenhouse Gases Initiative (RGGI), the country's first market-based power sector emissions reduction program. We find that in RGGI states the percentage of people of color that live within 0-6.2 miles from power plants is up to 23.5 percent higher than the percent of the white population that lives within those same distance bands, and the percentage of people living in poverty that live within 0-5 miles from power plants is up to 15.3 percent higher than the percent of the population not living in poverty within those same distance bands. More importantly, the transition from coal to natural gas underway before RGGI formally started resulted in large increases in both the number of electric-generating units burning natural gas and total net generation from natural gas in environmental justice communities hosting electric-generating units, compared to other communities. Our findings indicate that power sector carbon mitigation policies' focusing on aggregate emissions reductions have largely benefitted non-environmental justice communities and have not redressed the fundamental problem of disparities in pollutant burdens between EJ and non-EJ communities. These must be directly addressed in climate change and carbon emissions mitigation policy.

Capacity optimization of pumped storage hydropower and its impact on an integrated conventional hydropower plant operation

The energy sector contributes to around 60% of total greenhouse gas emissions. To limit climate change, the world is going through an energy transition to clean and affordable energy, therefore the share of variable renewable energy is increasing day by day. Power systems require significant flexibility to operate reliably. Pumped storage hydropower allows load balancing and stable integration of intermittent renewable energy in the electrical grid. All energy storage technologies, including pumped storage hydropower, are considered a net negative contributor to the grid since they draw more energy than they deliver. This paper uniquely investigates the true potential of pumped storage hydropower and its optimum operation along with existing conventional hydropower. It considers power, energy production, and utilization for both installations to determine an equilibrium condition for a net positive energy balance. The case study of the 300 MW Balakot conventional hydropower plant in Khyber Pakhtunkhwa, Pakistan indicates that the pumped storage hydropower sites, where additional water streams reach the upper storage reservoir, can reduce pumping energy consumption by up to 166 GWh/year. Accordingly, a pumped storage hydropower facility is proposed at Paras, Pakistan, modeled, and optimized in an integrated manner with the Balakot conventional hydropower plant for a net positive annual energy generation and profitability. The integrated power and energy modeling and capacity optimization of the hydropower complex highlight the importance of suitable site selection for pumped storage hydropower near existing conventional hydropower reservoirs. Value-added contribution of this configuration is that it can enhance annual energy generation from integrated conventional hydropower, reduce the upfront capital cost of the project by 10–15%, squeeze the project implementation schedule and result in a smaller carbon footprint to meet the ultimate objective of limiting climate change. Additionally, it unlocks huge untapped pumped storage hydropower potential besides existing conventional hydropower. Furthermore, the study guides the scientific and engineering organizations on optimum capacity utilization without impeding energy generation from conventional hydropower facilities.

Optimization of Standalone Photovoltaic Drip Irrigation System: A Simulation Study

This paper presents the optimal design of a photovoltaic (PV) drip irrigation system. Designing a PV system is based on calculated motor power, solar irradiance level and other meteorological parameters at a certain geographical location. Therefore, a simulation study of the designed PV system were performed by a PVGIS simulation tool. The PVGIS simulation tool analyzes the potential of power generation with optimal PV modules tilt angle and orientation on a monthly and annual basis, and an analysis of the overall shading situation (horizon) as well as the internal shading between the PV module rows. The selection of water pump and motor depends upon the depth of water table and desired discharge and head to operate the irrigation system. Furthermore, a locally developed Solar-Drip Simulation Tool (SoSiT) was used for load and supply optimization. Based on ambient temperature, solar irradiation and water requirements, SoSiT calculates net generation by a PV system and resultant water output of the irrigation system. The particular drip irrigation site has two zones; the maximum water requirement for zone 1 (row crop) is 50,918.40 Liters/day and for zone 2 (orchards) is 56,908.80 L/day. From PVGIS simulation results, the maximum daily energy production of the designed PV system was 6.48 kWh and monthly energy production was 201 kWh in the month of May. SoSiT results showed that the PV system fulfilled the required crop requirement by only using 28% of the potential water supply, and 72% of the potential water supply from a solar-powered pump was not used. This value is high, and it is recommended to grow more or different crops to utilize the fuel-free electricity from the PV system. The unit cost of PV-powered drip irrigation is USD 0.1013/kWh, which is 4.74% and 66.26% lower than the cost of subsidized electricity and diesel, respectively.

A novel Hypertuned Prophet based power saving approach for IoT enabled smart homes

AbstractRecent advances in energy conversion, information technology, the internet, new types of web, and communication technologies have enabled the interconnection of all physical objects, including sensors and actuators. Web‐enabled smart objects have paved the way for smart homes by enabling innovative services. In this work, the idea of using time series analysis based on machine learning and forecasting considering the weather conditions is discussed, to enhance automation and improve intelligence. The proposed Prophet model is used to predict the future net energy consumption and generation for improving energy efficiency and enabling power backup. Energy efficiency is the need of the hour, wherein major utilization of energy is in the residential sector, it is gravely important to analyze current generation and consumption and act accordingly for the future predicted results. Moreover, smart homes are dependent on web technologies and telecommunication for the operation of every action, which makes it crucial to have necessary power backup. The Prophet forecasting model, after parameter tuning and logistic growth pattern with additional regressors, gives only 0.27 mean absolute error and 0.13 mean squared error for predicting future energy consumption as compared to other models.

Dissolved Organic Carbon Chemostasis in Antarctic Polar Desert Streams

AbstractDissolved organic carbon (DOC) is a key variable impacting stream biogeochemical processes. The relationship between DOC concentration (C) and stream discharge (q) can elucidate spatial and temporal DOC source dynamics in watersheds. In the ephemeral glacial meltwater streams of the McMurdo Dry Valleys (MDV), Antarctica, the C‐q relationship has been applied to dissolved inorganic nitrogen and weathering solutes including silica, which all exhibit chemostatic C‐q behavior; but DOC‐q dynamics have not been studied. DOC concentrations here are low compared to temperate streams, in the range of 0.1–2 mg C l−1, and their chemical signal clearly indicates derivation from microbial biomass (benthic mats and hyporheic biofilm). To investigate whether the DOC generation rate from these autochthonous organic matter pools was sufficient to maintain chemostasis for DOC, despite these streams' large diel and interannual fluctuations in discharge, we fit the long‐term DOC‐q data to a power law and an advection‐reaction model. Model outputs and coefficients of variation characterize the DOC‐q relationship as chemostatic for several MDV streams. We propose a conceptual model in which hyporheic carbon storage, hyporheic exchange rates, and net DOC generation rates are key interacting components that enable chemostatic DOC‐q behavior in MDV streams. This model clarifies the role of autochthonous carbon stores in maintaining DOC chemostasis and may be useful for examining these relationships in temperate systems, which typically have larger sources of bioavailable autochthonous organic carbon than MDV streams but where this autochthonous signal could be masked by a stronger allochthonous contribution.