•A spectral index, NSSI, is built for NPV-soil separation using two NIR bands.•The bands used in NSSI is suitable for Sentinel series sensors.•Avoiding SWIR bands can decrease the influence from ...water for NPV discrimination.•Feasibility on Sentinel images enhance the chance of continuous monitoring.•Applicability over woodland, grassland, and cropland is validated and discussed.
Non-photosynthetic vegetation (NPV) is an essential component in various vegetation-soil ecosystems. Both phenology and disturbance lead to a transition from photosynthetic vegetation to NPV and vice versa. Due to the similar spectral reflectance of NPV and bare soil (BS) in the visible-near infrared region (400–1000 nm), NPV and BS separation is relying on the shortwave infrared (SWIR) bands in most cases. The lignin and cellulose absorption feature is around 2100 nm, which is the most distinctive feature of NPV. However, the water absorption feature is much stronger in the SWIR, increasing the difficulty for NPV-BS separation when wet. Recently, Sentinel-2/3 satellites add more bands in the near infrared (NIR), which provide an extra opportunity for index building and application. Based on the difference captured by derivative spectra, a spectral index, NPV-Soil Separation Index (NSSI), is proposed to realize the separation using two NIR bands within 750–900 nm range in this study. Using spectra of photosynthetic vegetation (PV), NPV, and BS acquired from world-recognized spectral libraries, NSSI is built and validated as effective for lab-collected data. With the triangle method, one of the linear spectral unmixing methods, the fractional cover of PV, NPV, and BS can be estimated. Over a woodland study area, the fractional cover retrieved by cellulose absorption index (CAI) and NDVI combination of ZY1-02D AHSI hyperspectral image is 26.41%, 37.56%, 36.03% for PV, NPV, and BS in order. With the proposed NSSI-NDVI combination, the corresponding estimated fractional cover is 23.31%, 38.44%, 38.25% using Sentinel-2 MSI and 24.58%, 36.74%, and 38.68% using Sentinel-3 OLCI image. The comparable validation result confirms that the proposed NSSI is effective for NPV-BS separation. Moreover, the triangle method of NSSI-NDVI combination is applied on both grassland and cropland images to examine its feasibility on varied types of typical vegetation-soil ecosystems, and the well-built triangular space supports its feasibility. Relying on NIR bands, NSSI can avoid strong water absorption in the SWIR. Also, the feasibility of NSSI being used on multiple multispectral satellite sensors, especially the Sentinel series, makes continuous mapping for NPV over a large spatial scale possible.
With the upgrading of urbanization and improvement of living standards, the volume of municipal solid waste (MSW) is increasing in China. The waste-to-energy (WTE) incineration industry promotes the ...harmless disposal and recycling of MSW. It is an important part of the energy conservation and emission reduction tasks of “12th Five-Year Plan” period (2011–2015). Based on the development status of WTE plants in China, this paper makes an analysis of the WTE incineration industry from two aspects. The one is the analysis of political, economic, social and technological factors that influence the external environment of this industry. The other one is the discussion of technologies, costs and performances of some WTE plants in China, including a detailed cost-benefit analysis. It proves that the external environment is conducive to the development of WTE incineration industry and this industry is faced with good market prospects. Also, the net profit margin and return on investment (ROI) of WTE plants is attractive, up to 25% and 18% respectively. The pay back period is 12.73 years and the internal rate of return (IRR) is 10.94%. Thus, WTE plant has good profitability and economic benefit. Besides, WTE incineration has significant environmental benefits.
Combined cooling, heating, and power (CCHP) is an economic and eco-friendly technology to mitigate energy issues with remarkable energy efficiency improvement. This study formulates a mixed integer ...nonlinear programming (MINLP) model for a combined CCHP system coupled with renewable energy, i.e. RCCHP system, which is applied in five different buildings to evaluate the economic and environmental performance under two optimization modes. Net present value (NPV), internal rate of return (IRR) and dynamic payback period (DPP) are introduced as economic indexes, while CO2 emission reduction rate (CER) is considered as the environmental indicator to determine the optimal combination, capacity, and operation strategies for energy technologies. Results indicate that a combination of electricity purchased at valley period during night with power generated by the combined heating and power (CHP) unit coupled with wind turbine in peak period during daytime is cost-optimal which also enables higher energy efficiency. Meanwhile, the feed-in tariff as well as the uncoordinated electrical and thermal loads both show a significant impact on real-time operation strategies. Compared with the reference separate production (SP) system, the combined system shows better performance when applied to shopping mall under both optimization modes, e.g., with NPV up to 67.65 and 46.61 million RMB, IRR up to 20.70% and 25.10%, and the minimum DPP is 5.49 and 4.82 years under NPV and IRR maximization, respectively.
•Present a MINLP optimal design and dispatch model for RCCHP system.•Formulate a mathematical matrix for prime mover selection.•Introduce dynamic efficiency, carbon tax, and electricity feed-in tariff.•Conduct NPV- and IRR-objective optimization for five building types.•Optimize hourly operation strategy with economic and environmental evaluation.
A thermo-economic assessment of bubbling fluidized bed paddy dryers under atmospheric conditions applying the response surface methodology (RSM) was carried out on three atmospheric bubbling ...fluidized bed dryers to investigate the effects of inlet air temperature, superficial air velocity and amount of paddy on exergy efficiency at the equilibrium moisture content (EMC). Furthermore, experiments were also performed in the designed cone-shaped dryer as per the experimental matrix obtained from the software design of experiments (DoE). Experimental results were utilized to develop the quadratic model and predict the exergy efficiency. The desirability approach was used to find the optimum value of 65 °C for inlet air temperature, 2.1 m/s for superficial air velocity and 3 kg of paddy with an overall desirability index of 0.996. The optimum values were experimentally tested and verified with the least error levels. The conical dryer with a larger degree of cone angle had a higher exergy efficiency. The maximal exergy efficiency of 0.41 was observed when a spiral was attached to the dryers. All dryers benefitted from a 28% increase in exergy efficiency due to the spiral. Furthermore, an economic analysis of the dryers was also carried out on the three dryers. A higher profit/year value of ($ 1171.87) was observed to be associated with dryers having a higher cone angle with a shorter payback period (0.43 years). As a result, a higher cone-angled dryer is proven to be the optimum option for drying paddy grains.
•The thermo-economic analysis of three bubbling fluidized bed dryers was performed.•The DoE-based RSM statistical tool was used to model the exergy efficiency.•The maximum exergy efficiency was 36.6%, with a desirability approach of 0.996.•The profit per day increased by 62.7% as the cone angle increased.•The selling price should be higher than $ 0.19 to make a profit and reduce BEP.
For the nonlinear parameter‐varying (NPV) model of unmanned surface vehicle with the consideration of the velocities on yaw and surge as well as wave disturbances, a robust H∞$$ {H}_{\infty } $$ ...control method is proposed based on extended homogeneous polynomial Lyapunov function (EHPLF) to regulate heading for the superior performance on the rapidity, accuracy, and robustness. First, a NPV model of heading error is established to design a general form of a state feedback controller with a robust H∞$$ {H}_{\infty } $$ performance. Second, a Lyapunov matrix with full states and varying parameter is constructed to derive the robust H∞$$ {H}_{\infty } $$ global exponential stability conditions by Euler's homogeneity relation for the NPV system, known as the EHPLF stability conditions. Third, since the EHPLF stability conditions consist of a set of nonlinear coupled inequalities that cannot be directly solved by sum of squares (SOS) toolboxes, they are decoupled with matrix transformations to obtain the EHPLF‐SOS stability conditions, which is solved for the parameters of the state feedback controller. Finally, the simulation results indicate that EHPLF method exhibits a superior performance on dynamic, steady‐state, and robustness.
•Techno-economic analysis of gravity energy storage.•Energetic performance of Gravity Energy Storage (GES) with a wire rope hoisting system.•Energy storage LCOE and LCOS comparison•GES and GESH offer ...interesting economic advantages for the provision of energy arbitrage service.
Interest in energy storage systems has been increased with the growing penetration of variable renewable energy sources. This paper discusses a detailed economic analysis of an attractive gravitational potential energy storage option, known as gravity energy storage (GES). The economic performance of this energy storage system is compared to other alternative energy storage technologies such as pumped hydro energy storage (PHES) and compressed air energy storage (CAES). Moreover, a life cycle costs and levelized cost of electricity delivered by this energy storage are analyzed to provide expert, power producers, and grid operators insight about the economic implications of this grid-scale gravitational energy storage technology. Depending on the considered scenarios and assumptions, the levelized cost of storage of GES varies between 7.5 €ct/kWh and 15 €ct/kWh, while it is between 3.8 €ct/kWh and 7.3 €ct/kWh for gravity energy storage with wire hoisting system (GESH). The LCOS of GES and GESH were then compared to other energy storage systems. The obtained results show that GESH is very cost-competitive with pumped hydro and Compressed Air Energy Storage technologies; while GES is competitive with PHES and may be cost-competitive with CAES depending on the operation cycles. The performed analysis has also shown that both GES and GESH offer interesting economic advantages for the provision of energy arbitrage service.
•Develop algorithms for sizing grid-connected bifacial PV power plants.•HHOSA identifies the optimal configuration of components and installation parameters for bifacial PV power plants, maximizing ...or minimizing performance metrics.•HHOSA efficiently handles multiple design options within a short timeframe.•Techno-economic analysis of bifacial PV power plant.•Sensitivity analysis on bifacial PV parameters, cost considerations, and tailored ground cover enhance bifacial PV power plant success.
This paper presents an optimal design for ground-mounted grid-connected bifacial PV power plants using a Computational Intelligence (CI)- based Harris Hawks Optimization (HHO) algorithm. This HHO algorithm identifies the best configuration of components and installation parameters for the bifacial PV power plant, aiming to maximize the final yield, minimize the Levelized Cost of Electricity, and boost the Net Present Value. Four variables were optimized: the bifacial PV module model, inverter model, tilt angle, and module elevation. Furthermore, the paper introduces a Harris Hawks Optimization Sizing Algorithm (HHOSA) to address the sizing challenges. The presented HHOSA was purely developed in Matlab R2017b. The usage of PVsyst was only limited to the derivation of irradiation data at different tilt angle of PV array. These data were later used in HHOSA. To verify its effectiveness, HHOSA was benchmarked against other CI algorithms, including the Slime Mould Algorithm (SMA), Firefly Algorithm (FA), Manta Ray Foraging Optimization (MRFO), and Cuckoo Search Algorithm (COA). The evaluation considered the algorithm’s stability, local search capability, convergence rate, computation time, and required population size. Findings suggest that the HHOSA outperforms its peers, marking it as a potential leader for designing bifacial PV power plants. The results indicate that the HHOSA algorithm exhibits superior performance in these aspects, making it a promising approach for optimizing the design of bifacial PV power plants. Moreover, this study provides insights into the economic and technical viability of bifacial PV systems under various environmental and system conditions. A sensitivity analysis, focusing on the interplay of three decision variables − albedo values (25 %, 50 %, and 75 %), tilt angles (10°, 25°, and 35°), and module elevations (0.5 m, 1.5 m, and 2 m) − was conducted. It assessed their influence on final yield, additional bifacial PV module yield, Levelized Cost of Electricity, and the system’s Net Present Value. The results emphasize the importance of carefully considering the impacts of albedo, module elevation, and tilt angle on the financial performance of bifacial PV installations.
•A novel combined heating and power (CHP) cycle is proposed.•Energetic, exergetic, environmental and economic analysis of cycle are sought.•Payback period and net present value methods are utilized ...for economic evaluation.•Comprehensive parametric study of some design parameters is carried out.•Energy and exergy efficiencies of system are 69.37% and 37.95% in base conditions.
This research aims at developing a small-scale novel cogeneration system to satisfy all of the electrical and heating demands of a typical residential complex. The proposed system is integrated of a gas turbine cycle (GTC) and a Kalina cycle (KC). A comprehensive parametric study is presented for evaluating the proposed system from energy, exergy, environmental and economic (4E) points of view. The system’s governing equations are solved and validated through developing a high-accuracy computational code in Engineering Equation Solver (EES) software. The effects of some important design parameters (including compressor pressure ratio, base ammonia concentration, generator pressure and condenser pinch point temperature difference) are investigated on four appropriate criteria of energy efficiency (ηth), exergy efficiency (ηex), levelized total emissions (LTE) and levelized total costs (LTC). Furthermore, two economic methods, payback period (PP) and net present value (NPV), are also investigated. The results show that, the simulation outputs at base design conditions are as ηth = 69.43%, ηex = 37.90%, LTE = 87998 kg/kW, LTC = 8958 $/kW, PP = 3.34 years and NPV = 878679 $. The results of parametric analysis reveal that there is an optimal compressor pressure ratio which leads to maximum ηth and ηex and minimum LTE and LTC. The combustion chamber of GTC has the maximum share in system’s total exergy destruction (with 55.95% of total exergy destruction). Also, the entire KC has a low contribution of 3.396% in total exergy destruction.
•Pilot study of solar/hybrid/storage system for vertical farming under tropical climate condition with a case study at Malaysia.•Energy utilization and management via optimized building geometry ...modeling integrated with energy yield estimation tool to evaluate the potential of integrating green energy into urban agriculture.•Comprehensive analysis and assessments including technological, economic and environmental aspects of the proposed work.•The proposed work is evaluated under different design configuration (grid connected, stand alone, hybrid, storage etc) considering various optimization and design requirements and real-life constraints.•Comparative studies with hypothetical model and verification with additional energy modeling tool.
Human population is projected to reach 9.7 billion in 2050 and strike 11.2 billion by 2100. Residence shift from countryside to cities will occur and the human population resides in the cities is envisaged to rise from 55% to 68%. Vertical farming was proposed to address food insecurity caused by overcrowded population and farmland shortages. The compound annual growth rate (CAGR) of vertical farming in the Asia Pacific is forecasted to grow at 22.1% with a market size reaching USD 2,101.0 million by 2024. Malaysian government encourages the implementation of vertical farming as the production of major agricultural commodities has contracted by 3.4% from 2015 to 2017. However, high energy consumption is one of the shortcomings of a vertical farm as the estimated annual energy consumption for each square meter of growing area is 3500 kW h. Thus, this paper proposes an optimized building geometry modeling integrated with energy yield estimation tool to evaluate the potential of integrating green energy into urban agriculture. This research examines the load demand in the vertical farming systems and develops solar/hybrid/storage for vertical farming system with energy yield, performance ratio, economics and environmental assessments. Preliminary resources assessment by analyzing the solar radiation of the sites was carried out at stage 1. At stage 2, load consumption was calculated, and specifications of the system were justified. Stage 3 included the development of solar PV system for the vertical farms, the economic evaluation in the context of net present cost (NPC), levelized cost of energy (LCOE) and investigation of the environmental impact. Grid-connected and standalone solar PV systems were developed for comparative studies. The estimated daily energy consumption for vertical farms in Selangor and Kuching was 430.116 kW h and 1002.024 kW h. Energy generated by grid-connected solar PV systems supported 11.6% and 8.35% of the load consumption in Selangor and Sarawak. The performance ratios of grid-connected solar PV systems in both selected sites were 82.22% and 82.56%. The finding proved that proposed work has significantly reduced the dependency of the utility grid. Additionally, the LCOE with solar PV integration vertical farming system appeared to be lower than the LCOE of the grid and lower CO2 emission. This paper serves as a reference guide to the vertical farming stakeholders, national policy-decision makers and non-profit organizations who planned for similar initiatives especially those within the tropical climate regions.
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