Terms Of Power Production Research Articles

Refining the airborne wind energy system power equations with a vortex wake model

Abstract. The power equations of crosswind Ground-Gen and Fly-Gen airborne wind energy systems (AWESs) flying in circular trajectories are refined to include the contribution from the aerodynamic wake, modeled with vortex methods. This reveals the effect of changing the turning radius, the wing geometry and the aerodynamic coefficients on aerodynamic performances and power production. A novel power coefficient is defined by normalizing the aerodynamic power with the wind power passing through a disk with a radius equal to the AWES wingspan, enabling the comparison of different designs for a given wingspan. The aspect ratio which maximizes this power coefficient is finite, and its analytical expression for an infinite turning radius is derived. By considering the optimal wing aspect ratio, the maximum power coefficient is found, and its analytical expression for an infinite turning radius is derived. Ground-Gen and Fly-Gen AWESs, with the same idealized characteristics, are compared in terms of power production, and later three AWESs from the literature are analyzed. With this modeling framework, Ground-Gen systems are found to have a lower power potential than Fly-Gen AWESs with the same geometry because the reel-out velocity makes Ground-Gen AWESs fly closer to their own wake.

Thermal-hydraulic modelling and stade staty analysis of a LS-VHTR reactor

The Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR) is a liquid salt cooled and TRISO fueled reactor, which presents very good features in terms of power production and safety aspects. The advantage of using liquid salt as coolant is mainly related with its high efficiency of heat transfer and operation at low pressures. This work evaluates the thermal hydraulic performance of the heat removal system and the reactor core, in steady state conditions, starting from the single channel level and concluding with the full core model. The LS-VHTR is a new reactor concept that introduces some different features in relation to other nuclear reactors. In this way, a thermal modeling of this reactor has been developed using the RELAP5-3D code using a point kinetic model. A modeling with three channels has been presented. The core coolant temperature increase, the core coolant mass flow and the pressure along the core were simulated and presented in good agreement with the expected behavior

A study on the influence of the numerical scheme on the accuracy of blade-resolved simulations employed to evaluate the performance of the NREL 5 MW wind turbine rotor in full scale

We present a numerical investigation on the influence of the numerical arrangement in the accuracy of the NREL 5 MW wind turbine rotor performance evaluation in full scale, using a Computational Fluid Dynamics (CFD) methodology which employs the Finite Volume Method (FVM) implemented in the OpenFOAM software. The nonlinearity of the Navier–Stokes equation, which requires special treatment and still represents a subject under intense debate in the scientific community, is tackled by using two different discretization schemes for computing the convective term. In addition, since the advection scheme numerically interacts with the turbulence closure model employed in the numerical simulations, we considered the URANS k-ω SST and DES k-ω SST models to perform the blade-resolved simulations. A hybrid central/upwind scheme, namely the LUST scheme, was considered for discretizing the convective term for both URANS and DES simulations, while the second order accurate upwind given by the LUD scheme was considered only in the URANS simulation. Considering the LUST scheme, an investigation on the temporal and spatial discretization was performed for both turbulence closure models. The performance of the NREL 5 MW rotor for offshore application in full scale was assessed in terms of power production, generated thrust, and forces distribution along the blade span, for the operation condition of optimal wind-power conversion efficiency. We provide detailed information regarding the flow features and computational cost, and verified the results from each case by comparing the CFD results against values obtained using the blade element momentum theory implemented in OpenFAST. For the spatial discretization considered in one of the meshes, the LUD scheme showed low accuracy in the results, being more susceptible to the grid influence for the URANS simulations compared to LUST, while the URANS-LUST and DES-LUST approaches were both suitable options for all the meshes investigated. The DES-LUST approach was less affected by the variation in the size of the time step employed. Additionally, finer flow structures were captured with the DES-LUST simulations at an affordable computational cost.

Which power cycle is the best fit for parabolic trough solar collectors? A comparative and comprehensive case study for six sub-configurations of the three main cycles

In this study, the integration of a Parabolic Trough Collector with different power cycles was investigated on an annual basis in terms of Energy, Exergy, Economics and Environmental under different meteorological conditions. A parabolic trough collector with 500 collectors with a gross and net aperture area of 432,000 and 817.43 m2, was installed in a place that has a high solar energy potential. With a Parabolic trough collector, hourly Direct Normal Irradiation, wind speed, wind direction, ambient temperature and incident angle values were obtained for the 15th of each month for a year. The performance of the 3 power cycles with 6 different configurations using the Parabolic trough collector as the heat source was comprehensively analyzed and compared. During the dynamic data use and various commonly used power systems comparing study, it was aimed to answer the most commonly asked questions by the researchers in this area. To do this, the effect of direct normal irradiation and incident angle on the performance of systems to reach the maximum net power was studied. After calculations, the maximum net power was not found on July 15 (12:00) when the maximum direct normal irradiation (840.868 W/m2) was seen. The maximum net power (67867 kW) was found on September 15 (12:00) when the incident angle was minimum (1.71°) along with the high direct normal irradiation. Steam Rankine Cycle, Organic Rankine Cycle and Kalina Cycle performance comparisons were made both annually depending on time and with different configurations and fluids. In addition to tangibly showing the superiority of incident angle on direct normal irradiation, the present study aimed to present the best-performing system configuration for the researcher, user, scientists, and manufacturers. Interestingly, while the Organic Rankine Cycle with heat exchanger with R123 showed better performance in terms of power production and carbon dioxide emission reduction, the Kalina Cycle was found much more feasible in terms of economics.

Analysis of Consumer Willingness to Pay for Community Solar Business Using Contingent Valuation Method

Electricity production using renewable energy instead of fossil-fuel-based energy sources has been expanding worldwide. Recently, the South Korean government has set a transition from a government and power company-led energy system to a public-participatory energy system as a basic policy direction in terms of power production. It has been actively providing budgetary and institutional support. A comprehensive understanding of the consumer (public)-oriented preferences of potential business participants is crucial for implementing a successful community solar business. This study analyzes the preferences of potential participants in the community solar business from the perspective of policymakers to derive policy implications. We used the contingent valuation method of the stated preference approach targeting potential participants (public) to create a hypothetical market for community solar businesses and measured the value by inducing survey respondents to trade for goods or services. The monthly average willingness-to-pay was estimated to be 25,572 won (USD 21.90), and gender, photovoltaic business experience, and income were the main influencing factors. Based on the results of this study, the preferences of potential consumers in South Korea were analyzed to contribute to the effectiveness of the national energy policy.

Aerodynamic Interactions of Wind Lenses at Close Proximities

The fundamental aerodynamic interactions between a pair of wind lenses is experimentally investigated. In prior work, wind tunnel testing of lensed turbines in a side-by-side configuration revealed that one lensed turbine outperformed its counterpart in terms of power production. In the current study, particle image velocimetry (PIV) was performed in the wake of three different pairs of wind lens profiles and revealed an inherent bias in the wake properties at close proximities which led to one turbine outperforming the other. The merged wake location is skewed to a single lens in the lens pair depending on the extent of cancellation of inboard vorticity magnitude. At 0.1 to 0.2 x/D,the individual wakes merge as one, at which point the vortex shedding frequency and the modal strength behind the lens pairs is reduced. Coincidentally, it is at this spacing that the net power output of lensed turbines placed in a side-by-side configuration reaches the maximum.

Neutronic analysis of Indian helium-cooled solid breeder tritium breeding module for testing in ITER

India has proposed the helium-cooled solid breeder blanket concept as a tritium breeding module to be tested in ITER. The module has lithium titanate for tritium breeding and beryllium for neutron multiplication. Beryllium also enhances tritium breeding. A design for the module is prepared for detailed analysis. Neutronic analysis is performed to assess the tritium breeding rate, neutron distribution, and heat distribution in the module. The tritium production distribution in submodules is evaluated to support the tritium transport analysis. The tritium breeding density in the radial direction of the module is also assessed for further optimization of the design. The heat deposition profile of the entire module is generated to support the heat removal circuit design. The estimated neutron spectrum in the radial direction also provides a more in-depth picture of the nuclear interactions inside the material zones. The total tritium produced in the HCSB module is around 13.87 mg per full day of operation of ITER, considering the 400 s ON time and 1400 s dwell time. The estimated nuclear heat load on the entire module is around 474 kW, which will be removed by the high-pressure helium cooling circuit. The heat deposition in the test blanket model (TBM) is huge (around 9 GJ) for an entire day of operation of ITER, which demonstrates the scale of power that can be produced through a fusion reactor blanket. As per the Brayton cycle, it is equivalent to 3.6 GJ of electrical energy. In terms of power production, this would be around 1655 MWh annually. The evaluation is carried out using the MCNP5 Monte Carlo radiation transport code and FEDNL 2.1 nuclear cross section data. The HCSB TBM neutronic performance demonstrates the tritium production capability and high heat deposition.

Ambient temperature and solar irradiance forecasting prediction horizon sensitivity analysis

Selecting the correct weather forecasting technique is a crucial task when planning an efficient solar energy generation system. Estimating accurate solar photovoltaic systems power output depends on the correct modeling of solar irradiance and ambient temperature, evidencing the need for a framework to select the correct technique to forecast these parameters. This paper presents a review of the forecasting methods to predict solar irradiance and ambient temperature, considering the sensitivity to the forecasting horizon. The methodology includes estimating an interval for ambient temperature and solar irradiance by using the Mean Absolute Error as the percentage of variation in these parameters. To provide context, the study considers best-case and worst-case scenarios for four cities, estimating the power output for a sample array and analyzing the differences between the cases. The power output estimation of the PV array varied between 36% and 50% (on average) for the short-term prediction, and 54% to 95% for the long-term. The changes in the location produced an average variation of 43% in terms of power production, and up to 187% in economic value (USD) for the short term, and 44.5% and 187% for the long term. The results suggest a marked sensitivity to the variation in the forecasting horizon and significance with regards to location selection (considering the changes in solar irradiation and the cost of electricity).

Validation of wind turbine wakes modelled by the Meso-NH LES solver under different cases of stability

In wind farms, the wakes of upstream turbines impact the downstream ones in terms of power production, loads, and fatigue. The wake properties depend on many parameters such as the stratification, Coriolis force, large-scale forcing and orography. To simulate this interdependence, the actuator line method (ALM) has been implemented in the atmospheric code Meso-NH, which is an LES research code developed by the French weather services. This implementation has already been validated for the blade force distribution on the NewMexico case (uniform inflow in a wind tunnel) and for the interaction with the atmosphere on the Horns Rev photo case. The work presented here aims at completing the validation in a realistic atmospheric boundary layer (ABL), with a focus on velocity deficit and wake meandering. It is based on the international SWiFT benchmark which compares the results of many numerical models with LiDAR measurements in the wake of a single turbine for three cases of atmospheric stability: neutral, unstable and stable. The good results show the capacity of Meso-NH/ALM to generate realistic wakes in a representative ABL.

Parametric design of a resonant point absorber with a fully submerged toroidal shape

The parametric design of a resonant point absorber, equipped with a fully submerged toroidal shape and connected to a permanent magnet linear generator lying on the seabed, is performed to investigate the effectiveness of the new WEC device in terms of power production and cost of energy. After developing a non-linear time-domain model for the heave, surge and pitch motions of the floating buoy and the vertical motion of the Power Take-Off translator mass, a comparative analysis is performed among a reference WEC device and the new layout. The Annualised Energy Production of the WEC devices is assessed with reference to a candidate deployment site located in the western Mediterranean Sea. The scantling of the tensioned line, connecting the floating buoy to the Power Take-Off unit, is carried out based on both Ultimate and Fatigue Limit State design conditions. Subsequently, the Levelised Cost of Energy is determined and a sensitivity analysis is performed to detect a possible pathway to further reduce the power production costs. Based on current results, the new WEC device seems to be a promising layout to gain the EU target for the marine renewable energy sector that should be reached by 2025.

Piezoelectric Energy Harvesting Controlled with an IGBT H-Bridge and Bidirectional Buck-Boost for Low-Cost 4G Devices.

In this work, a semi-submersible piezoelectric energy harvester was used to provide power to a low-cost 4G Arduino shield. Initially, unsteady Reynolds averaged Navier–Stokes (URANS)-based simulations were conducted to investigate the dynamic forces under different conditions. An adaptive differential evolution (JADE) multivariable optimization algorithm was used for the power calculations. After JADE optimization, a communication cycle was designed. The shield works in two modes: communication and power saving. The power-saving mode is active for 285 s and the communication mode for 15 s. This cycle consumes a determinate amount of power, which requires a specific piezoelectric material and, in some situations, an extra power device, such as a battery or supercapacitor. The piezoelectric device is able to work at the maximum power point using a specific Insulated Gate Bipolar Transistor (IGBT) H-bridge controlled with a relay action. For the extra power supply, a bidirectional buck–boost converter was implemented to flow the energy in both directions. This electronic circuit was simulated to compare the extra power supply and the piezoelectric energy harvester behavior. Promising results were obtained in terms of power production and energy storage. We used 0.59, 0.67 and 1.69 W piezoelectric devices to provide the energy for the 4G shield and extra power supply device.

Integrated wind farm layout and control optimization

Abstract. The objective of this paper is to investigate the joint optimization of wind farm layout and wind farm control in terms of power production. A successful fulfilment of this goal requires the following: (1) an accurate and fast flow model, (2) selection of the minimum set of design parameters that rules or governs the problem, and (3) selection of an optimization algorithm with good scaling properties. For control of the individual wind farm turbines with the aim of wind farm production optimization, the two most obvious strategies are wake steering based on active wind turbine yaw control and wind turbine derating. The present investigation is limited to wind turbine derating. A high-speed linearized computational fluid dynamics (CFD) Reynolds-averaged Navier–Stokes (RANS) solver models the flow field and the crucial wind turbine wake interactions inside the wind farm. The actuator disc method is used to model the wind turbines, and utilizing an aerodynamic model, the design space of the optimization problem is reduced to only three variables per turbine – two geometric and one carefully selected variable specifying the individual wind turbine derating setting for each mean wind speed and direction. The full design space is spanned by these (2N+NdNsN) parameters, where N is the number of wind farm turbines, Nd is the number of direction bins, and Ns is the number of mean wind speed bins. This design space is decomposed into two subsets, which in turn define a nested set of optimization problems to achieve a significantly faster optimization procedure compared to a direct optimization based on the full design space. Following a simplistic sanity check of the platform functionality regarding wind farm layout and control optimization, the capability of the developed optimization platform is demonstrated on a Swedish offshore wind farm. For this particular wind farm, the analysis demonstrates that the expected annual energy production can be increased by 4 % by integrating the wind farm control into the design of the wind farm layout, which is 1.2 % higher than what is achieved by optimizing the layout only.

Bioelectrochemical behaviour of a sequentially added biocatalytic coculture in a microbial fuel cell.

Bacterial isolates Pseudomonas aeruginosa BR, Alcaligenes faecalis SW and Escherichia coli EC from a microbial fuel cell (MFC) were cocultured with each other. The isolates were added in a specific sequence one after the other (two cultures in one reactor). The study helped us conceptualise the synergistic and antagonistic behaviour of bacterial isolates and also emphasised the sequence in which a culture can be introduced in an anode chamber. The coculture conditions were evaluated on the basis of redox activity, electron transfer rate, columbic efficiency, and internal resistances. A good syntropy in terms of power production was found between P. aeruginosa BR and E. coli EC that recorded a power generation of 207.593 ± 1.705 µW/m2 . The addition of any culture in any sequence affected the performance of P. aeruginosa BR. This culture when added as a secondary culture in the reactor enhanced the performance of that reactor. The sequence of addition of a culture in a reactor affected the performance in the combinations of (a) P. aeruginosa BR and A. faecalis SW and (b) A. faecalis SW and E. coli EC.

영농형 태양전지 스트링 구성에 따른 발전량 및 농업생육환경 분석

The distributed solar module composition in small size is necessary for simultaneous crop cultivation and power generation in agrophotovoltaic (APV). The purpose of this study is to compare and analyze PV power generation and agricultural environment changes according to different cell string composition (3×12 and 4×9 module). Ground solar radiation was simulated and a test-bed was constructed, with 30% shading rate, to collect monthly power and agricultural environment data for 10 months. The 3×12 module had a 0.7% higher ground solar radiation value than the 4×9 module in the simulation results. In test-bed, though the 4×9 module may be considered for use in the APV in terms of power production, ground solar radiation, and soil humidity, the 3×12 module should be considered that the damage of crops caused by waterdrop can be mitigated when the PV module has fewer strings. These results can contribute for the selection of standard APV module design in terms of installing 10GW of APV by government vision.

An Energy-Maximising Linear Time Invariant Controller (LiTe-Con) for Wave Energy Devices

A Linear Time Invariant (LTI) energy-maximising control strategy for Wave Energy Converters (WECs) is proposed in this paper. Using the fundamental requirement of impedance-matching, the controller is tuned to maximise the energy obtained under polychromatic wave excitation. Given the LTI nature of the proposed controller, the design and implementation procedure is significantly simpler than well-established energy-maximising controllers, including state-of-the-art numerical optimisation routines, which are predominant in this field. Additionally, a LTI constraint handling mechanism is provided. The effectiveness of both the LTI control strategy and the constraint handling mechanism are assessed using regular and irregular waves in unconstrained and constrained cases. The resulting performance is compared to those obtained using existing WEC optimal control strategies. Finally, the benefits, in terms of power production, for both the controller and the constraint handling mechanism are explicitly highlighted by means of an application case.

A New Approach for Grid-Connected Hybrid Renewable Energy System Sizing Considering Harmonic Contents of Smart Home Appliances

Even renewable energy sources provide several advantages, especially from an environmental point of view, where the world has faced great challenges in the last few decades; several negative issues also exist regarding the integration of renewable resources-based power production units in electric power systems. One of the main problems related to pivotal renewable energy resources such as solar, wind, etc., is their stochastic and uncontrollable nature in terms of power production. Therefore, this stochasticity in the supply side of the power system may pose many challenges for system operators. This issue is also problematic for smaller applications where the stochastic production by a main resource, such as a roof-top photovoltaic system, and load demand may not match perfectly at each time instant and therefore should be compensated by additional resources such as battery-based energy storage systems. Herein, the economic considerations to ensure minimum costs for such a hybrid system design are vital so as to increase the penetration of such systems. Therefore, the optimal sizing and planning of hybrid systems have recently gained increasing importance to enhance power system operation in the context of the smart grid paradigm. From a different perspective, harmonics are one of the most important power quality problems in system operations caused by widespread integration of power electronic loads with non-linear characteristics that should be considered. Thus, a new approach for grid-connected hybrid renewable energy system sizing is provided. In order to determine optimal capacities for photovoltaic (PV) and energy storage system (ESS) units for covering residential consumer demand, a mixed integer linear programming (MILP)-based formulation is presented. The main objective is minimizing total costs of the system consisting of investment, capital and maintenance cost functions. A daily power curve is created accurately with real measurements of non-linear loads considering harmonic contents of smart home appliances in Yildiz Technical University, Istanbul, Turkey. In addition, real radiation and temperature values are used in PV production as well as dynamic pricing schemes for realistic evaluations. Moreover, optimal sizing results are compared for both the harmonic-based power curve and rated power curve in terms of satisfying objective function.

Thermodynamic, financial and resource assessments of a large-scale sugarcane-biorefinery: Prelude of full bioenergy carbon capture and storage scenario

A large-scale sugarcane-based ethanol biorefinery is assessed and analyzed as a conceivable integration of plantation-biorefinery for large-scale carbon dioxide drainage by coupling production of bioenergy to carbon capture and storage (BECCS) vis-à-vis the conventional biorefinery. The plantation-biorefinery integration is simulated to assess ethanol production, power production through bagasse-fired cogeneration, heat demand, water demand, carbon dioxide intake, profitability and resource utilization. Results are compared with several metrics of maximum possible outcomes without violating the Second Law of Thermodynamics. Typical results for a conventional biorefinery processing 1,000 t/h of sugarcane comprises 284 MW of net electricity exportation, emissions of ≈0.7 tCO2 per ton of sugarcane, 3,616.4 t/h of water consumption accounting for blowdown and evaporation in the cooling-tower, 550.2 MMUSD of fixed capital investment and 709.6 MMUSD of net value from ethanol/electricity revenues at 10% annual interest rate. On the other hand, the proposed BECCS re-configuration stands as a large-scale atmospheric carbon dioxide drainage system with potentially impressive negative emissions, power exportation of 88.5 MW, BECCS potential of 5.72 MtCO2/y, resource utilization and profitability analyzed via Sankey diagrams. Profitability of the BECCS biorefinery is warranted provided the captured carbon dioxide is traded for enhanced oil recovery. The limiting power production for the sugarcane intake is estimated via two thermodynamic approaches: maximum Carnot equivalent power and maximum power at 25°C and 1atm via the Second Law of Thermodynamics. The assessment reveals the thermodynamic inefficiency of the actual biorefineries in terms of power production. Future studies should investigate exergy efficiencies and expand the study beyond the biorefinery boundary to include carbon emissions in the sugarcane supply-chain.

Gasification of yeast industry treatment plant sludge using downdraft Gasifier.

Sludges produced in biological wastewater treatment plants have rich organic materials in their characteristics. Recent research studies have focused on the energy recovery from sludge due to its high organic content. The gasification process is a thermal conversion technology transforming the chemical energy contained in a solid fuel into thermal energy and electricity. The produced syngas as a mixture of CO, CH4, H2 and other gases can be used to generate electrical energy. The gasification of yeast industry sludge has been experimentally evaluated in a pilot scale downdraft-type gasifier as a route towards the energy recovery. The gasifier has 20 kg biomass/h fuel capacity. During gasification, the temperature achieved was more than 1,000°C in the gasifier, and then the syngas was transferred to the gas engine to yield the electricity. A load was connected to the grid box and approximately 1 kWh electrical power generation for 1 kg dry sludge was determined. The characteristics of residuals - ash, glassy material - were also analyzed. It was found that most of the heavy metals were fixed in the glassy material. Experimental results showed that the yeast industry sludge was an appropriate material for gasification studies and remarkable energy recovery was obtained in terms of power production by using syngas.

High Temperature ORC Systems

ORC systems are well known as the best available technology for electricity production from low temperature heat sources -such as geothermal ones - and continuous technical development is done to optimize performances by means of finding new working fluids and improved design criteria and thermodynamic cycles.With regard to medium and high temperature heat sources exploitation for electric power production, ORC technology and Steam Rankine Cycle solutions are competing in terms of power production, capital expenditures and O&M costs to become the preferred choice on a case-by-case basis.Commercially available ORC technology is currently limited to a maximum working fluid operating temperature of about 300°C, leading to a strong limitation on performances achievable. Finding new working fluids that could operate at Higher Temperatures and developing the related technical solutions, will enable to improve ORC technology competiveness also in other niches that now are Steam Rankine Cycles territory. Very High Temperature ORC technology will lead to new solutions for both power only production and cogeneration, allowing ORC technology to enter market segments traditionally belonging to other technologies (e.g. Steam Rankine Cycles, Otto Cycles, Bryton Cycles, etc.).The paper will present the technical and industrial development on High Temperature ORC systems, potential market development and a technology comparison to other generation technologies.

Effects of aeroelastic tailoring on performance characteristics of wind turbine systems

Some interesting challenges arise from the drive to build larger, more durable wind turbine rotors. The rationale is that, with current designs, the power generated is theoretically proportional to the square of the blade length, however, theoretical mass increases cubically. Aeroelastic tailoring aims to improve the ratio between increased power capture and mass by offering enhanced combined energy capture and system durability. As such, the design and full system analysis of two adaptive, aeroelastically tailored wind turbine blades is considered herein. One makes use of material bend-twist coupling, whilst the other combines both material and geometric bend-twist coupling. Each structural design meets a predefined coupling distribution, that approximately matches the stiffness of a baseline blade.The performance characteristics of the wind turbine systems are assessed and compared in terms of power production, load alleviation and pitch system considerations. The blade with both couplings displays scope for potential increases in energy yield. Additionally, beneficial flapwise load alleviation is demonstrated by the adaptive blades from both International Electrotechnical Commission prescribed fatigue, and extreme operational gust analysis. Finally, the adaptive blades display power smoothing capabilities and reductions in pitch rate, however, increases in blade root torsional moment possibly contrast these pitch system benefits.