Controlling power output of solar chimney power plant according to demand

ABSTRACT

The solar chimney power plant (SCPP) is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. Using computational ?uid dynamics (CFD) techniques; we have simulated a two-dimensional axisymmetric model of a SCPP with the RNG k-ε turbulence. In this model, the discrete ordinates (DO) radiation model was implemented to solve the radiative transfer equation, using a two-band radiation model. The main objective of this work is to explore dynamic control over plant power output. We have presented a technique to control the power output of the solar chimney power plant, in order to deliver power according to specified demand patterns. In order to present this, the reference plant model was modified to include a secondary and tertiary collector roof under the existing main collector. In terms of base load electricity generation, the inclusion of a secondary and tertiary collector roof produces good control over plant output.     

Solar energy performance analysis of basin-type solar still under the effect of vacuum pressure

ABSTRACT

This paper deals with a solar still for distilled water, using the heat of the sun to evaporate, cool and then collect the water. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight; vacuum pressure is delivered to still-type solar. The reason for selecting vacuum pressure is that during the monsoon and cloudy days, solar intensity will not be high as it leads to evaporation at lower temperature saline water under the soar still. The basin area for the production of 5 litres per day of fresh water is determined as 1.44?m²and the solar still basin area of 1.44?m² and 21.5° tilt angle are designed. Solar energy be may used full to alternate in electrical power and to purify water in future. Finally, the performance was analysed for the solar still with a vacuum pressure at 0.6 bar. The outcome of the theoretical analysis shows that adoption of 0.6 bar pressure inside the solar still improves the average performance by 30%. In order to overcome this problem, vacuum could be applied for the better performance of the solar still during the low solar intensity periods.     

Application of solar energy for milk pasteurisation: a comprehensive review for sustainable development

ABSTRACT

Solar energy is available freely. Hence, nowadays people are working on solar energy when compared with conventional sources of energy. Dairy industries require heat, which can be generated by the use of boiler with the aid of wood. Hence, due to increment in global warming, it is necessary to use renewable energy. The primary aim of this review paper is to study various researchers’ work on solar milk pasteurisation system. Hence, it also covers important aspects required for solar pasteurisation like flat plate collector, heat exchanger and solar water heating system.     

Analysis and design of a robust controller for a grid-connected photovoltaic power plant

ABSTRACT

Application of renewable energy systems has a drastic impact on the present power system. In particular, solar photovoltaic power generation is expanding exponentially. Hence, in this article analysis and design of a 1 Mega Watt (1?MW) solar power plant has been modelled. The obtained power is given as an input to the voltage source converter, which contently regulates the active and reactive power by controlling the pulse width modulation signals. In this article, robust control schemes were discussed to support the required active and reactive power. Further, a detailed analysis has been presented at various fault conditions and the results are explored.     

Multi-step-ahead forecasting of daily solar radiation components in the Saharan climate

ABSTRACT

Accurate estimation of renewable energy sources plays an important role in their integration into the grid. An unexpected atmospheric change can produce a range of problems related to various solar plant components affecting the electricity generation system. Global solar radiation (GSR) assessment has been increased in the past decade due to its important use in photovoltaic application. In this paper, we propose the use of machine learning-based models for daily global and direct solar radiation forecasting in a semi-arid climate, using a combination set of meteorological parameters on a horizontal surface in the Ghardaïa region. The models are presented and implemented on 3-year measured meteorological data at Applied Research Unit for Renewable Energies (URAER) at Ghardaïa city between 2014 and 2016. The results show that both MLP and RBF models perform well for three-step-ahead forecasting with a slight improvement in MLP models in terms of statistical metrics.     

A preliminary study of wind–solar hybrid systems potential in Jammu and Kashmir

ABSTRACT

This paper deals with the study of wind–solar hybrid systems in the region of Jammu and Kashmir. Due to scarcity of less renewable energy resources in the J&K region, National Institute of Wind Energy, Chennai had installed different wind monitoring stations to measure the wind data at different locations. The survey reveals that four districts (LEH, KARGIL, POONCH and REASI) are suitable for small wind–solar hybrid systems. BIDDA (REASI) and CHUSHUL (LEH) are the two sites for small wind farm development due to the highest wind speed (more than 7?m/s) and power density (more than 400?W/m²) at 100?m agl.     

Mitigating the risk of photovoltaic power generation: A complementarity model of solar irradiation in diverse regions applied to Brazil

Several countries face the challenge of reducing the intermittency of solar photovoltaic (PV) generation due to changes in climatic conditions. Considering that Brazil has continental-scale dimensions and diversified geography, an alternative that allows smoothing the intermittency in solar PV power generation is needed. The novelty of this study lies in the proposal to allocate the production of PV solar energy between the interconnected regions of the country efficiently, forming an optimal portfolio with the highest productivity and the least intermittency. Thus, the regional allocation process for solar generation is formulated through an optimization problem with two objective functions: to increase the country's productivity and simultaneously control the variability of the supply of solar energy. This study concluded that the current planning models for the expansion in Brazil (both centralized and distributed generation) do not consider the variability of incident solar radiation in its five regions; therefore, the formation of the current regional portfolio of investments in power generation from solar PV energy is not efficient.     

Fabrication of solar energy UAV

ABSTRACT

Unmanned Air Vehicles (UAVs) are of tremendous help in the situations where human loss and injury can be avoided. Solar energy is completely dependable and bolstering form of energy which would be compliant to quench the needs of future energy requirements. Combining both Solar power and UAV will but buttress a variety of operations, limited only by imagination. The aircraft we have designed is in UAV, which can be used for short-range surveillance. The UAV runs on solar power and electric motors and therefore is reliable, cost-effective and non-polluting. Unlike others, UAVs are very light weight, making them portable. The wing uses SD7032 aero foil to support the sail plane characteristics of the t UAV. The tail plane is of V tail type to cut down weight. It can be controlled from the ground using a transmitter/receiver set. Proper utilisation of the UAV promises life-saving situations and a perfect substitute for manned surveillance.     

Renewable energy scenario in Telangana

ABSTRACT

This article presents an analysis of the current situation of renewable energy in Telangana, India, and predicts the future of renewable energy resources in the state. In India, maximum power is generated using conventional energy sources such as coal and mineral oil. They highly pollute the atmosphere. If new power plants are to be set up, then the import of highly volatile fossil fuels is inevitable. Though nuclear energy is a good alternative to reduce fossil fuel consumption, it is equally hazardous to human life. Hence, the energy world should think of judicious use of renewable energy resources such as solar, wind, ocean, biomass, and geothermal energy. The R&D activities carried out in India in the past three decades have shown good progress in finding a feasible solution to the problem of searching new renewable energy resources. Telangana is the state committed to use the renewable resources in a better way to fulfil its electrical energy needs. This article also analyses the current energy needs of the state and forecasts energy consumption and production in the future with the aim of finding whether the state can continue on the path of development and augment its renewable energy resources.     

TRNSYS simulation for solar-assisted liquid desiccant evaporative cooling

ABSTRACT

Recently, desiccant cooling systems are well thought of as a competent method for controlling the water content in the air. A solar flat-plate collector has been used as it decreases the dependency on non-renewable resources. Solar-aided liquid desiccant systems have been used to reduce the dependency of air-conditioning systems on non-renewable sources of energy. Manipal’s humid and searing climate provides certain benefits in setting up such a system. The suggested system has reliability and equipment life and also takes complete advantage of the available solar energy for the renewal of the liquid desiccant. TRNSYS simulation is used to predict the efficiency and feasibility of the system. The temperature and energy-load variations were successfully obtained. An effective simulation was developed whereby the solar air conditioning of a room was indicated.     

A novel application of stand-alone photovoltaic system in agriculture: solar-powered Microner sprayer

In this paper, a stand-alone photovoltaic (SAPV) power supply system for Microner sprayer is identified and proposed. The designed system was composed of three main parts: sprayer, solar power supply and control system. Initially, the control board and data acquisition system were designed and simulated by the Proteus software and then implemented using an AVR microcontroller and tested via LabVIEW in the laboratory. Next, a prototype system was fabricated for evaluation purposes. A PV panel size of 88.5?cm², positioned horizontally above operator's head that generates 26.4?Wh/day was used as a solar energy source. A small 2?Ah (12?V) battery is installed in the system as a stabiliser. This sprayer can work seven to nine hours daily. It is calculated that the average loss of collected energy due to non-application of maximum power point tracker was approximately 25%.     

Performance analysis on improved efficiency in a hybrid solar still and solar heater

ABSTRACT

This paper deals with solar still. Today fresh water demand is increasing continuously, because of the industrial development, intensified agriculture, improvement of standard of life and increase in the world population. Only about 3% of the world water is potable and this is not evenly distributed on the earth. On deserts and islands, underground water is not readily available and the cost of shipping to other places is high, it is worthwhile to consider producing potable water from saline water using solar energy that is in abundant in deserts. The efficiency of the solar still can be increased by increasing the evaporation rate and by minimising the convective and radioactive losses in still. The evaporation rate can be increased effectively by coating the still base with photocatalyst materials or by pre-heating the inlet water of still. The easily available GAC is one of the best photocatalyst materials suitable for the solar still for enhancing the evaporation rate. Solar-still technology is a renewable and efficient technology for pre-heating the inlet water to solar still. Hence the combination of GAC coating and solar-still technology can increase the evaporation rate and efficiency of solar still.     

A comprehensive review of the solar dryer

ABSTRACT

Drying of agricultural products is an energy-demanding process. High costs, scarcities in fossil fuels and environmental threats attract the use of solar energy as an alternate source, especially in developing countries. Increasing environmental concerns led to the use of clean and green energy resources in the field of drying agricultural products. A solar dryer integrated with a thermal energy storage system is reasonably efficient for continuous and uniform drying of agricultural produce in the temperature range of 40–75°C which is the requisite for drying most of the products. Such dryers have become a natural choice to replace drying systems based on fossil fuels. Many studies have been performed till date by a number of researchers for the last few decades for drying agriculture and food products by a solar dryer. This review paper primarily presents an appraisal of the significant contributions made so far in the field of solar drying systems, with the latest updates in drying technology. Solar dryers which offer drying during off-sunshine hours have been specially mentioned. Some novel ideas like use of phase change materials and desiccant materials which enhance the performance and effectiveness of the dryer have also been attempted.     

24V/5A太阳能控制器设计

近年来再生能源技术广受重视,而太阳能发电由于有先进的电力电子技术辅助,已成为极具潜力的再生能源之一。文章介绍了太阳能电池的基本原理和伏安特性,提供了一套小24V/5A太阳能控制器的电路。该电路将太阳能电池阵列与蓄电池直接耦合,采用低功耗的单片机P87LPC767作为控制回路的核心,实时测量蓄电池的端电压,通过脉宽调制控制太阳能电池阵列的充电电压,并通过功率管控制蓄电池与负载的通断,实现对蓄电池的放电保护。     

Field performance of a Japanese low energy home relying on renewable energy

This paper describes the construction and evaluation of an experimental low energy home assisted by a hybrid system using natural energy resources and unused energy. The home, for which a ground source heat pump (GSHP) system has been installed, was built on the campus of Hokkaido University, Japan in March 1997. The total floor area of the home is 192 m². This home is super insulated and airtight; the calculated coefficient of heat loss is 0.97 W/m² K. It has various passive strategies including direct solar heat gain and a ventilation system with an exhaust stack. Photovoltaic (PV) modules, wind power and solar collectors are adopted in order to achieve self-sufficiency in electric power and domestic hot water (DHW) supply. A GSHP is used for space heating and cooling. Two vertical steel wells are used as vertical earth heat exchangers (VHE). In summer, there is a floor cooling system using piped cold water from the VHE.Approximately 80% of the home’s total energy was provided by PV modules, solar collectors, as well as underground and exhaust heat. The annual amount of purchased energy during the test period was 12.5% that of a typical home in Hokkaido.     

Uncertainty in estimating renewable energy utilisation potential: a case of solar thermal power generation in India

Estimation of renewable energy utilisation potential is important for identification of niche areas and prioritisation amongst different options. However, large variation in the potential estimates has been observed in different studies for the same renewable energy technology. This study is an attempt to analyse such a variation in the estimated potential for solar thermal power generation in India. From the analysis of three studies, it is found that the values of input parameters and the assumptions made substantially affect the estimated potential. The estimates of the utilisation potential depend upon the categories of wastelands selected, the chosen values of threshold DNI and wind speed as well as the criteria used for allocating suitable wastelands between solar photo-voltaic (PV) and thermal power generation. It is therefore critically important that reported values of renewable energy utilisation potential be interpreted and used with full cognisance of assumptions made and input parameters used in estimation.     

Annual performance analysis of various energy storage materials in the upper basin of a double-basin solar still with vacuum tubes

ABSTRACT

A double-basin solar still with vacuum tubes showed impressive distillate output due to getting potable water from lower and upper basins. But it is also true that distillate output of the upper basin is lower compared with that of the lower basin. Hence, work is required to increase distillate output of the upper basin. In the present work, the upper basin was used with various energy-absorbing materials like black granite gravel, pebbles and calcium stones. The main purpose of using absorbing materials is to store excess energy during sunshine hours and release during off-sunshine hours. Therefore, the distillate output of the upper basin is increased compared with a still with only an upper basin. Hence, continuous work on a double-basin solar still with vacuum tubes (DBSWVT) by putting above energy absorbing materials is carried out during clear sky days of July 2014 and in June 2014. For comparison of a still with energy-absorbing materials, experimental readings of three days of May 2014 (1st, 5th and 9th) are chosen to determine the performance output of the present still with the said energy-absorbing materials. At last, yearly average distillate output of DBSWVT is carried out with said energy absorbing materials, cost of potable water/INR, energy payback time found 0.509 and 109 days. Also, on comparison with other researchers’ work in terms of percentage increment in distillate output 229.2% increment was found compared with a passive solar still.