Power supply for pumping systems in northern Chile: Photovoltaics as alternative to grid extension and diesel engines

This paper examines and compares the cost-effectiveness to energize pumping systems in remote areas on northern Chile by means of photovoltaic systems, diesel engines and grid extension. Variables such as the distance to the power grid, the voltage grid, the prices of electricity and fuel, and the required investments, are taken into account. The comparison is made for wide range of variable values, distances and pumping requirements. The results obtained are useful for choosing the best alternative for the power supply of pumping systems in wells in Northern Chile.     

Systematic procedures for sizing photovoltaic pumping system,using water tank storage

In this work, the performances of the photovoltaic pumping destined to supply drinking water in remote and scattered small villages have been studied. The methodology adopted proposes various procedures based on the water consumption profiles, total head, tank capacity and photovoltaic array peak power. A method of the load losses probability (LLP) has been used to optimize sizing of the photovoltaic pumping systems with a similarity between the storage energy in batteries and water in tanks. The results were carried out using measured meteorological data for four localities in Algeria: Algiers and Oran in the north, Bechar and Tamanrasset in the south. The results show that the performance of the photovoltaic pumping system depends deeply on the pumping total head and the peak power of the photovoltaic array. Also, for the southern localities, the LLP method shows that the size of the photovoltaic array varies versus LLP on a small scale. On the other hand, for the northern localities, the sizing of the photovoltaic array is situated on a large scale power. Because of the current high crud-oil price, the photovoltaic pumping still to be the best adopted energy resource to supply drinking water in remote and scattered villages.     

Optimal sizing of photovoltaic pumping system with water tank storage using LPSP concept

This paper recommends an optimal sizing model, to optimize the capacity sizes of different components of photovoltaic water pumping system (PWPS) using water tank storage. The recommended model takes into account the submodels of the pumping system and uses two optimization criteria, the loss of power supply probability (LPSP) concept for the reliability and the life cycle cost (LCC) for the economic evaluation.With this presented model, the sizing optimization of photovoltaic pumping system can be achieved technically and economically according to the system reliability requirements. The methodology adopted proposes various procedures based on the water consumption profiles, total head, tank capacity and photovoltaic array peak power. A case study is conducted to analyze one photovoltaic pumping project, which is designed to supply drinking water in remote and scattered small villages situated in Ghardaia, Algeria (32°29′N, 3°40′E, 450 m).     

A model for optimal sizing of photovoltaic irrigation water pumping systems

The previous methods for optimal sizing of photovoltaic (PV) irrigation water pumping systems separately considered the demand for hydraulic energy and possibilities of its production from available solar energy with the PV pumping system. Unlike such methods, this work approaches the subject problem systematically, meaning that all relevant system elements and their characteristics have been analyzed: PV water pumping system, local climate, boreholes, soil, crops and method of irrigation; therefore, the objective function has been defined in an entirely new manner. The result of such approach is the new mathematical hybrid simulation optimization model for optimal sizing of PV irrigation water pumping systems, that uses dynamic programming for optimizing, while the constraints were defined by the simulation model. The model was tested on two areas in Croatia, and it has been established that this model successfully takes into consideration all characteristic values and their relations in the integrated system. The optimal nominal electric power of PV generator, obtained in the manner presented, are relatively smaller than when the usual method of sizing is used. The presented method for solving the problem has paved the way towards the general model for optimal sizing of all stand-alone PV systems that have some type of energy storage, as well as optimal sizing of PV power plant that functions together with the storage hydroelectric power plant.     

Assessment and applications of wind energy in Jordan

A technical and economic assessment has been made of the generation of electricity using windmills located at three most promising potential wind sites in Jordan: Ras Muneef (RA), Mafraq (MF), and Aqaba (AQ). The assessment was made for two different systems, one using a relatively large single windmill and the other using 25 small windmills arranged in a wind farm. The power output of each system at each site was determined, and the electricity-generating costs in each case were also determined and compared with the generating costs of generating electricity using steam or gas turbines, furnished by the Jordanian Electricity Authority (JEA).Finally, the possibility of water pumping from 30-m and 100-m deep wells using a windmill is investigated and the quantities of water pumping from these depths at each of the three sites are given.     

Photovoltaic water pumping systems installer training: a partnership experience between the university and São Francisco hydroelectric power plant

A broad demonstration process of photovoltaic solar technology for the powering of rural areas lacking power and water supply is currently being developed in Brazil. Due to the severe and problematic drought that now impacts an extensive area of Brazil, particularly the northeast region, compromising agriculture and with a more serious consequence affecting water supply for human and animal consumption, emergency actions to mitigate these conditions are being undertaken. For this purpose, the Program for Energy Development in States and Municipalities (PRODEEM) aims to install approximately 800 photovoltaic water pumping systems, of which approximately 236 by mid 1999. The massive process of installation and maintenance of these systems, requires skilled technical staff. In order to accomplish such a broad program, the universities play a key role: the training of human resources. The Group of Research on Alternative Sources of Energy of the Federal University of Pernambuco (FAE/UFPE Group) has a long tradition on human resource training on solar energy, and it was invited to participate in this process by teaching training courses to several groups of middle-level technicians. Some 145 technicians, coming from several states of the northeast involved in the program were trained in only three weeks, after which they installed approximately 86% of the expected systems (225). The systems are now running in the communities. This paper provides a detailed report on the training process, on the course evaluation accomplished by the students, the difficulties and the logistic problems found, and the lessons learned.     

Solar water pumping

The principles of solar water pumping are briefly described. The mechanical energy needed for pumping water may be produced by thermodynamic, or direct-conversion methods. In thermodynamic conversion a fluid with high internal energy is produced in solar collectors or concentrators. The internal energy of the fluid may be utilized in Rankine-, Brayton-, or Stirling-cycles or in specially designed devices. The nature of irrigation in the arid regions calls for scattered water pumping stations, hence small solar pumps. These pumps may be mass produced and delivered to the site. The direct conversion includes photovoltaic, themoelectric and thermionic processes. With the current prices of solar cells photovoltaic water pumping seems to be economically competitive with the current solar Rankine-cycle system in the power ranges of below 5 kW, especially when both systems have to be imported by a developing country.     

RS抽油机节能减速器在A油田的应用

A油田部分油井存在供液不足、泵效低、耗电高等问题。要提高油井泵效和节能效果,就需要降冲次。在成本、改造技术难度等方面对比了各种降冲次方法的优缺点,最终确定采用安装节能减速器的方法来降低冲次。在抽油机的电机和减速箱之间增加一套辅助减速装置即为节能减速器。减速器可大幅降低抽油机的惯性负荷,因此能起到一定的节能作用。介绍了节能减速器安装尺寸的确定方法。A油田在126口井安装、应用了节能减速器。安装节能减速器后,126口井平均消耗功率由3.526kW下降到3.000kW,综合节电率达到14.08%;系统效率由5.943%上升到7.116%;平均单井日节电13.2kW.h,预计可实现年节电60.7×104kW.h;抽油机运转较平稳,减小了惯性载荷,从而减少了抽油机的机械故障;优化了油井运行参数,提高了泵效,减少了杆管磨损。     

Design of stand-alone brackish water desalination wind energy system for Jordan

More than 100 underground water wells drilled in Jordan are known to have brackish water with total desolved solids (TDS) over 1500 ppm but not greater than 4000 ppm. The world standard for potable water limits the TDS count to 500 ppm in addition to being free from live microorganisms or dangerous mineral and organic substances. A reverse osmosis desalination scheme powered by a stand-alone wind energy converter (WEC) is proposed to produce fresh water from wells located in potentially high-wind sites. A conceptual design of such system is developed and the design parameters are identified, in addition, a preliminary economic analysis is made. It is found that brackish water pumping and desalinating using WECs costs 0.67 to 1.16 JD/m³ (JD = Jordanian Dinar, 1US$ = 0.68 JD), which is less than using conventional diesel engines especially in remote areas. In addition, the wind-reverse osmosis system becomes more economically feasible for higher annual production rates or in good wind regimes.     

Improving the effectiveness of a photovoltaic water pumping system by spraying water over the front of photovoltaic cells

The photovoltaic cells will exhibit long-term degradation if the temperature exceeds a certain limit. Photovoltaic cells are the heart of photovoltaic water pumping systems. In order to utilize PV power and increase photovoltaic water pumping system efficiency, it is necessary to keep PV cell temperature and cell reflection as low as possible. The purpose of this study is to investigate the possibility of improving the performance of a photovoltaic water pumping system. This is performed by spraying water over the photovoltaic cells. The results are compared with traditional systems. Experimental results show that the cells power is increased due to spraying water over the photovoltaic cells. This can significantly increase the system and subsystem efficiency and the pump flow rate when operating under different heads. Measurements of the short circuit current of the module, which is nearly temperature-independent, indicated that the water spray improved the system optical performance.     

A maximum efficiency-photovoltaic-induction motor pump system

It is not economically viable to connect remote areas to the national electric grid, so pumping systems based on photovoltaic energy sources are suitable for these areas. The induction motor is more rugged, reliable, and maintenance free than d.c. motors. In this paper, a pumping system based on an induction motor driven by a voltage source inverter is investigated. Two control strategies are considered. First, the system is controlled to operate on the maximum power line of the PV array, with variable water discharge Q. Second, the induction machine is controlled to operate at maximum efficiency. The operating characteristic of the array is thus controlled to match the voltage and current required by the motor. Comparison is carried out between the two operating schemes.     

Simulation of grape culture irrigation with photovoltaic V-trough pumping systems

In large areas of the Northeast of Brazil, the population is faced with the severe problem of water shortage aggravated with the lack of electric power. However, some places, like the area next to the river São Francisco, near the city of Petrolina, in the state of Pernambuco, have become quite prosperous with the cultivation of grape crops, either for wine production or to be consumed as fruits. Wine exports have grown as an important economic activity in the region. On the other hand, in areas far from the electric network, photovoltaic pumping systems have contributed to the supply of water for local rural communities. Production of fruits, with water supplied by photovoltaic systems, might, then, become a good alternative in terms of local economic activities. The viability of this proposal depends strongly on the market value of the crop. Taking advantage of some significant technical benefits provided by low concentration tracking devices we propose to use those systems to drive local irrigated crops. Among the large family of concentrators available, V-troughs are particularly adequate for photovoltaic applications since, for certain combinations of the concentration ratio (C) and vertex angle (Ψ), they provide a perfectly uniform illumination in the region where the modules are located (absorber region). A drip irrigation system, located in the city of Petrolina, has been simulated and the maximum surface that can be irrigated by a V-trough photovoltaic pumping equipment was estimated by performing a water balance on a monthly basis. With an array of 1.3 kW_p it was found that the system is able to irrigate, without deficit, 2.11 ha. A fixed photovoltaic pumping equipment, with the same photovoltaic array, is able to irrigate an area of 1.20 ha. In both cases, the water stored in the soil contributes with an increase of 33% to the irrigated area, as compared to the case where that contribution is not considered.     

Wind resource assessment of the Jordanian southern region

Wind data in terms of annual, seasonal and diurnal variations at Queira, which is located in the southern part of Jordan was studied and analyzed. For this purpose, long-term wind speed data for a period of 12 years (1990–2001) was used. The analysis showed that the seasonal and diurnal pattern of wind speed matches the electricity load pattern of the location. Higher winds of the order of 6 m/s and more were observed during both the summer months of the year (May–August) and peak hours (1100–1500) of the day. The wind duration availability is discussed as the number of hours during which the wind remained in certain wind speed intervals. The possibility of electricity generation from wind power at Queira was carried out using three different wind energy systems of sizes 100, 22 kW rated power, and a wind farm consisting of 25 small wind turbines; each of 4 kW rated power with hub heights of 20, 30, and 40 m. The energy production analysis showed higher production from the wind farm with a 20 m hub height than the production from the other two wind turbines. Similarly, the cost analysis showed that the lowest generation costs of 1 kWh were obtained for the wind farm compared to the other two wind turbines. The possibility of water pumping using the wind farm was also investigated. The results showed that water pumping using wind turbines is an appropriate alternative for the photovoltaic water pumping in the region.     

VAPOR OPERATED SOLAR PUMP

The choice of a water pumping system in remote areas depends on the type of energy available for power generation. In most of these areas where electricity and other sources of energy are not available or expensive to obtain, solar energy offers a cheap source of energy which can be utilized for operating water pumping systems. This paper describes a simple low technology vapor operated solar pump having minimum number of moving parts. The system is easy to manufacture and requires low maintenance. The performance of the system is experimentally investigated and the results obtained are presented and discussed.     

Modelling photovoltaic water pumping systems and evaluation of their CO2 emissions mitigation potential

In photovoltaic (PV) water pumping design, the accurate prediction of the water flow is a key step for optimized implementation and system robustness. This paper presents a model to characterize the motor-pumps subsystems used in PV pumping installations. The model expresses the water flow output (Q) directly as a function of the electrical power input (P) to the motor-pump, for different total heads. The actual model is developed using the experimental results obtained by the use of several motor-pump subsystems of different types and technologies. This work details the investigations concerning centrifugal and positive displacement motor-pump subsystems. The experimental tests are used to validate the developed model. Based on the motor-pump subsystem model, a method is proposed to estimate the amount of carbon dioxide (CO₂) emissions saved by the use of water pumping facilities powered by a photovoltaic array instead of diesel fuelled generators. This work shows that the dissemination of PV water systems not only improves the living conditions in remote areas, but is also environment friendly.     

Sustainable application of renewable sources in water pumping systems: Optimized energy system configuration

Eighteen years ago, in Portugal, the expenses in a water supply system associated with energy consumption were quite low. However, with the successive crises of energy fuel and the increase of the energy tariff as well as the water demand, the energy consumption is becoming a larger and a more important part of the total budget of water supply pumping systems. Also, new governmental policies, essentially in developed countries, are trying to implement renewable energies. For these reasons, a case-study in Portugal of a water pumping system was analysed to operate connected to solar and wind energy sources.     

Hydrogen production through solar energy water electrolysis

Various methods of making hydrogen from water have been proposed, but at the present time the only practical way to make hydrogen from water without fossil fuel is electrolysis. The development of a new, advanced, water electrolyser has become necessary for use in hydrogen energy systems and in electricity storage systems. All the new possible electrolysis processes, suitable for large-scale plants, are being analysed, in view of their combination with solar electricity source. A study of system interactions between large-scale photovoltaic plants, for electrical energy supply, and water electrolysis, is carried out. The subsystems examined include power conditioning, control and loads, as they are going to operate. Water electrolysis systems have no doubt been improved considerably and are expected to become the principal means to produce a large amount of hydrogen in the coming hydrogen economy age. Thus, the present paper treats the subject of hydrogen energy production from direct solar energy conversion facilities located on the earth's oceans and lakes. Electrolysis interface is shown to be conveniently adapted to direct solar energy conversion, depending on technical and economical feasibility aspects as they emerge from the research phases. The intrinsic requirement for relatively immense solar collection areas for large-scale central conversion facilities, with widely variable electricity charges, is given. The operation of electrolysis and photovoltaic array combination is verified at different insolation levels. Solar cell arrays and electrolysers are giving the expected results during continuously variable solar energy inputs. Future markets will turn more and more towards larger scale systems powering significantly bigger loads, ranging from hundreds of kW to several MW in size. Detailed design and close attention to subsystem engineering in the development of high performance, high efficiency photovoltaic power plants, are carried out. An overall design of a 50 MWp photovoltaic central station for electricity and hydrogen co-generation is finally discussed.     

杏北开发区油井间抽技术研究与应用

大庆油田杏北开发区已进入高含水后期,低产低效油井不断增加,造成电能浪费和抽油设备的无功摩损。确定了间抽井的选井原则,避免了这部分井影响原油产量和机采指标。确定合理间抽制度的方法有两种,一是根据泵抽产量曲线、泵抽沉没度曲线和沉没度恢复曲线确定间抽井的起停时间;二是使用智能型微电脑采油控制器确定间抽制度。根据间抽制度的长短,分别实施人工间抽和使用间抽控制器自动间抽两种方式。间抽井存在着一个高产、高效区域,间抽制度能否体现高产、高效的原则,不但与泵抽时间有关,而且与恢复时间有关。采取新的间抽生产制度后,不仅能降低能耗、有效延长油井的检泵周期和举升设备的使用寿命,还可以协调附近井组的供排关系,使注入液体的流向更加合理。对于高含水后期油田减少无效产出,提高开发效果具有重要意义。     

Energy management algorithm for an optimum control of a photovoltaic water pumping system

The effectiveness of photovoltaic water pumping systems depends on the adequacy between the generated energy and the volume of pumped water. This paper presents an intelligent algorithm which makes decision on the interconnection modes and instants of photovoltaic installation components: battery, water pump and photovoltaic panel. The decision is made by fuzzy rules on the basis of the Photovoltaic Panel Generation (PVPG) forecast during a considered day, on the load required power, and by considering the battery safety. The algorithm aims to extend operation time of the water pump by controlling a switching unit which links the system components with respect to multi objective management criteria. The algorithm implementation demonstrates that the approach extends the pumping period for more than 5 h a day which gives a mean daily improvement of 97% of the water pumped volume.     

Review of modern methods and technologies for using of solar energy in the operation of anaerobic digestion systems

The article presents various methods and technologies for using of solar energy in anaerobic bioconversion systems. Various methods of convertion of solar radiation are consistently considered – from its direct use to photovoltaic, thermal, photovoltaic thermal and concentrating. Schemes for introducing solar energy converters into anaerobic bioconversion systems, as well as various solar radiation converters for heat and electricity supply of anaerobic bioconversion systems, are proposed. As power generating components in the article also discusses photovoltaic modules with an extended rated power period, photovoltaic thermal roofing panels with a two-component polysiloxane compound, thermal and photovoltaic thermal solar roofing panels, air-cooled photovoltaic thermal siding panel and concentrator solar photovoltaic thermal module with high-voltage matrix photovoltaic converters. The proposed schemes of systems and design of solar modules will ensure a reduction in the use of thermal energy from the produced gas for power supply for the own needs of anaerobic bioconversion systems, which will make them cheaper and more efficient in operation.