Performance of submersible PV solar pumping systems under conditions in the Sudan

Water pumping for domestic use and irrigation purposes can be considered as one of the basic needs in the rural areas of Sudan. For the favourable solar radiation conditions in the country (6 kW h/m²/day), solar water pumping may be a competitive application against diesel-driven pumps for remote areas.Three SP4–8 Grundfos submersible pumps, installed at three different locations in the country, were evaluated. Two of these pumps were driven by M-51 Arco Solar modules, while the third was driven by M-53 Arco Solar modules. For each of these pumps, solar radiation in the plane of the PV array, ambient temperature, PV array voltage and current, water discharge and water delivery pressure were monitored using a data logger.Grundfos solar pumps used in the Sudan have proven in most cases to be reliable. However, their performance was 10–25% less than predicted by the manufacturer's literature. In general the product of the daily water demand (m³ per day) and the total pumping head (m) should not exceed 750 m⁴ for sites with good solar radiation.     

Experience with a surface floating PV pumping system: A case study in Khartoum

In a country like Sudan, where the power grid extension is limited to a small area, and fuel shortages and road inaccessibility cause major problems in providing the basic energy needs to rural areas, small scale PV systems could be a comparable application against diesel driven units. One of the main needs is water pumping for drinking, as well as irrigation purposes, so PV power pumping systems could be one of the solutions to the growing energy demand in rural areas. Such systems should ensure high reliability and low/no maintenance cost, otherwise they cannot compete with conventional systems, even in the long term. Therefore, the investigation of the field behaviour of new products is essential to characterize such designs under prevailing conditions. In this paper, a surface floating PV pumping system's performance and its technical feasibility under Khartoum's climatic conditions are investigated. Technical problems encountered with the operation of this system are clearly defined, and suggestions for design modification are advanced.     

Renewable energy strategies for rural Africa: is a PV-led renewable energy strategy the right approach for providing modern energy to the rural poor of sub-Saharan Africa?

Rural areas continue to be home to majority of the population in Africa. The importance of providing modern energy to rural areas cannot, therefore, be overemphasised. Despite numerous efforts by Governments and donors in the region to promote solar photovoltaics (PVs) for rural electrification (almost every country in the region has had a rural electrification PV project), access to modern energy in rural Africa continues to be woefully low. In addition to being unaffordable to the rural masses, solar PV has the limitation that it can only be used for lighting and powering low-voltage appliances. This article reviews emerging trends in the rural energy sector of sub-Saharan Africa, and discusses the limitations of over-reliance on solar PV. It suggests possible options that could have greater impact on rural clean energy development. For the majority of rural households in the region, biomass fuels will continue to be the dominant fuel of choice. Efficient technologies for the use of biomass would, therefore, ensure that scarce biomass resources are effectively utilised, and reduce the negative impacts of biomass use on women and children's health. Solar thermal, windpumps, micro-/pico-hydropower and cleaner fuels such as kerosene and LPG, have not received adequate attention from policy makers. These energy options could significantly improve the performance of rural small- and micro-enterprises. This article argues that rural energy policies that emphasise a broader range of renewables and target income-generating activities are likely to yield greater benefits to the rural poor than the current policies that rely on the solar PV option.     

Feasibility study of brackish water desalination in the Egyptian deserts and rural regions using PV systems

Fresh water is the most important source for life on the earth. In the Egyptian deserts and rural areas, there is a shortage of fresh water in spite of the presence of large sources of brackish water. Solar energy is abundant in these remote areas of Egypt, where the amount of sunshine hours is around 3500 h/year. This paper introduces a feasibility study of water desalination in these areas using photovoltaic energy as the primary source of energy. The availability of water resources and solar energy in these areas has been investigated. Also, a design of a PV powered small scale reverse osmosis water desalination system is studied and economically estimated. It is found that the cost of producing 1 m³ of fresh water using the small PV powered RO water desalination systems is 3.73$. This cost is based on using a small system that is operating during the daylight only. If the system size and the daily period of operation are increased, the price of producing fresh water will be decreased in these regions. Also, it is important to mention that using renewable energy sources in feeding different systems in these rural areas with their energy demands will maintain their environment clean and healthy for people.     

On the wind energy resources of Sudan

The imminent exhaustion of fossil energy resources and the increasing demand for energy were the motives for those reasonable in Sudan to put into practice an energy policy based on rational use of energy; and on exploitation of new, and renewable energy sources. After 1980, as the supply of conventional energy has not been able to follow the tremendous increase of the production demand in rural areas of Sudan, a renewed interest for the application of wind energy has shown in many places. Therefore, the Sudanese government began to pay more attention to wind energy utilisation in rural areas. Because the wind energy resource in many rural areas is sufficient for attractive application of wind pumps, and as fuel is insufficient, the wind pumps will be spread on a rather large scale in the near future. Wind is a form of renewable energy, which is always in a non-steady state due to the wide temporal and spatial variations of wind velocity. A number of years worth of data concerning wind speed in Sudan have been compiled, evaluated and presented in this article. The need for the provision of new data stations in order to enable a complete and reliable assessment of the overall wind power potential of the country is identified and specific locations suggested. This paper presents the background and ideas of the development of the concept as well as the main results, and experience gained during ongoing project up to now. In Sudan, various designs of wind machines for water pumping have been developed and some designs are presently manufactured commercially. Results suggest that wind power would be more profitably used for local-and small-scale applications especially for remote rural areas. It is concluded that Sudan is blessed with abundant wind energy.     

A comparison of diesel,biodiesel and solar PV-based water pumping systems in the context of rural Nepal

Nepal is heavily dependent on the traditional energy sources and imported fossil fuel, which has an adverse impact on the environment and economy. Renewable energy technologies promoted in the country are regarded as a means of satisfying rural energy needs of the country for operating different rural end-uses. In this context, this article is prepared to investigate energy alternatives to pump drinking water in one of the remote rural village of Nepal, which has no means of running water source. Analyses in this article are based on the formulation of three technical scenarios of water pumping using petro-diesel, jatropha-based biodiesel and solar photovoltaic pumps. The technical system design consists of system sizing of prime mover (engine, solar panel and pumps) and estimation of reservoir capacity, which are based on the annual aggregate water demand modelling. With these investigations, detailed financial modelling is carried out in a spreadsheet to compare the alternatives on the basis of the economic parameters; net present value, equivalent annualised cost and levelised cost of water pumping. Analysis is carried out considering different influential parameters; water head, discharge, incentives on the investments, which have effects on the cost of pumped water. Likewise, in case of biodiesel-based system, different yield rate of jatropha plants is also considered in estimating the cost of producing biodiesel. It is found that for operating a biodiesel-based pumping system for the study area, the levelised cost of pumping 1 L of water is higher than that of a solar pump and even higher when compared with diesel, if the seed yield per plant is less than 2 kg and without subsidy on the investment cost of cultivation and processing. With the productivity of 2.5 kg/plant, a biodiesel-based system is more attractive than that of the diesel-based pump, but still remains more expensive than that of solar pump. From the technical perspective (reliability and easiness in operation) and economic evaluation of the technical alternatives, solar pumping system is found to be the most viable solution to pump drinking water in the project area.     

Feasibility study of a solar water pumping system

Solar photovoltaic (SPV) water pumping systems have the potential to provide clean drinking water to millions of unserved people around the world. The abundant solar energy resource and groundwater availability in the Pacific Island Countries (PICs) can be combined to make much needed potable water available to remote island communities in these countries. This paper looks at the feasibility of using a SPV pumping system in one of the villages in the Fiji Islands.     

Renewable energy activities in Senegal: a review

Like many countries in Africa, Senegal is facing economical decline, energy crisis and serious desertification problem in rural areas. These issues could be removed if renewable energy is used as a primary source of energy in rural areas. What is required is a strategy to implement renewable energy technologies at large scale. The government and many non-governmental organisations (NGOs) have tried to comprehend and have strived to address the problem of energy. This paper presents a review of activities in the field of renewable energy applications in Senegal, which goes back to the mid 1970s and will discuss the socio-economic benefits that the country has derived from these environmentally sound and appropriate sources of energy. The development and trial of systems were mostly funded so far by donor agencies in collaboration with government and NGOs. Among the applications being supported are solar lighting, water pumping and small power plants. Recent efforts have been aimed at restructuring the programmes and giving them a market orientation. Future trends, some suggestions and recommendations for successful dissemination of renewable energy sources are also drawn. The present situation is seen to be much more promising and favourable for renewable energy.     

Solar thermal heat engines for water pumping: An update

Solar thermal-driven heat engines for water pumping have been previously reviewed for some authors in the past century. However, some devices have not been treated as metal hydride-based systems or the pumping subsystems of solar thermal-driven reverse osmosis desalination systems. Following the typical classification given in the previous literature, in this work an update of the solar heat engines for water pumping based in thermodynamic methods (conventional and unconventional) is presented. Besides small remarks about systems previously quoted by other authors, new designs found in the literature are described. In general, the main characteristics of these systems is their low efficiency, low power output and, in the case of unconventional designs, its simplicity. This work in conjunction with previous review papers make up reference point for the knowledge of the use of solar thermal energy for liquid pumping purpose.     

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.     

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.     

A model for small-scale photovoltaic solar water pumping

A simple method for modelling the output of a solar photovoltaic water pumping system is presented. The model relies on data that can be quickly and relatively easily measured. The procedure of modelling is applied to Solar Star 1000 pumping system. The resulting model predicts the flowrate to within 8% of the measured values.     

Comparison of the performance of PV water pumping systems driven by fixed, tracking and V-trough generators

Photovoltaic pumping systems with solar tracking, coupled to low concentration cavities, have been proposed as a viable alternative to reduce the final cost of the pumped water volume. V-trough concentrators are particularly appropriate for photovoltaic applications since, for certain combinations of the concentration ratio (C) and vertex angle (Ψ), they provide uniform illumination on the region where the modules are located. Water pumping systems are only operational when the irradiance is larger than a minimum irradiance level (I_C). Solar tracking increases the average collected irradiance and, for a system operating with a given critical irradiance level (I_C), it is verified that the smaller the relationship , the larger the useful energy. Thus, the gain, in terms of pumped water volume, provided by solar tracking systems, can be larger than the gain in collected solar radiation. The combination of both devices, tracking and concentration provides an additional increase of the benefits resulting from the use of solar trackers. By means of the “Utilizability Method”, we estimate the long-term gains of pumped water volume, for tracking systems, with and without concentration, against fixed systems. The long-term water volume has been calculated using the characteristic curve of a tested PVP system with a tracking V-trough concentrator. Results show that, for the climate of the city of Recife (PE-Brazil), the annual pumped water volume of the tracking system is 1.41 times the value obtained with the fixed system. In that case, the gains observed for the collected solar energy were around 1.23. For the PVP system with tracking V-trough concentrator the annual benefits for pumped water volume are around 2.49, while for collected solar radiation we found 1.74. The annualized cost of the cubic meter of pumped water has been estimated for the three configurations. Results show a cost reduction of the order of 19% for the tracking system and of 48% for the concentrating system, when compared to the fixed configuration.     

太阳能光伏水泵和照明综合应用系统

本文介绍光伏水泵和照明综合应用系统,以及光伏水泵系统的发展情况。利用太阳能光伏水泵系统解决无电地区农牧民人蓄饮水、农田灌溉问题是一条经济可行的途径。光伏水泵系统具有广阔的推广应用前景。     

太阳能提水泵站优化设计

太阳能离网利用中主要以提水为主,提出了一种太阳能提水泵站的优化设计方法,解决了目前太阳能提水泵站建设存在的容量不匹配、效率低、保证率差等问题。通过科学合理的计算,选择了最佳匹配的太阳能电池、控制器、水泵等部件,实现了太阳能提水泵站的可靠运行,解决了无电地区的饮水和灌溉问题。     

Overview of renewable energy sources in the Republic of the Sudan

Sudan is an agricultural country with fertile land, plenty of water resources, livestock, forestry resources and agricultural residues. An overview of the energy situation in Sudan is introduced with reference to the end uses and regional distribution. Energy sources are divided into two main types: conventional energy (biomass, petroleum products and electricity) and non-conventional energy (solar, wind, hydro, etc.). Sudan possesses a relatively high abundance of solar radiation, moderate wind speeds, hydro and biomass energy resources. Application of new and renewable sources of energy available in Sudan is now a major issue in strategic planning for alternatives to fossil fuels to provide part of local energy demand. Sudan is an important case study in the context of renewable energy. It has a long history of meeting its energy needs through renewables. Sudan’s renewables portfolio is broad and diverse, due in part to the country’s wide range of climates and landscapes. Like many of the African leaders in renewable energy utilisation, Sudan has a well-defined commitment to continue research, development and implementation of new technologies. Sustainable low-carbon energy scenarios for the new century emphasise the untapped potential of renewable resources. Rural areas of Sudan can benefit from this transition. The increased availability of reliable and efficient energy services stimulates new development alternatives. Renewable environmentally friendly energy must be encouraged, promoted, implemented and demonstrated, for use in the Republic of the Sudan.     

Bangladesh energy resources and renewable energy prospects

Bangladesh is a low-economy country with annual commercial energy consumption of only 35 kgOE/capita. Fossil fuel reserves are meagre; about 80% of the total energy supply comes from biomass. The fuel import bill is ~ 70% of total export earnings. Solar and wind energy have bright prospects for parts of the country where natural gas is not available and the cost of electricity, generated from oil-fired units, is high. Solar energy is abundant while wind speeds are high in some coastal areas. For rural electrification, the high cost of distribution lines makes solar electricity viable for remote locations, while wind machines may be set up in coastal areas.     

A comparison of the solar-gas and solar-electric interface

Solar energy has several distinguishing features that bear heavily upon the eventual interfacing with gas and electric utility systems. Chief among these is its intermittent or diurnal nature, which presents differing considerations and challenges for use in conjunction with gas and electric utilities.Gas utilities provide for a winter peaking by producing year-round and storing natural gas in large underground formations, principally aquifers. Electric utilities produce on demand and rely on reserve capacity to meet summer peaks. The gas production-pipeline-storage-distribution system is chemical in nature and relatively tolerant to addition of gas of varying composition and nature. Electric systems are dynamic in nature and relatively intolerant ot the introduction of off-specification energy forms, and thus require elaborate interface protection. The storability of natural gas complements the noncontinuous aspect of solar energy and makes gas-augmented solar systems attractive. These systems can, and in many cases must, be located near the end-use site. Dispersed solar systems are attractive for electrical energy production and consumption at remote locations, for example, for irrigation water pumping. Solar electric systems that are grid connected must be of sufficient magnitude to justify the interface costs with the national grid.Solar-gas systems are preferable for space and water conditioning for homes and institutional buildings. Solar-electric systems can be either dispersed or grid connected, but the scale of technology required is considerably different in these two applications.     

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.     

A decision-making approach for energy efficiency improvement in municipal water pumps during water scarcity scenario

Cities in Sub-Saharan Africa suffer from widespread disparities in water supply due to depletion in groundwater and global-warming-induced changes in weather patterns. The offset of water head from the design considerations of water pumping systems has increased energy requirements leading to worsening of the situation with respect to availability of energy and water. Consequently, highly capitalized water supply schemes, which have been designed to meet the demand, are underutilized leading to operational inefficiencies. Robust empirical equations can help detect inefficiencies in water pumping systems, and this paper discusses the equations which were developed by analysing data obtained from various water supply utilities facing water scarcity. These equations provide cost-benefit analysis for decision making in water utilities and can bring about energy efficiency in municipal pumping operations.