Renewable energy technologies for irrigation water pumping in India: A preliminary attempt towards potential estimation

Simple frameworks have been developed for estimating the utilization potential of: (a) solar photovoltaic (SPV) pumps; (b) windmill pumps; (c) producer gas based dual fuel engine pumps; and (d) biogas based dual fuel engine pumps for irrigation water pumping in India. The approach takes into account factors such as: solar radiation intensity, wind speed, availability of bovine dung and agri-residues, and their alternative uses, ground water requirements for irrigation and its availability, affordability, and propensity of the users to invest in renewable energy devices, etc. SPV pumps are estimated to have the maximum utilization potential in India, followed by windmill pumps.     

Solar thermal power plants in the world: The experience of development and operation

The main areas of large-scale development of solar energy are: —conversion of solar energy into low-grade heat, and using the latest in heating systems of residential, municipal facilities, public and industrial buildings that consume energy such as temperature capacity; —conversion of solar energy into electricity through photovoltaic and thermodynamic converters. This report provides short information of the dynamics of the creation and operation of solar power plants (SPP) with the thermodynamic conversion, and the criteria for reducing cost of electricity produced from them.     

Assess the potential of solar irrigation systems for sustaining pasture lands in arid regions – A case study in Northwestern China

The combined impact of global climate change and increasing human activities has led to the severe deterioration of grasslands in China. Using the solar irrigation systems is an effective way for sustaining pasture lands in arid regions. A solar irrigation system is the device that uses the solar cell from the sun’s radiation to generate electricity for driving the pump. And photovoltaic pump consists of an array of photovoltaic cells and pumps water from a well or reservoir for irrigation. Although ecologists and organizations constantly work and find ways to conserve grasslands through irrigation systems that use solar energy, issues on water resources are not yet thoroughly discussed. This paper takes into account the main factors in the study of water resources, including precipitation and groundwater, to analyze the feasibility of using a photovoltaic (PV) pumping irrigation. The appropriate area for such a PV pumping irrigation in Qinghai Province is also presented. The results show that the grasslands appropriate for PV pumping cover about 8.145 million ha, accounting for 22.3% of the grasslands in the entire province. Finally, the problems and countermeasures of PV pumping irrigation, including the impact on regional water balance, groundwater level and highland permafrost, are also considered.     

New and emerging developments in solar energy

Solar energy can potentially play a very important role in providing most of the heating, cooling and electricity needs of the world. With the emergence of solar photocatalytic detoxification technology, solar energy also has the potential to solve our environmental problems. However, we do not see widespread commercial use of solar energy. Some of the emerging developments in solar may change that situation. This paper describes some of the new and emerging developments, with special emphasis on: (1) nanoscale antennas for direct conversion of sunlight to electricity with potential conversion efficiencies approaching 80–90%; (2) new thermodynamic cycles for solar thermal power, that have the potential to reduce capital costs by 50%; and (3) solar photocatalytic oxidation for cleanup of industrial wastewater, drinking water, soil and air. The paper describes the fundamentals of each of these developments, their potential, present status and future opportunities for research.(1) Nanoscale antenna solar energy conversion: The current photovoltaic technologies rely on the quantum nature of light and semiconductors which are fundamentally limited by the band-gap energies. A revolutionary new approach suggested by Professor Robert Bailey in 1972 revolves around the wave nature of light. Professor Bailey suggested that broadband rectifying antennas could be used for solar to d.c. conversion. These rectennas would not have the fundamental limitation of semiconductor band-gap limiting their conversion efficiencies. Rectennas for solar conversion would have dimensions of the order of the wavelengths of solar radiation which falls mostly in the sub-micron range. The challenges in actually achieving the objectives are many. This paper describes the challenges and approaches to their solution.(2) New thermodynamic cycles for solar thermal power: It is recognized that the capital costs of solar thermal power will have to be reduced by about 50% in the near future in order to make it competitive with fossil fuels (especially natural gas) based power systems. Potential exists for meeting this goal by reducing the costs and improving the thermodynamic performance of power cycles by hybridization and combined cycle approaches and by employing new and innovative ideas in thermal power cycles. This paper describes the new thermodynamic approaches with an emphasis on an innovative new thermodynamic cycle using ammonia and water mixtures as the working fluids.(3) Solar photocatalytic detoxification and disinfection of water and air: Although the potential of solar radiation for disinfection and environmental mitigation has been known for years, only recently has this technology been scientifically recognized and researched. Solar photocatalytic oxidation has been demonstrated to effectively treat groundwater, drinking water, and industrial wastewater. In some applications such as decoloration and reduction of COD it may be the only effective method of treatment. Treatment of indoor air by the photocatalytic method has been demonstrated as the most effective technology for that application. This paper describes the recent developments and identify challenges and future research opportunities.     

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.     

Performance of solar systems with non-linear behavior calculated by the utilizability method: application to PV solar pumps

Based on the utilizability method we derived, in the first part of the paper, an analytic expression to calculate the time average of physical quantities non-linearly dependent on collected solar radiation. Results are applied to photovoltaic pumping systems (PVPS). Water flow propelled by various types of pumps, centrifugal or progressive cavity displacement, for example, can be conveniently written as a second degree polynomial of the collected solar radiation. In that case, the long-term time average of relevant physical parameters, like water flow or hydraulic power, can be calculated with a very simple expression. The procedure is validated comparing long-term averages of maximum water volume pumped by a PV system, obtained with the utilizability method, with those found by running a 10-year time series. Comparison is made for several climatic regions in Brazil. Results show very good agreement for every month of the year and all locations, with a maximum deviation of 1.7%. The method applied to calculate long-term averages, maximum water volume for example, can be useful for evaluation and design procedures of photovoltaic pumping equipment.     

Experimental investigation of solar powered diaphragm and helical pumps

For several years, many types of solar powered water pumping systems were evaluated, and in this paper, diaphragm and helical solar photovoltaic (PV) powered water pumping systems are discussed. Data were collected on diaphragm and helical pumps which were powered by different solar PV arrays at multiple pumping depths to determine the pumping performance, efficiency, and reliability of the different systems. The highest diaphragm pump hydraulic efficiency measured was ∼48%, and the highest helical pump hydraulic efficiency measured was ∼60%. The peak total system efficiency (e.g. solar radiation to pumped water) measured for the diaphragm and helical pumps were ∼5% and ∼7%, respectively (based on PV modules with ∼12% efficiency). The daily water volume of the three-chamber high head diaphragm pump performed better than the dual-chamber high head diaphragm pump (∼5 to ∼100% depending on PV array input power and pumping depth). Use of a controller was shown to improve the quad diaphragm pump performance below a solar irradiance of 600 W/m² (20 m head) to 800 W/m² (30 m head). While diaphragm pumps made mostly of plastic demonstrated similar to much better pumping performance than diaphragm pumps made with a high proportion of metal, the metal pumps demonstrated a longer service life (>2 years) than the plastic pumps service life (<2 years). Helical pumps analyzed in this paper were capable of deeper pumping depths and usually demonstrated a longer service life than the diaphragm pumps that were analyzed.     

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.     

Experimental investigation and CFD analysis of a solar hybrid PV/T system for the sustainable development of the rural northern part of Bangladesh

An attempt has been made to utilise solar energy more efficiently by developing the single pass hybrid photovoltaic thermal system at the climatic condition of Bangladesh. As the electric energy conversion efficiency of the photovoltaic module falls with the surrounding temperature and air or water used as a suitable solution to make it cool. In this study, air was used as the cooling medium for the solar panel and circular copper tube was placed on the glazed collector for water heating to ensure maximum exploitation of solar energy. Moreover, the photovoltaic panel power was used to circulate the air and make the system self-powered. Maximum collector efficiency was 24.64% for water and 11.20% for air is observed at a mass flow rate 0.00158 and 0.00221 kg/s for water and air respectively at a solar radiation of 1050 W/m². In addition, the combined efficiency of the hybrid system was about 39.68%. By adding glycerin with water at a ratio of 50:1 (% of weight) the combined efficiency reached up to 45.76%. The computational fluid dynamics (CFD) simulation and economic analysis of the designed system strongly support the feasibility of the solar hybrid photovoltaic thermal system as the future sustainable energy source.     

Low‐grade heat‐driven Rankine cycle,a feasibility study

Conversion of low‐grade heat to high‐quality energy such as electricity using the Rankine cycle poses serious challenges. When such conversion is possible, it is invariably expensive or unacceptable due to environmental concerns associated with the working medium. The low‐grade heat can either be from exhaust systems or from solar radiation. Thus, the topic addresses a very useful subject, combining energy efficiency and renewable energy. Although high‐grade heat recovery and energy conversion is a mature technology widely covered by the literature, low‐grade energy conversion, especially using thermodynamic cycles, has not been sufficiently addressed to date. This paper addresses the feasibility of a low‐grade heat‐driven Rankine cycle to produce power using a scroll expander, a low toxicity, low flammability, and ozone‐neutral working fluid. A cost benefit analysis of the recommended system shows that it is a viable option for solar power generation, at about one‐third the cost of a comparable photovoltaic system. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis and simulation of a solar water pump for lift irrigation

A solar water pump for lift irrigation, which was shown to be economically viable, was proposed by Rao and Rao [5]. A “modified pump” is suggested, which is suitable for village water supply. The thermodynamic analysis of the pumps is presented. Though the solar water pump is intended to be operated with flat-plate collectors, it is analysed whether the pump could be run more efficiently when coupled with concentrating collectors. The analysis is also applicable for bellow actuated solar water pumps.Preliminary experimental studies showed that the heat losses are 2–3 times the theoretical energy requirement and the losses to the water tank shell accounted for a major part of the total heat losses. To reduce these losses, it is proposed that the inner surface of the water tank shell be lined with a resin bonded cork insulation. A method to evaluate the heat losses to the shell with insulation by solving the unsteady state heat conduction equation for a composite cylindrical body with time varying convective boundary conditions is presented. The heat losses are reduced to 5–15 per cent of the theoretical energy requirement with the use of the internal insulation. The major problem encountered in operating the pump was the inadequate condensation of the working fluid, which resulted in failure of the suction of water into the water tank. To ensure proper suction of water, the conditions to be maintained are analysed. The presence of water vapor and air in the spent vapor has to be taken into consideration while designing the condenser.An algorithm to evaluate the year round performance of the water-cooled pump for any location, given the lift and collector area, is presented. The cost of the water-cooled pump is compared with the costs of other types of solar water pumps and it is shown that the pump under consideration costs several times less than the other ones. The conditions at which the pump will be economical vis-a-vis diesel and electrical pumps are presented.     

A low lift solar water pump

A model of a diaphragm pump using an automatic valve mechanism consisting of a set of permanent magnets and springs was developed for lowlift solar water pumping. The pump that has been developed is based on the thermodynamic conversion method using an intermittent Rankine cycle with freon-113 as a working fluid. Solar radiation collected on a simple flat-plate solar collector (size 1.4 m²) is used to vaporize the liquid freon. The vapour pushes a rubber diaphragm which in turn pumps the water. The exhaust vapour is condensed and collected in a container. The condensate is charged into the flat-plate solar collector by gravity for use during the next day's operation. Test results showed that with a constant input vapour pressure the discharge of the pump decreased as the head increased. The discharge of the pump was 4.3 l./min at a 3 m head while it reduced to 2.8 l./min at a head of 6 m with a freon pressure of 2.4 mg/cm² (240 kN/m²) inside the collector. The head increased as the input vapour pressure increased.     

Comparative study in supplying electrical energy to small remote loads in Libya

The main sources of energy that might be available in remote low populated areas Libya are either diesel generating units or wind mills for water pumping. Several problems in the working performance of these two types of energy production may arise due to environmental conditions. The lack of qualified technicians for regular and emergency maintenance reduces the energy sources' availability. Direct conversion of solar energy can replace other ways of energy delivery or production, specially in this country where the solar radiation all over the year is relatively high. On the other hand the direct conversion of solar energy is relatively expensive, however the cost of erecting long feeders and supervising them may be much expensive than the usage of solar systems. This paper investigates the economics associated with either solutions of energy production. A case study is given in details to supply one of the remote areas with population of about 250.     

Small-scale solar pumping: The technology

The present work is concerned with the direct use of solar energy in water pumping. The available technologies of photovoltaic, thermal and other solar pumping systems are examined. It appears that the most suitable system for solar pumping is the one that satisfies several requirements such as: no movable mechanical parts, reasonable thermal efficiency, minimum manufacturing cost and compact in size.     

Design and development of a water piston solar powered steam pump

Most solar pumping systems are based on photovoltaic receivers driving electric pumps. An alternative system is to use a boiling water solar receiver to operate a direct acting steam pump. The advantages lie in the relative simplicity of the pump giving ease of manufacture, maintenance, reliability and low cost. At De Montfort University a simple direct acting steam pump has been developed over many years, so it has been a natural development to link this with a boiling water solar receiver. This paper is primarily concerned with the operation of the pump and overall system employed.     

太阳能驱动的固体氧化物电解池制氢系统性能研究

采用太阳能驱动电解水制氢是实现将太阳能转换为氢能来存储的最佳方式。该文提出一种采用光伏、光热协同驱动固体氧化物电解池（SOEC）进行高温蒸汽电解的制氢系统。建立各子系统数学模型,选取北京地区夏至日气象参数,分析太阳辐照度对制氢系统的性能影响,最后对整个系统进行能量及火用分析。结果表明,电流密度和温度是影响SOEC工作的重要因素。在电流密度较大的情况下升高温度,将有利于提高电解效率。耦合太阳能后系统最大能量及火用效率分别达到19.1%和20.3%。火用分析结果表明系统最大有用功损失发生在光电转换过程,火用损比例为87%。提升光电效率,将成为提高太阳能-氢能转换效率的关键。     

Diverting indirect subsidies from the nuclear industry to the photovoltaic industry: Energy and financial returns

Nuclear power and solar photovoltaic energy conversion often compete for policy support that governs economic viability. This paper compares current subsidization of the nuclear industry with providing equivalent support to manufacturing photovoltaic modules. Current U.S. indirect nuclear insurance subsidies are reviewed and the power, energy and financial outcomes of this indirect subsidy are compared to equivalent amounts for indirect subsidies (loan guarantees) for photovoltaic manufacturing using a model that holds economic values constant for clarity. The preliminary analysis indicates that if only this one relatively ignored indirect subsidy for nuclear power was diverted to photovoltaic manufacturing, it would result in more installed power and more energy produced by mid-century. By 2110 cumulative electricity output of solar would provide an additional 48,600 TWh over nuclear worth $5.3 trillion. The results clearly show that not only does the indirect insurance liability subsidy play a significant factor for nuclear industry, but also how the transfer of such an indirect subsidy from the nuclear to photovoltaic industry would result in more energy over the life cycle of the technologies.     

Integrated solar pump design incorporating a brushless DC motor for use in a solar heating system

Most solar thermal hot water heating systems utilize a pump for circulation of the working fluid. An elegant approach to powering the pump is via solar energy. A “solar pump” employs a photovoltaic module, electric motor, and pump to collect and convert solar energy to circulate the working fluid. This article presents an experimental investigation of a new integrated solar pump design that employs the stator of a brushless DC motor and a magnetically coupled pump that has no dynamic seal. This design significantly reduces total volume and mass, and eliminates redundant components.The integrated design meets a hydraulic load of 1.7 bar and 1.4 litres per minute, equal to 4.0 watts, at a rotational speed of 500 revolutions per minute. The brushless DC motor and positive displacement pump achieve efficiencies of 62% and 52%, respectively, resulting in an electric to hydraulic efficiency of 32%. Thus, a readily available photovoltaic module rated 15 watts output is suitable to power the system.A variety of design variations were tested to determine the impact of the armature winding, pump size, pulse width modulation frequency, seal can material, etcetera. The physical and magnetic design was found to dominate efficiency. The efficiency characteristics of a photovoltaic module are such that over-sizing is wasteful.The integrated design presents a robust, efficient package for use as a solar pump. Although focus has been placed on application to a solar thermal collector system, variations of the design are suitable for a wide variety of applications such as remote location water pumping.     

A procedure to size solar-powered irrigation (photoirrigation) schemes

The high cost of photovoltaic solar power makes it necessary, before undertaking any subsequent study, to dimension photovoltaic installations as accurately as possible. We here present a procedure to estimate the required dimension of a photovoltaic installation designed to power a pumping system for the drip irrigation of an olive tree orchard in SW Spain. The method consists of three main stages: (1) One determines the irrigation requirements of the specific estate according to the characteristics of its soil-type and climate. (2) A hydraulic analysis of the pumping system is made according to the depth of the aquifer and the height needed to stabilize the pressure in the water distribution network. (3) Finally, one determines the peak photovoltaic power required to irrigate a 10 ha sub-plot of the estate taking into account the overall yield of the photovoltaic-pump-irrigation system.We call this arrangement “photoirrigation”, and believe that it may be of great utility to improve the output of such socially significant crops as olives and wine grapes, optimizing the use of water and solar energy resources at the same time as preserving the environment.