Systems In Remote Areas Research Articles

Sizing of stand-alone photovoltaic power supply system based on genetic algorithm and neuro-fuzzy: application for isolated areas

This paper deals with the application of genetic algorithm (GA) and an adaptive neuro-fuzzy inference scheme (ANFIS), for the prediction of the optimal sizing coefficient of stand-alone photovoltaic supply (SAPVS) systems in remote areas. A database of total solar radiation data for 60 sites in Algeria has been used to determine the iso-reliability curves of a PVS system (C A, C S) for each site. Initially, the GA is used for determining the optimal coefficient (C Aop, C Sop) for each site by minimising the optimal cost (objective function). These coefficients allow the determination of the number of PV modules and the capacity of the battery. Subsequently, an ANFIS is used for the prediction of the optimal coefficient in remote areas based only on geographical coordinates. Therefore, 56 couples of C Aop and C Sop have been used for the training of the network and four couples have been used for testing and validation of the proposed technique. The simulation results have been analysed and compared with the alternative techniques. The technique has been applied and tested for Algeria locations, but it can be generalised for any location in the world.

Access to artemisinin combination therapy for malaria in remote areas of Cambodia

BackgroundMalaria-endemic countries are switching antimalarial drug policy to artemisinin combination therapies (ACTs) and the global community are considering the setting up of a global subsidy mechanism in order to make them accessible and affordable. However, specific interventions may be needed to reach remote at-risk communities and to ensure that they are used appropriately. This analysis documents the coverage with ACTs versus artemisinin monotherapies, and the effectiveness of malaria outreach teams (MOTs) and Village Malaria Workers (VMWs) in increasing access to appropriate diagnosis and treatment with ACTs in Cambodia, the first country to switch national antimalarial drug policy to an ACT of artesunate and mefloquine (A+M) in 2000.MethodsA cross-sectional survey was carried out in three different types of intervention area: with VMWs, MOTs and no specific interventions. Individuals with a history of fever in the last three weeks were included in the study and completed a questionnaire on their treatment seeking and drug usage behaviour. Blood was taken for a rapid diagnostic test (RDT) and data on the household socio-economic status were also obtained.ResultsIn areas without specific interventions, only 17% (42/251) of respondents received a biological diagnosis, 8% (17/206) of respondents who received modern drug did so from a public health facility, and only 8% of them (17/210) received A+M. Worryingly, 78% (102/131) of all artemisinin use in these areas was as a monotherapy. However, both the VMW scheme and MOT scheme significantly increased the likelihood of being seen by a trained provider (Adjusted Odds Ratios (AOR) of 148 and 4 respectively) and of receiving A+M (AORs of 2.7 and 7.7 respectively).ConclusionThe coverage rates of appropriate diagnosis and treatment of malaria were disappointingly low and the use of artemisinin monotherapy alarmingly high. This reflects the fragmented nature of Cambodia's health system in remote areas and the reliance placed by these communities on informal vendors from whom artemisinin monotherapies are widely available. However VMWs in particular are an effective means of improving access to malaria diagnosis and treatment. The VMW scheme and the social marketing of RDTS and blister-packaged artesunate and mefloquine have both been scaled up nationally. Case management in the public sector has also reportedly improved. Given recent concerns regarding the development of artemisinin drug resistance on the Thai-Cambodia border, the effectiveness of these measures in reducing the use of artemisinin monotherapy needs to be urgently re-evaluated.

Electrodialysis of brackish water powered by photovoltaic energy without batteries: direct connection behaviour

The shortage of drinking water is a major problem in the South East of Spain. In these areas, it is essential to make use of water from underground reservoirs, most of which are over exploited and suffer from saline contamination given their proximity to the sea. The desalination of brackish water by electrodialysis is a useful method for obtaining low cost drinking water. Photovoltaic energy can be used to power the electrodialysis system in remote areas in a reliable and autonomous way. Moreover, the photovoltaic array can be connected directly to the electrodialyzer, that is without batteries. Thus, the environmental threat of improper battery disposal is eliminated and increases the sustainability of the process. The aim of our paper is i) to demonstrate the feasibility of the desalination of brackish water by means of an electrodialysis system powered directly by photovoltaic solar panels, and ii) to explain theoretically the interaction between the photovoltaic generator and the electrodialysis system during the process. These systems are appropriate for small applications in isolated locations with lack of electric grid, where it is not necessary to produce water continuously and the volume of daily treated water required is small — about 1–10 m 3.

A Study on Network Configuration of Distributed Flexible Network PV System

The introduction of Distributed Flexible Network Photovoltaic (DFNPV) system is going towards solving the shortcomings of stand-alone systems in remote areas. Three types of configurations of DFNPV system are studied: star, loop, and mesh. Each configuration has many subsystems, which are assumed to have the similar characteristics and location, and consist of PV panel, DC/DC converter, and dc load.Comparative study had been carried out from the viewpoint of power losses in wires, wire length, and initial cost. First of all for estimating the size of DFNPV system within acceptable voltage drop, relations between wire length, power loss, wire cost, and cable types are discussed. The problem in DFNPV System is to find the best location of the battery bank from a many viewpoints, minimum extension cost and minimum losses in wires. This paper describes how to optimize the best location of the common battery bank from the viewpoints of the cost of power losses and the extension cost. The results of optimizing configurations show that a star configuration for initial installations is most effective, in future expansion; loop network is more cost effective. In addition, the economic study shows the final cost advantage of DFNPV system, for three types of configurations over stand-alone ones.

The learning potential of photovoltaics: implications for energy policy

This article examines the prospects for cost reductions of flat panel photovoltaic (PV) electricity. Current PV production cost ranges are presented, in terms of cost per peak W and cost per kWh, for single crystalline and multi-crystalline silicon, as well as for thin-film technologies. Possible decreases of these costs are assessed, as expected based on learning curves. The cumulative production needed to reach ‘breakeven’ (at which PV is competitive with conventional alternatives) is estimated for a range of values of the learning curve parameter. The cost of this cumulative production is calculated, and the question is posed whether and how the ‘cost cap’ can be bridged, the latter being the difference between what this cumulative production will cost and what it would cost if it could be produced at a currently competitive level. We also estimate how much PV could gain if external costs (due to environmental and health damage) of energy were internalised, for example by an energy tax. The conclusions are: (1) mainly due its high costs, PV electricity is unlikely to play a major role in global energy supply and carbon emissions abatement before 2020, (2) extrapolating past learning curves, one can expect its costs to decrease significantly, so that a considerable PV electricity share world-wide could materialise after 2020, (3) niche-market applications, e.g. using stand-alone systems in remote areas, are crucial for continuing “the ride along the learning curve”, (4) damage costs of conventional (fossil) power sources are considerable, and they could provide an important part of the rationale behind major policy efforts to encourage increased use of PV. The costs involved with such policies would be elevated, but a considerable share of these costs could be justified by the fact that conventional power damage costs constitute a significant fraction of the cost gap, although probably not enough to close it.

Operation strategy of residential centralized photovoltaic system in remote areas

Photovoltaic (PV) systems have found fairly wide application in remote isolated area. However, each individual PV system usually supplies energy only to one consumer. In such a case we have several consumers that each one of them uses a stand-alone PV system. This situation would expose such stand-alone systems to transient excessive loads larger than the power generated by the PVs, and then the battery is bound to discharge even during the day. For overcoming this problem, we suggest an autonomous centralized PV system, comprising one battery bank and plural subsystems connected to each other. From solar radiation data and load profiles, the performance of the PV centralized system is simulated by using a time step scheme. The advantages of this system are found to be the large charging rate of power, high efficiency, and low cost compared with conventional individual PV systems and hybrid systems. In addition, the economic study shows that the life cycle cost and the price of kilowatt hour generated in the centralized system is lower than that for the individual systems.

Power Electronic Converters Devoted to Stand-Alone Wind-Energy Generating Systems

Small to medium rating (up to 25 kW wind generators are usually used in stand-alone generation-battery systems in remote areas where the cost of transmitting energy is prohibitive. Wind-energy generating systems, operating at variable-speed. need power electronic converters in order to achieve best wind energy exploitation. Selection of the most suitable converter topology for wind energy generating systems depends-on the medium amount of wind available, the user devices voltage level, the sizing and the number of semiconductor and passive power components used in the electronic converter. This paper deals with prototypal generating systems composed of direct-drive PM synchronous generator, diode bridge rectifier, d.c.-d.c. converter and storage battery. Different d.c.-d.c. converter topologies are analyzed; first theoretical investigations highlight the clear superiority of step-up converter and step-down converter with respect to the other topologies. Computer simulations allowed an exhaustive investigation of both the step-up and the step-down converter configurations. Experimental comparison between different power electronic converter topologies for wind-energy generation was achieved during the carried our laboratory tests on a prototypal system.

The economic feasibility of small solar MED seawater desalination plants for remote arid areas

The objective of this paper is to compare the economics of using solar energy to operate small multiple effect seawater distillation systems in remote areas with the conventional method of using fossil fuels. The particular multiple effect system used is an advanced horizontal tube, falling film system called “multiple effect stack”, MES, in which the pumping energy requirement is relatively low compared with the horizontal in-line system. Three system configurations were investigated: (1) conventional system using a steam generator to provide steam for the MES evaporator and a diesel generator to provide pumping power, (2) solar-assisted system which uses solar thermal collectors to provide hot water (instead of steam) for the evaporator and a diesel generator for pumping power, and (3) solar stand-alone system which uses solar thermal collectors for the evaporator heat requirement and a solar PV array to provide electrical energy for pumping. At the present time, solar energy cannot compete favorably with fossil energy particularly under the present international market prices of crude oil. However, in many remote sunny areas of the world where the real cost of fossil energy can be very high, the use of solar energy can be an attractive alternative. Two important cost parameters affect the relative economics of solar energy vis-à-vis conventional (fossil) energy: the collector cost in $ per square meter and the cost of diesel oil in $ per Giga Joule. Solar energy becomes more competitive as the local cost of procuring conventional fuel increases and as the collector cost decreases. The water cost from a solar thermal-diesel-MES system (Configuration #2) can be seen to approach the water cost from a steam generator-diesel-MES system (Configuration #1) when the collector cost drops to 200 $/m 2 and diesel oil cost at the remote site reaches 50 $/GJ. Using a 100% solar system (Configuration #3) with solar thermal and solar PV collectors being utilized, the economics was seen to improve in favor of the solar system. Even when diesel fuel can be procured at 10 $/GJ at the remote site, the cost of water from the solar system can be seen to approach that from a conventional plant when thermal collectors costing 200 $/m 2 are used. The cost of water from the solar system was shown to be always less than that from a conventional system which uses diesel oil procured at the high price of 50 $/GJ but always higher than water produced from a conventional system using diesel oil at the low price of 10 $/GJ.

Use of a reluctance stepper motor for solar tracking based on a programmable logic array (PLA) controller

The tracking of solar cell panels in solar-generation systems has improved their overall efficiency to a great extent. The methods used previously were either active or passive. In order to ensure a relatively small position resolution for the panel axis, the DC motors ordinarily used for active solar tracking need a complicated gear system. In this work, a 8/6 four-phase, reluctance stepper motor (RSM) controlled by a programmable logic array (PLA) is used. The angular position resolution for the RSM is 7.5°. This resolution is guaranteed due to locking of the RSM at each step through a power converter fed from a 220 V DC supply. The control circuit for the power converter consists of an Erasable Electronic Programmable Read Only Memory (EEPROM) and a PLA chip. The control circuit is fed from two separate sensing cells which determine the movement to the next angular position. The application of this tracker is essential for stand-alone systems in remote areas. Its use may result in improving the solar energy generation by a considerable factor. The control system is a completely closed loop system without any human interference.

Economics of small solar-assisted multiple-effect stack distillation plants

The objective of this paper is to compare the economics of using solar energy to operate small, multiple-effect seawater distillation systems in remote areas with the conventional method of using fossil fuels. The particular multiple-effect system used is an advanced horizontal-tube, falling-film system called “multiple-effect stack” (MES) in which the pumping energy requirement is relatively low compared with the horizontal in-line system. Three system configurations were investigated: (1) a conventional system using a steam generator to provide steam for the MES evaporator and a diesel generator to provide pumping power, (2) a solar-assisted system which uses solar thermal collectors to provide hot water (instead of steam) for the evaporator and a diesel generator for pumping power, and (3) a solar stand-alone system which uses solar thermal collectors for the evaporator heat requirement and a solar PV array to provide electrical energy for pumping. At the present time, solar energy cannot compete favorably with fossil energy, particularly under the present international market prices of crude oil. However, in many remote sunny areas of the world where the real cost of fossil energy can be very high, the use of solar energy can be an attractive alternative. Two important cost parameters affect the relative economics of solar energy vis-à-vis conventional (fossil) energy: the collector cost in dollars per square meter and the cost of diesel oil in dollars per giga Joule. Solar energy becomes more competitive as the local cost of procuring conventional fuel increases and as the collector cost decreases. The water cost from a solar thermal-diesel-MES system (configuration #2) can be seen to approach the water cost from a steam generator-diesel-MES system (configuration #1) when the collector cost drops to $200/m 2 and diesel oil cost at the remote site reaches $50/GJ. Using a 100% solar system (configuration #3) with solar thermal and solar PV collectors, the economics was seen to improve in favor of the solar system. Even when diesel fuel can be procured at $10/GJ at the remote site, the cost of water from the solar system can be seen to approach that from a conventional plant when thermal collectors costing $200/m 2 are used. The cost of water from the solar system was shown to be always less than that from a conventional system which uses diesel oil procured at the high price of $50/GJ, but always higher than water produced from a conventional system using diesel oil at the low price of $10/GJ.

Renewable energy systems for remote areas in Australia

It has been long thought that the northern and central regions of Australia are ideal places for the installation of remote area power supplies (RAPS) based on renewable energy. In particular the solar regime in these areas is among the highest in the world. The Centre of Appropriate Technology has been undertaking a project, as part of the Australian Cooperative Research Centre for Renewable Energy research program, to look at the viability of renewable energy systems in remote areas of northern and central Australia. The study has involved compiling a database of existing knowledge of renewables in these areas combined with a set of site visits and case studies to look at both community attitudes to renewable energy and the actual operation of the systems. The study started in early 1997 and is due to be completed towards the end of 1999. The present paper outlines the logistics of the study and some of the results. The emphasis so far has been on wind and solar systems (including hybrid diesel systems) in Aboriginal communities. Some work has progressed for systems in pastoral properties and tourist ventures. The fieldwork to date has covered northern South Australia and the Northern Territory. Further fieldwork will occur in northern Queensland and Western Australia in mid 1999.

Renewable energy options for hot water systems in remote areas

Providing hot water for remote indigenous communities in Australia has become a priority as part of the effort to improve indigenous health. Earlier work by Healthabitat, among others, has identified washing people to be important in overall health outcomes. In the remote central and northern regions of Australia, the solar regime is very good and the potential for the use of solar hot water systems has been thought to be among the best in the world. Reports from communities in these areas, however, have been pointing to severe problems with the operation of solar hot water systems. The present paper gives the results of a trial of 29 hot water systems in remote locations with the view to identifying the best systems. Of the 29 systems, 14 were solar systems, six were heat exchange systems and the remainder gas and electric. In addition, four biomass heaters (CAT chip heaters) were trialed alongside solar systems. The hot water systems were located at Napranum (northern Queensland), Kintore (NT), Kalka (SA), Wataru (SA) and Alice Springs (NT). The trial started in June 1997 and finished in October 1998. Data loggers were placed on the systems to monitor water temperature, electricity consumption and water flow. Solar radiation and ambient temperature were also monitored at each site. The project was funded by the Aboriginal and Torres Strait Islander Commission (ATSIC).

99/04029 Computer-aided analysis of the integration of renewable-energy systems in remote areas using a geographical-information system: Muselli, M. et al. Applied Energy, 1999, 63, (3), 141–160

99/04029 Computer-aided analysis of the integration of renewable-energy systems in remote areas using a geographical-information system: Muselli, M. et al. Applied Energy, 1999, 63, (3), 141–160

Induced flow reciprocating pumps Part 1

A water column, contained in a rigid pipe equipped with a foot valve, may be set in oscillation and bounced against a hydraulic spring at the lower end. In this way, water may be lifted inertially. The use of such induced flow pumping stretches back to at least the eighteenth century. After exploring these roots the paper proceeds to illustrate modern applications, mainly for hand-and wind-operated water-lifting systems in remote areas. Two arrangements for maintaining the water column in oscillation are examined. By analysis and experiment it is shown that greatly improved performance is achieved by permitting the water column to rebound freely.

Computer-aided analysis of the integration of renewable-energy systems in remote areas using a geographical-information system

The main objective of this project is to realize an integration plan for various renewable-energy systems in remote areas using a geographical-information system (GIS) in order to determine the optimal management and use of energy in these locations. The area studied is Corsica, an island located in the south-east of France. For the remote site considered, four systems supplying electricity are compared: a stand-alone photovoltaic (PV)/batteries system, a hybrid PV/batteries/back-up generator system, an engine generator and an extension of the existing electrical network. The most economic configuration was chosen as the best solution to electrify the remote site. Physical and technical-economical processes are integrated in the GIS. This GIS is used to determine the profitability boundaries for PV systems compared to a grid extension and under four different load profiles, and has led to the elaboration of an integration plan of renewable energies in south Corsica. The study has shown that for 60–90% of remote sites, a PV decentralized electricity system is the most economical means of electrification.

Utilization of meteosat satellite-derived radiation data for integration of autonomous photovoltaic solar energy systems in remote areas

Due to the importance of the relief of Corsica, striking contrasts occur and turn a coastal Mediterranean climate on the littoral into an alpine one in the high mountains. Firstly, we demonstrate, computing a spatial correlogram, that for such countries it is not possible to deduce the solar irradiation received on any part of the island from the meteorological network. Consequently, satellites offer a good alternative for determining these solar data. We demonstrate a good accordance between daily solar irradiation values estimated from Meteosat satellite data and measured data on the considered sites. From the previous data of daily horizontal total irradiations, hourly total irradiations on tilted planes have been computed. These data have been used in an optimal sizing method of PV system, easily applicable to any site. So, for each site on the island of Corsica, we can determine the best adapted PV system, and we analyse differences between sizing characteristics according to the site of installation. Lastly, we have shown very good accordance between sizing results calculated, on the one hand, from measured irradiation hourly data and, on the other hand, from daily satellite images.

98/00475 Utilization of Meteosat satellite-derived radiation data for integration of autonomous photovoltaic solar energy systems in remote areas

98/00475 Utilization of Meteosat satellite-derived radiation data for integration of autonomous photovoltaic solar energy systems in remote areas

Portable end-to-end ground system for low-cost mission support

This paper presents a revolutionary architecture of the end-to-end ground system to reduce overall mission support costs. The present ground system of the Jet Propulsion Laboratory (JPL) is costly to operate, maintain, deploy, reproduce, and document. In the present climate of shrinking NASA budgets, this proposed architecture takes on added importance as it should dramatically reduce all of the above costs. Currently, the ground support functions (i.e., receiver, tracking, ranging, telemetry, command, monitor and control) are distributed among several subsystems that are housed in individual rack-mounted chassis. These subsystems can be integrated into one portable laptop system using established Multi Chip Module (MCM) packaging technology and object-based software libraries. The large scale integration of subsystems into a small portable system connected to the World Wide Web (WWW) will greatly reduce operations, maintenance and reproduction costs. Several of the subsystems can be implemented using Commercial Off-The-Shelf (COTS) products further decreasing non-recurring engineering costs. The inherent portability of the system will open up new ways for using the ground system at the “point-of-use” site as opposed to maintaining several large centralized stations. This eliminates the propagation delay of the data to the Principal Investigator (PI), enabling the capture of data in real-time and performing multiple tasks concurrently from any location in the world. Sample applications are to use the portable ground system in remote areas or mobile vessels for real-time correlation of satellite data with earth-bound instruments; thus, allowing near real-time feedback and control of scientific instruments. This end-to-end portable ground system will undoubtedly create opportunities for better scientific observation and data acquisition.

Design of control circuit of solar photovoltaic powered regulated cathodic protection system

Cathodic protection (CP) system objective is to protect metallic structures against corrosion caused by chemical reaction between metallic structures and surrounding medium such as soil or water. To overcome such a problem a sacrificing anode is connected to the protected structure (which acts as a cathode) through a d.c. power supply. The d.c. power required for CP systems is characterized by low voltage and high current. This power may be obtained from a.c. power source, if available, and a rectifier. The second alternative is to use a diesel generator and a rectifier, but this system requires frequent fuel addition and maintenance. If the location of the system is remote, maintenance and fuel transport become costly. Recently solar photovoltaic (PV) systems are used to provide cathodic protection systems in remote areas by d.c. power. Solar PV systems are modular so that they may be designed to operate at the required voltage and current easily. PV systems are maintenance free. To stop the corrosion entirely, the protected structure is to be fed by a constant current determined by structure's metal, area and the surrounding medium. The major difficulty to achieve this goal is the variations of the surrounding medium resistivity due to climatic conditions changes. Conventional CP systems resolve this problem by periodical manual adjustment of the d.c. voltage to obtain a constant current. Such adjustment depends on the experience of the technician and the accuracy of the measuring equipment used. Moreover if the interval between two successive adjustments is relatively long, an appreciable corrosion may take place because of the non accurate d.c. voltage applied to the system. To overcome this difficulty, an automatically regulated CP system is discussed by Anis and Alfons [ Solar Energy, 53(2), pp. 211–214, 1994]. The proposed system senses the variations of surrounding medium resistivity and adjusts the d.c. voltage of the system automatically so that the d.c. current is kept almost constant at the required level regardless of soil resistivity variations. In this work the design of the electronic control circuits of the regulated CP system is thoroughly investigated.

Computer‐based Audiographics for Distance Education: An Inexpensive, Interactive and High‐quality Alternative

Abstract The high cost of delivery systems, the lack of highspeed telecommunications systems in remote areas, and the lack of appropriate features to support instruction have all hampered adoption of the most widely promoted distance education systems, such as compressed video. The higher education system in the state of Nevada exemplifies the many obstacles that must be overcome in initiating distance education programmes. A set of ideal system characteristics has been identified which would overcome many of these obstacles. A PC computer‐based audiographics system known as SMART is described which meets most of these criteria. It is inexpensive, usable in almost any location, highly interactive, able to use most existing instructional materials, and requires less training than most other systems. This paper describes the critical features of this audiographic system and concludes with a brief discussion of how this type of system allows for control of instructional variables critical for student learning.