A study on renewable energy based hybrid system for rural electrification | |
| Author | Napaporn Phuangpornpitak |
| Call Number | AIT Diss. no.ET-07-07 |
| Subject(s) | Renewable energy sources Rural electrification |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral of Engineering in Energy Technology, School of Enviroment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ET-07-07 |
| Abstract | Renewable energy based hybrid system is an important option for rural electrification. The fastest growing renewable energy technology in the rural (off-grid) energy supply has been solar photovoltaic (PV) energy as its cost is declining with technological improvements and economies of scale in production. Application of PV hybrid system has great potentials to meet the energy needs of rural areas as these could provide electricity in a cost effective way. Many such systems have been installed in recent years primarily in rural areas that do not have access to electricity. Noting the lack of rural electrification in the developing countries, the ever-increasing price of petroleum products (now about US$ 100 a barrel) and the reduction in cost of PV systems, opportunities for PV hybrid systems to address rural electrification seems to be increasing. However, to achieve commercialization and widespread use, a number of issues need to be addressed. These issues are related to the design and sizing of the system, its operation and maintenance, user acceptability and social issues involved. The overall objective of this research is to address the issues related to the use of PV hybrid system for rural electrification (villagelisland communities). The PV hybrid system"considered in this study consists of PV array, diesel generator, battery and inverter. From a review of literature, earlier studies on PV hybrid systems have been in terms of modeling, system sizing and performance, while studies based on experience in operating PV hybrid systems in the field are limited. Tools are available for PV hybrid design and sizing, and these are designed for specific objectives, such as design based on life cycle cost or according to the expected function of the system. In this study, the PV hybrid system model was developed that incorporates technical, financial and social aspects. This would be useful to predict the performance of the system, financial analysis and the user perspective on a PV hybrid system. This research also carried out experimental studies and survey on a PV hybrid system installed in an island community and in the laboratory. Observation and analysis of results have been used to validate the model proposed. A small scale PV hybrid system was installed in the laboratory which mainly considered technical performance, while the real scale system was conducted at the rural island community for which technical, financial and social aspects have been considered. Experimental studies on the small scale PV hybrid system have been carried out to compare and verify theoretical predictions. The system consisted of 0.9 kWp PV array coupled to a 10 kW diesel generator. The observations indicated that actual performance is comparable to rated (or model) component performance. The performance indicators at the system level are yield, losses and performance ratio. The variation of these parameters over the months indicated that the daily final yield and the performance ratio (PR) ranged from 0.6-1.9 kWhlkW, and from 0.24-0.67, while the overall plant efficiency was 4%. Compared to the previous studies for PV /diesel hybrid system using the same lead acid battery as storage, the PR has been found to increase from about 0.30 to 0.67 in the present study, primarily due to its operation at higher load and use of a reasonable operation of diesel generator. The results from the model (technical performance) have been compared to the experimental results. The calculated performances are comparable to the experimental results. The calculated results agree well with the experimental ones. The mean bias error (MBE) and root mean square elTor (RMSE) of the yields were 0.22 kWhlkW and 0.11 kWhlkW, while they were -0.32 kWhlkW and 0.15 kWhlkW for losses. Field studies were carried out on the PV hybrid system of an unelectrified area (Kohjig, an island in the Gulf of Thailand) to analyze the system performance, financial viability and social issues involved. The real scale system consists of 7.S kW p PV array coupled to a 60 kW diesel generating system. The daily final yield and PR ranged from 3.1-4.9 kWh/kW, and from 0.61-0.82, while the overall plant efficiency was 9%. The experimental results correspond reasonably well with the model evaluations. The MBE and RMSE of the yields were 0.23 kWh/kW and 0.14 kWh/kW, while they were -0.13 kWh/kW and 0.09 kWhlkW for losses. An analysis of the operation strategy (based on an evaluation procedure developed in this study) applied to a rural island indicated that to charge battery from 60% state of charge (SaC) to 70% sac, fuel consumption and maximum diesel generator operation was 41.6 liters/day and 5.3 hours, while fuel consumption and maximum diesel generator operation was 43.5 liters/day and 10 hours to charge battery from 40 to 90% Sac. The diesel generator is used frequently (apparently on a daily basis at the peak hours). When the charging current is increased, though the maximum diesel generator operation is reduced, fuel consumption is also increased. The PV hybrid system at Kohjig appears to be worthwhile in terms of the return on investment as NPV was positive, IRR and B/C ratio has been found to be 19% and 1.3 respectively. Compared to similar types of systems installed earlier in other remote/rural areas, the system at Kohjig provides a good case to invest even when excluding the addition of environmental externalities. The acceptance of the new technology and its user acceptability are the key factors for successful implementation of the PV hybrid system for rural electrification. This study also considers the social aspect, especially user satisfaction of the system by the use of a questionnaire survey. The level of satisfaction ranked from satisfaction (5) to dissatisfaction (1). The attitude of the islanders to the PV hybrid system is mostly positive. Users were satisfied that they could use electric appliances whenever they needed and they were also satisfied with the reduction of environmental impacts. According to the users, the system is reliable and the availability of lighting appears to be the most important benefit to the users. Overall, the islanders rate the PV hybrid system to be very satisfactory compared to the earlier system of using household based diesel generators. Earlier studies on the PV hybrid system focus on its performance, while this dissertation analyzes and reports the system in terms of technical performance, financial viability and social acceptability. The integrated model would be useful to developers and practitioners of renewable energy systems and to policy makers to gauge the role of renewable energy based hybrid systems to supply electricity in rural areas. Additional contributions from the present study include social issues which reflect the attitude of the PV hybrid system users at the system site to use the system has not been reported in the literature so far. The present study has achieved this. The study clearly illustrates the potential to use the PV hybrid system to supply basic energy services that is desired in rural settings. PV hybrid systems have been installed in Thailand for national parks, wildlife preservation areas and remote temples. These systems have distributed electricity for offices and visitor lodges, and have been considered as single-user. This dissertation addressed the first PV hybrid system installed for multi-user in Thailand. One problem of renewable energy based hybrid system for rural electrification is the difficulty in selecting a suitable operation strategy for implementation in the field area where the system has been installed. A procedure for renewable energy based operation strategy evaluation has been developed and also verified with the field scale system |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ET-07-07 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Kumar, S.; |
| Examination Committee(s) | Nadarajah, Mithulananthan ;Manukid, Parnichkun; |
| Scholarship Donor(s) | Asian Institute of Technology ;Energy Policy and Planning Office, Thailand; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2007 |