Prospect of Hybrid Wind System in Bangladesh (Thakurgaon)
Shahidul I. Khan, Mohammad Upal Mahfuz*, Tareq Aziz, N. M. Zobair
Department of Electrical & Electronic Engineering,Bangladesh University of Engineering & Technology, Dhaka-1000, Bangladesh
*Faculty of Engineering, American International University – Bangladesh (AIUB), Banani,Dhaka-1213, Bangladesh.
https://www.buet.ac.bd/eee/icece2002/paper_054.pdf
Abstract – In future, renewable energy like solar, wind, wave and tidal could be utilized in some areas of Bangladesh. The geographical location of Bangladesh is ideal for tapping solar energy effectively. There is also enormous potential for harnessing electrical power from wind in some selected areas of the country and in the coastal region. In this paper possibility of wind-solar hybrid system has been studied. There is a possibility of a total of 100 MW hybrid power generation in coastal areas. After a preliminary survey supported by measured field data of wind velocities and solar radiation all over the country, two specific sites Patenga and Thakurgaon have been primarily identified where more than 100 kW wind-solar hybrid power generations is possible.
Keywords: Wind energy, hybrid system
1. INTRODUCTION
Bangladesh is a developing country lying in the northeastern part of South Asia and is situated between 20_ 30´ to 26_ 38´ north latitude and 88_ 04´ to 92_ 44´ east longitude. The vast Bay of Bengal on the south of the country along with the V-shaped coastal belt is the main source of the southwesterly wind blowing over the terrain. The geographical location of the country has become an ideal place for utilization of solar energy. It has also a bright prospect of electricity generation from wind, especially in some northwestern districts and in the southern coastal areas. In some parts of the country electricity demand is met by the existing power generating plants primarily run by imported furnace oil and high-speed diesel. Considering diurnal variation of wind velocities and available wind speed
pattern [1], the existing diesel generation can be partially replaced by Wind Energy Conversion Systems (WECS) and also new wind-solar hybrids can be set up. According to the Bangladesh Power Development Board (BPDB) and Local Government Engineering Department (LGED), there is huge potential of wind-solar-diesel and wind-diesel hybrid systems in Bangladesh and they could be future energy option of rural electrification [2] purpose in areas where the expansion of national grid is very bleak.
This study finds that Patenga and Thakurgaon are the two most promising sites of wind-solar hybrid system. Patenga is a rural area near Anowara thana in the district of Chittagong, the gateway of Bangladesh. The western side of Patenga is surrounded by the Bay of Bengal. The site consists of five villages. The total population [1] is around 5,000. Thakurgaon is a district situated near the northern boundary of Bangladesh with a population 1,010,948 of which 916,442 (i.e. 90.65%) are rural inhabitants. Only 8.26% of the total households have access to electricity, which is principally generated by the 10.5 MW diesel generator [3].
2. THEORY
Wind energy is the kinetic energy of the moving air mass. The power, P, in watts, possessed by wind blowing with a velocity of V, in meters per second, is directly proportional to the rotor swept area and to the cube of the wind speed, and is given by;
P = (½). r. A. V3 (in Watts) (1)
where, A is the area perpendicular to the direction of flow, meter2, r, density of air, kgm-3, is approximately 1.2 kg/m3, V, wind velocity, meters per second. Only a part of the total available power calculated by equation 1 can be extracted and is given by;
P = (½). r. A. V3. Cp (in Watts) (2)
Cp, the power coefficient [4] is the ratio of power extracted by a wind turbine to power available in wind at that location. A theoretical maximum of 59.3% of available power can be extracted; i.e. Cp is 0.593. Practically a typical maximum of 40% is achievable.
Solar cells represent the fundamental power conversion unit of photovoltaic system. They are basically p-n junctions made of semiconductor. Incident sunrays are converted directly into electricity by solar cells.
3. ANALYSIS
For this study the wind speed records of 20 nation-wide wind speed monitoring stations of the Meteorological Department of Bangladesh for fifteen years (1981-1995) have been primarily studied for power generation purpose. But these data are meant for weather forecasting only and lack reliability, accuracy and appropriate height. A more recent set of wind speed data has been used to determine wind power densities at different locations of Bangladesh [1]. Calculated available wind power densities are shown in Table 1. The available wind power densities of the country are also depicted in Figure 1. Solar radiation [5] at different major cities of Bangladesh has been shown in Table 2. The sunshine profiles [6] of three cities Dhaka, Rajshahi and Barisal are shown in Figure 2.
| Table 1. | ||
| Wind power densities at 20 different locations of Bangladesh | ||
| Stations Annual | Average Speed (m/s) | Available (Theo.) wind Power Density P/A=0.6 A. V3 (W/m2) |
| Barisal |
2.66 |
11.31 |
| Bogra |
2.82 |
13.47 |
| Chittagong |
4.65 |
60.35 |
| Coxs Bazar |
3.81 |
33.2 |
| Dhaka |
4.52 |
55.43 |
| Dinajpur |
2.83 |
13.62 |
| Hatiya |
3.74 |
31.4 |
| Jessore |
4.93 |
71.91 |
| Khepupara |
4.24 |
45.78 |
| Khulna |
2.89 |
14.5 |
| Kutubdia |
2.32 |
7.51 |
| Patenga |
7.48 |
251.14 |
| Sandwip |
2.76 |
12.63 |
| Satkhira |
4.37 |
50.09 |
| Teknaf |
3.17 |
19.13 |
| Thakurgaon |
6.59 |
171.73 |
| Comilla |
2.78 |
12.91 |
| Mongla |
2.2 |
6.4 |
| Rangamati |
2.15 |
5.98 |
| Sylhet |
2.38 |
8.11 |
|
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4. RESULTS
A generalized program called HYBRIDPOWERC is developed in C++ language to calculate power at different sites. The coastal site of Patenga and the two northwestern districts of Thakurgaon and Jessore have the highest wind power densities of 251.12 Wm-2, 171.71 Wm-2 and 71.89 Wm-2 respectively. One wind generator with rotor diameter of 10 meter and considering maximum power coefficient of 0.40, 8.0 kW and 5.4 kW of power can be harnessed from Patenga and Thakurgaon sites respectively. With this specifications 13 and 19 wind turbines are required to generate 100 kW at Patenga and Thakurgaon respectively. Due to seasonal dependence of wind energy, solar-wind hybrid system can increase availability of useful power. Ample sunshine can provide extra power by solar modules during the
winter when average wind speed is comparatively a little bit lower than that of the monsoon. During rainy season (May-July) wind electricity can predominate the solar electricity. So 100 kW hybrid wind-solar power can be available throughout the year. The only problem is that, there is probability of cyclone in every 10 years or so. Sufficient control techniques can be provided to prevent overstressing of the turbine in high-speed wind during cyclone. Tilting the wind wheel and changing the blade angles to lower their loads during the high-speed wind period may protect wind turbines. An average yearly wind speed of at least 4 m/s is necessary to justify the use of a wind generator in a hybrid system [7]. The annual average wind velocities of Patenga and Thakurgaon are 7.48 ms -1 and 6.59ms -1 respectively. Hybrid power generation is definitely worth considering at these particular sites. A standalone hybrid system is preferred. Battery banks will be there which are typically sized for one to three days of windless operation [8]. Solar panel sizing will be provided in the full paper. The cost of the hybrid system has been estimated as $1,200 per kW installed for medium (50 kW -100 kW) systems and $1,000 per kW installed for comparatively larger-systems.
5. CONCLUSIONS
The proposed Patenga and Thakurgaon 100 kW wind-solar hybrid system will be the largest of its kind in Bangladesh. In this paper in-depth study is presented on hybrid wind-solar system in Bangladesh after studying available data from Meteorological Department and some recent studies by several nongovernmental organizations of the country. The right set of circumstances, a well-designed wind energy system can provide many years of cost effective, clean and reliable green power. Renewable energy systems are very much site specific and designing such a system is complicated. From this study a conclusion can be drawn that there is huge potential of hybrid wind-solar power generation in Bangladesh.
Second International Conference on Electrical and Computer Engineering
ICECE 2002, 26-28 December 2002, Dhaka, Bangladesh ISBN 984-32-0328-3 212
REFERENCES
[1] S. Ahmmed, “Investigation and Analysis of Wind Pumping System for Irrigation in Bangladesh”; February 2002, Ph.D. Thesis, Department of Mechanical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka-1000, Bangladesh.
[2] M. U. Mahfuz, “Wind Energy Status in Bangladesh” in Wind Engineering -International Journal of Wind Power, Vol.25 No.3, Multi-Science Publishing, Leicestershire, UK
[3] Primary Grid System of Bangladesh Power Development Board (BPDB), as of January 2001, prepared by Directorate of System Planning, BPDB.
[4] M. M. Alam, “Wind Energy Resources in Bangladesh”, in proceedings, National Workshop on Renewable Energy Application for Rural Areas of Bangladesh, 18-24 August, 2001,BUET, Dhaka, Bangladesh.
[5] M. Islam, “Assessment of Renewable Energy Reserves of Bangladesh”, version: May 1, 2002, pp.6-9. Website:https://Shakti.hypermart.net/
[6] S. Rafique, R. R. Khan, I. Jabiullah, Md. S. Alam and Q. N. Begum, “Time Series-Spectrum Analysis of Solar Radiation in Bangladesh”, in proceedings, 2nd International Seminar on Renewable Energy for Poverty Alleviation, 26-27 November, 1999, Institution of Engineers, Bangladesh (IEB), Dhaka, Bangladesh.
[7] “Hybrid Energy Systems”, Alternative Energy Systems Co.,
[8] Website: www.poweriseverything.com/imptinfo/hybridsyspage.html, on May 24, 2002.
[9] “Small Wind Energy Systems for the Homeowner”, Consumer Energy Information, Energy Efficiency and Renewable Energy Network (EREN), US Department of Energy. Website:www.eren.doe.gov/erec/factsheets/wind.html, on May 24, 2002.
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