Wind Energy in Bangladesh
Dr. Anwar Hossain Former Chairman, BAEC, Ex-Consultant LGED,Presently Energy Advisor, BCAS
Government has recognized the importance of renewable energy in our energy planning programme and a draft Renewable Energy Policy is on the verge of being approved. In the context of Bangladesh, renewable energy consists mainly of biomass, solar energy and wind power. Hydropower potential appears very limited. Studies could be made for microhydropower which could meet some of the local needs of electricity. This would, however, be seasonal and other forms of power generation may be required during some months of the year. There is little chance of geothermal power and further R&D would be needed to exploit wave/tidal power.
Wind energy has the potential to provide mechanical energy or electricity without generating pollutants. Historically it was used in many countries, especially, the Netherlands, as a source of mechanical energy, e.g. grinding corn or pumping water. In Bangladesh, as in many other countries, wind energy has also been used toprovide some motive force to boats with sails of various designs. Unfortunately, not much research has been conducted in these areas, although renewed interest have recently been generated in utilizing the energy of wind for wind pumps and sailing boats.
Wind electricity for decentralized system or hybrid generation of electricity using other energy sources as complementary to wind energy has now been given some attention and this could be suitable in low wind regimes for localized small grid systems or battery charging. For low wind speed, wind pumps could also be a viable option.
Bangladesh is situated between 20O34'-26038 North Latitude and 88001'-92041' East Longitude. The country has a 724 km long coast line and many small islands in the Bay of Bengal, where strong south-westerly tradewind and sea-breeze blow in the summer months and there is gentle north-easterly tradewind and land breeze in winter months.
In Bangladesh, little systematic wind speed study has been made. Data collected by the meteorology department are usually meant for weather forecasting and are insufficient for determining wind energypotential. In an early study report in 1982, a 30-year meteorological data from a number stations throughout the country were considered. It was found that wind speeds in the districts of Chittagong and Cox's Bazar were the only ones which showed promise. Extending the idea, only coastal area and the bay islands showed promise for possible electricity generation from wind.
Recently, some measurements were made by F. Rahman in some coastal areas followed by a year's measurement in Patenga (Chittagong) at a height of 20 m in 1995. It was found that wind speed is higher than the values obtained by the meteorological department. This led to a year-long systematic wind speed study at seven coastal sites in 1996-97 at a height of 25 m by Bangladesh Centre for Advanced Studies (BCAS), in collaboration with Local Government and Engineering Department (LGED) and Energy Technology & Services Unit (ETSU), UK which was financially supported by the British Government
(DFID). A parallel study was also conducted by another Group (REVB1 GTZ).
The BCAS study first made an analysis of available meteorological data and established the following worthwhile information:
Wind speeds are higher in coastal areas.
Wind speeds exhibit strong seasonal cycle, lower in the September to February period and higher in summer (March to August).
Wind speeds exhibit a diurnal cycle, generally peaking in the afternoon and weakest at night (the trends are also similar in West Bengal, India).
The wind speed measurements by BCAS Group and GTZ group confirmed that wind speed is much higher in summer months (due to monsoon wind) than in winter months. Actual wind speed found by GTZ was slightly higher than those of BCAS Group; but the frequency distribution was similar. Diurnal variation confirmed the trend observed by the meteorological department.
Power curves of wind turbines with two different installed capacities from two different manufacturers have been used to calculate energy generation. The estimated annual energy outputs for Kutubdia and Kuakata are 133 MWh and 160 MWh for a 150 KW wind turbine; while the outputs are about 200 MWh and 230 MWh respectively from a 250 KW station at these places.
Some of the specific projects that could be undertaken were pointed out by the WEST study as follows:
A study may be undertaken to assess the performance of wind pumps for lifting water for drinking (Kutubdia) and irrigation for crop production (Chittagong).
Some wind-pv generators (100 W to 2KW) may be set up at remote locations to charge battery systems for specific users.
It is necessary to continue the present effort of collecting, processing and analysis of wind-data from the existing monitoring sites for at least three years for developing realistic plans and projects on wind energy.
In addition, other monitoring sites should also be selected for proper assessment of the wind-regime of the country. The proposed sites may include different terrain conditions including the coastal region.
As an initial step, demonstration and pilot plants may be set up to examine the technical, operational and economic viability of wind energy in the country.
Recently, several small wind generators have been installed by BRAC (11 small wind turbines in various coastal sites) and Grameen Shakti (two wind generators of 300 W and 1 KW at its Chakoria Shrimp Farm). These are small DC operation type systems supplying power to target groups to improve their quality of life. Their results are not well documented. Grameen Shakti has recently installed 4 small wind generators (3xl.5KW + ONE 10 KW) in Barguna district (coastal south). They are planning to develop these stations into hybrid systems later, first with diesel and then with solar pv, to maximize the energy output and then study the cost economics. Their final quantitative results would be awaited with great interest.
While the Government is yet to undertake extensive wind mapping followed by wind monitoring, a research Group of Bangladesh University of Engineering and Technology (BUET) is now conducting a wind speed study at Chandana, Gazipur (near Dhaka) at a height of about 60ft and, as expected from previous meteorological studies, the speed is between 2-3 m/see. Wind speed measurements are also being taken at St. Martin Island on top of a lighthouse by BCSIR. Extensive study is likely to discover wind pockets in the country, especially in the hilly areas (e.g. Chittagong Hill Tracts) and in coastal islands.
As for mechanical power from the wind, recently two groups have worked in such projects. The first one, form LGED, has set up a number of 27 ft high windpumps at Tangail, Kuslitia, Cox's Bazar and other places. Theoretically, these indigenously made windpumps have a power of 0.5 h.p. (385W) at a windspeed of 4m/ see. The pump outlet is narrow and the output was found to be 25 liter/minute at windspeed of 3.2 m/see. No quantitative results are, however, available. The second Group from BCAS installed a windpump designed by the IT (Intermediate Technology) Group of the UK and made in Karachi (Pakistan). The windpump was located in an agricultural field in Patenga (Chittagong). The Tower height was 40 ft and the rotor consisted of 12 blades. Daily water output has been varying and the average water output between November and January was about 8000 liters/day. It appears that suitability designed wind pumps can be extensively used for irrigation of vegetables in winter months in the coastal region. It should also be possible to draw fresh underground water for drinking purposes in the coastal islands.
The potential of wind energy has not been fully explored in Bangladesh, mainly due to lack of reliable wind speed data. It appears that the wind speed will not be high but wind energy can be put to a variety of uses, especially for wind pumps, hybrid electricity generating systems with wind as one of the energy sources, small battery chargers at isolated places and electricity inputs to local grids in some coastal areas or the bay islands. To mention some practical applications, wind energy in Bangladesh could be used in shrimp production, fish/poultry firming, salt/ ice production, fish-mill industries, hatcheries, domestic applications and vegetable irrigation - all using decentralized electricity (hybrid or mechanical energy from wind). Wind energy is a clean renewable energy source cheaper to maintain, saves fuel and can give decentralized energy. Weshould make maximum use of it (including more efficient boat sails where wind energy is directly used). This needs creation of necessary data and manpower base, setting up some demonstration plants at appropriate locations and carrying out research and studies for indigenization of technology.