Solar Energy Resources
Potentials in Bangladesh :
Bangladesh is situated between 20.30 - 26.38 degrees north latitude and 88.04 - 92.44 degrees east which is an ideal location for solar energy utilization. Daily average solar radiation varies between 4 to 6.5 kWh per square meter. Maximum amount of radiation is available on the month of March-April and minimum on December-January. Different R&D Organizations, Institutes and Universities are collecting solar insolation at different parts of Bangladesh.
There is a good prospect of harnessing solar power in Bangladesh. In a recent study conducted by Renewable Energy Research Centre, it is found that average solar radiation varies between 4 to 6.5 kWhm-2day-1. Maximum amounts of radiation are available in the month of March-April and minimum in December-January. Following map has illustrated prospect of solar radiation in Bangladesh.
Solar irradiation maps of Bangladesh, Source: RERC
Available Solar Insolation Data :
At present, solar insolation data can be found from the following sources:
-
Renewable Energy Research Centre (RERC), Dhaka University (DU) is the only source which has got long-term measured data of Dhaka city in Bangladesh [UNESCAP 2000]. The published data are average of results of hourly measurements of over three years global (G) and diffuse (D) radiation with Eppley Precision Pyrometer.
-
Bangladesh Meteorological Department has 34 sunshine recording stations situated generally in towns and cities.
-
Department of Mechanical Engineering, Bangladesh University of Engineering (BUET) and technology, has also got time series data of Dhaka city.
Apart from the above-mentioned sources, few other organizations or institutes have also measured time series of global radiation, direct or beam radiation, diffuse radiation, sunshine hours and temperatures of different parts of the country. But for meticulous estimation and simulation of different solar energy applications several other parameters are required which are not available at the moment. Monthly Global Solar Insolation at different cities of Bangladesh and Daily Average Bright Sunshine hour at Dhaka city are presented in tables below respectively :
|
Month |
Dhaka |
Rajshahi |
Sylhet |
Bogra |
Barishal |
Jessore |
|
January |
4.03 |
3.96 |
4.00 |
4.01 |
4.17 |
4.25 |
|
February |
4.78 |
4.47 |
4.63 |
4.69 |
4.81 |
4.85 |
|
March |
5.33 |
5.88 |
5.20 |
5.68 |
5.30 |
4.50 |
|
April |
5.71 |
6.24 |
5.24 |
5.87 |
5.94 |
6.23 |
|
May |
5.71 |
6.17 |
5.37 |
6.02 |
5.75 |
6.09 |
|
June |
4.80 |
5.25 |
4.53 |
5.26 |
4.39 |
5.12 |
|
July |
4.41 |
4.79 |
4.14 |
4.34 |
4.20 |
4.81 |
|
August |
4.82 |
5.16 |
4.56 |
4.84 |
4.42 |
4.93 |
|
September |
4.41 |
4.96 |
4.07 |
4.67 |
4.48 |
4.57 |
|
October |
4.61 |
4.88 |
4.61 |
4.65 |
4.71 |
4.68 |
|
November |
4.27 |
4.42 |
4.32 |
4.35 |
4.35 |
4.24 |
|
December |
3.92 |
3.82 |
3.85 |
3.87 |
3.95 |
3.97 |
|
Average |
4.73 |
5.00 |
4.54 |
4.85 |
4.71 |
4.85 |
Source : Dr. Shahida Rafique, Department of Applied Physics, Dhaka University, recorded from 1988 to 1998
Daily Average of Bright Sunshine Hours at Dhaka City
(Average period: 1961 to 1980)
|
Month |
Daily Mean |
Maximum |
Minimum |
|
January |
8.7 |
9.9 |
7.5 |
|
February |
9.1 |
10.7 |
7.7 |
|
March |
8.8 |
10.1 |
7.5 |
|
April |
8.9 |
10.2 |
7.8 |
|
May |
8.2 |
9.7 |
5.7 |
|
June |
4.9 |
7.3 |
3.8 |
|
July |
5.1 |
6.7 |
2.6 |
|
August |
5.8 |
7.1 |
4.1 |
|
September |
6.0 |
8.5 |
4.8 |
|
October |
7.6 |
9.2 |
6.5 |
|
November |
8.6 |
9.9 |
7.0 |
|
December |
8.9 |
10.2 |
7.4 |
|
Average |
7.55 |
9.13 |
6.03 |
Application of Satellite Remote
Sensing for RET Projects :
Unfortunately, all the measured data of above-mentioned sources are collected for main cities of the country, which are electrified and not a prospective site for RET application. The surface topology has a major influence on micro-climate resulting in highly variable wind resources and significantly variable solar resources over small areas. Due to this reason, for assessment of RET projects in the far-flung areas of Bangladesh, Satellite Remote Sensing technology can be applied. Hourly global insolation from satellites with a ground resolution of a few kilometers reproduce data sets with a relative Root Mean Square Error (RMSE) of typically 20-25% [Perez et. al. 1999]. But it has been found out from rigorous analysis that for hourly data, the satellite data become more accurate than a local ground station if the distance from the station exceeds 34 km [Perez et. al. 1997]. At present, many organizations provide remote sensing data, gathered from geo-stationary or polar orbiting satellites, appropriate for RET project appraisal.
NASA has recently launched a renewable energy resource web site called “Surface meteorology and Solar Energy Data Set (SSE)” available in the Internet free-of-charge. Another advantage of user friendly SSE is linked with the Renewable Energy Project Analysis Software (RETScreen) which will be used in this thesis work for analysis of RET Projects in Chapter 6. Application of SSE for solar energy resource assessment is presented in the next topic.
SSE for
Solar Energy Resource Assessment :
SSE data set is formulated from NASA satellite- and reanalysis-derived insolation and meteorological data for the 10-year period from July 1983 through June 1993. Results are provided for 1° latitude by 1° longitude grid cells over the globe. The SSE global data set makes it possible to quickly evaluate the potential of renewable energy projects for any region of the world and is considered to be accurate for preliminary feasibility studies of renewable energy projects [Charles H. Whitlock et. al. 2000].
SSE provides:
-
over 100 satellite-derived meteorology and solar energy parameters
-
monthly averaged from 10 years of data
-
data tables for a particular location
-
color plots on both global and regional scales
-
global solar energy data for 1195 ground sites
Estimated uncertainties of SSE data set for solar energy parameters are found by comparing with (1) World Radiation Data Center (WRDC) ground measurement data (2) RETScreen Ground Monitoring Stations Weather Database and (3) The RETScreen database available from the RETScreen Website which are shown in Table
|
Parameter |
Global sites WRDC |
Global sites RETScreen |
Renewable sites RETScreen |
|
Near-Surface Air Temperature (K) (10 meter altitude) |
14.2% |
< 243 K = 3.2% > 263 K = 1.1% linear variation between 243 K and 263 K |
1.2% |
|
Heating Design Temperature (K) |
|
|
1.3% |
|
Cooling Design Temperature (K) |
|
|
1.4% |
|
Summer mean daily design range (K) |
|
|
0.9% |
|
Heating degree-days below 18° C (degree-days) |
|
|
14.6% |
Example of SSE
Application :
Thanchi is one of the remotest thana (sub-district) located in the Chittagong Hill Tracts regions of Bangladesh. People of Thanchi suffer from inconvenience due to poor communication system of the area, particularly with the district town. The local river “Shangu” is navigable only for five months in a year. By an engine boat it often takes 15 hours and by road 2 days with a night halt to reach the district town Bandarban. National electricity grid is not present in Thanchi and chances of extending them is also bleak in the near future. So, Thanchi is an ideal place for application of RETs, especially Solar Photovoltaic. For using the RETScreen Solar Photovoltaic Project Model, site specific solar insolation and temperature data has to be fed. These two parameters can be obtained from SSE web site with respect to the latitudes and longitudes of Thanchi and presented tables below
Average Daily Radiation on Horizontal Surface in Thanchi (in kWh/m2/day):
|
Months |
10 Year Average Daily Insolation |
|
Jan |
4.88 |
|
Feb |
5.41 |
|
Mar |
6.22 |
|
Apr |
6.14 |
|
May |
5.68 |
|
June |
3.62 |
|
July |
3.43 |
|
Aug |
3.67 |
|
Sep |
4.09 |
|
Oct |