Tests with LED lamps at the lakes Bolgoda and Maduganga / Madampe in Sri Lanka
This project during three months with the title "LED Lamps for Fishing and Housing at Bolgoda Lake and Maduganga/Madampe Lakes" is being sponsored by the small project fund of GTZ/GATE: The long-term aim is to support the adoption of energy-saving LED lamps for night fishing and other uses such as internal illumination of dwelling houses and public buildings in Sri Lanka. The local project partners of Global Nature Fund in Sri Lanka are the NGOs Nagenahiru Foundation and EMACE. The project areas in the South West of Sri Lanka are the lakes and wetlands Maduganga/Madampe (www.globalnature.org/maduganga/) and Bolgoda (www.globalnature.org/bolgoda/).
Night fishing with LED lamps
Until now there is little experience with the use of solar energies and little knowledge about the use of energy-saving CFL or LED lamps for the night fishing in the wetlands in Sri Lanka. At present the fishermen at both lakes use kerosene lamps in order to draw and catch the prawns in the darkness. Using this traditional catching method the prawns, which are swimming with the flood tide inside the wetland areas connected with the ocean, are attracted into a bow net system with three chambers and be fished then. The bow nets are built with bamboo. This sustainable and ecologic form of prawn fishing is a central source of income for the village community. It is an alternative to the commercial prawn breeding in farms which has extremely negative effects on the mangrove systems.
Disadvantages of the traditional (Ja-kotu) system are:
- Unreliable technique: lamps do not work with strong wind and have to be enkindled several times.
- Leaking kerosene can pollute water bodies and breeding areas.
- Health risks for the fishermen through smoke emissions, skin contact with kerosene and through burnings by kerosene ignitions.
Test with LED lamps
Experts from EMACE and Nagenahiru are currently carrying out comprehensive tests to prove how kerosene lamps for the night prawn fishing can be substituted by LED lamps. The used LED lamps are operated over water but should at least be protected from splash water. Both Chinese LED’s and European LED’s were tested; they were put together on site. The rate of failures and the low durability of the Chinese LED’s showed a problem. Also a test arrangement with direct current entry (220 V) out of the power line nearby riparian situated bow nets was installed. The output of the LED lamps was maximum 3 Watt. It is recommended to use LED lamps with maximum 5 Watt to avoid over-fishing effects.
The present results have shown that with an illumination durance of 8 to 10 hours per night with the use of popular metal hydride rechargeable batteries and orange coloured LED’s the best catch results were achieved. The catch results were comparable or better than the catch results with conventional kerosene lamps. Tested LED’s with the white and blue light colours showed bad results. More tests are carried out in time with LED prototypes in amber and red orange. At the moment a test series should clarify if continuous light is more suitable than pulsed light.
More emphases of the tests were the equation of different storage battery systems (lead gel, nickel metal hydride, nickel-cadmium, lithium ions), required storage battery capacity as well as the luminous intensity and the light angle of the tested lamps. By the use of a 3 Watt LED, a block of storage batteries with 10 NiMh batteries (size AA, 2,200 mAh) was used, equipped with additional electronic and arranged in a waterproof housing. In case of the lead gel batteries, different rating classes of 4 Ah (costs approx. 10 – 15 €, capacity 1.5 nights, weight 1.5 kg) till 16 Ah (costs approx. 40 – 50 €, capacity 7 nights, weight 5 kg) were used. This storage medium is easily reloaded, facile to obtain and cheaper than NiMh batteries. Lead batteries should be once more 30 to 50 % cheaper, but in relation to the environmental tolerance they are estimated as problematical.
Illumination of housings with LED lamps
Solar LED lighting systems were used in a lower amount as firstly planned, because the supply of the electricity network is better than expected. The solar systems are principally used in the
