Case study of augmenting livelihood of fishing community at Sagar Island, India, through solar thermal dryer technology

Drying of fish at the Sagar Island (21.7269 degrees N, 88.1096 degrees E) is generally carried out in open sun on the seashore on plastic sheets or mat of palm leaves. This is not an environment-friendly and healthy practice. To alleviate the limitations of open sun drying, 600 kg (300 kg x 2) walk-in solar thermal dryer was installed at a fishing cooperative. The dryer consequently augmented the income of the fisher folk by enhancing throughput and refining the quality of dried fish. The design incorporated, (a) 80% UV cut-off film to take care of appearance of the dried fish; (b) facilitating proper air flow pattern for uniform both side drying; (c) completely dismantlable system to take care of incoming storms/cyclones in advance; (d) solar photovoltaic powered dehumidifiers to control the relative humidity at night and achieve a dried batch in less than 24 h. The fabricated solar thermal dryer had drying temperature in the range of 36.9-53.1 degrees C throughout the day. Due to the use of the dehumidifiers, an entire batch of fish could be dried from an initial 80% to final 10% moisture content (wet basis) in less than 24 h compared to 38 h in open sun drying. The solar thermal drying efficiency was 30.24% and specific energy consumption was found to be 2.35 kg/kWh. The embodied energy was 10,756 kWh and CO2 emission was calculated to be 422 kg per year, which was lower than other fossil-driven drying systems.