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° N, 88.1096° 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 × 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 °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.