Performance of a solar greenhouse-biogas hybrid dryer for dehydration of water hyacinth (Eichhornia crassipes)

Abstract The development of a solar greenhouse dryer combined with an anaerobic digester for biogas production can reduce carbon emissions and create zero waste. This paper presents the performance of a solar greenhouse biogas dryer (SGBD) that burns biogas to supplement the drying of water hyacinth. The SGBD has an overall efficiency of 87% for 100 kg of fresh water hyacinth. The auxiliary heating system enabled the SGBD to achieve drying temperatures of 24.5 to 45.0 degrees during cloudy and rainy days and produce high quality dried products. There was a fivefold increase in drying capacity and a reduction in drying time of six hours (38%) using the SGBD. End users of the dried product judged it to have improved consistency in color and shape. The SGBD cost less than US$3800 to build with a payback period of five months. This design demonstrates a low-cost and simple technology for small businesses.