THIRUVANANTHAPURAM: Tapioca is in vogue in Kerala. First, the government created a buzz with its idea to make spirits from tapioca. Now, a scientist based in Thiruvananthapuram has developed a technique to produce electricity from its leaves. The concept of clean energy from cassava leaves -- ‘Cassa Dipah’ -- was a by-product of the biopesticide manufacturing process, said Dr C A Jayaprakas, principal scientist at the ICAR- Central Tuber Crops Research Institute (CTCRI) here.
The CTCRI has been engaged in biopesticide production from tapioca leaves for several years. With patented technology, the centre has developed three brands of biopesticides -- ‘Nanma’, ‘Menma’ and ‘Shreya’.
Jayaprakas -- whose tapioca power project was funded by the Department of Atomic Energy -- said the idea of generating electricity struck him as he thought of making use of the biowaste left after extracting insecticidal molecules from the cassava leaves.
"Methane production from biowaste is common. But leaves are not a viable source for methane production owing to the presence of cellulose, hemicellulose and lignin in them,” he explained.
“Still, I took the waste to an expert microbiologist to explore the possibilities.” That was the turning point. Dr Krishna Kumar B, senior principal scientist at the National Institute for Interdisciplinary Science and Technology (NIIST), found that methanogenic bacteria grew well in the extraction waste, Jayaprakas said.“The bacteria could multiply in it because the original molecular structure of the leaves was disrupted in the heating process as part of pesticide-making,” he said.
The next challenge was to eliminate carbon dioxide and traces of hydrosulphide from the emission. “I overcame that, too. Carbon dioxide was trapped using molecular sieves and water content was removed through filtering,” he said.
Finally, methane was collected in balloons and used for power generation with the help of a customised generator provided by a Thrissur-based technopreneur named Francis, of Power Hawk Biogas Generators.
Jayaprakas said Dr Rajalekshmi, a chemist, and PhD students Sreejith S and Joseph Tom, too, assisted him in pulling off the ambitious project.
According to a preliminary estimate, 1kwa of electricity can be produced from 7kg of cassava leaves waste. Further explorations may lead to another source of income for tapioca farmers, believes Jayaprakas. Five tonnes of leaves and stems are wasted after tapioca harvest on one hectare of land, he noted.