[DHAKA] Researchers in the United States say agricultural waste from coconut and mango farming could generate significant amounts of off-grid electricity for rural communities in South and South-East Asia.
Many food crops have a tough, inedible part which cannot be used to feed livestock or fertilise fields. Examples of this material — known as 'endocarp' — include coconut, almond and pistachio shells, and the stones of mangoes, olives, plums, apricots and cherries.
Endocarp is high in a chemical compound known as lignin. High-lignin products can be heated to produce an energy-rich gas that can be used to generate electricity.
The researchers identified high-endocarp-producing regions of the world – and noted that coconut and mango agriculture account for 72 per cent of total global endocarp production. Coconut production alone accounted for 55 per cent.
They then overlaid these findings with energy consumption data to identify communities with little access to electricity, who could benefit from endocarp-based energy.
"We noticed that production was unevenly distributed around the globe, which could make a very significant contribution to the energy budget in some countries like Sri Lanka, Indonesia, and the Philippines, [as well as] regions of India," Tom Shearin, co-author and a systems analyst at University of Kentucky, United States, told SciDev.Net.
Writing in the Proceedings of the National Academies of Sciences (February 21), the researchers said endocarp bioenergy could meet up to 30 per cent of total energy needs in Sri Lanka, 25 per cent in the Philippines, 13 per cent in Indonesia, and 3 per cent in India.
Shearin said endocarp was preferable to crop-based biofuels as it had no value as a food item. "Its exploitation as energy source does not compete with food production," he said.
Wais Kabir, executive chairman of the Bangladesh Agriculture Research Institute, told SciDev.Net that most of the country's agricultural waste, including non-edible by-products, was already used to generate bioenergy.
"I don't think that supply of adequate volumes of coconut shell, [for example] to run a power plant, is possible at this stage until we go for its production in a planned way," he said.
The researchers acknowledged that efforts to scale up infrastructure to deliver decentralised bio-energy in developing countries would face economic, technical and social challenges.
Advocates of an endocarp-based energy sector would also have to persuade investors that it would be financially viable.
Abser Kamal, managing director of Grameen Shakti, a renewable energy firm in Bangladesh, said: "We have to check if these are cost-effective or not".
Islam Sharif, CEO of the Infrastructure Development Company Limited (IDCOL), a state-run renewable energy financing firm in Bangladesh, said IDCO would encourage investment in endocarp-based energy production if it was found to be financially viable.
"Bangladesh needs more energy sources to meet its power needs," Sharif told SciDev.Net.
PNAS doi: 10.1073/pnas.1112757109 (2012)