Integrated Rural Energy Centres for Agriculture-Based Economies

Abstract

After supplying (a) food materials (rice, cassava, coconut oil etc.) and (b) industrial products (coconut fibre, rubber, timber etc.) there are left (c) energy raw materials, which are often burnt inefficiently and wrongly thought of as wastes (coir dust, wood chips, bagasse pith etc.)

Energy raw materials may be incinerated, or hydrolysed, or digested etc. for industrial purposes. They may also be used as fuels for combustion—in domestic cookers, or for steam raising in industry. Energy efficiency may be improved by briquetting energy raw materials to make them more satisfactory as fuels. In addition, modern methods of gasification of some of the briquettes can make producer gas to fuel small, ordinary internal combustion engines. The power may be mechanical as shaft power, or as electricity for lighting, operating machinery etc. Integrated rural energy centres (IRECs) involve this sequence of drying, briquetting, gasifying some of the briquettes to make power, and using the rest of the briquettes for industry for steam raising instead of the wood or oil that is so often the normal fuel. An alternative possibility, particularly for higher ranges of power generation (about 300–500 kW) is to burn the energy raw material at high efficiency in a fluidized bed combustor (FBC), and make use of the hot gases produced to generate power through steam or externally-fired gas turbines,

Briquetting techniques are simple and capable of much further development. Gasification techniques are also simple (with proper design) and also capable of further development. Heat recovery for product drying, for example, can be a useful feature of a combined electrical and heat energy generation system, adopting the gasification or efficient direct burning in an FBC route.