Off-grid systems are immune to high losses. It can cater to a whole range of rural consumers
Big is beautiful
What happens when being off-grid is a necessity and not an option? India has nearly 25,000 villages where extension of power from the main grid line is neither technologically feasible nor affordable. These villages are either located in remote areas or are inhabited by people whose capacity to pay for power is limited. Their need for power -- when they get it -- is primarily for electric lights to replace kerosene lamps and for water supply.
With the price of fossil fuel rising prohibitively, a diesel power supply system is ruled out. Depending on availability of local resources in these areas, alternative options like wind, biomass, biogas, solar photo voltaic (spv) and micro hydel-based power generation can be used, with distribution being taken care of by an off-grid supply system. A multiple mode of generation through a hybrid set up is common. In West Bengal, such schemes started under state funding, with people's-participation from concept to commissioning, maintenance and operation to revenue collection. Over fifty villages now serve as models. The emergence of private and cooperative systems also signal a shift from subsidies to a more commercial regime.
The concept of off-grid power supply has emerged from government resolutions to provide villages with power to meet essential demand for lighting. The National Rural Electrification Plan aims to reach electricity to all villages by 2007 and to all households by 2012. It spells out a proposal for a power supply system where mini-generation plants with an associated distribution system work in off-grid mode in the evening or for short spells during the day.
A cheap alternative Sizewise, off-grid power plants are in the wide range of 10-500 kilowatt (k w), catering to nearly 50-3,000 consumers, with operating hours usually restricted between 5-10 hours a day. The connected load allowed to domestic consumers is within 100-150 w whereas in case of commercial, water supply and industrial supply this may vary between 100-2,000 w. Energy conservation measures such as the use of compact fluoroscent lamps and smaller and more efficient motors are essential here.
Switching from kerosene (costlier by the day, dim and messy) to alternatively generated lighting can be a boon for domestic consumers to use in the evening for study and household work. To give an instance, 40 students in a tribal area who used to spend Rs 2,500 a month on kerosene in their hostel managed to cut it down to Rs 1,000 by switching to a small spv power unit.
Small users benefit Apart from domestic use, off-grid will also benefit a whole range of small users, like shops, photocopy and repair centres. Also possible will be potable water from tube wells or micro-irrigation for agriculture, which will contribute to the community's health and economy.
Off-grid line meets the needs of the people to an optimal extent unlike the grid system that is typically prone to poor load factor or very low off-peak to peak ratio of demand. Off-grid systems have little line-loss compared to the abnormally high system loss in grid supply. Grid lines in rural areas usually deliver poor quality of power (low voltage and load shedding). The off-grid system is immune from this.
To improve the quality of life of people living far away from developed localities and deprived of essential necessities, and to provide opportunities for economic growth and social welfare, power is required. Off-grid systems of power supply that harness natural resources offer a more sustainable option. Here is ample proof of the philosophy that small is beautiful.
C R Bhattacharjee is a consulting engineer who has a special interest in renewable energy
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