Going off-grid: A Solution

Friday, December 12, 2012
Avinash Jha

A house in Ward, Colorado, at the elevation of 9000 ft, has been off-grid since it was built in 1972. When that house was built, the nearest grid was over miles away, and it would have cost around $70,000 to get power from the grid. So the owner decided to install an independent hybrid electric system powered by wind and solar at the total cost of $20,000 for 10 KW in 1972. Likewise, in inner Mongolia there are over 30,000 small scale wind powered generators used by herders for powering lights, televisions and radios.

In Nepal with more than 83% of total population living in rural areas, only 40% of them have access to electricity. For the rest it is perpetual darkness once the sun goes down. With Nepal diversified land structure supplying electricity via grid is not feasible in many places because it is very expensive.

Given the technical and economic constraints for grid expansion, supplying electricity to the rural people has to be off-grid. Whilst urban people consuming almost three quarter of nation’s total energy production, more than 50% of rural people rely exclusively on kerosene for lighting their home. Unfortunately, increasing cost of kerosene, including its transportation cost to those remote areas, make powering these communities a difficult task.

Although Nepal has high potential for renewable energy resources, only 1% has been exploited so far, excluding hydro power. Relatively quick and easy installation can make wind power plants a feasible option for areas that are not connected to the grid. A typical 10 MW wind farm can be constructed within two months. Wind power can be very cost effective in the places where wind speed readings are good enough.

Exploiting renewable energy resources and developing community based independent systems, called off-grid systems , are the only next viable solution that can address the problem of rural electrification. These small scale localized approach are economically feasible, easily manageable with low energy losses and can give a productive end use for income generating activities enhancing the livelihood of rural people. These systems operate exactly as large grid connected systems except for continuous supply of electricity is provided by storage batteries. The wind generator starts generating power when wind speed reaches the cut-in speed of 3m/sec and the output is stored in the battery bank. Stored energy is drawn by the electrical loads through the inverter, which converts DC power into AC power. The inverter has in-built potential against short-circuit, overload and overheating. The battery banks can then feed the loads even when the wind is not blowing. The number of hours that can be supplied by batteries is determined by battery storage capacity.

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