This is the second in the series published by the Alliance for Rural Electrification, an international business association that provides efficient renewable solutions for rural electrification in developing countries.
There are three basic technical approaches to bring electricity to remote areas:
1) National grid. Rural areas are normally located far from the national grid; therefore the high cost of extending the transmission lines usually makes these projects unfeasible. Rural areas are vast and have relatively small energy demand per connection; for public authorities or very impoverished utilities there is little economic interest in grid connection. Furthermore, the electricity provided by utilities in developing countries often lack security of supply and quality. Consumers may only have access to the electricity during limited hours each day and blackouts or brownouts are common. Grid extension increases the demand, but if there is not a consequent increase in the energy generation capacity, adding new consumers only aggravates the situation and reduces the quality of the service.
Table 1. Grid extension costs
2) Energy Home Systems (EHS). These small power systems are designed to power individual households or small buildings and provide an easily accessible, relatively cheap and easy to maintain solution. The dispersed character of rural settlements is an ideal setting for these solutions, in particular with renewable energies (RE) that are especially competitive in remote areas. Pico PV system (PPS), solar home systems (SHS), small hydro plants (SHP), or wind home systems (WHS) almost always offer a potential solution for providing electricity to isolated places. In these stand-alone systems, power generation is installed close to the load and there are no transmission and distribution costs. Moreover, to keep prices affordable, components can be minimized and capacities maintained low mainly serving small DC appliances for lighting and communication.
Table 2: Types of EHS
3) Mini-grids (sometimes referred to as isolated grid) provide centralized electricity generation at the local level, using village-wide distribution networks not connected to the main national grid. Mini-grids mostly use low AC current (230 or 155V), with a centralized production and storage with an installed capacity between 5 and 50 kW although larger systems exist. Mini-grids provide capacity for both domestic appliances and local businesses, and have the potential to become one of the most powerful technological approaches for accelerated rural electrification. They can be powered by fossil fuel (mostly diesel), but they also lend themselves for utilizing local renewable energy (RE) resources. Diesel remains the most used technology because it used to be the cheapest option and it requires rather modest initial investments. However, RE present numerous competitive advantages including lower cost.
A hybrid power system uses RE as a primary source and a genset (most of the time diesel but potentially with gasoline and LPG) as back up. This solution is especially interesting for isolated villages/small towns, away from the national electricity grid. Moreover, they provide enough power to satisfy modern domestic needs (lighting, communication, refrigeration, water supply) as well as public services (health centres, schools etc.) and the development of a local economy (small industries, related services such as telecommunication towers and water irrigation systems etc). Finally, the implementation of mini-grids has proved to have a positive social impact by fostering and improving local governance structures through the involvement of the community in the decision-making linked with the energy system.
A hybrid system can use several RE technologies and balance the specific advantages and shortcoming of each resource. Small hydropower continuously produces costs competitive electricity for villages close to water resources, but is very site specific and may be dependant on seasonal effects. As solar resources are abundant, PV can be used almost everywhere, especially in Southern countries, but has rather high requirements for storage since there is no generation after nightfall. The generation of WHS follows the site-specific wind profile over the year. Diesel, gasoline, and LPG generators can be added as complementary sources to ensure the continuity of supply and maximize the lifetime of components by reducing the stress on the overall system thus reducing the overall costs.
Hybrid mini-grids are in many cases the most economical solution for village electrification. Numerous studies and simulations have shown that they are competitive in comparison with conventional energy supply systems based on fossil fuels.
Figure 1. Cumulative costs: Diesel vs. PV/Diesel hybrid system
The authors Simon Rolland and Aneri Patel work for Alliance for Rural Electrification. The next article in this series will focus on different renewable energy technologies available and options/mix that works best for rural electrification.
The next article in the series will focus of policy options and the role of government in expanding rural electrification.
2. All information, including from tables and figures are from the Alliance for Rural Electrification