Hydro power is one of the largest renewable energy resources being used for generation of electricity. SHP projects are classified based on capacity as follows:
- Micro hydro: up to 100 kW
- Mini hydro: 101 kW - 2 MW
- Small hydro: 2 - 25 MW
SHP projects are classified based on head as follows:
- Ultra low head: below 3 m.
- Low head: 3 - 40 m head.
- Medium / high head: above 40 m.
Technology: Hydro power is obtained from the potential energy of water flowing from a height. The energy contained in water is converted into electricity by using a turbine coupled to a generator. The hydro power potential of a site is dependent on the discharge and head of water. It is estimated by the following equation:
P (power in kW) = Q × H × 9.81 × η; where Q is discharge (rate of flow) in m³/s, H is head in m, η is overall power generating system efficiency.
SHP projects can be setup on rivers, canals or at dams. The components of SHP projects are:
- Diversion weir / barrage power channel.
- Desalting devices.
- Fore bay tank / balancing reservoir Penstock.
- By-pass arrangement / spillways Powrhouse building.
- Power evacuation arrangement.
Advantages: A few major advantages of SHP projects are:
- Flexibility of installation and operation in a distributed mode.
- Standard indigenous technologies and manufacturing base available, which requires only minor adaptation to specific site conditions.
- Compatible with use of water for other purposes such as irrigation and drinking water.
- Environment-freindly because it causes negiligible or no submergence, minimal deforestation, and minimal impact on flora, fauna and biodiversity. Environment Impact Assessment (EIA) is not needed for SHP.
Cost: While SHP projects on rivers involve higher costs of civil works than those on canals, the cost of eqipment for canal-based projects is higher. SHP projects cost Rs. 7 - 8.5 crore/MW, depending on location and site topography. Pay back period is 5 - 7 years depending on capacity utilization factor.
Water Mills: Water mills, also known as gharats in the northern part of the country, have traditionally been used to convert the energy of water to useful mechanical energy. In the Himalayan region, about 100 000 water mills are being used for mechanical applications such as grain grinding and oil extraction. In general, water mills have low conversion efficiency. Improved water mills have been developed for mechanical applications as well as electricity generation. For the development of water mills, MNRE provides subsidy of up to ₹ 30 000 in mechanical mode and ₹ 1 lakh in electrical / electromechanical mode. Uttranchal has set up over 500 such water mills in its remote and isolated areas.