Indian RECs 
What is Hydroelectric Energy?
This is the use of the mechanical energy of flowing water by moving it through piping called penstock, which then turns a generator which produces power.
What are the Advantages of Hydroelectric Energy?
High efficiency
High level of reliability
Low operating and maintenance costs
Can easily adjust to meet load changes
What is the cost for Hydroelectric power?
The cost of Hydroelectric power depends on the size of the power plant. However, the larger the hydroelectric power plant, the cheaper the cost per kilowatt to produce the electricity.
When the cost of hydroelectric power is compared to the other means of producing electricity, it only costs about 1/3 of the cost for fossil-fuel production and less than 1/4 the cost of gas turbine electrical production.
Is it possible to generate electricity from waves and tides?
Producing electricity from waves or tides is optional. Water from high and low tides can be used to spin turbines that can produce electricity.