Advantages of Hydroelectric Energy:
1. Hydropower uses the velocity of flowing water and therefore meets the definition of renewable energy.
2. Hydropower possesses unique operational flexibility capable of reacting immediately to fluctuating demands for electricity and is the best source to support the exploitation of wind or solar energy. It is more reliable than wind, solar, tidal, or wave power.
3. Hydropower reservoirs collect rainfall, thereby, they can store and supply freshwater for drinking, sanitation, and irrigation. This storing of freshwater safeguards aquifers and diminishes our susceptibility to floods and droughts.
4. Hydropower is an apparently environmentally friendly, renewable clean source of electricity as it emits a small number of greenhouse gases, no other forms of air pollutants, and doesn’t produce any hazardous byproducts.
5. It is a clean source of energy. By offspring carbon discharges from fossil-fuel-driven power plants, hydropower contributes to reducing air pollution and slows down global warming.
6. Hydropower development brings about power, roadways, industries, and commerce to the public, promoting the economy, ameliorating access to health and education, and improving the quality of life with little or no negative consequences.
7. Hydropower guarantees an effective power networking system through its supple, dependable process, where the enactment of thermal plants is boosted and air emissions are decreased.
8. Water from rivers is a renewable source that is outside the scope of fuel price fluctuations or supply constraints. Therefore hydropower fosters energy independence and security.
9. With an average lifetime of 50 to 100 years, these projects are long-term investments that can without difficulty be improved to avail gains of the new technologies and normally pay back within a short period of time. Hydropower is a power source with protracted feasibility and very low maneuver and maintenance costs that one generation presents to the subsequent generations to come.
10. Hydropower projects grow and operate in an economically feasible, environmentally sound, and socially accountable manner that characterizes sustainable development.
Disadvantages of Hydroelectric Energy:
1. Usually it takes a long time to build a hydroelectric power plant as compared to that a thermal power plant.
2. Dams are quite expensive to build. The cost is also three times higher than setting up a thermal power plant.
3. Usually a large dam will overflow an extensive area upstream.
4. Essentially the land should have a slope.
5. Perennial rivers must be selected but most rivers in India are monsoon fed. Seasonal failure may affect water flow.
6. Temperature of water should be above 4°C or else the water will freeze during winter.
7. Land acquiring problems: Hydropower projects face a plethora of land acquisition bottlenecks due to litigation problems, poor keeping of land records, etc.
8. Resettlement and rehabilitation problems: Reservoir schemes require the evacuation of large extents of land and result in the displacement of entire communities.
9. Law and order problems: Projects in some states face problems on account of insurgency, terrorism, etc.
10. Difficult/Inaccessible sites: In remote areas, infrastructure such as roadways needs to be first built prior to the onset of work. Power supply in remote areas also requires the construction of long transmission lines with natural logistical problems.
11. Geological Surprises: In the mountains, geological surprises while tunneling is time-consuming and lead to cost overruns.
12. Postponements in the environment and forest clearances: Getting environment and forest clearance is burdensome and involves inputs from the concerned departments of the state and center which is becoming more and more difficult with rising awareness making way for stringent legislation.
13. Inter-state aspects: Inter-state water disputes if any may unnecessarily take away time.
14. Funding of hydropower projects: Hydro projects were chiefly funded government agencies and hence limited number could be taken up.