± 2700 TWH is generated every year. Hydropower supplies at least 50% of electricity production in 66 countries and at least 90% in 24 countries.
There are basically four types of power plants: -
1. Pelton turbines - It is impulse turbine which is normally used for more than 250 m of water head.
The major components of a Hydroelectric Power Plant are:-
Micro: upto 100 KW
A hydroelectric power plant consists of a high dam that is built across a large river to create a reservoir, and a station where the process of energy conversion to electricity takes place.
The first step in the generation of energy in a hydropower plant is the collection of run-off of seasonal rain and snow in lakes, streams and rivers, during the hydrological cycle. The run-off flows to dams downstream. The water falls through a dam, into the hydropower plant and turns a large wheel called a turbine. The turbine converts the energy of falling water into mechanical energy to drive the generator After this process has taken place electricity is transferred to the communities through transmission lines and the water is released back into the lakes, streams or rivers.This is entirely not harmful, because no pollutants are added to the water while it flows through the hydropower plant.
Three gauges project in China on Yang-Yang river is the largest power station in the world having installed capacity of around 18,200 MW.
The hydropower generation is highly capital-intensive mode of electricity generation but being renewable source of energy with no consumables involved; there is very little recurring cost and hence no high long term expenditure. It is cheaper as compared to electricity generated from coal and gas fired plants. It also reduces the financial losses due to frequency fluctuations and it is more reliable as it is inflation free due to not usage of fossil fuel.
Hydropower is called renewable source of energy because it uses and not consumes the water for generation of electricity, and the hydropower leaves this vital resource available for other uses.
The oldest Hydropower power plant is in Darjeeling District in West Bengal. It's installed capacity is 130KW and was commissioned in the year 1897.
The hydropower potential of India is around 1,45,000 MW and at 60% load factor, it can meet the demand of around 85, 000 MW.
Around 26% of Hydropower potential has been exploited in India.
Different types of dams are conventional concrete dam, Roller compacted concrete dam, rock fill dam, Concrete Faced Rock fill Dam(CFRD), Earth fill dam, arch dam, barrages etc.
Since the size of hydro generating machines are based on availability of water in river and the water head available at a particular project site, the size of the machines keeps varying from location to location and river to river. The sizes are also based on logistics and variation of water in river during the year
Chamera - II HE Project (300 MW) in Distt. Chamba, HP. has been completed in a record period is Four & Half years .
Dhauliganga HE Project (280 MW)in the Distt. of Pithoragarh of Uttranchal was completed in Nov. 2005. It is selling electricity @ Rs.1.83 / Kwh to beneficiary States of Northern Region.
Different types of Hydro Schemes are :
i. Purely Run - of - River Power Station. ii. Storage type Power Station. iii.Run - of - River Stations with Pondage.
The world's Largest Hydro Electric Power Station is ITAIPU with installed capacity of 12600 MW and a reliable output of 75,000 MU in a year. It is located at the Border of Brazil and Paraguay.
Seasonal load curves of our regional grids match with the pattern of hydro power generation. During summer/monsoon season when the generation at hydro power plants is high, the load factor of the system is high due to heavy agricultural load. During winter, the thermal stations operating at base load and hydro stations working as peak load stations will take care of weather beating loads. Thus the operational needs of hydro & thermal stations are complimentary and the balanced mix helps in optimal utilization of the capacity.
Due to its unique capabilities of quick starting and closing, hydropower stations are found to be economical choice to meet peak load in the grid.
The following are some approaches to tackle sedimentation problem of reservoir:-
· Catchment Area Treatment (CAT) for reduction of silt load includes forestations of the catchment area and constructions of check dams on the tributaries and upstream of the river.
The major effects of reservoir sedimentation are :
Following safeguards/management plans are implemented at various NHPC projects to ensure development of hydropower in an environmentally sustainable manner:
Submergence of land, thereby loss of flora and fauna and large scale displacement, due to the hydropower projects is sometimes exaggerated. Study shows that project catering only to hydro power needs, cause little submergence. A sample of 12 projects of NHPC contributing 6231 MW of power required submergence of only 4850 ha of land i.e. the area of submergence per MW is only 0.78 ha.
This is not always true. Considering 16 hydropower projects of NHPC covering commissioned Power Stations, under- construction projects and proposed projects it can be seen that number of displaced families per MW is only 0.26, whereas, number of affected families per MW is 0.66
Due to the fact that hydropower projects are primarily located in hilly areas, where forest cover is comparatively better than plain areas, diversion of forest land is sometimes unavoidable. However, efforts are made to minimize the utilization of forests by hydropower developers. Compensatory Afforestation is mandatory in accordance with Forest (Conservation) Act, 1980, which has to be fulfilled along with other cconditions laid down by MOEF while according forest clearance to a project
Total capital expenditure incurred for commissioning of a project is project cost and it is mainly funded by the equity and Loan.
Standard Debt Equity Ratio is 70:30
Since cost of equity is higher than cost of debt, so equity portion is kept low.
Generally main source of Debt is loan from Domestic Financial Institutions, Government of India and foreign Loan and Equity is sourced from Government of India and through IPO.
The objectives of the new Tariff Policy are :-
It has three parts:
Hydro tariff means Annual Fixed Charges (AFC) in respect of each Hydro Generating Stations which is determined by the appropriate Regulatory Electricity Commission.
The components of AFC are:
Return on Equity is allowed @ 14% p.a. on the equity amount
Tax on income, Extra Rupee Liabilities (FERV) are pass through components in tariff i.e. they are to be reimbursed separately to the Hydro Generating Stations as per Actuals.
NPV is present value of future cash flows. NPV compares value of money today to the value of that money in the future taking inflation & returns into account. If the NPV of a project is positive then the project is financially viable. If NPV of a project is negative the project is not viable.
It is interest rate that makes NPV of all cash flows of a project equal to Zero. Essentially this is the return that a project would earn if it invest money in itself rather than elsewhere. This is the rate which equates discounted cash outflows flows & discounted cash inflows. Higher the IRR of the project better is the financial return on the Investment