FAQs on Hydropower

Answer :

How much is the world's electricity supplied by Hydroelectric Power Plants?

± 2700 TWH is generated every year. Hydropower supplies at least 50% of electricity production in 66 countries and at least 90% in 24 countries.

What are the different types of Hydroelectric Power Plants?

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.
2. Francis - This is a reaction turbine which is used for head varying between 2.5m to 450m.
3. Kaplan - It is propeller type of plant with adjustable blades which are used for heads varying between 1.5 m to 70 m.
4. Propeller - It is used for head between 1.5 to 30 m
5. Tubular - This is used for low and medium height projects. Normally for head less than 15 m.

What are the major components of a Hydroelectric Power Plant?

The major components of a Hydroelectric Power Plant are:-
1. Dam/Barrage
Head works i.e. power intake, head regulator and desilting chambers etc.
2. Head race tunnels/channels
3. Surge shaft/surge chambers
4. Pressure shaft/Penstock
5. Underground and surface power house
6. Tailrace channel or tailrace tunnel.

What is the classification of Hydro Projects based on Installed Capacity?

Micro: upto 100 KW
Mini: 101KW to 2 MW
Small: 2 MW to 25 MW
Mega: Hydro projects with installed capacity >= 500 MW
Thermal Projects with installed capacity >=1500 MW

How energy is generated in Hydroelectric Power Plant

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.

Which is the largest Hydropower station in the world?

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.

How does cost of generation from Hydropower Plant compare with other sources of electricity?

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.

Why hydropower is called renewable source of energy?

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.

Which is the oldest Hydropower Plant in India?

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.

What is the estimated total Hydropower potential of India?

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.

How much of the total Hydropower potential has been exploited so far in India?

Around 26% of Hydropower potential has been exploited in India.

What are the different types of dams?

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.

Why the unit sizes of hydro generating machines are not standardized as in case of thermal power plants?

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

What is the record completion period of a Hydro Power Station in India of more than 100MW ?

Chamera - II HE Project (300 MW) in Distt. Chamba, HP. has been completed in a record period is Four & Half years .

Which Hydro Station has been completed recently which has the lowest tariff rate?

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.

What are the different types of Hydro Schemes?

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.

Which is the largest Operating Hydro Power Station in the World?

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.

What are the major reasons for balancing Hydro-thermal mix?

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.

Why Hydropower stations are preferred solution for meeting peak loads in grids?

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.

What are approaches to tackle sedimentation problem of reservoir?

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.
· Effective desilting arrangements for prevention of silt.
· Silt resistant equipments of withstanding the silt.
· Effective operation of the reservoir to minimize silt deposition.

What are the effects of sedimentation in Hydropower stations?

The major effects of reservoir sedimentation are :
·It reduces the active storage capacity, which may reduce the capability of the reservoir to deliver the benefits in course of time.
·It makes the flood management in the reservoir more difficult.
·Damages to turbines and other under water parts due to abrasive action of silt.

What are the major thrust areas in the field of Environmental Conservation & Management for developing hydropower?

Following safeguards/management plans are implemented at various NHPC projects to ensure development of hydropower in an environmentally sustainable manner:
· Compensatory Afforestation in lieu of forest land diverted for the project.
· Catchment Area Treatment (CAT) to minimise erosion in the catchment of the reservoir, thereby reducing siltation in the reservoir.
· Resettlement & Rehabilitation of Project Affected Population.
· Restoration of Dumping Sites and Quarry Sites using engineering and biological measures.
· Reservoir Rim Treatment plan to stabilise reservoir periphery.
· Conservation measures for flora and fauna, to conserve flora and fauna native to the ecosystem of the area.
· Subsidized Fuel Distribution to worker population and project affected population to minimise fuel demands on the adjacent forests.
· Health Management Plan for the worker population and affected population to prevent epidemics and maintain optimum health standards.
· Fishery Management by construction of fish ladders wherever possible, to enable migration of fishes and by promoting reservoir fisheries.
· Green Belt Plan to make the surroundings of project construction areas green. · Dam Break Analysis and Disaster Management Plan for downstream areas vulnerable to flooding in case of Dam breach.

Do Hydropower projects involve large submergence of land

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.

Does development of Hydropower project leads to large-scale displacement?

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

Do Hydropower projects cause huge destruction of forests?

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

What is the project Cost and how it is funded?

Total capital expenditure incurred for commissioning of a project is project cost and it is mainly funded by the equity and Loan.

What is the standard debt equity ratio for financing a hydropower project?

Standard Debt Equity Ratio is 70:30

Why, in the financing of project cost, Equity component is kept lower than Debt?

Since cost of equity is higher than cost of debt, so equity portion is kept low.

What are the main sources of Debt and Equity?

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.

What are the objectives of Tariff Policy of Govt. dated 6.01.2006?

The objectives of the new Tariff Policy are :-
· To ensure availability of electricity to consumers at reasonable & competitive rates.
· To ensure financial viability of the sector & attract investments.
· To promote transparency, consistency & predictability in regulatory approaches across jurisdictions & minimize perceptions of regulatory risks.
· Promote competition, efficiency in operations & improvement in quality of supply.

What is Availability Based Tariff (ABT)?

ABT means
· It is a performance-based tariff for the supply of electricity by generators owned and controlled by the central government.
· It is also a new system of scheduling and despatch, which requires both generators and beneficiaries to commit to day-ahead schedules.
· It is a system of rewards and penalties seeking to enforce day ahead pre-committed schedules, though variations are permitted if notified One and one half hours in advance.
· The order emphasises prompt payment of dues. Non-payment of prescribed charges will be liable for appropriate action under sections 44 and 45 of the ERC Act.

It has three parts:
- A fixed charge (FC) payable every month by each beneficiary to the generator for making capacity available for use. The FC is not the same for each beneficiary. It varies with the share of a beneficiary in a generators capacity. The FC, payable by each beneficiary, will also vary with the level of availability achieved by a generator.
- In the case of thermal stations like those of NLC, where the fixed charge has not already been defined separately by GOI notification, it will comprise interest on loan, depreciation, O&M expenses, ROE, Income Tax and Interest on working capital.
- In the case of hydro stations it will be the residual cost after deducting the variable cost calculated as being 90% of the lowest variable cost of thermal stations in a region.
- An energy charge (defined as per the prevailing operational cost norms) per kwh of energy supplied as per a pre-committed schedule of supply drawn upon a daily basis.
- A charge for Unscheduled Interchange (UI charge) for the supply and consumption of energy in variation from the pre-committed daily schedule. This charge varies inversely with the system frequency prevailing at the time of supply/consumption. Hence it reflects the marginal value of energy at the time of supply.

What are the components of Bulk Electricity tariff of Hydro Plants?

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:
1. Interest on Loan Capital
2. Depreciation & Advanced Against Depreciation
3. Return on Equity
4. Operation and Maintenance expenses
5. Interest on Working Capital.
The AFC is recovered in the form of Capacity and Primary Energy Charges.

How much Return on Equity is allowed to Hydro Generating Stations?

Return on Equity is allowed @ 14% p.a. on the equity amount

What are the 'pass through' components in the tariff of Hydro Generating Stations?

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.

What is Net Present Value (NPV)?

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.

What is Internal Rate of Return (IRR)?

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