Wind Power Plant
The development of wind power in India began in the 1990s, and has progressed steadily in the last few years. The short gestation periods for installing wind turbines, and the increasing reliability and performance of wind energy machines have made wind power a favoured choice for capacity addition in India.
The total wind energy potential in India has been estimated at over 50,000 MW. India’s wind energy sector has seen significant investments spurred by the development potential, availability of wind farm equipment at competitive prices and conducive government policies. Currently more than 70% of the installed generation capacity from renewable sources is accounted by wind power.
Wind Power Installed Capacity (MW) in INDIA
(Up To 31st March 2012)
|Up to March’2002||93.2||181.4||69.3||2.0||23.2||400.3||16.1||877.0||1.1||3.2||1666.8|
|Potential at 80m Hub Height
As of Aug. 2012 the installed capacity of wind power in India was 17967.15 MW, mainly spread across Tamil Nadu (7000 MW). Wind power accounts for nearly 8% of India’s total installed power capacity, and it generates 1.6% of the country’s power.Source: mnre.gov.in
Wind power is continuously growing in the world and acting as mainstream power supplier in many countries instead of it is viewed as a intermittent source of energy. Wind Energy plays a significance role in electricity supply. It contributes around 430 TWh to world electricity supply, ~ 2.5 % of global electricity demand in 2010.
The worldwide installed capacity of wind power reached 2,00,000 GW in the year 2011 . USA (35,159 MW), Germany (25,777 MW), Spain (19,149 MW) and China (25,104 MW) are ahead of India in fifth position. China (44,733 MW), US (40,180 MW), Germany (27,215 MW) and Spain (20,676 MW) are ahead of India in fifth position. Also in many countries wind is contributing a major portion of total generation like Denmark (21%), Portugal (18%), Spain (16%), and Germany (9%).
Wind Power Institutions and Associations in India:
Wind Energy Research Institutions
- Center for Wind Energy Technology-CWET: - has been established in Chennai in the year 1998, as an autonomous R&D instititution by the MNRE. It is a knowledge based institution of high quality and dedication, offers services and seeks to find complete solutions for the kinds of difficultites and improvements in the entire spectrum of the wind energy sector by carrying out further research. It has a Wind Turbine Test Station (WTTS) at Kayathar with the technical & partial financial support by DANIDA, Govt. of Denmark. It’s main functions are R&D, Wind Resource Assessment, Testing Services, Certification services and Training.
- World Institute of sustainable Energy (WISE)
Wind Energy Associations:
- Indian Wind Energy Association (INWEA)
- Indian Wind Turbine Manufactures Association (IWTMA)
- Indian Wind Power Association
Policies For Wind Power Development in India
- 80% AD for the projects commissioned before 30th September and 40% AD for the projects commissioned before 31st March of the same financial year.
- GBI scheme for grid interactive wind power projects.
- REC Mechanism.
- Concession on import duty on specified wind turbine components.
- 10 year income tax holiday for wind power generation projects.
- 100% exemption from excise duty on certain wind turbine components.
- 100% FDI investment allowed in renewable energy generation projects.
- Special incentives provided for promotion of exports from India for various renewable energy technologies under renewable sector specific SEZ.
- Generation Based Incentive:
i) Mutually exclusive with Accelerated Depreciation scheme.
ii) Applicable for IPP’s having minimum installed capacity of 5 MW
iii) Not applicable for capacities set up for captive use, third party sale, merchant plants.
iv) Incentive @ Rs. 0.50/Unit for electricity fed into the grid over and above the tariff approved by the SERC’s in states.
v) Incentive released by IREDA on half yearly basis.
vi) 4 years < Incentive Duration < 10 years.
vii) Cap of Rs. 62 lakhs/MW.
viii) Maximum disbursement in a year will be Rs. 15.50 lakhs/MW for first four years.
- Clean Development Mechanism.
Essential requirements for a wind farm
An area where a number of wind electric generators are installed is known as a wind farm. The essential requirements for establishment of a wind farm for optimal exploitation of the wind are
1. High wind resource at particular site
2. Adequate land availability
3. Suitable terrain and good soil condition
4. Proper approach to site
5. Suitable power grid nearby
6. Techno-economic selection of WEGs
7. Scientifically prepared layout
Wind turbine Components
The blades and the hub together are called the rotor. It is the rotating component which converts kinetic energy available in the wind to mechanical energy. The rotor hub connects the rotor blades to the rotor shaft. It is also the place where the power of the turbine is controlled physically by pitching (A method of controlling the speed of awind turbineby varying the orientation, or pitch, of theblades, and thereby altering its aerodynamics and efficiency) the blades. Hubis one of the critical components of the rotor requiring high strength qualities.
Blade is a rotating component designed aerodynamically to work on the principle of lift and drag to convert kinetic energy of wind into mechanical energy which is transferred through shaft then converted to electrical energy using generator. Most turbines have either two or three blades. Wind blowing over the blades causes the blades to “lift” and rotate. Mechanical applications like pumping water, grinding uses more number of blades as it requires more torque. Blade length is key factor determining power generation capacity of a wind turbine.
The nacelle is an enclosure that sits atop the tower and contains the gear box, low-speed shaft and high-speed shaft, generator, controller, and brake. Some nacelles are large enough for a helicopter to land on. The nacelle also protects turbine components from atmospheric weather conditions and reduces noise.
- Low-speed shaft
Low-speed shaft is the principle-rotating element which transfers torque from the rotor to the rest of drive train. It also supports the weight of the rotor.It is connected to the gearboxto increase the rpm.
- Gear box
Gear box steps up the speed according to the requirement of the electric generator.Gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm, the rotational speed required by most generators to produce electricity. The gear box isone of thecostliest (and heavy) partsof the wind turbine and there
are also “direct-drive” generators that operate at lower rotational speeds and don’tneed gear boxes.
Types: Planetary Gear Boxes, Parallel shaft gear.
- High-speed shaft
Transmits the speed & torque from the gearbox and drives the generator.
During the periods of extremely high winds and maintenance,brakes are used to stop the wind turbine for its safety.
Types of Brakes: i) mechanical brake (Disc brake, clutch brake), ii) Aerodynamic brake (Tip brake and spoilers)
Generator converts the rotational mechanical energy into electrical energy. Usually wind electricgenerator produces 50-cycle AC electricity.
Types: i) Synchronous generator (Electrically excited, permanent magnet), ii) asynchronous generator (Squirrel cage, Slipring)
The controller starts up the machine at cut-in wind speed (generally 3 m/s) and shuts off the machine at cut-out wind speed (generally 25 m/s) as per the design requirement. The controllers also operate the turbine to produce grid-quality electricity. The controller measures and controls parameters like Voltage, current, frequency, Temperature inside nacelle, Wind direction, Wind speed, The direction of yawing, shaft speed, Over-heating of the generator, Hydraulic pressure level, Correct valve function, Vibration level, Twisting of the power cable, Emergency brake circuit, Overheating of small electric motors for the yawing, hydraulic pumps, Brake-caliper adjustment etc.
Anemometer is a sensor used for measuring the wind speed. Other than using it for wind resource assessment, it is normally fixed on top of the wind turbine to provide input to the controller for power regulation and braking beyond the cut out & survival wind speed .
Blades are turned or pitched, out of the wind to control the rotor speed and keep the rotor from turning in winds that are too high or too low to produce electricity.
The tower enables wind energy utilization at sufficient heights above ground, to absorb and securely discharge static and dynamic stress exerted on the rotor, the power train and the nacelle into the ground.
Types of Towers:
i) Tubularsteel tower: Area of contact is more–hence more loading but evenly distribution– attractive–cost is more.
ii) Tubular concrete: Area of contact is more– high elasticity – loading high but even distribution–cost slightly less.
iii) Lattice tower: Area of contact is less–less loading –load distribution is uneven – transportation / fabrication easy.
iv) Three legged tower: Area of contact is less–less loading –load distribution is uneven– transportation / fabrication easy.
v) Guy wired tower: Area of contact is less – less loading – load distribution even – transportation / fabrication easy and not suitable for huge wind turbines.
vi) Hybridtower: A combination of tubular and lattice- Less obstruction- Strong
- Foundation (not shown in the picture)
Foundation is needed to support and absorb the loads from the wind turbine. The choice of foundation type is much dependent on the soil conditions and water table location prevailing at the planned site of a wind turbine.
Onshore Foundation Types:Slab Foundation (preferred when the top soil is strong), Pile Foundation (Preferred when the top soil is of a softer quality)
Offshore Foundation Types:Monopile, Gravity base, Tripod
- Wind vane
Measures wind direction and communicatewith thecontroller for orienting theturbine properly (yawing)with respect to the winddirection.
- Yaw drive
Yaw drive turns the nacellewith rotoraccording to the wind direction using a rotaryactuator engaging on a gear ring beneath the nacelle. Yaw system keeps the turbinealwaysfacing the wind.
- Yaw motor
Yaw motor is to power the yaw drive.
Offshore Wind Development
- India’s Wind Energy Capacity of nearly 15GW .
- Currently 5th largest wind installations in the world.
- Vast 7600km coastline.
- Yet to set up its first offshore pilot project.
- Less interest shown by GOI.
- Installation cost is higher because of additional costs associated with subsea studies, drilling & foundation works, transportation etc.
- Development cost of offshore projects varies from $4.5mn to $5.5mn per MW, depending on the water depth and infrastructure requirements such as subsea cabling & onshore electric grid requirements.
- 2-3 times more expensive compared to onshore farms.
Points in favour of Off-shore projects
- Onshore projects—negative visual impact or noise, land use disputes and limited land availability.
- High wind speed available for a longer duration over the seascape due to negligible wind flow obstructions & temperature variability.
- High efficiency of offshore projects makes their development economically viable.
- Levelised tariff for offshore projects in Europe and China ranges from Rs6-7 pu.,while the levelised tariff for solar projects developed under JNNSM ranges from Rs13.25-17 pu.
- A full – fledged study to assess the off shore potential is yet to be conducted in India. There are several pockets in Indian Ocean and Bay of Bengal that may have offshore potential.
- Issues related to
- Seabed and marine conditions
- Shipping constraints
- Navy & Radar constraints
- Designated & Conservation zone clearances
- Operation & Maintenance arrangements
- Laying of submarine cables & foundations
- Corrosion & Scouring of underwater structures as well as other sea related factors as mean depth, tidal range, sea temperature and currents.
These have been successfully managed by developers around the world, and hence should not stand as a stumbling block in the sector’s growth.
- The TATA Power Company, India’s largest private power utility, plans to set up one in Gujarat.
- ONGC had proposed to set up 2 pilot projects off the coasts of Tamilnadu & Gujarat.
- Primarily it’s because of the lack of guidance & policy support from the govt.
- It could take another 3-5 years before any offshore project is set up in India.
Comparison between Fossil Fuels and Wind
|Availability||Usable as it exists||Have to be procured and made usable through laborious and environmentally damaging processes|
|Limitation on availability||Inexhaustible resource||Limited in reserves, expected to get completely exhausted in the coming 60 years|
|Transportation||Used where it is available||Have to be transported from the site for further processing exposing environment to danger|
|Use in production||Zero emission||Used in producing electricity releasing green house gasses|
|Geo-political Implications||Reduces our reliance on oil, safeguarding national security||Over-reliance on oil as a resource has undermined our energy security. E.g. OPEC crises of 1973, Gulf War of 1991 and Iraq War of 2003|
|There is no adverse effect on global environment. The whole system is pollution free and environment friendly.|
The main advantages of power generation from wind energy are:
1. The capital cost is comparable with conventional power plants. For a wind farm, the capital cost ranges between 4.5 crores to 6.85 crores per MW, depending up on the type of turbine, technology, size and location.
2. Construction time is less.
3. Fuel cost is zero.
4. O & M cost is very low.
5. Capacity addition can be in modular form.
6. There is no adverse effect on global environment. The whole system is pollution free and environment friendly.
1. Wind machines must be located where strong, dependable winds are available most of the time.
2. Because winds do not blow strongly enough to produce power all the time, energy from wind machines is considered “intermittent,” that is, it comes and goes. Therefore, electricity from wind machines must have a back-up supply from another source.
3. As wind power is “intermittent,” utility companies can use it for only part of their total energy needs.
4. Wind towers and turbine blades are subject to damage from high winds and lighting. Rotating parts, which are located high off the ground can be difficult and expensive to repair.
5. Electricity produced by wind power sometimes fluctuates in voltage and power factor, which can cause difficulties in linking its power to a utility system.
6. The noise made by rotating wind machine blades can be annoying to nearby neighbors.
7. People have complained about aesthetics of and avian mortality from wind machines.
Content Addition & Updation by,
Saurabh Srivastava (MBA-10th Batch, NPTI, Faridabad)