Harnessing wind power

ISHAN MITTAL

• Energy is a major input for all overall socio-

economic development. Fossil fuels are

currently major sources of energy.

• These fossil fuels release harmful gases as

by - products on combustion thereby causing ,

not only depletion the ozone layer, But also

increase the amount of green house gases in the

atmosphere. Prices of the fossil fuels are steeply

increasing

introduction

• Hence ,Renewables are expected to play a key

role in accelerating development and sustainable

growth in the second half of the this century,

accounting then to 50 to 60% of the total global

energy supply.

• Wind energy is one such form of renewable resources which is not only clean but also exploitable to a great extent at a low cost

Role of renewables

Growth &Potential

Wind is currently the world’s fastest growing energy source www.wind.net

now, The world wide installed capacity of wind is growing at a rapid pace of over 30% per year,while solar capacity at about 20% &coal is decreasing at 1%

Factors for such steep rise in wind resources are:declining cost of wind power (4-6 cents kw/h)technological advances revenue for landowners & tax jurisdictionsconsumer demand

Wind energy is big business turning over $13 billion globally and employing 1,00,000people today. By 2020, the industry is expected to employ 1.8 million people and beworth of $120 billion a year.

Wind Power Density of India

www..maps of india.com

Available wind power potential in India

www.indianwindpower.com

www..maps of india.com

All India Fuel wise Installed Capacity

Hydro 26%

Gas10%Coal

58%

Nuclear2%

Wind3%

Diesel1%

www.indianwindpower.com

This shows that wind contributes to only 3% of total installed capacity, Despite the tremendous potential . coal is still the major energy source with 58% share .The current installed capacity for the wind in india is 11,180 MW , fifth largest worldwide

Techniques to capture

wind power

 

Power of the Wind • Wind Turbine Power input is given by the following formula:

• P = 0.5 x rho x A x Cp x V3 x Ng x Nb• where:• P = power in watts• rho = air density • A = rotor swept area, exposed to the wind (m2)

• Cp = Coefficient of performance • V = wind speed in meters/sec• Ng = generator efficiency

   

  Power density function

For the grey curve, we multiply the power of each wind speed with the probability of each wind speed and we get the distribution of wind energy at different wind speeds = the wind power density function

The graph consists of a number of narrow vertical columns, one for each 0.1 m/s wind speed interval. The height of each column is the power (number of watts per square metre), which that particular wind speed contributes to the total amount of power available per square metre.

The area under the blue curve tells us how much of the wind power we can theoretically convert to mechanical power. (According to Betz' law , this is 16/27 of the total power in the wind). The total area under the red curve tells us how much electrical power a certain wind turbine will produce at this site.

Power Coefficient

 The ratio for actual energy captured by a wind turbine to that which could be captured is the Power Coefficient, the wind speeds must be within the optimum range throughout the year at the designated location to enable the turbine to operate at its maximum power coefficient. Other selection parameters include installation height, blade parameters, airfoil characteristics, and aerodynamic requirements;

Velocity with Heightwww.worldwind.asc..gov

(p)The wind speed is 1.5 times greater ….at aheight of 16m…than what It is at the groundleve;.t this can be used to calculate the hub height

Tip speed v/s wind speedwww.worldwind.asc.gov

The relationship of the blade speed (measured at the tip) to the wind speed is the tip speed ratio

(P)We can use this to calculate the required Blade length as For a given blade area… Cp on y –axis...is max only for a specific tip speed at a given wind speed on the x-axis… hence we can get the corresponding blade length and breadth for that tip speed and blade area

Now,The higher the design tip speed ratio, the lower is the required ratio of total blade area to swept area (called solidity) because obviously for a given blade area & wind speed , if you increase the tip speed ratio and hence the blade length, the swept area increases and the solidity decreases

For many mechanical applications, such as water pumping, high torque is of primary importance, Hence low tip speed is needed for a given power of the turbine, because as we already know , Power is the product of torque (“twisting force”) and rotational speed

Blade length

(P)Now Once blade length has been selected we can calculate generator capacity according to this figure i.e if we get a length of 27 m……. we must use a generator of 225 KW capacity.….

we Can’t use a large generator because it requires larger power to turn .Hence the reason why we get more output from a relatively smaller generator in a low wind area is that the turbine runs more hours during the year

Operation & types of WT

Horizontal axis (hawt)

www.wikipedia .org

Now As the wind strikes the blades It turns the low speed shaftWhich turns the orange gear box And the the blue generator coils

The nacelle is the housing of this whole mechanismThe yaw drive turns the nacelle according to the wind direction

• Lift is the main force

• Variable blade pitch , optimum angle of

• attack

• Nacelle is placed at the top of the tower

• Yaw mechanism is required

• Cyclic stress is produced

Characterstics

Two types of HAWTDOWNWIND TURBINEUPWIND TURBINE

In the downwind turbine, the tower faces the wind and hence a problem of cyclic stress exists .the Upward facing blade experiences a force backward due to the wind & the downward facing blade does not experience this force because the tower obstructs the wind. Hence ,cyclic stress is produced. The combined twist is worst in machines with an even number of blades, where one blade is straight up when another is straight down

www.wikipedia .org

In the upwind turbine the blades face theWind and therefore no problem of cyclic stress exists

• Drag is the main force

• Nacelle & generator is placed at

• the bottom

• Yaw mechanism is not required

• Lower starting torque

• Difficulty in mounting the turbine

• Unwanted fluctuations in the power output

• Height limitations allow use in low speed areas only

VERTICAL AXIS (VAWT)

www.wikipedia .org

Economics

• Wind Speed and density

• Turbine design & construction– 75% of total cost

• Rated capacity of the turbine

• Exact Location – inland or coastal

• Improvements in turbine design

• Capital available – capital intensive source

Determining Factors

• Wind turbines undergo major economies of scale avantage as for 1MW of installed capacity we need 1 -2 million & for 2 MW of installed capacity, only 2.8 million is needed. Also energy production cost per KW/hr decreases increasingly with increasing capacity

• To take advantage of economies of scale, wind power facilities should be in excess of 20 MW. So if the average wind turbine is rated at 750 kilowatts (kW) in capacity, this means at least 26 turbines must be installed and an initial investment of $20 million dollars is needed

 

Economies of scale

• Size: 51 MW

• Wind Speed: 13-18 miles/hour

• Installation cost : around $45 million

• Annual production: 150 million kW-hr

• Electricity costs: 3.6-4.5 cents per KW/hr

• Payback period: 10 years

Typical cost statistics

innovations

Maglev turbine

www.magturbine.com

This works on the theory of magnetic levitation. The vertically oriented blades of the wind turbine are suspended in the air above the base of the machine, replacing the need for ball bearings. The turbine uses “full-permanent” magnets, not electromagnets — therefore, it does not require electricty to run. The full-permanent magnet system employs neodymium (“rare earth”) and there is no energy loss through friction. This also helps reduce maintenance costs and increases the lifespan of the generator

Maglev working

Maglev wind turbines have several advantages over conventional wind turbines. For instance, they’re able to use winds with starting speeds as low as 1.5 meters per second (m/s). Also, they could operate in winds exceeding 40 m/s. Currently, the largest conventional wind turbines in the world produce only five megawatts of power. However, one large maglev wind turbine could generate one gigawatt of clean power, enough to supply energy to 7,50,000 homes. It would also increase generation capacity by 20% over conventional wind turbines and decrease operational costs by 50%. If that isn’t enough, the maglev wind turbines will be operational for about 500 years

Advantages of maglev

Floating turbine

This is an offshore wind turbine , mounted on a floating structure that allows the turbine to generate electricity in water depths where bottom-mounted tower are not feasible.

http://news.bbc.co.uk

Typical Concerns & solutions

• Visual impact

• Off shore turbines

• Arrangement

• Avian concerns

• Suitable choice of site

• Using tubular towers instead of lattice tower

with diagonal stringers – no place to perch

• Using radars

• Noise

• Varies as 5th power of relative wind speed

• Streamlining of tower and nacelle

• Acoustic insulation of nacelle

• Specially designed gear box

• Use of upwind turbines rather than downwind

• Cost:

• Wind turbines are Not good for small scale

applications due to higher cost

• Clean , environment friendly resource

• Easy in construction

• Low maintenance costs

• Reliable and durable equipment

• Additional income to land owners

• More jobs per unit energy produced

• No hidden or socio economic costs

ADVANTAGES

Conclusion

• Since, Wind energy is a pollution free and nature

friendly resource, It has very good potential and it is

the fastest growing energy source

• The future looks bright for wind energy because

technology is becoming more advanced and windmills

are becoming more efficient

THANK YOU