wind energy lecture 1

8/19/2019 Wind Energy Lecture 1

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Lebanese University, Faculty of Engineering

Mechanical Engineering Department

Wind Energy

Lecture Notes For

Mechanical Engineering Students

2014 - 2015

12/29/2014 1Bassam Riachi



12/29/2014 Bassam Riachi 2



References

1- Renewable and Efficient Electric Power

Systems, Gilbert M. Masters

2- Wind Energy Explained, J.F.Manuel

3- Aerodynamics of Wind Turbines, Martin

4- Renewable Energy Fundamentals, Bistritski





• Wind power could generate up to 18% of the world’s

electricity by 2050, compared with 2.6% today.

• The nearly 400 gigawatts of current wind powerworldwide must increase eight- to ten-fold to achievethe IEA roadmap’s vision.

• It sees China overtaking OECD Europe as the leadingproducer of wind power by 2020 or 2025, with theUnited States ranked third.

• Wind power deployment under this vision would saveup to 4.8 gigatonnes of CO2 emissions per year by 2050



Top 15 countries

by nameplate wind power capacity




Top 10 countries by wind power

electricity production [2012]




Wind energy cost

Fixed / Initial + Operating

• The cost of a wind system has two components:

initial installation costs and operating expenses.

• The initial installation cost includes the purchase

price of the complete system (including tower,wiring, utility interconnection or battery storage

equipment, power conditioning unit, etc.) plus

delivery and installation charges, professionalfees and sales tax.




Operating costs

• Operating costs include maintenance and

service, insurance and any applicable taxes.

• A rule of thumb estimate for annual operating

expenses is 2% to 3% of the initial system cost.

• Another estimate is based on the system’s

energy production and is equivalent 1 to 2

cents per kWh of output.




Cost of installed KW

• A grid-connected residential-scale system (1-10 kW) generally costs between $2,400 and$3,000 per installed kilowatt.

• A medium-scale, commercial system (10-100kW) is more cost-effective, costing between$1,500 and $2,500 per kilowatt.

•

Large-scale systems of greater than l00 kWcost in the range of $1,000 to $2,000 perkilowatt




Calculating the Cost Per kWh


Annual Cost = (Initial Cost/Expected Life) +

Annual Operating Costs

Wind turbine manufacturers estimate a useful

life of between 20 and 30 years for their

product.

• Cost Per kWh = Annual Cost/Annual Energy

Output



example


• Annual cost = ($100,000/25 years) +

$1,000/year = $4,000 + $1,000 = $5,000/year

• Cost per kWh = ($5,000/year)/100,000

kWh/year = $0.05 per kWh

• US cost: 2.5 – 5 cents per KWh



Cost comparison based on levelized

energy costs LEC


The LEC represents the total cost

to build and operate a new power

plant over its life divided to equal

annual payments and amortizedover expected annual electricity

generation.

It reflects all the costs including

initial capital, return oninvestment, continuous operation,

fuel, and maintenance, as well as

the time required to build a plant

and its expected lifetime



Lifecycle greenhouse gas emission estimates for

electricity generators, according to Benjamin K.

Sovacool's comparison


https://en.wikipedia.org/wiki/Benjamin_K._Sovacool








World’s First Wind Turbine




https://www.youtube.com/watch?v=llIbjC49Fjs




http://www.energy.gov/eere/wind/how-does-wind-turbine-work




Types of Wind Turbines




The cost of a turbine

increases roughly in

proportion to blade

diameter, but power isproportional to

diameter squared, so

bigger machines have

proven to be more costeffective.




ρ = f (p,T)





USA

Europe

Impact of Tower Height



• For large machines, when a blade isat its high point, it can be exposed tomuch higher wind forces than whenit is at the bottom of its arc.

• This variation in stress as the blademoves through a complete revolutionis compounded by the impact of thetower itself on wind speed-especiallyfor downwind machines, which havea significant amount of windshadowing as the blades pass behindthe tower.

• The resulting flexing of a blade canincrease the noise generated by the

wind turbine and may contribute toblade fatigue, which can ultimatelycause blade failure.




• For a given wind speed, rotor efficiency is a function ofthe rate at which the rotor turns.

• If the rotor turns too slowly, the efficiency drops offsince the blades are letting too much wind pass by

unaffected.• If the rotor turns too fast, efficiency is reduced as the

turbulence caused by one blade increasingly affects theblade that follows.

• The usual way to illustrate rotor efficiency is to present

• it as a function of its tip-speed ratio (TSR).

• The tip-speed-ratio is the speed at which the outer tipof the blade is moving divided by the wind speed.




A 40-m, three-bladed wind turbine produces 600 kWat a wind speed of 14 m/s. Air density is the standard1.225 kg/m3. Under these conditions:

a. At what rpm does the rotor turn when it operates

with a TSR of 4.0?

b. What is the tip speed of the rotor?

c. If the generator needs to turn at 1800 rpm, whatgear ratio is needed to match the rotor speed to thegenerator speed?

d. What is the efficiency of the complete wind turbine(blades, gear box, generator) under these conditions?


wind energy lecture 1

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