November21st.CEE265.docx

4 Pages
127 Views
Unlock Document

Department
Civil And Environmental Engineering
Course
CEE 265
Professor
Phillip Savage
Semester
Fall

Description
CEE 265 November 21, 2013 RECAP: Power Content of the Wind  Dependence on the cube of the wind speed  Important in choosing where to construct a wind turbine  Rotor efficiency indicates how much kinetic energy will be extracted by the turbine o Actual wind turbines can’t actually get all kinetic energy from wind o Based on limitation of generator  Wind speed distribution and average wind speed important for deciding turbine location  We also talked about capacity factor and effectiveness of turbine o Impossible to get high CF and EFF (the ideal) o Always a trade-off Cost of Wind Power  Triple bottom line: economics, performance, and social factors o Professor used baseball example  For wind turbine o Capital cost = cost of turbine rotor + blades + tower + electromechanical system o Capital cost (CC) increases as PR(rated power output) increases In-Class Problem 21.3: wind turbine energy payback time  Rate power of 2 MW running at 25% capacity o Required 100,000 kg of steel to make o Assume 40 kWh energy input to make each kg of steal  What is the payback period? o Embedded energy = (40 kWh/kg steel)*(1000,000 kg steal) = 4,000,000 kWh o Electricity production rate = (2 MW)*(1,000 kW/MW)*0.25 = 500 kW o Payback period = (4,000,000 kWh/500kW) = 8,000 hours  There are 8,760 hours in a year o So it takes almost an entire year to generate enough electrical energy to recover the energy used to build the turbine o The turbine might only last 25 years o So these are the sorts of things that a life cycle analysis helps us to understand Triple Bottom Line Aspects of Wind Power  Advantages: o Renewable energy source  fuel cost is nearly zero o Low operating cost o Low carbon emissions  footprint in assembly of course, but overall low  Disadvantages: o Large land use requirement o High capital cost  greater uncertainty because of availability of resources o Materials used in turbine assembly and their associated impacts o Noise issues o Aesthetic issues  they don’t look great in a backyard o How they effect animals in the ecosystem  kills birds Offshore Wind Farms and the Triple Bottom Line  Advantages: o Reduced land use intensity o Less obtrusive o Higher category winds  less turbulence  Disadvantages: o More expensive to build/operate o Undersea cable required for connecting to grid o Interference with waterways Key Points:  The power content of the wind is proportional to the cube of the wind speed  The recoverable kinetic energy from the wind is limited by the physics of Betz’s law  Large diameter turbines/large tower heights more cost–effective for wind energy capture  In selecting the rate power of a turbine, one must consider the capacity factor and effectiveness SOLAR ENERGY Sun emits enormous amount of energy across the electromagnetic spectrum  Sun’s spectrum almost matches a blackbody  Varies according to the season o Earth’s orbit is not quite elliptical o Also have a tilted axis o Means the regional variation of energy received depends on position on Earth also  Amount of insolation available depends on latitude, day, and cloud cover o Sun path diagrams and clear sky insolation tables are helpful o Solar noon = half way between sunrise and sunset on a given day o Spring and fall equinoxes are the only days that it perfectly rises in the East and sets in the West  Sun path diagram for Michigan at 40 N latitude o Shows the equinoxes are March 21 and September 21 o If you look at different altitude you would have different sun path diagram o Useful for trying to analyze shade effects when building something  Clear sky insolation table o Shows you how much insolation is available in watts per m by
More Less

Related notes for CEE 265

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit