Energy and Environment II

HW#8

Due Friday, March 1, 2002

 

1.      A wind turbine operated at constant speed has the following power versus wind speed.  When the wind speed is 9 m/s, the tip speed ratio (l = VTtip/Uo) is 6 and the power coefficient (Cp) is 0.46.

 

Uo (m/s)      Power (kw)

3.5       2                cut-in (starting)

5          15

6          33

7          57

8          90

9          130

10        170

11        205

12        220

15        225

20        225

25        225           shut down

 

Determine the following:

  1. The radius of the turbine (R, meters)
  2. Rotational speed (N, rev/sec)
  3. l for each Uo
  4. Cp for each Uo
  5. Conversion between m/s and miles per hour (mph).

 

Make a plot of Cp versus l.  

 

2.      Now operate this turbine for constant l – that is, for the l that corresponds to the highest Cp.  Determine the rotational speed (N) and the Power (kw) for each wind speed (Uo).

 

Plot the power versus Uo for both the constant speed and constant l cases.  (Restrict your plot to the 0 to 1000 kw range.)

 

3.      Consider wave energy.  Take one of the following two positions:

A.     “Wave energy will significantly grow and will be competitive with other forms of renewable energy.”

B.     “Wave energy will mainly remain a “curiosity” and will not gain significant market-share.”

List and back up your reasons.  List as “bullets” – five bullets maximum.  Must be typed.