Discussions

« Back 1 2 3 [4]

This discussion relates to Technology Review's article Chasing the Sun.

• 
  arno
  

  Posts:
  1

  Reply

  07/02/2009 05:24 PM

  PV

  Where is the cost of the backup generators that have to be on constant stand-by for when there is no sun. If you just run them 24/7 you don't need PV.

  Rate this comment:
  • 
    kd brown
    

    Posts:
    4

    Reply

    07/03/2009 02:41 PM

    Re: PV

    Ah, yes, but then you haven't done anything about GHG, have you?
    
    Note as well: "no sun" meaning clouds? Sunlight still does get through, and PV will work, tho' not at peak efficiency. Mr. Z probably has the figures at his fingertips on cloudy day electricity output on cloudy days...

    Rate this comment:
• 
  bfiedler
  

  Posts:
  1

  Reply

  10/11/2009 11:41 PM

  my letter to the editor

  This was my letter to the editor, which was not accepted for publication.  Some of these points have already been made by others.
  
  --------------------------------------------------
  
  About "Chasing the Sun" July/August 2009:
  
  A common mistake in writing about renewable energy is to neglect the low capacity factor of wind and solar power. For sunny southern California, the industry quotes a capacity  factor of 20%.  Using the California number, the "$6 a watt to build" should have been written as a capital investment of "$6 per watt of peak capacity and $30 per watt of average production". Though a natural gas plant requires a continual purchase of fuel in addition to the "$1 a watt" to build, such plants do tend to run at full capacity.
  
  The opening paragraph uses "home" as a unit of power, which is unfortunately common in press releases. DoE tells us the typical home (family of 4) uses approximately 2 kW of electricity (requiring about 6 kW of combustion in a thermo-electric plant).  So either the homes you are quoting are rather profligate, or the 10 MW quoted for the 39 acre plant was the peak capacity, not the anticipated average production, which would be 2 MW.  (By the way, 2 MW production is possible with a single giant wind turbine of 7 MW capacity).

  Rate this comment:

« Back 1 2 3 [4]