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All Generation Methods Aren’t Equal, Pt 1

May 13, 2014

Renewables have been promoted as clean energy without much attention being given to their cost or effectiveness.

This results in an illusory view of renewables, which these two articles address.

The different types of power generation equipment, from coal-powered steam turbines to wind turbines, are assigned nameplate ratings.

The nameplate rating defines the amount of electricity a unit can produce if operated continuously.

One measure of effectiveness is capacity factor.

Capacity factor is a measure of the amount of electricity actually generated by an installation, compared with the theoretical amount that could be generated based on its nameplate rating.

The measurement relates to power generation for the grid. PV solar on roof tops need to be evaluated differently, which was done in the article The Solar-Induced Death Spiral.

The capacity factor of a nuclear power plant is typically 90% or slightly more. This means that an investment in a nuclear power plant can be expected to generate 90% of the electricity that could theoretically be generated based on its nameplate rating.

Wind turbines have a capacity factor of around 30%. This reflects the fact that they don’t generate electricity when the wind isn’t blowing or when the wind blows too hard, say over 55 mph. It also reflects that between the units lowest operating speed, say 5 mph, to its most efficient operating speed, say 35 mph, it operates at different efficiencies. Wind turbines are least efficient at low wind speeds; say 5 mph, with efficiency gradually increasing as wind speed increases, until the wind turbine is operating most efficiently.

The American Wind Energy Association (AWEA) actually misleads the public when it announces that “x” megawatts (MW) of wind turbines have been installed during the year.

Comparing the MW of installed wind turbines with the MW of installed nuclear, coal or NGCC, overstates the amount of electricity that can be produced by wind turbines.

The AWEA compares apples with oranges, and misleads people into thinking that equal investments in MW of wind or NGCC power plants produce equal amounts of electricity.

Capacity factors for major types of power generation installations are:

  • Nuclear 90%
  • Coal 85%
  • Natural Gas Combined Cycle (NGCC) 85%
  • Wind 30%

The effect of capacity factor can be seen by making a few calculations.

Typical wind turbines are rated at 1.5 MW.

Because their capacity factor is only 30%, it would take 2,000 wind turbines to generate the same amount of electricity as one 1,000 MW nuclear power plant, or over 1,600 wind turbines to replace one 850 MW natural gas combined cycle (NGCC) power plant.

Wind turbines also have to be spaced far enough apart that the back flow from one turbine doesn’t affect another so that they require around 50 acres per turbine. A 2,000 turbine wind farm, therefore, could require around 100,000 acres.

Wind turbines require considerably more space, with supporting roads and transmission facilities, than do either a single nuclear power plant or a single NGCC power plant.

Concentrating solar power has a capacity factor of around 25%2.

Solar Tower Two. Photo from NREL.

Solar Tower Two. Photo from NREL.

The largest such plant built in the United Sates is the Ivanpah concentrating solar power plant, rated at 377 MW, built in the California desert.  The plant required 4,000 acres.

Approximately 9 Ivanpah’s would be required to produce the same amount of electricity as one, 1,000 MW, nuclear power plant, or 8 Ivanpahs would be needed to replace one, 850 MW, NGCC power plant.

Area wise, 9 Ivanpah’s would require 36,000 acres.

Nuclear, coal-fired and NGCC power plants all require less than 1,000 acres.

Similar conclusions can be reached for coal-fired power plants.

It’s evident, therefore, that renewables are not as effective as nuclear, NGCC or coal-fired power plants.

This effectiveness can be translated into costs, which is the subject of the next article.


  1. Interestingly, the news story from KQED Science, on February 13, 2014, said the Ivanpah plant would provide enough electricity for140,000 homes per year, whereas, the official press release from Brightsource, the developer of Ivanpah, said it would provide enough electricity for 140,000 homes during peak hours. This is an amazing difference that KQED Science, failed to recognize, which misrepresented the facts to the public.

  While anyone can make a mistake, it reemphasizes the importance of carefully reading and understanding media reports.

  1. CSP capacity factor can be increased with 6 hours of thermal storage, and, according to a report by the CSP industry, It is increased to approximately 45%.


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9 Comments leave one →
  1. May 13, 2014 8:54 am

    30% is a generous average for wind factories – many don’t come anywhere near that, often times producing nothing at all.

    There is virtually NO Capacity Value, or firm capacity, for wind factories – making the volatile power they do produce, redundant generation – and obviously responsible for “necessarily skyrocketing” our electricity rates, just as Obama forewarned his ‘green’ energy policy would.

    According to NYISO’s Goldbook, New York State’s installed wind factories averaged a pathetic 23% Capacity Factor in 2012. New York State wind factories are not generating enough electricity to even pay for themselves over their short life spans. See:

    New York Wind Wars – Hiding the Facts:

    Using EIA production data, Wind Action determined the average annual capacity factors by project, by State, and for the US. The final spreadsheet is here:

    Also see:

    Wind Performing Badly:

    Industrial Wind is The Great American “S-WIND-LE” – Not Clean, Not Green, Not Free!:

    • May 13, 2014 9:15 am

      Mary Kay:
      Thanks for the additional information.
      I used 30% for the capacity factor for wind though I am aware that in many installations the actual capacity factor is lower.
      The spreadsheet of actual state by state data is very revealing, and I suggest that people take the time to read it.
      Most people aren’t aware of how badly wind farms actually perform. I didn’t mention that wind is unreliable, but have done so in previous articles.
      Thanks for your comment

  2. May 13, 2014 9:41 am


    Euan Mearns had an interesting post entitled “Did wind power cause Scottish blackout?” the other day that you might find of interest.

    I concur with his assessment of wind (or solar for that matter): “Absent grid scale storage, renewables can only function on a FF based grid and the current market mechanisms are enabling renewables to kill off that FF based host upon which they are dependent. Cheap, efficient grid scale storage changes everything.”

  3. May 13, 2014 9:42 am


    Big Picture reality is what’s needed for all energy policies, especially renewables — and how much public money to throw at it. Thanks again for the time you take to elucidate this critical area.

  4. May 13, 2014 9:58 am

    Thanks for your comments.
    The link in Kakatoa’s comment is interesting. FF, of course, means fossil fuels.
    Cheap, efficient storage would make a big difference, but it’s no where in sight.

    • May 13, 2014 11:43 am


      Google agrees with your assessment of efficient energy storage not being available currently.

  5. Jon permalink
    May 17, 2014 1:47 am

    Offshore wind turbines have a higher capacity factor and also don’t take up land mass that generally belongs to farmers. The European nations have exploited this.

    • May 17, 2014 8:55 am

      That’s true. Off-shore wind farms have a capacity factor of around 39%. Installing them off-shore is far more expensive than wind farms on land. The cost of electricity from off-shore wind farms is, therefore, much higher than from land based wind farms.


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