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Old 09-26-2008, 05:48 AM   #69 (permalink)
rob13572468
the devil's advocate...
 
Join Date: Feb 2005
Location: chicago
Posts: 884
Quote:
Originally Posted by Rich H View Post
What's giving you trouble is the fact that, barring error, all utility capacity was built to serve forecast load. The subtlety is that capacity additions require a long time to plan and build, and necessarily come on line in large block increments (i.e., say a 2,000 megawatt baseload plant), whereas load growth occurs gradually in small bits, as consumers add appliances one at a time.

So if a utility always maintains at least its planning reserve margin for reliability, it will inevitably experience significant stretches of time where, arithmetically, it appears to have more capacity than needed while load growth catches up to large increment capacity additions. And that capacity can reasonably be used to serve temporary loads. But that capacity cannot suddenly be declared "excess" in a snapshot analysis and earmarked for new permnent loads that were not in the forecast, without ultimately leaving the utility short of capacity to serve all anticipated loads.
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This is a really good point that I believe is quite non-intuitive for most people... The idea that unused capacity will never really be unused for long since our energy consumption is always increasing and also that peak reserve power can be used economically during off-peak hours.
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