garyshu’s Recent Comments

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  Whoa there, careful with the data interpreations...

  RE: "...for at least one individual coal plant, CO2 emissions per megawatt-hour inched up (bottom graph) when the plant was run at 50 percent capacity (top graph). If that’s a common problem, then it might suggest that it would be better to shut one coal plant down entirely, rather than turning several plants down a bit.  The reality might be more complicated, and the economics hard to figure out.."

  Hard to figure out?  Not really.  In deregulated markets with each plant bidding in their offer curves (i.e. supply curve, for those of the economics persuasion) to an system operator dispatch, if you have a carbon price, this would adjust the curvature of their bids and the dispatch would take care of the rest.

  RE: "One possible interpretation: coal remained much cheaper than natural gas last year, so when electricity demand declined, power producers turned down the gas more than they ramped down coal."

  There's a couple of ambiguities here that EcoJane hints.  Coal indeed remained cheaper than gas, but it's electricity from coal and electricity from natural gas we're comparing.  And that's almost always true.  Coal usually doesn't get ramped down - that's why it's baseload.  It needs to stay hot and fired to be efficient.

  Finally, looking at one plant is especially bad: sample size of one, anybody?  There could be a number of reasons why its capacity factor turned down and its intensity went up from poor quality coal shipped in to needed maintainence.  How else can you explain that the Amos' coal plant capacity factor went down while the overall share of electricity from coal went up at the same time?

  On Coal the culprit in rising emissions intensity posted 7 months ago 2 Responses

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  There's a pretty simple explanation why carbon intensity went up -- the peaker and more expensive natural gas plants (with half the carbon intensity of coal) turned on less often, making power cheaper, but also more of it powered by coal.

  On Power plant performance down in 2008 posted 7 months, 2 weeks ago 6 Responses