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Power generation specs I see quoted

Discussion in 'Electronic Basics' started by PT, Mar 20, 2005.

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  1. PT

    PT Guest

    This may not really be a good quesion for this group since it is really
    about power generation on the utility level rather than about
    electronics but here goes since I am sure many of you will have some
    insight to this stuff...

    Today's Boston Globe had an article about places like Fenway Park (Red
    Sox), the Fleet Center (Celtics & Bruins) and Gillette Stadium (Pats)
    and the amount of power they use during a game. The numbers under the
    photos gave stats like '3000 kilowatts used during a game, enough to
    power 2250 average homes'. So I am sitting there drinking my coffee and
    reading this and thinking to myself, self, this doesn't seem right
    since that is less than 1.5kW per home. A single hair dryer will draw
    more power than that.

    But as it turns out, this appears to be a number that is often quoted
    for stating the generation capability of a power plant. 1MW for 750
    homes. While I understand that not each and every home is going to be
    pulling as much as they can all the time, it does seem likely that a
    significant number of them would be needing more than a single hair
    dryer of power. At 3am, most home are not using much power, but at say
    8pm, MOST of those 750 homes probably have the TV on, a half dozen or
    more lights on, fridge is running since it has been opened a lot for
    dinner, etc. Even if only half those 750 homes are using only 3kW, that
    is well over the 1MW capacity of the utility.

    So my question is, how does this number hold up? Seems like yes it is
    possible that over the course of a day many homes will not be using
    that much, it seems as likely that many homes would be using a
    significant amount of electricity at the same time many times a day and
    you would have more brown outs and power failures than we have. So what
    is the deal?

    PT
     

  2. Firstly, I cannot answer your real question without
    either doing some tedious research or making the
    same kind of off-the-cuff analysis you have. But
    since your post is lingering unanswered here, I
    will offer these few thoughts and suggestions.

    1. Getting one's view of reality from the Boston Globe
    or any other single member of the mainstream media
    is a formula for becoming misinformed and ignorant of
    events and situations you would want to know about.
    So, on that basis alone, I see no reason to worry about
    explaining a discrepency between what your common
    sense tells you and what that paper says. Reporters
    are notoriously loose with facts and numerical facts
    are often taken from one context and used in another
    with (one hopes) little idea of the resulting distortions.

    2. It is a near certainty that your power company
    knows the right number for houses in general and
    likely breaks them down somewhat further. You
    might be able, with a few phone calls or a visit to
    their website, be able to get the right number.

    3. You could ask your friends and neighbors what
    their electricity bills have been. That would quickly
    provide a quick sanity check on that suspect report.

    4. You could look at your own electricity bill and
    compare your level of consumption to what you
    know or surmise about other households, then
    make a straightforward calculation to derive your
    own number. I would tend to believe that over an
    unattributed number in a mainstream rag any day.

    I, too, am skeptical of that number, both for its
    magnitude and from its source. It certainly does
    not comport with what my family uses or any of
    my neighbors, from what I can see. But it is not
    quite so low as to be patently ridiculous. (It is
    close, but maybe Bostonites are very good at
    the whole panoply of conservation tactics.)
     
  3. BobG

    BobG Guest

    Average usage is about 1000 KWhrs. My bill is about $120 and price is
    about $0.12 a KWhr. However, I have a 100 amp vreaker on my panel at
    240V, so with everything on, I might be pulling 20KW. As you said
    things start browning out about 5 when everyong gets home, turns on the
    tv, stove, opens the fridge, lowers the ac, etc etc
     

  4. Power generation and distribution isn't quite as simple as just saying X
    Megawatts for Y homes. There are three different types of powerplants.
    Base load, intermediate load, and peaking plants. Base load plants are
    primarily (in the US anyway) composed of coal and nuclear plants that
    operate for as much of 24 hours a day as possible at as close to 100%
    capacity factor as possible. Base load plants are normally expensive to
    build, but are optimized for high thermal efficiency and consequently low
    fuel cost. Intermediate load plants typically operate somewhat less than 24
    hours a day, but more than peaking plants. Peaking plants are not designed
    for high efficiency, they are designed for low capital cost. They are also
    designed to be turned on and off on short notice. These plants will
    typically operate for only a few hours a day, just during the peak
    consumption periods of the day. Oil (very expensive fuel cost), low thermal
    efficiency natural gas, and many hydroelectric generating stations are
    examples of peaking plants, at least in the US.

    I assume that number quoted in your newspaper article was a long term
    average of sorts, but I don't know.
     
  5. JeffM

    JeffM Guest

    '3000 kilowatts used during a game, enough to power 2250 average
    homes'.
    The thing being that you don't run it continuously.
    These thing are meaned out over time.
    The fridge and A/C are the heaviest draw and they are intermittent too,
    cutting in & out as the thermostat demands.
    If everybody's peak demand came at he same moment,
    yeah, there'd be a problem.
     
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