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Ok im mad confused about generators and kilowatt/kw hours

  1. Mar 30, 2008 #1
    Ok im mad confused about generators and kilowatt/kw hours....

    And how the power companies price stuff.

    http://www.peakpowertools.com/ProductDetails.asp?ProductCode=GGNQT100&Show=ExtInfo [Broken]

    That thing produces 100kW

    I pay roughly 7 cents per kW hour from my power company.

    So if I used the same amount of power as that generator puts out running for a full month at that price, would I pay $7 or would it be more cause its rated at kW and not kW hour, which im sure is the case, I just dont know how much more... how much more would I pay???

    Cause for the size of that generator running for a whole month I would expect it to put out a hell of alot more that $7 of electricity.
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Mar 30, 2008 #2

    dlgoff

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    If you have a load of 100 watt for 10 hours, that's 1 kwh.
     
  4. Mar 30, 2008 #3
    OK... im confused by your confusion.

    If you were using 100 kW for 1 hour and paying 7 cents per kW-hour, you would pay $7 for the privilege. A month would be longer.
     
  5. Mar 30, 2008 #4

    brewnog

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    A kWh (kilowatt-hour) is a unit of energy. A kW (kilowatt) is a unit of power. One kWh is the amount of energy transferred over one hour at a power of 1 kW. If you ran a 5kW heater for 2 hours, you would use 10kWh of energy.

    If you use 100kW constantly for thirty days, that would be 72,000kWh of energy (720 hours x 100 kW). At 7 cents per kWh, that works out at $5,040.
     
  6. Mar 30, 2008 #5

    russ_watters

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    Just a note, I don't know the purpose of this exercise, but real commercial electric bills are much more complicated. You pay based on load factor (how consistent the load is) and demand as well as total consumption. So if you're trying to decide if a generator might be a good idea to cut your electric bills, you'll need to take that into account.
     
  7. Mar 30, 2008 #6
    Ok yah this is exactly what I was think, but I had nothing to base it off of to be sure. Thanks guys.
     
  8. Apr 1, 2008 #7
    Average actual cost of electric power in the United States is 10.6 cents per KWhour. It varies greatly from state to state. The cheapest is Washington state at 7 cents. I imagine it's a result of readily available hydrolic power, and federally subsidized dams.

    Hawaii has the highest prices at 24 cents. 51% of electric power generation is through burning coal, having exceptional energy per dollar cost for heat engine generation.

    Those in low sulpher, coal rich states should experience a better price break than average. Environmental and community activism can push up the price in places like California where they pay 14 cents.
     
    Last edited: Apr 1, 2008
  9. Apr 2, 2008 #8

    stewartcs

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    Good point.

    I think load factors are such a rip-off, you have to pay more for using less.

    CS
     
  10. Apr 2, 2008 #9

    brewnog

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    But how would you feel if you were a power company trying to guarantee supply for a completely unpredictable demand?
     
  11. Apr 2, 2008 #10
    Wow the fuel consumption on that generator is 15 gph of lp. If I bought enough gas to run it for a month it would cost $40,000.

    Electricity is cheap.
     
  12. Apr 2, 2008 #11

    brewnog

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    15gph of lp?

    What does that mean?
     
  13. Apr 2, 2008 #12

    Integral

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    lp = liquified Petroleum = propane

    gph = gallon per hour.
     
  14. Apr 2, 2008 #13

    russ_watters

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    Note, natural gas is slightly more than half the cost of propane.
     
  15. Apr 2, 2008 #14

    Averagesupernova

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    Natural gas also has less BTU per unit than propane. Not sure how much, but it is significant.
     
  16. Apr 2, 2008 #15

    stewartcs

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    The demand is predictable, it's just not constant which is why they charge you the load factor. Load factors are used by power companies to "spread" the cost of the capital expenditures they have incurred as a cost of doing business. The cost of doing buisness is the power line, transformers, etc. in the distribution system that were orginally designed for a predicted load. So, if you don't use power as they predicted, you have to pay more so they can make the profit they want.

    CS
     
  17. Apr 2, 2008 #16

    russ_watters

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    It is, but even when you include that, propane is still almost twice as expensive on a per btu basis.
     
  18. Apr 3, 2008 #17

    jim mcnamara

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    You seem to be in the US - most utiltities here allow cogeneration. Ask your power company. You can actually sell power back to the the "grid" and keep track of it with net metering

    If your operation runs mostly during the day, projections for energy generation costs strongly suggest that you look at photovoltaic cogeneration. This has limited practicality right now for high demand applications, like running an electric kiln. Most US utilities have a fuel adjustment or fuel surcharge that the public power commission allows them to charge. A LOT of bucks will be in that one item as time goes on and as fuel costs rise.

    The other price driver is demand. If you turn on all your compressors (as an example) at 8:00 am you are pushing demand thru the roof. Each KwH costs more as demand goes up. For the whole month.

    Sequentially starting large motors- ie. start #1 wait a minute, then start #2, etc. will decrease demand. But if you screw up just once, then increased demand charges will be in effect for the whole monthly billing period.

    Get an energy audit - if you do not know which gizmo drives up demand/consumption, ask for check meters to be installed for a month or two.
     
  19. Apr 3, 2008 #18
     
  20. Apr 3, 2008 #19

    dlgoff

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    Not according to http://www.propanecost.com/btu.php" [Broken].
    $5.68/million BTU for propane
    $5.00/million BTU for natural gas

    EDIT: this was copyrighted in 2003
     
    Last edited by a moderator: May 3, 2017
  21. Apr 4, 2008 #20

    FredGarvin

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    I've had the privilege of helping to look at how our company can save electrical costs. I can say with some certainty that the way electric bills are calculated is an order of magnitude more complicated than the systems used for cell phones and airline ticket pricing.
     
  22. Apr 4, 2008 #21

    stewartcs

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    I didn't think that was possible! :rofl:

    CS
     
  23. Apr 4, 2008 #22

    russ_watters

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    I think that may just be a sample calculation - none of the numbers look anywhere close to what the fuels actually cost (their propane number is one fifth what it actually costs!). I last did this calculation a year ago, but here are the numbers for my last months' propane bill:

    $2.695/gal
    91,000 BTU/gal (91 MBH)
    $.0296/MBH

    For natural gas, these prices may be wholesale, so if anyone has a bill, that would be helpful...
    http://tonto.eia.doe.gov/oog/info/ngw/ngupdate.asp [Broken]
    $18/1,000,000 BTU
    $.018/MBH

    Difference: 65%

    So perhaps not as bad as I thought - perhaps natural gas has been rising faster than propane: my propane is 15% more expensive this year than last.
     
    Last edited by a moderator: May 3, 2017
  24. Apr 4, 2008 #23

    russ_watters

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    I disagree: my dad makes a living by saving companies money on utility bills and at the very least, there are far fewer electric rate options. And those calculations take a short one-page Excel spreadsheet. He spends much more time on phones than electric rates.

    Commercial electric bills work something like this:

    Fixed per kW fee (somewhere around $12/kW)
    Three tiers of kWh fees, something like 80*kW, the next 80*kW, and the rest. (these are broken down further into generation, distribution, and transition charges, but they are constant for each tier)
    Various fixed fees

    There are a variety of optional things, but virtually all of them reduce your bill, they don't increase it (such as time of day metering)

    Now the thing about the demand is that not only does it make the per kWh charge higher (the first tier is more expensive than the third) and not only does it have its own fee associated with it, but the electric company uses your summer peak to set the minimum (usually 80%) for the rest of the year. So an extra kW of demand for a half an hour in the summer may cost you $100 or more.
     
    Last edited: Apr 4, 2008
  25. Apr 6, 2008 #24

    russ_watters

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    I'm at my parents' for brunch today - my dad paid $1.30/ccf last month for natural gas, so that's $.015/MBH -- and propane is a lot worse than it was before: 127% more expensive than gas. My dad was saying that natural gas has actually come down a little in the past year and propane tends to follow oil prices (since it is a derivative of oil).
     
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