Volume of coal per kWh

Discussion in 'General Electronics Chat' started by mOOse, Sep 15, 2007.

  1. mOOse

    Thread Starter Member

    Aug 22, 2007
    I found this article at howstuffworks interesting:

    Here is a summary (my words & format) of their results (with a small correction):

    So they end up with an answer of 712 lbs or 323 kg.
    I wondered how big a pile of coal that was.

    The density of coal is 1.1 - 1.5 g/cm^3 (average 1.3g/cm^3).
    323000 g / 1.3 g/cm^3 = 248461 cm^3 (a cube 63cm or 25in on a side)
    = 0.25 cubic meters = 8.8 cubic feet = 248 L = 66 gallons (55 imperial)

    That's per year. And per day it's

    248 L/yr = .68 L/day = .18 gallons = .72 quarts = 2.9 cups = 1.45 pints

    Here are the figures per kWh:

    .28 L = .075 gallons = .30 quarts = .6 pints = 1.2 cups

    So, on the order of a cup (or quarter liter) per kWh.

    [BTW, is there a list of useable tags?]
  2. recca02

    Senior Member

    Apr 2, 2007
    a minor clarification
    by generator efficiency you/they mean plant/overall efficiency i suppose.
    generator efficiency are quite high.(210/215 IIRC)
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    What kind of coal? I've seen figures range from 7000 to 12500 BTU per pound for coal. (That would be roughly 4.5 to 8.13 KWH per kilogram.) The density of coal also varies by both type and purity. Also, the size of a pile of coal will vary based on how finely broken up it is.
  4. recca02

    Senior Member

    Apr 2, 2007
    that is very true.
    generally power plants are designed for the coal that wud be available to them(thus depending on geography of the region).
    calorific value as well as volatile content etc varies from various grades of coal bituminous, lignite, peat, etc.
    hence blending of coal is done to get the calorific value for which the plant is designed.
    however the plant efficiency remains almost unaffected. i:e 0.4 with all regeneration and reheating etc.