Can someone explain what this sentence means?

"The mean power produced in this plant is 100 MW with a mean productivity of 5100 kWh/tcoal."

Specifically what does 5100 kWh/tcoal and 100MW mean?

  • 2
    $\begingroup$ I would guess it stands for "average power output of 100 megawatts" and "an average of 5100 kilowatt hours per ton of coal". $\endgroup$
    – Drew_J
    Commented Apr 3, 2018 at 14:01
  • $\begingroup$ I was about to guess the same - no issues with the units really ... $\endgroup$
    – Solar Mike
    Commented Apr 3, 2018 at 14:02
  • $\begingroup$ Well, @Drew_J , since you ninja'd the rest of us, might as well post as the answer. $\endgroup$ Commented Apr 3, 2018 at 15:47
  • $\begingroup$ The first is an efficiency figure of the power plant. Higher is better. In automotive they use kWh/g or kilowatthour per gram fuel used. It just how much energy you extract from a certain amount(weight) of fuel. The second is just the power available from the plant. $\endgroup$
    – Bart
    Commented Apr 3, 2018 at 18:59

2 Answers 2


On average, the power plant produces 100 MW of electricity, or 100 000 kW of electricity.

Per tonne of coal burned, the plant produces 5100 kWh.

Thus, the average amount of coal the plant burns per hour to generate this energy is 100 000/5100, which is 19.608 tonnes per hour.


FWIW, Wikipedia quotes coal's energy content as on the order of 6.7 kWh per kilogram. Data provided here cites anthracite as being nearly 1.5 X as energy-dense as bituminous, 30 vs 20 kJ/g . If you take those numbers you can now calculate the efficiency of the power plant in question. -- With the caveat that I'm not sure whether that's an English or metric ton referred to.

  • $\begingroup$ What on earth is an "English" ton? Do you mean the US Short ton or the Imperial long ton? That said, anything quoting in kW will almost certainly be using a metric ton. Mixing units systems is extremely unusual and heavily frowned upon. $\endgroup$
    – AndyT
    Commented Apr 4, 2018 at 7:50
  • $\begingroup$ @AndyT it may be frowned upon for us scientists, but for a "director of communications" who's promoting his power plant, all bets are off. :-( $\endgroup$ Commented Apr 4, 2018 at 13:37

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