August 14, 2014

IE Question: Why Power And Energy Are Not The Same

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Credit: ABC

Credit: ABC

Knowledge is power.  Staying power.  Absolute power.   My power just went out!

It’s an everyday word we use to convey a sense of strength.   Or in the last case, electricity.  Meaning energy, right?

A sleepy planet Earth seems to think so in a groovy tune called ‘The Energy Blues’ by Schoolhouse Rock:

“Energy, sometimes I think I’m running out of energy.  Seems like we use an awful lot for heatin’ and lightin’ and driving’, readin’ and writin’ and jivin’.”

As a reporter, I use the words energy and power almost interchangeably when talking about the industry.  That is, until I was corrected by an engineering professor last week.  So, I thought I would set the record straight, lest you be confused by Schoolhouse Rock.

Merriam Webster defines energy as ‘usable power,’ and also as ‘a usually positive spiritual force,’ though that one is a bit off-topic.

So, energy is the amount of work that can be done.  Power, in this context, is defined as the rate at which work is done.  They sound similar, I know, but the difference could help you understand your utility bill.

Here is a good example from a Boulder, Colorado company called Continental Control Systems that specializes in electric power metering:

A lightbulb uses 100 watts of power.  If you turn on that light for eight hours every day, it will consume 0.8 kilo-watts of energy per day.  Another way of looking at it: power is like your speedometer and energy is like your odometer.

Power usage will go up and down depending on what’s turned on or off.  But electricity usage will always go up.

It would appear then, that Schoolhouse Rock got it right on energy when it sang, “Seems like we use an awful lot for heatin’ and lightin’….”

So next time you think to yourself, ‘I just don’t have the energy to finish reading through this blog post,” at least you’re using the right word.  Because, after all, knowledge is power.