kW and kWh - The media dont know the difference

Plasticman

fluffnutter wrote: »

That's an interesting distinction but I'm wondering if the nuances aren't lost on most of the listeners. If the presenter had said 'Google uses x amount of billions of kWh per year' with x being the same as the x you quote in your example then I assume you'd have been happy. I'm also assuming that the listener is actually interested in the accumulated total used in a year (kWh) not the amount of energy Google uses (kW).

I wouldn't worry about the nuances - the facts are probably lost on most of the listeners. They probably didn't get much further than "Man on radio says Google is evil".

fluffnutter

Perhaps I didn't need to go any further than...

fluffnutter wrote: »

I'm also assuming that the listener is actually interested...

We have a radio on in our office (horrors!) and it's pretty evident that I'm the only person who even notices it. If I'm particularly distracted and ask for it to be turned off, the most common response is 'I didn't even realise it was on - I tune it out and don't listen to it'. Makes you wonder why they bother switching it on each morning...

pknottm

ComplexP wrote: »

'Google uses x amount of billions of kW per year'.

kW is an instantaneous measure. kWh is accumulated total.

So for example, if your electric heater uses 2kW of power that means it is using 2kW of power if it is on, full stop. If you leave it on for 8 hours, it's used 2x8 = 16kWh (kW Hours) of energy during that time.

Just to add to the confusion:-

Surely "kW per year" is also an accumulated total of power used as well, ie: the amount of instantaneous kW used in a year. Admittedly it's not the standard unit of power.

1 billion kW per year = 1,000,000,000/(365*24) = 114,155.25kWh

Radio 2 could either have quoted the wrong units, or they could have quoted kW per year to make the consumption sound worse than it actually is.... 1 billion kW per year sounds more than 114,155.25kWh?!!

ComplexP

pknottm wrote: »

1 billion kW per year = 1,000,000,000/(365*24) = 114,155.25kWh

Interesting thought, and I know what you mean but I'm not quite sure it follows because...

What you have worked out there is not kWh but the kW per hour (kW/h) for the year and that's assuming that ever hour of the year was exactly the same in terms of power consumption, in that case a constant 1 billion kW. If it wasn't, you've basically just worked out the average hourly kW figure.

If something was running at 1 billion kW constantly for a year you'd actually have 1,000,000,000*(365*24) = 8.76x10^12kWh or

8,760,000,000,000kWh

if you prefer it in non-standard form

DVardysShadow

ComplexP wrote: »

I just heard a factoid on Radio 2 (which I love by the way) saying that Google uses more power per year than some countries to power its search engine which is quite interesting.

But predictably they quoted the figures in kW, ie. 'Google uses x amount of billions of kW per year'. ...


It's a small thing but I wish they'd get it right.

It all starts to go wrong when they say "power per year' They mean energy per year.

DVardysShadow

pknottm wrote: »

Just to add to the confusion:-

Surely "kW per year" is also an accumulated total of power used as well, ie: the amount of instantaneous kW used in a year. Admittedly it's not the standard unit of power.

1 billion kW per year = 1,000,000,000/(365*24) = 114,155.25kWh

Radio 2 could either have quoted the wrong units, or they could have quoted kW per year to make the consumption sound worse than it actually is.... 1 billion kW per year sounds more than 114,155.25kWh?!!

Full marks for adding to the confusion. kW per year is a rate of change of power. It doesn't make a lot of sense. But it would be correct to say something along the lines that the daily peak power consumption of an area was increasing by so many kW per year.

I would agree that

1 billion kW per year = 1,000,000,000/(365*24)

but this is 114,155.25kW/h - ie kiloWatts per hour NOT kWh - ie kiloWatthours.

ComplexP

DVardysShadow wrote: »

It all starts to go wrong when they say "power per year' They mean energy per year.

Good point.

ComplexP

DVardysShadow wrote: »

I would agree that

1 billion kW per year = 1,000,000,000/(365*24)

but this is 114,155.25kW/h - ie kiloWatts per hour NOT kWh - ie kiloWatthours.

That's what I said :beer:

pknottm

ComplexP wrote: »

Interesting thought, and I know what you mean but I'm not quite sure it follows because...

What you have worked out there is not kWh but the kW per hour (kW/h) for the year and that's assuming that ever hour of the year was exactly the same in terms of power consumption, in that case a constant 1 billion kW. If it wasn't, you've basically just worked out the average hourly kW figure.

If something was running at 1 billion kW constantly for a year you'd actually have 1,000,000,000*(365*24) = 8.76x10^12kWh or

8,760,000,000,000kWh

if you prefer it in non-standard form

oops, sorry, yes you're right! :beer:

What I meant to say is that the original fact may have been correct as they stated power (kW) per year. If they had stated energy, then it should have been kWh.

energy (kWh) = power (kW) x time (hr)

I agree that original fact is very confusing. Perhaps an email to radio 2 to clarify whether they meant energy or power?!

ComplexP

They'd probably put it in the 'loony' pile. :rotfl: