[OT] Re: Gore brainwashing world to ban the light bulb!

On Mar 22, 1:54 pm, Paul Anderson <paul.ander...@xxxxxx> wrote:
In article <4602ca9a$0$8753$ed261...@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
"John Wallace" <johnwalla...@xxxxxxxxxxxxxxxx> wrote:

I put 1 kilowatt of electric power into a light, any kind of light,
tungsten, carbon arc, CFL, I get 1 kilowatt of heat in the room.
Efficiency 100%.

Creating the electiricy in the first place is usually far below 100%
efficiency.


Isn't some of the energy used to make light? Or is it less than .5%
and you are rounding up?

I think that somewhere between 5 and 15% of the electricity going
through an incandescant light bulp turns into light. But the light
bounces around the room and on each bounce a significant fraction of
it is absorbed, turning into heat. So unless some of the light goes
out the window, 100% of the light eventually ends up as heat anyway.


I put gas or heating oil, at a rate equivalent to 1 kilowatts input
power, into a typical central heating boiler (you call them
"furnaces"?) and a good part of the power input goes up the chimney
(flue?). Efficiency maybe 40-70% depending on various factors (though
modern condensing boilers allegedly do rather better than 90%).

The electric light/heater is more efficient than gas or oil, on that
basis, because all the energy goes into heating the room rather than
some of it getting wasted up the chimney.

Why, then, is heating your house with electric heat more expensive than
heating it with a furnace that uses oil or gas? I thought it was due to
the inefficiency of the electric heater, but maybe it's due to the cost
of electricity compared to oil or gas.

Good point. While converting electricity into heat is 100% efficient,
the creation of that electricity is usually far below 100% efficient.
With steam turbines I think the efficiencies are maybe 35% (though I
think someone just quoted a higher figure but it is still far below
100%). That's why electric resistance heating is more expensive than
gas or oil heat. If you must use electricity to heat, consider a heat
pump, which is much more efficient than resistance heating.


Paul

--
Paul Anderson
OpenVMS Engineering
Hewlett-Packard Company

AEF

.

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