[FoRK] Mac Mini makes me ask: When does 12vdc become power standard?

Eugen Leitl eugen at leitl.org
Tue Jan 18 00:07:40 PST 2005


On Mon, Jan 17, 2005 at 09:41:39PM -0600, Wayne Baisley wrote:

> Yes.  Resistive power loss is I**2 x R.  Double the volts and you halve the 
> amps for the same power delivered.  Every halving of current cuts the line 
> losses to 1/4 of the previous.  Naturally, you then use smaller wires to 

Assuming I pave my roof with solar, or put a methane fuel cell in the cellar,
I only have to cover some 20 m worst case.

Sure, it would be a problem if it was 2-3 V, but whether it's 12 or 24, it
doesn't matter much for your typical fat copper cable.

> save money and the resistance goes up, plus you need better insulation for 
> the higher voltage.  Fairly quickly you exhaust the marginal utility.  And 
> don't forget transformer losses and the power factor losses from the 
> transformer inductances.  And safety's a factor.  We could be a lot more 
> efficient with 13.9 KV feeds to the house, but having experienced 110, I 
> think 220's too much.

I could imagine autonomous mobiles sucking their own methanol from a tank
with refuelling proboscis, or hooking up devices via hydrogen capillaries to
the house hydrogen line.

Would need leak detectors, though... one of the reasons russkies have these
yellow natural gas lines on the outside of old houses is because they're 
pretty leaky.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a>
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