Michel seriously needs to study electrical engineering, for the follow ing
post is permeated with ignorance and misunderstanding of history and phsyics
and the hows and whys that produced the system we now have.
----- Original Message -----
From: "Michel Jullian" <[email protected]>
To: <[email protected]>
Sent: Friday, September 18, 2009 5:56 AM
Subject: Re: [Vo]:DESERTEC solar thermal plan
According to that paper, electricity can be transported over very long
distances (from North Africa to all of Europe in their project) with
only minor losses (15%) using HVDC power lines.
HVDC has been used for lomg distance electric power transmission in Europe
for decades.
If that's true, it seems to me that with such a HVDC grid, renewable
energy doesn't have to be stored any more, apart from mobile
applications of course.
False. The problem of power storgae does not go away with HVDC. At
nightfall, the African solar arrays go dead.
An additional advantage of DC occurs to me, you no longer need an
expensive inverter to push your home grown power into the grid, a
simple boost converter does the trick!
False.
Solar cells produce volts, the transmission is in the hundreds of kilovolts.
The conversion, if efficient, requires expensive and sophistacted solid
state inverters -- much more expernsive than the transformers in an AC
system, and not as reliable.
Who was the idiot who invented AC power transmission in the first place?
;-)
Their names were Tesla and Stanley and were backed by Westinghouse. There
was an epic battle between Edison and Westinghouse over Edison's DC system
and the Tesla - Stanley approach. AC systems require sophisticated math to
understand, which Edison did not have. Motors, necessary for industry and
appliances, of the type known at the time, do not work well on AC. Tesla
invented the polyphase induction motor which was and is the key to
industrial and motive applications. Stanley develped the transformers which
efficiently interface between safe domestic voltage and high voltage long
distance transmission -- making the extensive power grid possible.
All this was done by very capable men working with the technology available,
to the benefit of millions in many nations.
M ichel's comment reveals who is the "idiot".
It was not until almost a century later that semiconductor technology was
able to propduce the "switching power supply" for both small and large scale
use. Transformers operating at 50 or 60 Hz must be massive and use lots of
iron and copper. If the transformers operate at tens or hindreds of
kilohertz, the amount of iron and copper is greatly reduced, but the
function remains. Switching power supplies are now found in computers,
CFLamps, and in AC/DC converters/inverters for HVDC power transmission.
Mike Carrell
