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Posted by Dan Bloomquist on December 29, 2005, 9:51 pm

daestrom wrote:

Thanks dawstrom,
I had thought I had learned that large generation was typically 12 phase
and that it was not uncommon to distribute 6 phase widely.

Best, Dan.

"We need an energy policy that encourages consumption"
George W. Bush.

"Conservation may be a sign of personal virtue, but it is not a
sufficient basis for a sound, comprehensive energy policy."
Vice President Dick Cheney

Posted by daestrom on December 29, 2005, 10:45 pm

Well, there are a *few* lines that are more than 3 phase, but the
complexities needed on each end to interface with distribution makes such
systems rare.  More often than not it is multiple 3 phase circuits.


Posted by Chris Torek on December 24, 2005, 5:09 am
In most (PV-vs-utility-power) situations, this will probably still
be the case.

I am not sure where "here" is for you, but in most of the US, expect
this figure to rise sharply next year.  Not only has the price of
natgas doubled or tripled, coal has also gone as high as $5/ton.
(This depends on the coal: Powder River Basin coal is still relatively
cheap at about $6.50 per short ton, spot price as of Dec 16.  See
<http://www.eia.doe.gov/cneaf/coal/page/coalnews/coalmar.html> .)

Coal tends to set baseload prices while natgas sets peak prices.
Retail customer prices are a function of those two (what function,
depends on whether your utilities are still largely self-generating
regulated systems or not).  In other words, the rest of the US is
about to experience what California did in 2000-2001 (sans rolling
blackouts, one hopes).  San Diego electricity (before the legislative
cap): $.25/kWh.  PG&E (after 2001 rate hikes): $.18/kWh (five-tiered,
but that is what I paid).  Rest of country: $.12?  $.15?  Long
Island was already at $.15/kWh; maybe they will go to $.22.

For most people: air conditioners and refrigerators (then lighting,
as a distant third).  Mandatory A/C efficiency boosts were rejected
this year, so electricity usage should continue to climb.

It does, they are (although there is contention over "acceptable",
and I sure wish I could find a store here in Utah that was like
the Ace Hardware in El Cerrito, with CFs on display).  LCD TV (and
computer) screens do take less power, inch-for-inch, but there is
a general trend towards replacing the 27-inch tube with the 60-inch
projection TV.

I would guess that electricity generation is probably bigger, or at
least has more "easily save-able" carbon, because the efficiency is
so low (at all stages, generation through transmission through --
especially -- use at the retail consumer end).  (The nuke input helps
keep this down though.  Eyeballing <http://eed.llnl.gov/flow/02flow.php> ,
they actually look about equal carbon-wise to me.)  More CHP would
certainly switch it around though -- combined heat and power will
save huge amounts of "wasted" carbon-footprint, and also save huge
amounts of dollars (my WAG: somewhere around $0 billion a year in
the US alone).  The question here is not "if" but rather "when"
(and also "who gets the cash flow").

I agree with that.  Still, solar PV is fun. :-)
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (4039.22'N, 11150.29'W)  +1 801 277 2603
email: forget about it   http://web.torek.net/torek/index.html
Reading email is like searching for food in the garbage, thanks to spammers.

Posted by Jeff Thies on December 24, 2005, 7:44 am
 Chris Torek wrote:

Georgia. I think Ohio price (where I spend part of year) is slightly
higher. It's been stable for some time, but I guess those days may be

I just looked this up here:

<URL: http://floti.bell.ac.uk/energymanageme/chapter_16_main.htm  >

I'm not exactly sure what those figures mean but at 7,400 kWh / ton of
coal that would be less than a penny per kWh. Surely something is wrong.

Ouch. That makes life hard. Since deregulation for home natural gas
prices have soared to about $/therm (including all overhead).  I'm
doing spot heating with electical space heaters and I never would have
considered that before!

Not sure about the color spectrum but... I'm pleased with my GE 10,000
hour lights. About $.50 at Walmart, the ballast seems to run cooler
(and all bulbs have no flickering) than The "Bright Effects" $.00
lights from Lowes. The twist tubes (all of the above) are much better
than the folded. I've never seen them demoed side by side.

   LCD TV (and

Like SUV's huh?

Interesting chart, and it surprises me. Where are all the losses? From
what I can find of distribution losses it's about 7.2% in the states
(lost the link). The plants are so huge that I would have thought they
would be more efficient than smaller generators. My Dad used to work for
an electrical utilty (generation) and I've both seen them in action and
the diagrams of the power generation. Very complex and it sure looked to
me that they got everything out of them they could. I must be missing
something... unless this is the use at consumer end you mentioned above.
I know vampire watts (consumed when appliance is off) are often higher
than "on" watts. And I know those side by side refrigerators are none
too efficient.

   More CHP would

Well, we know where the cash has been flowing.

Fascinates me too.


Posted by daestrom on December 24, 2005, 4:26 pm

The HHV (higher heating value of coal) can run around 7400 kWh/ton.  But
that is the raw energy output.  When it is used to make electricity, the
steam plant runs at only between 25-35% efficiency (well, some modern units
are up into the 40's, but most units are older and lower).  So you only get
about 2625 kWh/ton electric at the 'busbar' at the power station.  That
works out to about 2.5 cents per kWh for $5/ton coal.

But of course, the fuel cost is only one component of the price of
electricity.  There is O&M (operating and maintenance costs), T&D losses
(transmission and distribution), and capital costs.

Most of the losses you see there are in the thermal->electric conversion (or
thermal -> mechanical in the transportation sector).  Newer plants,
especially combined-cycle gas turbine units have higher efficiencies, but
even the 'state of the art' is only about 60%.

Yes, they do try very hard.  Mainly because of the cost of the fuel used.
With high NG prices, NG plants have even more incentive to push efficiency
levels than coal plants have traditionally.

But the maximum operating temperature is limited by materials, and maximum
temperature limits any heat engine's efficiency.


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