[LINK] Hold up your hands if you Like HT Transmission Lines -Was - solar plants

[Tom Koltai]

> -----Original Message-----
> From: link-bounces at mailman.anu.edu.au 
> [mailto:link-bounces at mailman.anu.edu.au] On Behalf Of Kim Holburn
> Sent: Monday, 20 June 2011 4:33 PM
> To: Link list
> Subject: Re: [LINK] Hold up your hands if you Like HT 
> Transmission Lines -Was - solar plants
> 
> 
> While I don't disagree that home solar panels are the way to 
> go I don't agree with some of your figuring.  Also we're 
> still going to need baseload power generation so solar is not 
> going to allow us get rid of HT lines.  
> 
> On 2011/Jun/20, at 10:28 AM, Tom Koltai wrote:
> 
> >> -----Original Message-----
> >> From: link-bounces at mailman.anu.edu.au
> >> [mailto:link-bounces at mailman.anu.edu.au] On Behalf Of 
> >> stephen at melbpc.org.au
> >> Sent: Sunday, 19 June 2011 11:55 PM
> >> To: link at anu.edu.au
> >> Subject: [LINK] solar plants
> >> 
> >> World's largest solar plants for NSW, Qld
> >> 
> >> June 18, 2011 
> >> http://news.smh.com.au/breaking-news-national/worlds-largest-s
> >> olar-plants-
> >> for-nsw-qld-20110618-1g8my.html
> >> 
> >> <SNIP>
> > 
> > Err. In case anyone worked out the numbers,
> > They equal $18,460.86 per home (for 1.5 kWH equivalency) or about a 
> > 12% increase in cost over the recent Solar power initiative 
> rolled out 
> > in NSW with panels installed on consumers roofs.
> > 
> > If we add line loss (transmission loss) we find that unless 
> the power 
> > is utilised within 100 km radius we can add another 4-8% 
> transmission 
> > loss to the cost.
> 
> I don't accept those figures.  The total losses in the whole 
> of the US grid is around 6.5%.  Where does your 100km figure come in? 
> 
> https://secure.wikimedia.org/wikipedia/en/wiki/Electric_power_
> transmission
> As of 1980, the longest cost-effective distance for DC 
> electricity was 7,000 km (4,300 mi) (4,000 km (2,500 mi) for 
> AC), although all present transmission lines are considerably 
> shorter. 
> http://www.geni.org/globalenergy/library/technical-articles/tr
> ansmission/cigre/present-limits-of-very-long-distance-transmis
> sion-systems/index.shtml
> 
> 

And if the HVDC transmission lines were the only point of loss in the
Transmission network, then I might agree with you.



The 100 km figure comes in from the averages of the transmission line
length at 750/500.345/10/6.6 and .450 transmission voltages (Kv).

Additionally there is loss in each conversion of DC to AC and AC to DC
(Which is another 10% minimum on each conversion....).

DC to AC Conversion loss Problem Capital Raising:
Quote/
Google Ventures. Other investors include Kleiner, Perkins, Caufield &
Byers, Foundation Capital, and Lux Capital. It has raised $38 million in
three rounds of venture funding and received a Department of Energy
ARPA-E grant last July for about $2.95 million. 
/Quote: [From http://news.cnet.com/8301-11128_3-20035490-54.html]

Much of the worlds Transmission systems rely on old AC systems as do the
local distribution sub-stations. However, long distance are being
converted to HVDC. 

So 6.6% + 10% ... + ???

The losses also depend on the load on the local segment of the Grid at
the time, [i.e.: have the Grid operators reduced the input power to
match the load], the temperature, how hard the wind is blowing, rain,
how old are the cables, humidity and how many other feeder lines are
trying to dump power into the local section of the Grid.

And how fast can they shed load ? Believe me it isn't fast enough. Just
what does happen to all that extra unshedded load ? Is it lost as
Ballast into the local dummy load ? 
Your mission is to calculate just how many millions KV's are lost to
Grid load management feeder cut-backs... 
We are no longer talking about 6.6% + 10%.

You quoted the same segment of Wikipedia, that well known final arbiter
of all things technical in April this year. I didn't answer then,
because quite frankly the learning curve is so steep that this forum is
far from a suitable environment within which to attempt to teach such a
topic, AND I am not a qualified teacher.
http://mailman.anu.edu.au/pipermail/link/2011-April/092929.html

However I quoted a source then (the 100 mile thing):
http://kovtr.com/data/Graph_Relative_line_losses_for_various_transmissio
n_voltages.gif

Which would still be relevant today.

Utility companies realise that the public need to believe that
Transmission losses are low so that the argument for centralised power
transmission can continue to be sold as an ipso facto "best practices"
bill of goods.

With Hydro and Coal Mining Sources, it was fifty years the "cheaper"
option.

The national trading of electricity in all countries depending on the
daily temperature and loads would be contra-indicative truism of that
particular logic [bill of goods].

An excellent blog article : AC vs. DC - The Westinghouse / Edison War
Continues

http://energyzarr.typepad.com/energyzarrnationalcom/2009/02/ac-vs-dc-the
-westinghouse-edison-war-continues.html

TomK