[LINK] Geo-thermal: clean, permanent electricity

[Tom Koltai]

> -----Original Message-----
> From: stephen at melbpc.org.au [mailto:stephen at melbpc.org.au] 
> Sent: Saturday, 10 January 2009 10:12 PM
> To: tomk at unwired.com.au; link at anu.edu.au
> Subject: RE: [LINK] Geo-thermal: clean, permanent electricity

> Haha .. and as usual Link choruses .. prove this .. where are 
> your url 
> references for your facts .. or, are Link simply meant to believe you?
> 

Actually - yes.
I worked on the Southern Cross Energy rollout in 2004-06 and prepared
working papers for the UN-SIDS and OEDC on alternative energy proposals
for underdeveloped economies.
I have also worked on several economic models for Carbon Credit trading
and am one of Australias 265 NEM registered REC issuers.
Additionally, I have toured Geothermal and hot rock plants in NSW, NZ,
Rejkavik and Nevada.

You quoted Wiki as stating that HVDC lost 3% over 1000 Km. I stated 2.1
kw per Km.
You omitted the Wiki part about losses :
----------------Quote
Losses
Transmitting electricity at high voltage reduces the fraction of energy
lost to Joule heating. For a given amount of power, a higher voltage
reduces the current and thus the resistive losses in the conductor. For
example, raising the voltage by a factor of 10 reduces the current by a
corresponding factor of 10 and therefore the I^2R\,\! losses by a factor
of 100, provided the same sized conductors are used in both cases. Even
if the conductor size is reduced x10 to match the lower current the
I^2R\,\! losses are still reduced x10. Long distance transmission is
typically done with overhead lines at voltages of 115 to 1,200 kV. At
extremely high voltages, more than 2,000 kV between conductor and
ground, corona discharge losses are so large that they can offset the
lower resistance loss in the line conductors.
Transmission and distribution losses in the USA were estimated at 7.2%
in 1995 [2], and in the UK at 7.4% in 1998. [3]
----------------Unquote

Ummm, what they are effectively saying is that if all your Grid
Transmission systems are sent on the same sized towers with the same
spacing between the ceramics - THEN transmission loss can be reduced to
around 11% per 100 miles.

Unfortunately in Australia, much of the GRID in NSW and VIC is 315KV
(e.g.: Snowy mountains) and Shepparton 450KV and is AC, not the DC
standard that you quoted as being more loss resistant and no where near
the 10,000 KV required to transmit power at the low loss rates you
suggested were attainable. 
Mt Piper and Wallerawang Transmission is at 10000 KV.

An excerpt from a Victorian report states that losses can be as high as
30%.
-----------------Quote
2.3.1 Transmission losses
(http://www.rirdc.gov.au/reports/AFT/04-098.pdf)
Regional generation has significant transmission loss advantages over
centralised large scale generation. Using Victoria as an example and
Melbourne as the main user of electricity in the state as having a
"transmission loss factor" (TLF) of 1.00, the variation in this
transmission loss factor across the state provides an indication of the
total loss. Yallourn Power Station, in the Latrobe Valley where the
majority of Victoria's electricity is generated has an equivalent TLF of
0.95 while Mildura and Horsham, more remote areas of the state have TLFs
of 1.09 and 1.07 respectively (Australian Greenhouse Office, 2003)1.
This suggests a relative loss of 11 per cent from the Latrobe Valley to
Horsham. Incremental losses at the end of lines may be as much as 30 per
cent (Schuck pers. comm.)
-----------------Unquote

And that's 30% for only 150 kilometres.

> And, one example (Wikipedia) "The advantage of HVDC is the ability to 
> transmit large amounts of power over long distances with 
> lower capital 
> costs and with lower losses than AC.  Depending on voltage level and 
> construction details, losses are quoted as about 3% per 1000 
> km. High- voltage direct current transmission allows 
> efficient use of energy 
> sources remote from load centers." http://en.wikipedia.org/wiki/HVDC

Unfortunately Australia has multiple transmission line technologies,
operated by different companies.
Less than 25% utilse the DC high voltage methodology due to the cost of
replacing legacy systems.

I have made available a 2 page exerpt of the draft version of a paper
that I wrote in 2005. Please review the Figure 4 Peak Energy Losses
Schematic on page 35. (http://www.kovtr.com/Energyloss.pdf) (The
finalised copy was/is commercial-in-confidence.)

Could I further recommend if you have a unikey "Numerical study of
electron leakage power loss in a tri-plate transmission line"
Barker, R. J.; Goldstein, S. A.

And for an understanding from the generators point of view.
http://www.aph.gov.au/senate/Committee/ecita_ctte/completed_inquiries/20
04-07/trr/submissions/sub06c.pdf

> 
> > Secondly - Hot Rocks Powergen requires heat exchange from 
> injection of 
> > water. So first you need to get some water out there. (Lots 
> of piping 
> > required).
> 
> Any water used is condensed and relooped. Haha where are your 
> facts re water usage? I would be delighted to partake in 
> informed discussion Tom
>
Fine, I agree, in a closed system - water is recirculated, however if
the injection system is used (as most hot rock systems are), then please
read "THE REPLACEMENT OF GEOTHERMAL RESERVOIR BRINE AS A MEANS OF
REDUCING SOLIDS PRECIPITATION AND SCALE FORMATION @
http://pangea.stanford.edu/ERE/pdf/IGAstandard/SGW/1978/Martin.pdf
Which suggests that geothermal reservoirs require "clean" fresh
replacement water to stop the pipes from scaling. (It's an old paper,
but still cited currently as best practice.)

And I quote:
www.sandia.gov/energy-water/docs/121-RptToCongress-EWwEIAcomments-FINAL.
pdf.
-----------Quote (Page 66 with reference table at P 65.)
Closed-loop cooling systems withdraw much less water than open-loop
plants, as shown in Table B-1, but a significant fraction of the water
withdrawn is lost to the atmosphere by evaporation. Consumption of water
in these plants ranges from 300 to 720 gal/MWh
(EPRI, 2002a).
-----------Unquote

So it would apear that for every MWh generated they will need around
1000 litres of water.
Ive lived out there - and there aint a lot of water..... So as per my
earlier posting.... Pipe with pumps required.

- However, on the whole I agree that distributed power systems are a
good idea, provided the hot rocks are NEAR the consumer consumption
point AND there is fresh water near by.

I think that answers your main points of contention. 
And you're right, I shouldn't answer posts amongst such a prestigious
group unless I give my references for verification purposes. 
Unfortunately, I work around 18 hours per day, usually seven days a week
and normally charge for my time, as do many others on Link. I usually
only cite references when the work is aimed at an academic or government
audience. On link, we tend to offer each the professional courtesy of
accepting ones academic background as an indication that the poster is
most probably presenting their findings as a result of serious informed
cogitation.
So, where shall I send my bill ?  ;-)

Regards,


Tom