[LINK] Geo-thermal: clean, permanent electricity

[stephen at melbpc.org.au]

Tom writes,

> > .. where are your url references for your facts ?
> 
> 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.

Ah, good then .. the above personal experiences would certainly indicate
hot-rock smarts, and so in which case supplying urls as you have is easy.

Having toured four hot rock sites, though the engineering is different
to ours, tell me, it this true?  An engineering friend relates that the
degree to which our Australian geothermal plants can be 'closed systems'
depends on skill/luck with the detonation to shatter the hot granite bed-
rock between the two bore-holes so one pumps water and the other collects 
all of it. The ideal is, apparently, to create an 'enclosed bubble' effect
of shattered granite, with no crack reaching the surface of the bedrock.
This way, virtualy all the water pumped down is reclaimed as steam, and
dissolved salts aren't an issue. Care to comment on that comment, Tom?


I guess although numbers of people are already excited and drilling, lots
depends on the Goedynamics trial. Let's hope it will offer solid proof of
concept for gov types to 'invest in infructure' in such a really smart way

With a major power plant for each Capital (paid for by each State) in the 
Cooper basin complete with their own economical and dedicated HVDC cables,
many problems will be solved. That same number of power stations again may
mean that Australia makes electric cars mandatory in future. 

You will agree Tom that Australia is already at the forefront in hot rock
research, and i guess you'd join me in suggesting Linkers lobby a little,
just to see that such promising clean technology becomes priority Aussie
infra-structure.


On a low-tech green power-generation note, for coastal areas, you might
find this concept (and website) of interest. Free power 24/7 very easily.
And, yes, that's a rock tipped from a row-boat which anchors the system :)

 http://www.wavepartner.eu/


> 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 
> 


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