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PostPosted: May 28, 2016 7:24 pm 
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E Ireland wrote:
I am a little iffy about supercritical carbon dioxide, but I suppose its plausible, mainly I have been attempting to use proven technologies for everything I can.


Coming soon to the state of Texas: http://phys.org/news/2014-10-first-of-a ... rbine.html


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PostPosted: May 28, 2016 7:35 pm 
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Thats hardly a commercial unit I can place an order for from Siemens or similar tommorow if I had the money though is it?
~480-500C supercritical steam plants are almost off the shelf items for CSP and waste processing.


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PostPosted: May 29, 2016 10:31 am 
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E Ireland wrote:
Where is Cyril R when we need him?
Ah! Cyril R, "The Mercurial," is the highest posting member of this forum; numero uno at 4971 posts to date.

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PostPosted: May 29, 2016 10:47 am 
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Canuck wrote:
E Ireland wrote:
I am a little iffy about supercritical carbon dioxide, but I suppose its plausible, mainly I have been attempting to use proven technologies for everything I can.
Coming soon to the state of Texas: First-of-a-kind supercritical CO2 turbine
Exactly!

E: Have you read through GE doing sCO2 turbine PR? Kirk attended the recent conference on sCO2 engineering. Trying to find his post about it is a needle in a haystack.

I appreciate your "proven technologies" strategy but Adam Smith wisely observed in 1776 that improvement is what we do. And sCO2 is a serious improvement over steam. But you say "only at higher temperatures." I thought even at your proposed temperature range that a sCO2 turbo will still out-perform steam. The sCO2 turbine has fewer stages and is much smaller.
E Ireland wrote:
You do however store a bit more heat by heating the molten salt up to ~600C after melting it.
And so the answer is yes.

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Last edited by Tim Meyer on May 29, 2016 10:55 am, edited 1 time in total.

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PostPosted: May 29, 2016 10:53 am 
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E Ireland wrote:
That's hardly a commercial unit I can place an order for from Siemens or similar tomorrow if I had the money though is it?
~480-500C supercritical steam plants are almost off the shelf items for CSP and waste processing.
What is the schedule for your design? Toshiba is delivering their first-of-a-kind sCO2 turbine this September to La Porte, TX.

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PostPosted: May 29, 2016 11:43 am 
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That depends, we could start construction of an AGR with a high enough reactor outlet temperature for this tommorow if we wanted.
I am watching the supercritical turbines, but I am of the opinion it will take decades for them to matter.

I would be interested in what an AGR-derived design rebuilt with a direct cycle would look like.
Might be able to be competitive and buildable soon-ish.


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PostPosted: May 29, 2016 12:10 pm 
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Very nice, E! No worries on the sCO2 turbo tech. Steam. Very well. Advanced Gas-cooled Reactor in particular? (AGR Torness at 1,364 MW(e) is expected to operate until 2030.)

Please, 67CaCl2-33NaCl (mass) ~$3.48/kWh(e) versus x pumped storage? (Apologize.) Thanks. And then if your molten salt phase-change thermoelectric battery out-performs pumped storage, re-formed sea salt being one supply, the calcium-enriched salt is abundant.

What a monster proposal! Essayons!

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Last edited by Tim Meyer on Jun 03, 2016 9:07 am, edited 1 time in total.

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PostPosted: May 29, 2016 2:31 pm 
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I was just using an AGR type reactor as an example of a design that has been built and is operationally succesful with the outlet temperatures required.
The cheapest pumped storage proposal I know about at the present time in the west is a $40/kWh 500MWe scheme in the Scottish Highlands, at Coire Glass, using Loch Ness as its lower reservoir.
And there are obviously a limited number of places where one can build such a facility.

Imagine if you will, a trench 30m x 30m, something like 500m long.
Containing half a million cubic metres of salt.
Something like a million tonnes.
48GWh(e) or so.

Its a pity, but 4000 hours worth of storage would cost $12/W of installed capacity in just salt.
So true seasonal storage is still beyond us.

I don't suppose there is any chance of ~850C reactor outlet temperatures any time soon? Then you could use 50+% efficient USC stema turbines, or SCO2 turbines downstream of the salt, and melt pure NaCl.
Just for reference NaCl comes out at 520MJ/t (thermal) - and with ~50% efficiency (780C SCO2 cycle) that will translate to 72kWh(e) per tonne.
Which at $100/t translates to $1.35/kWh. Although to be honest it might be possible to reduce that in our glorious atomic future.
Although a multi million tonne lake of molten sodium chloride would have... interesting public perception issues.


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PostPosted: May 30, 2016 9:54 am 
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Excellent analysis, E, yes?
E Ireland wrote:
It's a pity, . . . true seasonal storage is still beyond us [now] . . . [but perhaps later] in our glorious atomic future. Although a multi-million tonne lake of molten sodium chloride would have . . . interesting public perception issues.
Your skills abound; the art of understatement. Public sentiment in all things nuclear is a very "interesting public perception issue." Here in Florida, one of the biggest phosphogypsum stacks covers two square kilometers (~500 acres), as an example of man-made environmental impact so that we can grow food.

Back to the drawing board? Molten salt reactors and thermo-electric batteries are like artificial lava engineering. A few places on Earth are amenable to geothermal works in the "all-of-the-above" energy policy. Dr. Alvin Weinberg, Dr. Seaborg, the other gifted scientists, engineers, and many others at Oak Ridge back in the heady days of the Cold War must have envisioned molten salt knowing how vulnerable a nuclear pile was to loss of water coolant; and they perhaps surmised that half of our Earth's internal heat is from nuclear decay. They evidently sought to emulate the genius of nature as we often do in engineering.

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