
Solar plant has generated “supercritical” steam - roberthahn
http://csironewsblog.com/2014/06/03/our-solar-team-sets-a-hot-and-steamy-world-record/
======
mmaunder
This is important because it increases generator efficiency.

[http://en.wikipedia.org/wiki/Supercritical_fluid#Supercritic...](http://en.wikipedia.org/wiki/Supercritical_fluid#Supercritical_fluid_in_power_generation)

Supercritical fluid in power generation

The efficiency of a heat engine is ultimately dependent on the temperature
difference between heat source and sink (Carnot cycle). To improve efficiency
of power stations the operating temperature must be raised. Using water as the
working fluid, this takes it into supercritical conditions.[20] Efficiencies
can be raised from about 39% for subcritical operation to about 45% using
current technology.[21] Supercritical water reactors (SCWRs) are promising
advanced nuclear systems that offer similar thermal efficiency gains. Carbon
dioxide can also be used in supercritical cycle nuclear power plants, with
similar efficiency gains.[22] Many coal-fired supercritical steam generators
are operational all over the world, and have enhanced the efficiency of
traditional steam-power plants.

------
quink
> The $5.68 million research program is supported by the Australian Renewable
> Energy Agency and is part of a broader collaboration with Abengoa Solar, the
> largest supplier of solar thermal electricity in the world.

Australian Renewable Energy Agency (ARENA). Let's see what the first Abbott
budget had to offer up on this matter:

> Finance Minister Mathias Cormann confirmed yesterday that the Australian
> Renewable Energy Agency (ARENA) will be discontinued in the 2014-15 Budget.

Fun times, Australia. What fun!

~~~
NamTaf
The CSIRO really is a gem in this country's crown. The amount they return on
investment given is really quite impressive and their focus is directed
towards our partiuclar problems (e.g.: agricultural research, ocean-based
research, etc.) which may not necessarily be considered as equally by overseas
research centres.

To gut their funding is really very depressing.

~~~
Gustomaximus
Not trying to turn this thread into a political discussion but this
announcement couldn't come at a better time for the Greens (for non-Aussies
they are an environmentally focussed political party with influence via their
holding balance of power to the major 2 parties). The Greens are looking to
block cuts to the Clean Energy Finance Corporation. It's not the CSIRO but
this showcases what some scientific investment can achieve and hopefully stops
the planned cuts across our research facilities being too deep.

[http://www.sbs.com.au/news/article/2014/06/15/greens-move-
bl...](http://www.sbs.com.au/news/article/2014/06/15/greens-move-block-clean-
energy-cuts-sets-double-dissolution-trigger)

~~~
quink
Ahhh, the CEFC.
[http://www.afr.com/p/national/clean_energy_profits_up_in_smo...](http://www.afr.com/p/national/clean_energy_profits_up_in_smoke_qQFE6H3pjYYoCcKnOim9cL)

$200 million annually in profit by 2017 for the government through investment
in renewables. But making money from renewable energy is, one should remember,
'utterly offensive':

[http://www.abc.net.au/news/2014-05-02/joe-hockey-wind-
turbin...](http://www.abc.net.au/news/2014-05-02/joe-hockey-wind-turbines-
utterly-offensive/5425804)

The CEFC is a commercial investment in actual rollouts of renewable energy
with a 7% return on investment. The Abbott government, however, says 'bugger
that, we hate evil renewable-tainted money' (or something like that) and is
currently looking forward to passing legislation to abolish the CEFC as one of
the first things the new Senate will do once the new Senate meets in about two
weeks' time.

Note also that, if it weren't for that the $200 million might well grow to
$520 million pretty handily - they've got $10 billion in applications:

> The Portfolio Budget Statement does not include the significantly higher
> positive contribution to the Budget the CEFC would make if it was able to
> continue to carry out its investment function over the forward estimates
> period. Were it to do so, the CEFC would deliver a net cash surplus (profit)
> for the Government of more than $520 million, net of operating costs.

This government is committed to throwing away $500 million and more for
taxpayers in money companies are willing to borrow and pay back - with
interest - to roll out renewable energy schemes.

It's like "Dear government, if you give us x amount of money, this lender over
there will give us 2x of money, and I'll pay you back both, with interest.
This is for us to change all the lighting across this huge area to use a third
of the energy.", and the government saying, instead of "let's have a look at
your business case and assure everyone this is a sound investment for us and
your claim actually checks out and we'll all make money" a "lol, no".

------
abdullahkhalids
Please keep in mind that efficiency in itself does not mean much. The variable
you have to optimize is cost per unit of energy.

Supercritical steam is useful for fossil fuel generation because it is
relatively easy to make closed off systems which can withstand high
temperatures/pressures. The optimum for solar power might lie at the much
lower temperature. Why? Because the cost of solar array as a function of
desired temperature rises much faster than that of a fossil fuel generator.

~~~
illumen
They address cost in the article.

"So instead of relying on burning coal to produce supercritical steam, this
method demonstrates that the power plants of the future could be using the
zero emission energy of the sun to reach peak efficiency levels – and at a
cheaper price."

They also say that it is not ready to be used commercially. But this
organisation is quite good at making things commercially viable. Rather than
just doing research for tax breaks.

From one of the researchers: “Steam flowed at around 330kg/hr , which equates
to a little over 300kW of adsorbed solar energy. The experiments were designed
to represent a single element of large scale design, so scale up is related
more to multiplicity than redefining heat and mass fluxes.”

This experiment was done so they could scale up production of power by just
adding more of these.

~~~
tankenmate
Actually the CSIRO (Commonwealth Science and Industry Research Organisation)
is owned by the Australian Government; so research for tax breaks isn't the
reason. The CSIRO has a largely good reputation amongst scientists and
researchers in Australia. And they have a reasonably good commercialisation
rate as well; their WiFi patents (most of which have recently expired if I
remember correctly) have earned the Australian government nearly one half a
billion dollars.

~~~
dwd
And the current pro-coal/oil/gas Abbott government is cutting funding to ARENA
(Australian Renewable Energy Agency), who funded this project, by $435 million
in the new budget.

------
Sniffnoy
Can anyone explain just what it means for the steam to be "supercritical"? The
article doesn't seem to have explained it at all.

~~~
jjoonathan
Temperature-pressure phase diagrams (example linked below)

[http://images.flatworldknowledge.com/averillfwk/averillfwk-f...](http://images.flatworldknowledge.com/averillfwk/averillfwk-
fig11_022.jpg)

have a line that separates gas from liquid, but this line has a finite length.
One endpoint is on the triple point (solid, liquid, gas coexist at one P,T)
and the other is on the critical point. That's where the distinction between
gas and liquid vanishes -- the viscosity, index of refraction, etc of one
phase approach those of the other until differences vanish altogether at the
critical point. It's a little arbitrary to say that steam at a given
temperature or pressure is supercritical (there IS a rigorous definition,
T>T_criticalpoint&&P>P_criticalpoint, I'm just saying that it's a bit
arbitrary), but the gist of it is that you're in the part of the phase diagram
where movement in the phase plane is going to avoid the gas/liquid transition.
Nothing physical happens in a liquid->supercritical or supercritical->gas
transition and there are no phase transitions in the supercritical region.

This is exploited for the production of aerogel. Normally you can't dry out a
gel and have it retain its shape because the liquid/gas interface during
evaporation/boiling has enough surface tension to tear apart the
microstructure of the gel. But if you scoot around the liquid/gas transition
in phase space (e.g. by heating past T_criticalpoint, lowering pressure below
T_criticalpoint, cooling below T_criticalpoint, and finally releasing any
lingering pressure, or in other words liquid->supercritical->gas) then you can
get rid of the liquid without ever boiling/evaporating it -> no nasty surface
tension to tear apart the microstructure!

Here is a video of CO2 being heated past the critical point. Since there is a
gas-liquid equilibrium, the system will move more or less exactly along the
curve separating gas from liquid until it "slips off the end" into the
supercritical region:

[https://www.youtube.com/watch?list=FLAv56CgHL4P8vk6FDm9s1Zw&...](https://www.youtube.com/watch?list=FLAv56CgHL4P8vk6FDm9s1Zw&feature=player_detailpage&v=GEr3NxsPTOA#t=150)

EDIT: || -> && in the formal definition

EDIT2: linked a phase diagram for those who don't stare at them all day :)

~~~
jwheeler79
in layman's terms anyone?

~~~
femto
If you heat water under a high enough pressure, when you release the pressure
it instantly becomes stream.

Normally, when you boil water the vapourisation happens piecemeal. That's why
you see bubbles rising to the surface. For supercritically heated water, the
vapourisation is a runaway chain reaction, triggered by a reduction in
pressure, so the whole body of water flashes into stream.

\--- Edit: added note about reduction in pressure being the trigger.

~~~
neltnerb
Apologies, I don't want to be pedantic, but this has nothing to do with being
supercritical.

[https://en.wikipedia.org/wiki/Supercritical_fluid#mediaviewe...](https://en.wikipedia.org/wiki/Supercritical_fluid#mediaviewer/File:Carbon_dioxide_pressure-
temperature_phase_diagram.svg)

You can note in this diagram that what you are describing is true whether or
not the system is supercritical, and can be seen in how water will boil into
steam when the pressure is decreased from atmospheric as well.

What you are describing is how higher pressures allow you to add energy to the
water while it remains liquid, and how if you add enough energy it will
overcome the enthalpy of vaporization and cause it to convert to steam as the
pressure is reduced.

~~~
femto
Point taken! I'm not an expert.

As I understand it, a container of boiling water will have liquid in the
bottom half and steam in the top half. As the pressure and temperature rise,
the steam/water goes supercritial, meaning the water/steam boundary disappears
and the whole container becomes a homogenous mush of supercritical fluid.

Am I right in thinking that this supercritical fluid can flash into steam
faster than a combination of water and steam? My thinking is that for a
water/steam combination to convert into steam, the water molecules have to
take the time to break their bonds and separate into a gas. For a
supercritical fluid it's faster because there are no bonds to be broken?

I'd be grateful if you can correct the above, as I can learn something here.

~~~
neltnerb
There aren't really formal bonds being broken transitioning from liquid to
gas, but I suppose it is fair to say that the supercritical state will
transition more quickly to steam than a subcritical liquid with enough energy
to become steam at atmospheric pressure.

The reason for that would be that there is a nucleation process in forming gas
from liquid, which does take some time. Or at least more than not needing to
do so.

There is some terminology you're using that bothers me, like "flash into
steam" isn't really a good way to describe it. At that point you'd be better
off describing it as "super pressurized steam" converting to "normal pressure
steam" or something. It's just expanding, but there is no flash (which to
implies a sudden change). It's gradually and continuously decreasing in
density.

I think part of this may be confusion over how we overload the word "water" to
mean "liquid water" as well as "water the chemical". I am meaning "water the
chemical" which can be a solid, liquid, or gas. Steam is water that is a gas.

With a supercritical system, you can take liquid water, stay in the liquid
state until the water becomes supercritical (where the liquid and gas phases
are indistinguishable), and then move across a boundary from "liquid like" to
"gas like", go back into a sub-critical state as gas, and never formally
boil/flash/etc.

~~~
femto
Thanks for the explanation.

------
keypusher
That's really great but the unsolved hurdle in solar power is energy storage.
You can generate a large amount of energy on bright, sunny days but what
happens at night when people go home and turn on their lights, television, and
computers? Without a way to offer on-demand energy, solar will never be able
to replace traditional coal and gas-fired plants. Wind power does fare better
throughout the day, but is still subject to the whims of the weather. The big
piece of the puzzle still to be solved is large scale battery/storage
technology.

~~~
TheSpiceIsLife
Why are people down-voting this comment? Is being correct not allowed? In
Australia it is often not sunny for days on end, also it is often not windy
for days on end, over huge areas of land - you know, like, bigger than a lot
of European countries.

For wind and solar to be economically competitive with coal / gas / nuclear
they have to be at price parity including 24+hrs storage. This isn't going to
happen any time soon without massive government incentive.

Professor Barry Brook of Adelaide University has been blogging about this for
a good few years now. We need to think critically about 'sustainable energy'.
I encourage you all to read his blog [1], particularly the TCASE [2] (Thinking
Critically About Sustainable Energy) series.

Let's level the playing field: ultimately there are only two good metrics
worth considering a) life-time cost per kWh and b) life-time CO2 emissions per
kWh --- but to level the playing field you need to consider each generating
technology on a base-load comparison. It's no good comparing a 1GW gas plant
and a 1GW nameplate solar installation _because the sun only shines about
6.5hrs per day averaged throughout the year in, say, Adelaide for example_ ,
so you typically need to over-build solar by a factor of 4 and then add
storage. When you do that the life-time cost and life-time CO2 emissions
aren't so crash got because of the massive amounts of energy intensive
stainless steel, steel, and concrete required, plus new transmission lines.

If you want to see a real-world example of how wind _does_ work, check the UK
National Grid Status site [3] - the wind hasn't been blowing in the UK for
_weeks_ , presently their 8GW of installed wind is generating 0.82GW
electricity.

The data speaks for itself, look at the graphs. A vote for wind / solar _is a
vote for new gas_ _because_ gas is easily load following. Of course, the gas
plant owners don't like that because when the wind blows their plants sit
idle.

The whole renewable energy push is an expensive mess. I've commented elsewhere
on HN about this, so I'll stop repeating myself now.

1\. [http://bravenewclimate.com/](http://bravenewclimate.com/)

2\. [http://bravenewclimate.com/?s=TCASE](http://bravenewclimate.com/?s=TCASE)

3\. [http://www.gridwatch.templar.co.uk/](http://www.gridwatch.templar.co.uk/)

Edit: formatting

~~~
threeseed
> The whole renewable energy push is an expensive mess.

So what ? ALL energy production is. But I would rather take a clean, renewable
source of energy over the polluting coal/gas or the unsafe nuclear kinds.

And a country like Australia would be amazing for renewables provided we could
have a country wide power grid. It is windy almost every day in say Fremantle
and likewise sunny almost every day in many northern/central areas.

~~~
TheSpiceIsLife
I'm not convinced you read my comment, so I'll repeat it in tl;dr format for
your convenience:

Once you tally up life-time CO2 emissions for solar & wind, including storage,
new transmission lines, and loses for 3000km long transmission lines, neither
of them stack up very well compared to, say, gas or nuclear.

And saying "nuclear is unsafe" is nonsense. Nuclear kills fewer people per
unit of electricity produced than even roof-top solar [1], _including_ the
deaths from Chernobyl and the deaths from the _evacuation_ of the area
surrounding Fukushima Daiichi. (I say "deaths from the evacuation" because, as
yet, no one has died as a direct result of the core melt downs [2]).

Saying things like "nuclear is unsafe because of Chernobyl / Three Mile Island
/ Fukushima" is like saying "Air travel is unsafe because of the Hindenburg
disaster".

Burning coal for electricity has released in to the environment more
radioactive material than nuclear power ever will. It's the only current
technology base-load capable electricity generator that has a completely
closed fuel cycle.

Additionally, we need to move away from saying things like "Australia would be
amazing for" this or that technology. Aside from the evidence pointing toward
'renewables' being a dumb idea environmentally and economically (just look at
the real world data), if China and India and the USA don't do anything about
their emissions Australia might as well not even bother. If Australia doesn't
do anything about transport (14%) [3], direct fuel combustion (15%) [3], and
agricultural, emissions (15.9%) [4], we might as well not even bother.
Electricity production emissions account for 36% [3] of Australia's GHG
emissions.

1\. [http://www.forbes.com/sites/jamesconca/2012/06/10/energys-
de...](http://www.forbes.com/sites/jamesconca/2012/06/10/energys-deathprint-a-
price-always-paid/)

2\.
[http://en.wikipedia.org/wiki/Comparison_of_Fukushima_and_Che...](http://en.wikipedia.org/wiki/Comparison_of_Fukushima_and_Chernobyl_nuclear_accidents)

3\. [http://www.carbonneutral.com.au/climate-change/australian-
em...](http://www.carbonneutral.com.au/climate-change/australian-
emissions.html)

4\. [http://www.csiro.au/Outcomes/Climate/Reducing-GHG/Carbon-
Aus...](http://www.csiro.au/Outcomes/Climate/Reducing-GHG/Carbon-Australian-
agriculture_CLI.aspx)

~~~
mercurial
Your numbers about mortality are interesting, but you are not saying a word
about the long-term pollution issues of nuclear. It's not like anybody is
going to move in next to a meltdown site anytime soon.

Edit: I'd like to see some sources for your claims wrt the footprint of
renewables, I haven't been able to find anything which supports your position.

~~~
TheSpiceIsLife
See my reference from my first comment
[http://bravenewclimate.com/?s=TCASE](http://bravenewclimate.com/?s=TCASE)

The Thinking Critically About Sustainable Energy series from
bravenewclimate.com - TCASE 4 [1] in particular. It references this [2]
document form The University of Sydney for wind, and this one [3] for solar.
TCASE 5 [4] looks wave power, and TCASE 7 [5] investigates scaling up Andasol
1 to baseload.

I also recommend reading the comments sections of those blog posts, there's
some good quality discussion there.

The "nuclear is bad beacuse meltdown" and "nuclear is bad beacuse bombs"
tropes have been dealt with extensively elsewhere. Both are hyped up FUD.
We're still waiting for Godzilla, or some green-glowing-three-eyed-monster to
appear.

1\.
[http://bravenewclimate.com/2009/10/18/tcase4/](http://bravenewclimate.com/2009/10/18/tcase4/)

2\.
[http://www.isa.org.usyd.edu.au/publications/documents/ISA_Nu...](http://www.isa.org.usyd.edu.au/publications/documents/ISA_Nuclear_Report.pdf)

3\. [http://www.needs-
project.org/docs/results/RS1a/RS1a%20D12.2%...](http://www.needs-
project.org/docs/results/RS1a/RS1a%20D12.2%20Final%20report%20concentrating%20solar%20thermal%20power%20plants.pdf)

4\.
[http://bravenewclimate.com/2009/10/25/tcase5/](http://bravenewclimate.com/2009/10/25/tcase5/)

5\.
[http://bravenewclimate.com/2009/12/06/tcase7/](http://bravenewclimate.com/2009/12/06/tcase7/)

~~~
mercurial
Thank you.

------
pinkskip
On the other hand Abbott's government in their recent budget announced cuts to
CSIRO and Clean Technology Innovation Program. Go Figure!

~~~
infectoid
I know it's done the rounds but I want to make sure that everyone has seen
it...

John Oliver on Tony Abbott
[https://www.youtube.com/watch?v=c3IaKVmkXuk](https://www.youtube.com/watch?v=c3IaKVmkXuk)

This guy man. I don't even know what to do about it.

~~~
kibibu
Encourage everybody you know to vote for an alternative.

In particular, though, don't tell Abbott voters how terrible they are for
voting for him. People will get defensive and actually strengthen their views
under criticism. ([http://youarenotsosmart.com/2011/06/10/the-backfire-
effect/](http://youarenotsosmart.com/2011/06/10/the-backfire-effect/))

------
jeffdavis
"The $5.68 million research program..."

It struck me how tiny the amount of money involved here is. Let's say this
engineering effort was a one one-thousandth step along the way to developing
the technology into a major energy alternative. Then that would be, what, $5B?

Perhaps I'm overestimating the significance of this discovery.

------
knowtheory
I'm unclear on why supercritical steam is important for electrical generation.
Anybody happen to know?

Reading through
[http://en.wikipedia.org/wiki/Supercritical_steam_generator](http://en.wikipedia.org/wiki/Supercritical_steam_generator)
indicates that Benson boilers are more fuel efficient (and perhaps less prone
to explosion), but reduction in amount of fossil fuels used to turn a turbine
seems to be sort of a moot point here.

Would super critical steam generation mean a solar plant can produce more
electricity? Or that a supercritical steam generating solar plant is cheaper
to operate?

~~~
cossatot
I'm not an expert here, but I believe that the maximum possible efficiency of
all heat engines is governed by the temperature difference between the heat
source and the heat sink [1,2]. Increasing the water T/P to supercritical both
increases the T at which it can enter the system and, from what I gather by
the link you posted and from [3], also results in some simplification of the
plant mechanics, which likely increases efficiency as well.

This should indicate that for a given amount of sunlight (or fossil fuels in a
conventional power plant), a greater amount of electricity can be created.

[1]:
[http://en.wikipedia.org/wiki/Carnot_cycle](http://en.wikipedia.org/wiki/Carnot_cycle)
[2]:
[http://en.wikipedia.org/wiki/Rankine_cycle](http://en.wikipedia.org/wiki/Rankine_cycle)
[3]: [http://www.brighthubengineering.com/power-
plants/32896-how-a...](http://www.brighthubengineering.com/power-
plants/32896-how-are-supercritical-boilers-different-from-subcritical-
boilers/)

~~~
neltnerb
This is the correct answer. Higher temperature steam allows a higher maximum
power extraction potential.

------
Gustomaximus
Does 'supercritical' steam have any storage benefit? Or is it more efficient
use of the solar energy? I ask as I read some articles about using a similar
focused mirrors to create molten salt which then could keep solar energy
running after the sun went down, one of the major drawbacks of solar.

[http://en.wikipedia.org/wiki/Solar_thermal_energy#Molten_sal...](http://en.wikipedia.org/wiki/Solar_thermal_energy#Molten_salt_storage)

------
achivetta
Thinking aloud: could one build a combination fossil fuel and solar steam-
powered turbine? When the sun is out, you use (supercritical) steam as they
describe being able to generate. If the sun goes away, you feed the same
turbine with steam generated with fossil fuels. You could use same turbine,
condenser, etc but just switch the heat source (or use both) as the
environmental conditions change.

------
rail2rail
Amazing that even our most cutting edge power generation schemes are still
just steam engines under the hood.

------
dang
Url changed from
[http://sciencealert.com.au/news/20140506-25618.html](http://sciencealert.com.au/news/20140506-25618.html),
which points to this.

~~~
roberthahn
Thank you, appreciate the consideration.

