
New material could up efficiency of concentrated solar power - LinuxBender
https://arstechnica.com/science/2018/10/new-material-could-up-efficiency-of-concentrated-solar-power/
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philipkglass
The author identifies the key appeal of concentrated solar thermal generation
vs. photovoltaics, but remains a bit too optimistic about how competitive this
race still is:

 _While a big boost in efficiency is great, concentrated solar is far enough
behind photovoltaics on price that it 's not going to make a big enough
difference in a direct competition. But the real competition here isn't
directly with photovoltaics; instead there are two separate competitions. One
is against photovoltaics plus batteries, since only that provides the
possibility of around-the-clock energy access. Here, the costs are changing
fast enough that it's difficult to figure out where things stand._

I would say that it is not particularly difficult to figure out where things
stand; absent a surprising catch-up from solar thermal power, photovoltaics-
plus-batteries is going to win. For one thing, CSP only works where there is
very high direct normal irradiance. Partially cloudy conditions cause its
performance to drop much faster than the actual intensity of illumination
drops. PV works fine with direct and indirect illumination. For that reason
CSP performance declines in wintertime in temperate regions worse than PV
does. You can see the effect by looking at performance-by-month for American
solar PV and solar thermal here:

[https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...](https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_6_07_b)

In June 2017, solar thermal plants had a capacity factor of 37.9% while PV
plants reached 35.7%. But in December 2017, thermal plants reached only a 9%
capacity factor while PV plants reached 17.4%.

This new material might be one way for thermal to compete better with PV. But
to do so it will need to enter commercial use soon. Commercial battery storage
projects are ramping up around the world. For stationary battery storage
applications, technical breakthroughs for higher energy density aren't
necessary; "last year's chemistry, but manufactured bigger and cheaper" is
just fine. Further, the whole-project cost of PV + batteries declines when
_either_ batteries or PV decline in price.

Even if solar thermal power doesn't pan out, this material might be useful in
future energy systems. I have been reading for many years about how Generation
IV nuclear reactors could run at high temperatures with supercritical CO2
turbines for compact, more efficient heat-to-electricity production. It's nice
to have some of the supporting technology developed ahead of time. Even if
such reactors never become competitive for terrestrial use, there is also the
rest of the solar system to consider.

~~~
mchannon
Total agreement. Although zirconium and tungsten aren't exactly the most
expensive metals, they are extremely hard and dense and processing them in
this manner would appear to be a big minus against this technology. I can
picture a factory warehouse putting out 40' containers of PV's, racking, and
backup batteries daily, while a far more massive smelter and mill next door
struggles to manufacture the equivalent for CPV.

I'm glad they addressed the thermolysis of CO2, because that was a major
concern. Having explored thermolysis as a method for reversing carbon dioxide
buildup in Earth's air, I realized quickly that breaking CO2 down into CO is
not challenging at all, but getting the CO to go to C is the highest
temperature reaction known.

Just because I don't think this breakthrough is going to win doesn't mean I'm
not thrilled they made it. Never know what other breakthroughs may leverage
this technology.

~~~
ars
> but getting the CO to go to C is the highest temperature reaction known.

Even higher than H2 + O ? (I'm sure it's not higher than H + H, but that one
probably doesn't count.)

And won't atomic carbon react with other carbon? So you don't actually need to
supply as much energy as it may appear.

~~~
mchannon
From chapter 211 of my book:

None have proposed then taking the CO through a final step and ending up with
simple C and O. This is not without good reason: out of all substances known
to thermally decompose, none does it at a higher temperature than carbon
monoxide. If you thought 2,000° was hard, try 3,870° C. That’s hot enough to
melt any known metal. That’s hot enough to melt any rock! The few substances
known to man that can be counted on to stay solid at that temperature can be
counted on one hand.

~~~
philipkglass
I tried searching for that excerpt from your book and couldn't find any
matches. Is the book published? I'd be interested in reading it.

If I wanted to turn carbon dioxide back into elemental carbon I'd probably try
to get there via the Bosch reaction with electrolytic hydrogen:

[https://en.wikipedia.org/wiki/Bosch_reaction](https://en.wikipedia.org/wiki/Bosch_reaction)

NASA has funded a fair bit of lab scale work on it for recycling breathable
atmosphere on space stations. It doesn't require heroic super-materials. You
can theoretically store the input CO2 and H2 in large buffers so as to smooth
out intermittently available input energy, without needing to firm up the
primary energy supply itself.

~~~
mchannon
The full book is not yet available anywhere. It's self-published (and I mean
that literally; I'm doing the printing and binding myself, to discourage
making it another $.99 Kindle throwaway or having a crappy low-res PDF version
of it floating on torrents or sci-hub).

List price on it will be in the hundreds of dollars. I'm not trying to sell as
many copies as cheaply as possible, which might be hard for some people to
understand.

Message me your info and I'll give you a discount on price.

Elemental carbon is probably the wrong goal: keeping a limited pool of CO2 and
thermally converting it to CO, then water-shifting the CO into CO2 + H2 is far
more practical.

If you want to bury the carbon, it's more practical to bury it as a
hydrocarbon, which is easily accomplished with the CO + H2 used through
Fischer-Tropsch.

If you want to convert the carbon back into food, there's probably some clever
process to convert F-T product oil into sugars and carbohydrates.

~~~
philipkglass
Yes, I am interested, though I'm not sure what your book is about in general.
I just emailed you from an .edu address.

What is the goal you're aiming at? Carbon-neutral synthetic fuels? From the
excerpt, I thought you might be considering converting atmospheric CO2 back
into relatively low-reactivity, compact, reduced forms of carbon for burial in
e.g. old coal mines. (Which would be _astonishingly_ energy intensive, but I
wouldn't put it past the capabilities of early-22nd-century civilization if
automation continues to advance and we avoid nuclear war, super-pandemics, and
other such disasters.)

------
ChuckMcM
This is a similar material that encases nuclear reactor fuel rods.

One of the things I like about concentrated solar power (CSP) vs photo-voltaic
power (PVP) was that the minimum technology levels to support it meant that
newish economies without a lot of technological infrastructure yet can still
build it and deploy it with locally developed materials and people.

Having a magical metal tube so that you can use super-critical CO2 kinda puts
a dent in this :-)

~~~
08-15
Zirconium and zirconium carbide are very different materials.

~~~
ChuckMcM
Yes, but I don't understand what you are trying to say. For example, it reads
like "Iron and Steel are very different materials" which is also true, but the
majority of the mass in steel content is the element iron.

Depending on when they were made, Nuclear fuel rods can be encased in
Zircalloy which is an alloy of zirconium and tin or niobium. The "magic"
material that is discussed in the article starts out as sintered zirconium
carbide structures which are then mixed with molten tungsten and copper[2]. It
isn't an alloy in the traditional sense I suppose.

[1]
[https://www.mne.psu.edu/motta/chapters/Book%20Aug%202011/Cha...](https://www.mne.psu.edu/motta/chapters/Book%20Aug%202011/Chapter17_ZrAlloys.pdf)

[2] _The zircon carbide ends up providing the material with a stiffness even
at high temperatures, while the tungsten is flexible enough to keep the whole
thing from being brittle. And the whole thing conducted heat better than the
metals currently in use._

~~~
08-15
Zirconium and zirconium carbide are about as different as aluminium and clay.
One is a metal, the other is a ceramic.

------
spenrose
This article should not have been written IMHO, though the reasons are not
obvious:

"This works more efficiently, potentially providing a boost of more than 20
percent, but ... [implementation would] involves balancing a lot of [currently
unsolved] factors"

That is another way of saying "nothing to see here; move along." A 25% gain in
efficiency would not be a game changer, and we can't implement it.

