
World’s Largest Solar Thermal Power Plant Delivers Power for the First Time - jes
http://www.technologyreview.com/view/519596/worlds-largest-solar-thermal-power-plant-delivers-power-for-the-first-time/
======
chime
The article claims a high cost of mirrors and steam turbines as the big
negative. Without seeing the cost-breakdown of the entire project, it is hard
to ascertain if materials are indeed the largest factor or if it is something
else like labor/salary or technology/licensing. If it costs $200m to build the
tower and buy turbines, $2B/200,000 mirrors = $10,000/mirror. I find it hard
to believe that cannot be lowered drastically once the research phase is over.

While I feel Solar Thermal (more appropriately CSP
[http://en.wikipedia.org/wiki/Concentrated_Solar_Power](http://en.wikipedia.org/wiki/Concentrated_Solar_Power)
) is very promising, for some reason many don't. Google invested in this
company ( [http://www.google.org/rec.html](http://www.google.org/rec.html) )
but has stopped investing more into CSP, preferring photovoltaics (
[http://www.evwind.es/2011/11/24/google-cans-concentrated-
sol...](http://www.evwind.es/2011/11/24/google-cans-concentrated-solar-power-
project/14860) ).

~~~
redwood
A reality in California is the high cost of regulatory siting. In this case
the desert tortoise issue was costly.

In many other cases, you see multi-year court battles (some in regulatory
proceedings rather than traditional legal courts). A lot of the time those
pushing the fight are not environmentalists but rather NIMBYs who use the
laws/regulations to try to prevent progress. Same with High Speed Rail, of
course.

The delay and uncertainty adds a higher-than-expected cost since the
investment appeal erodes.

It's interesting that California's pro-environmental laws can sometimes be a
hurdle to "green" projects in this sense. Different sides of the environmental
issue spectrum.

~~~
jonah
Finding and relocating all the tortoises and keeping an eye out for missed
ones while the construction was going on is expensive but not relative to the
total project cost.

Source: My uncle does this work and was on this project.

~~~
redwood
That's true, the tortoises cost $22 million, a small percent of the overall
cost.

But siting, getting approval, finding a place where few folks will fight you,
etc etc make it add up in terms of time and uncertainty and then when you do
find a place you can move forward on there's a good chance it'll be remote
enough to be extra costly to connect.

~~~
jonah
Granted.

However, the large, open, sunny spaces in CA tend to be far from large
population centers.

He's now working on the project to replace/upgrade the original transmission
lines from Hoover Dam which will pick up this power as well.

I'm in agreement with the other commenters saying energy production should be
distributed. However, this'll require a "smart grid" to balance things out -
which we don't have - as well as potentially being less efficient.

------
danbruc
_When you calculate the amount of power the plant is likely to produce over
its lifetime, the cost per kilowatt-hour is likely to be much higher than for
fossil-fuel power. It’s even likely to be higher than the cost of power from
solar panels, thanks to the fast drop in solar-panel prices in recent years.
If costs don’t come down — and decreasing the costs of mirrors and steam
turbines is hard to do — solar thermal power might prove to be a dead end._

I hate this attitude - the costs of the produced energy is not everything. Who
said that energy has to become cheaper and cheaper? If you want to reduce the
carbon dioxide emission just introduce additional taxes for fossil fuels or
even prohibit burning them or subsidize solar energy. Just accept the
increased costs and enjoy your clean air.

~~~
grannyg00se
I hate it as well, but I think it is generally anticipated that any greentech
solution is never going to be widely adopted until it achieves price parity.

~~~
e12e
Which is another way to say that we won't start using "green" energy until we
run out of hydrocarbon fuel.

It's a very dangerous attitude -- we need to use what's left of hydrocarbon
fuel to bootstrap new energy while we still can, and have the luxury to afford
to experiment.

I forget where the quote is from, but as has been said: "The definition of
modern agriculture, is that it is a way to transform hydrocarbons into
carbohydrates.". Unless we do something soon, running out of oil, will mean
running out of food. We need it for tractors, and for modern fertilizers, for
irrigation -- and for transport of food.

Oil (and coal) is cheap energy, because it's basically just laying around,
waiting for us to burn it. It's grown harder to get -- but it is ridiculous to
wait around for other energy to "become cheaper". If we don't make an effort
to change the entire infrastructure the world runs on (quite literally) --
what will happen is that oil will become as expensive as "green" energy -- not
the other way around.

And that is of course ignoring all the problems hydrocarbons leaves us with,
in the form of various forms of pollution. That we'll have to clean up and/or
deal with without cheap energy.

------
Shivetya
Does anyone have information on what type of system could be setup using
photovoltaics across a similar 3500 acre site? While its obvious not all the
acreage is used for mirrors I am curious as to difference is possible output.

Output is expected at 392mw. I found a few acreage references for coal/gas
plants but their output many times one of these plants. One solar plant I
found is 25mw using about 250 acres.

Just trying to understand the land use efficiency versus other solutions.
Fossil fuel plants do not count usage of road/rail in their size calculations
nor the size of the source of their fuels. (coal mines/pits/etc)

~~~
chiph
What's the reflectance of a PV panel? Wondering if the mirrors could be
replaced with them, knowing they aren't as good of a reflector as a mirror,
but perhaps they reflect enough to run the steam generator, and still produce
power themselves. Net win, perhaps?

~~~
debacle
If you could diffuse the spectrum, you could reflect the IR but absorb the UV.

Not being a physicist, I don't know what that would entail.

~~~
kaybe
That would probably be a bad idea: The main energy input will be by UV. If it
is absorbed, the material will heat up.

Physics states that (Reflection coefficient + Absorption coefficient +
Transmission coefficient = 1), all wavelength dependent. Now if you want a
high number for the reflectivity in IR, you will have a low number for the
absorption coefficient.

If you have a low absorption coefficient you will most probably have a low
emission coefficient since those two are linked (equal for black bodies, see
Kirchhoff's Law/gray body).

So you have a low emission coefficient in the IR, and the thermal emission due
to the heating from the absorbed UV will be quite inefficient, and thus there
will be more heating, which is bad (edit: the heat will not be transported
away and will accumulate).

Of course if you have good materials you might be able to migitate, but at
first glance it looks problematic to me. Sorry for inelegant language.

~~~
debacle
Don't the PVs heat up from the UV absorption anyway? Wouldn't removing the IR
from the light actually create a net loss of heat?

~~~
kaybe
Yes, they do. The question is what happens with the heat from the UV - it will
need to be transported away somehow. If we don't have significant heat
conduction or convection it will have to be radiated off.

Sunlight does not bring in a lot of IR, and almost all of that is absorbed in
the upper layers of the atmosphere. What you have to consider then is ambient
IR radiation from the surroundings due to thermal emission. The process is the
same as the one we're assessing for the PVs, and the wavelengths are not too
different. PVs are normally warmer than the surroundings due to their higher
temperature, so less energy will be absorbed that radiated off in the IR.

Hm, maybe I misunderstood how you want to remove the IR? Let's consider some
sort of reflectant shell around the PVs but not part of them. On the inside it
would receive the heat from the PVs and of course, also reflect great parts of
it back, letting it accumulate. We built an insulation. Not good. Maybe you
can explain your idea in more detail?

The mechanism I discussed above is of course not the only relevant process,
things like heat conduction and heat capacity of the material are also
important.

In conclusion: Yes, there would be a net loss of incoming energy, but the
mechanims that let energy be transported off might be severely hindered by our
alteration. Thus, an accumulation of heat.

There might be ways to make it happen nevertheless, eg with water cooling, but
it would require more infrastructure. (But then, I'm not an engineer..)

~~~
debacle
Not being an expert in the field, I'm not really sure - I know we have films
that block UV but not IR, but I'm not sure if the reverse is possible.

------
ajays
Steam turbines have been around since 1800s. The tech is well understood.
Mirrors are also cheap. These two can't be the reason for the high cost.

My guess is that the fancy molten salt stuff drove up the cost. Molten salt is
very corrosive.

I would _love_ to see the breakdown of the costs.

Aside: I drove past the plant this summer, and even from the highway it looked
awesome.

~~~
pjc50
The official fact sheet
[http://www.bechtel.com/assets/files/Renewable_%202013_Ivanpa...](http://www.bechtel.com/assets/files/Renewable_%202013_Ivanpah_Solar_Generating_Facility_4_2012.pdf)
makes no mention of molten salt, just a regular boiler on top of the tower.

------
grecy
For years there has been talk of building a 1km "solar tower" in my home town.

The basic plan is multiple square kilometers of greenhouses surrounding a 1km
chimney. The air inside the greenhouses will heat up and rise up through the
tower at high speed. The bottom of the tower will be filled with 32
generators, for a total of 200MW.

[http://enviromission.com.au/EVM/content/home.html](http://enviromission.com.au/EVM/content/home.html)

I still hope they build it.

~~~
benkillin
This is called a solar updraft tower (I like to call it a solar chimney):
[http://en.wikipedia.org/wiki/Solar_updraft_tower](http://en.wikipedia.org/wiki/Solar_updraft_tower)

------
bjz_
> When you calculate the amount of power the plant is likely to produce over
> its lifetime, the cost per kilowatt-hour is likely to be much higher than
> for fossil-fuel power.

Solar thermal is cost effective _if_ you take into account the economic
problems that carbon emissions cause over their lifetime in the atmosphere.
This is why putting a price on carbon emissions is so essential: to expose the
true cost of fossil fuels at the time of sale.

~~~
jpadkins
So how do you come up with a fair price to capture the carbon externality?

And do you add the externalities to green power like solar? More people have
died installing solar equipment than all nuclear accidents. Or what about
environmental damage during PV manufacturing? Do we add those to the price of
solar at the time of sale?

~~~
derobert
Indeed, it's difficult to exactly price externalities. There are published
estimates of the carbon externality. You do you best; it's far better than the
"estimate" we currently use ($0).

When comparing, you add in the externalities to everything. To be specific:

\- you don't count the deaths in PV installation as its not an externality.
The installers are an involved party; they can (for example) ask for higher
wages due to risk. (Also, if you wanted to compare this to nuclear, you need
to include deaths building those nuclear plants as well. And possibly mining
the uranium.)

\- you do count the environmental damage during PV manufacturing (and turbine
manufacturing, and coal mining, and oil drilling, etc.)

------
api
Any lifetime cost calculations must factor in the fact that the fuel is free.
I've seen quick comparisons with combined cycle gas, coal, etc. that neglect
this obvious difference.

~~~
_mulder_
api, this is a great point and one that is often overlooked with most
renewables vs non-renewables cost arguments. However, when you compare $/kwh
of the electricity it does take all of this into consideration.

~~~
api
I think of renewables' higher cost as basically paying up front for the fuel
instead of over time. At least that's how it should be thought of
economically.

~~~
_mulder_
You're right, but traditional fossil fuel plants still cost a lot (a
comparable amount infact) to build ($2billion for 600MW[1]). Renewables just
have a much lower energy output (only work when the sun shines/wind blows, and
at a lower capacity) and therefore a much longer payback. But you're right,
not having to pay for fuel would off-set some of these negatives.

[1] [http://www.synapse-
energy.com/Downloads/SynapsePaper.2008-07...](http://www.synapse-
energy.com/Downloads/SynapsePaper.2008-07.0.Coal-Plant-Construction-
Costs.A0021.pdf)

------
debacle
I wasn't aware we were building these solar towers in the US. How does this
compare to the solar updraft ones being built in Australia? It seems like the
solar chimney design is more simple, however there are obvious efficiency
concerns (kW/acre).

~~~
_nate_
I was going to bring up the same point. The solar updraft systems seem to be
more cost effective and generally easier to build. I don’t understand why
they’re not being built more. However, they definitely take up more land. And
nature advocates claim they are harder on the environment because they
essentially bake the top soil, killing everything (which is probably true).
But everything has trade offs.

[http://en.wikipedia.org/wiki/Solar_updraft_tower](http://en.wikipedia.org/wiki/Solar_updraft_tower)

~~~
debacle
It looks like the solar updraft systems are only cost effective when you have
vast amounts of cheap/free land - they are very inefficient in Watts per
square meter, getting around 1% efficiency compared to 20-35% for other
systems.

------
jes
Do solar sites ever use mirrors and PV panels, in combination?

~~~
_mulder_
Do you mean, concentrating sunlight onto PV? or Having PV cells that are also
reflective?

Reflective PV cells/mirrors wouldn't work well as you're taking the energy out
one way or another. The more you reflect, the less you can use for PV, and
vice-versa.

~~~
jes
Sorry for being unclear. I meant concentrating sunlight onto existing PV
panels. I suppose that I'm assuming mirrors << PV in terms of cost.

~~~
ajays
I've heard of some folks using a Fresnel lens to concentrate light onto a
smaller area, where the silicon is. It improves the efficiency significantly,
but can also cause heat issues (which can hurt efficiency).

------
sdoering
Does anyone have information on the water-consumption (steam-loss, cleaning
the mirrors, cooling the mirrors, and so on)? I would really love to see, if
this is a feasible method of producing energy in areas without that much
water.

But I really lack the necessary numbers in terms of consumption of water, to
built an idea, if this is a viable technology for deserts and other dry and
sunny places on this planet.

------
tonylemesmer
How do they keep the mirrors clean? How do you keep solar panels clean for
that matter? Must require quite a bit of upkeep.

~~~
_mulder_
Like this..
[http://www.youtube.com/watch?v=zLogKN80plY](http://www.youtube.com/watch?v=zLogKN80plY)

~~~
tonylemesmer
Ha! interesting. Sand and shiny mirrors don't mix very well.

------
adrianN
How can it be more expensive to produce a mirror than a solar panel? This
doesn't need astromony grade mirrors... Are steam turbines so expensive
compared to inverters?

~~~
rwmj
I guess it's not the mirror, but all of the motors and electronics that keep
the mirror pointing in the right direction. If only the Sun didn't move around
the sky, this would be very cheap!

------
ferdo
The biggest flaw I see with this solar project is that it's just another
continuation of the centralized model. We should be encouraging homes and
businesses to be producers of energy and decentralize our power grid.

$2 billion on a centralized project in the age of increasing decentralization
seems like waste of money.

~~~
tlb
I've heard various arguments for this, none of which seemed that convincing.
Centralized power generation seems like one of the great successes of the 20th
century. What do you think the advantages of decentralization are?

~~~
ferdo
> Centralized power generation seems like one of the great successes of the
> 20th century.

From the point of view of large producers and investors, sure. Tesla's idea of
decentralized power was viewed as pie-in-the-sky by his benefactor, JP Morgan.

I wouldn't call nuclear power a success story.

