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Solar PV comparable to gas fired power stations

  • Thread starter Dirk Bruere at NeoPax
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Dirk Bruere at NeoPax

Jan 1, 1970
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http://www.physorg.com/news/2011-02-key-low-cost-solar-power-lies.html

Thinking big while focusing on small, a solar company and a national
energy lab combined talents to develop a solar power concentrator that
generates electricity at prices competitive with natural gas.

The Amonix 7700 Concentrated Photovoltaic (CPV) Solar Power Generator,
developed by Amonix and the U.S. Department of Energy's National
Renewable Energy Laboratory, is the size of an IMAX screen but costs
much less than comparable generators, partly because of the efficiency
of its small solar cells. It delivers more "energy per acre" than
anything yet available in the solar energy world.

The public-private partnership won a 2010 R&D 100 award at the annual
event honoring the greatest breakthroughs in technology, often called
"The Oscars of Invention."

NREL's partnerships with industry, such as this one with Amonix, are key
to reaching aggressive White House goals including lowering solar
energy's installed cost to $1 a watt, which would make America a leader
in renewable energy.

The 7700 uses acrylic Fresnel lenses to concentrate sunlight up to 500
times its usual intensity and direct it onto 7,560 tiny, highly
efficient multi-junction PV cells.

The cells, originally developed by NREL scientists, can convert 41.6
percent of the sunlight that shines on them into usable electricity in a
laboratory setting, a world record. Production cells never work quite as
well as cells produced in the lab. But the multi-junction cells on the
Amonix 7700 are achieving 31 percent efficiency at the module level and
27 percent at the system level in the field, the highest ever achieved
for an operating CPV concentrator.

That unprecedented efficiency opened the door to reducing costs and
reducing land use — both key for solar electricity to reach cost-parity
with fossil fuels.

Seeing the potential for game-changing cost cuts, Amonix, with technical
support from NREL's High-Performance PV Project and financial support
through DOE and its Solar Energy Technologies Program, redeveloped its
flagship CPV system using the multi-junction cells.

A six-inch square silicon wafer in traditional photovoltaic (PV) panels
produces about 2.5 watts of electricity. That same-sized wafer, cut into
hundreds of square-centimeter cells in the Amonix 7700, each teamed with
a Fresnel lens, produces more than 1,500 watts. It reduces the required
area for cells 500 times.

The 7700 already has driven the price of electricity from solar down to
the price of electricity from natural gas, according to the California
Market Price Referent, which establishes a proxy price for electricity
generated by a new state-of-the-art natural gas plant. Solar power is at
or near price parity in six other states that share California's sunny
and dry climates — Arizona, Nevada, Utah, New Mexico, Colorado and Texas.

The 7700 also keeps down costs by integrating the lenses, the cells and
the mounting structure into a single unit that eliminates most of the
parts and costs associated with other concentrator designs. The seven
MegaModules that make up the 53-kilowatt system can be hauled on two
flatbed trucks, then assembled in the field in hours, rather than weeks.

Low-Cost, Efficiency Attract Interest from Utilities

Those cost-slashing measures, together with the Amonix 7700's
large-scale capacity, are catching the interest of utility companies
from California to Colorado. Twenty Amonix 7700s, erected on just five
acres of desert, can generate more than a megawatt of rated capacity,
enough to power 750 homes. That's half the space typically needed to
generate that much power.

The Southern Nevada Water Authority and California Polytechnic Institute
in California are among those that have purchased the Amonix 7700. The
DOE and Amonix are paying for testing of the 7700 at the Solar
Technology Acceleration Center (SolarTAC) in Aurora, Colo., to validate
the reliability of the system.

Multi-Junction Cells Key to Record-Setting Efficiency

The key breakthrough that lifted the 7700 to a 50 percent greater power
output than previous generations of Amonix generators was the
substitution of the multi-junction cells made of gallium indium arsenide
and gallium phosphide for the more common silicon cells.

Cells made from gallium, indium and other elements from the III and V
columns of the periodic table are more expensive to produce today, but
also can be more efficient at converting the sun's photons into usable
electrons for electricity.

NREL scientists had developed a high-efficiency multi-junction indium
gallium phosphide PV cell that had been used previously for energy for
spacecraft.

DOE, NREL High-Performance PV Project Funded Breakthrough

To offer up the more efficient multi-junction cell as a possible
replacement for the silicon cells used in most PV concentrators, NREL
issued a request for proposals for projects designed to accelerate
multi-junction cell development and their integration into CPV solar
systems. NREL awarded Amonix $1.2 million for a project that began in
2004 and concluded in 2008. At the end of the NREL project, Amonix was
able to demonstrate close to 31 percent efficiency for a
one-square-meter module — a world record at the time.

Martha Symko-Davies, a senior supervisor at NREL, recalled that most
concentrator companies could not see the benefits of switching to
new-generation solar cells, but Amonix was different, conducting
research and development with NREL to overcome stiff challenges.

The first NREL/Amonix project led to a larger award in 2007 from DOE for
$15.6 million leveraged by an additional $18 million of investor funds,
which helped make the transition to manufacturing of the Amonix 7700 at
the company's facility in Seal Beach, Calif.

Amonix has 15 years of experience developing CPV systems, while NREL has
a record of more than three decades of research and development in PV
technologies. The fruitful partnership, incoroporating the
high-efficiency multi-junction solar cell with Amonix's flagship CPV
system, came about through the High-Performance PV Project funded by the
DOE's Solar Energy Technologies Program.

Other DOE-funded support came from the Small Business Innovation
Research and Technology Pathway Partnership programs. DOE's Sandia
National Laboratories and Brookhaven National Laboratory also
facilitated the scale-up of this project.

A conundrum was how to use the highly efficient cells without breaking
the bank. Researchers solved that problem by teaming an inexpensive
Fresnel lens — at less than $2 a pop — with each of the 7,560 high
efficiency solar cells that make up one 53-kilowatt 7700 system. The
500-power amplification of the Fresnel lens allowed the solar cells to
be tiny — thus a small fraction of the cost of bigger cells — while
still packing record-setting efficiency.

There were other hurdles to clear, too.

Researchers developed a new receiver package of cells and lenses to
ensure that the cells would not short out. They solved the distortion
problem that happens when a lens doesn't focus all colors on the same
convergence point. And they overcame the thermal issues that crop up
when a cell has to handle the intensity of 500 suns.

Their efforts were rewarded in the form of $130 million in private
equity financing in 2010.

Expanding the Market to Everyone

Solar energy has found a niche on rooftops, especially of green-minded
homeowners. But if it is to play a major role in the broader electricity
market, it needs to come in at or below the costs of electricity
generated from coal, which is projected to cost from 6 cents to 15 cents
per kilowatt-hour in four years. The 7700's cost per kilowatt-hour is
expected to be well within those price ranges as production and sales
continue to grow.

"This development and R&D investment enabled the entire CPV industry,"
Symko-Davies said. "This could truly shake up the world and add
competition to the flat-plate technologies being deployed at utility scale."

The 7700's two-axis tracker can be repositioned throughout the day to
follow the sun, but also can be re-positioned to shield the cells from
extreme wind, increasing the life of the system. It allows the cells to
capture sunlight for a longer time throughout the day and through all
seasons of the year. Field tests indicate that depending on the
location, the two-axis tracker captures up to 50 percent more energy
than fixed one-axis systems.

Utilities expect their generators to last 50 years. The Amonix 7700 can
reach that target with proper maintenance and timely replacement of
certain parts, said a spokesman for the company.

Two Axis-Tracker, Modular Design Key to Cost Savings

The two-axis tracker is the only moving component on Amonix's CPV
systems and has been designed for reliability and minimum maintenance.
The energy needed to move the two-axis tracker amounts to less than 1
percent of the power output.

The system has just 12 subassemblies, which are shipped to installation
sites for deployment. Once the site is ready, an Amonix system can be
installed very quickly, within hours. By contrast, some systems require
shipment of thousands of parts to the installation site.

Cost savings were factored in every step of the way — from foundry to
grid — said Bob McConnell, who worked at NREL before he left the lab in
2007 to join Amonix and help bring the research to market.

The result is a generator manufactured at about a third to one half of
generators using crystalline silicon or thin-film approaches.

Multi-junction cells can operate at higher ambient temperatures than
traditional PV cells, making them ideal for sunny and dry climates in
the southwestern United States, and ripe for future cost reductions.

The concentrator also is kinder to the environment than most large
systems, using no water in its operation. Propped up two feet above the
land, it doesn't hinder the movement of wildlife.

"You simply can't put enough solar systems on rooftops to achieve the
scale and capacity necessary to generate electricity in the quantities
required by utilities and by society," said Amonix's founder and chief
technical officer, Vahan Garboushian. "This is a technology that can
meet the terawatt (trillions of watts) needs of the world for clean
electricity."



Dirk

http://www.neopax.com/technomage/ - My new book - Magick and Technology
 
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Artemus

Jan 1, 1970
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Snip callenged "John Larkin" wrote in message
Why post all that crap here?

John

Why repost all that crap just to add your 6 words?
Art
 
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Dirk Bruere at NeoPax

Jan 1, 1970
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Snip callenged "John Larkin" wrote in message


Why repost all that crap just to add your 6 words?
Art
Why not?
Bandwidth is cheap and the universe needs heating
 
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Sylvia Else

Jan 1, 1970
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It's not as though solar concentrator PV is a startling invention.

And the price competitivity claim is spurious anyway, because PV and gas
generation have different levels of availability.

Sylvia
 
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Sylvia Else

Jan 1, 1970
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Indeed. Stanford has (re-) invented the duplexer:
http://www.rfglobalnet.com/article.mvc/Stanford-Researchers-Develop-Wireless-0001


To be truly useful for something like WiFi as they suggest, I'd say you
really need at least 100dB of isolation between your Tx and Rx ports...
and 120dB would be significanatly better.

I'm betting they're at least 50dB shy of that, even acknowledging that
these days you can do a lot of neat stuff with DSP.

Quote:

"The group has a provisional patent on the technology and is working to
commercialize it. They are currently trying to increase both the
strength of the transmissions and the distances over which they work.
These improvements are necessary before the technology is practical for
use in Wi-Fi networks."

Um hmm.

What annoys me is how they claim that "textbooks say you can't do it"
and "people didn't believe sending and receiving signals simultaneously
could be done." What rot...

I wonder if it occurred to them when they had the insight that people
can talk and listen at the same time that while that works when both
parties speak at roughly the same volume, it fails spectacularly when
one is 100dB louder the other?

The central flaw appears to be this statement: "Their setup takes
advantage of the fact that each radio knows exactly what it's
transmitting, and hence what its receiver should filter out."

In fact a radio never knows exactly what it's transmitting, but only the
value to within a certain level of uncertainty. That would manifest as
noise added to the incoming signal.

I didn't understand the point about two aircraft transmitting
simultaneously, with neither getting through. That looks like an
entirely different problem.

Sylvia.
 
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Rich Grise

Jan 1, 1970
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Joel said:
What annoys me is how they claim that "textbooks say you can't do it" and
"people didn't believe sending and receiving signals simultaneously could
be
done." What rot...

Maybe they've never heard of the telephone.

Cheers!
Rich
 
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Joe

Jan 1, 1970
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---
So, according to you, they should all shut the **** up and kow-tow to
your edicts and abandon their quest for excellence because you say
they should?
---

Not at all, such an announcement should simply not be taken seriously.
The time to get excited about it is *after* it goes on sale to the
public.

Safe, practical, commercial fusion power has been twenty years away for
the last sixty years. Those who got excited about it sixty years ago
are probably now flagging a little.
Poor baby, you decry innovations because they weren't yours.

Again, I wouldn't have thought so. Innovation is always a good thing in
itself, but innovation which is practical and offers results better
than are currently available is much, much more valuable and much, much
rarer.

New is inherently good, but not necessarily better.

People such as Tony Blair tend not to understand this.
 
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Dirk Bruere at NeoPax

Jan 1, 1970
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And the price competitivity claim is spurious anyway, because PV and gas
generation have different levels of availability.

Gas power stations can be turned on and off quickly.
The perfect companion to solar electricity.
Because within a couple of decades solar will be so cheap during the day
that nothing can compete with it.
 
D

Dirk Bruere at NeoPax

Jan 1, 1970
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These sorts of development are interesting when real, entertaining
when not.

Let's look at some of the math, shall we?

"A six-inch square silicon wafer in traditional photovoltaic (PV)
panels
produces about 2.5 watts of electricity."

6" sq. = 0.023 m^2. Peak insolation is around 1kW/m^2 in the US, so
1kW/m^2 x 0.023 m^2 = 23W. 2.5W / 23W ~= 11% conversion. So far so
good.


"That same-sized wafer, cut into hundreds of square-centimeter cells
in the Amonix 7700, each teamed with a Fresnel lens, produces more
than 1,500 watts. It reduces the required area for cells 500 times."

That implies 500 suns' concentration, reduced by the added efficiency
factor 31%/11% or about 175 suns.

175 suns on a 1 cm sq. cell is about 18 watts' insolation. Seems
workable.


A congressman asked me why, if we can now run a whole LED flashlight
on a single alkaline AAA cell, why can't we (Congress) scale that
magic battery technology up and run electric cars on it?

He was a decent guy AFAICT, well-intentioned, and prepared (and in a
position) to commit several billions to exactly that.

You obviously missed your big opportunity:)
More seriously, how about a campaign to only elect people who have a
scientific or technical background to major political positions?

All of the Chinese leadership are scientists or engineers by training -
and it shows.
 
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Martin Brown

Jan 1, 1970
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Maybe not. That concentration works out to ~17-18W / cm^2. That's
not obviously impossible.

But it will require active cooling. If we are being generous then at
default solar flux the ambient surface temperature is T ~ 300 (a nice
round number 330 might be more accurate for sunny deserts and no wind).

Left to its own devices a PV cell receiving 500x more sunlight will end
up at T*(500^(1/4)) ~ 5T or 1500K. I grant you it is below the melting
point of silicon on my lower estimate but at that flux density you are
reliant on the flow of cooling water to keep the thing from cooking!
The Fresnel lenses still have to be the same size though. And I thought
that of these technologies the non-focussing flux concentrators were
preferred since they also work with diffuse light as well as sunshine.
These are spin offs from HEP photon collecting and counting systems.
Oops-I just posted the same. Should've read the whole thread first.

And the PV converts about 10-20% of that into electricity.
There is another more fundamental point here. The sun is an extended
object and round so the matching optics had better be right. A 1cm solar
cell to get a 500x increased flux would require a 25cmx25cm fresnel lens
in front of it with 1m effective focal length (doable).

My experience of flux concentrators with PV systems has been that they
do cook themselves fairly easily for even modest increases in flux
density of 3-10x - although it is the plastic parts that fail first
(either going opaque, yellow, brittle or combinations of all three).

In its favour if you can keep the system from cooking at these flux
densities you only need 1/500 of the amount of exotic semiconductor. Is
this thing a real product operating somewhere or a venture capital
launch announcement of an investment "opportunity".
Our Don Lancaster says a PV cell in the US yields roughly 5 hours'
peak output equivalent per day. So, that 1MW for 750 houses is about
6.7KWHr / day per house, which isn't unreasonable. Just do all your
air conditioning and cooking during the day, when you aren't home.

Traditional model is that you export it to the grid and it helps cool
your workplace or run industry when you don't need it.

Regards,
Martin Brown
 
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Dirk Bruere at NeoPax

Jan 1, 1970
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Fields is fixated with me. Kinda sick and iccky, in my opinion. He
goes ballistic when I express opinions, even when I express reasonable
opinions.

He told me he loved me once... look it up. That's even more iccky.

Yes, but in a manly way - not like you were a sheep or something
 
M

Martin Brown

Jan 1, 1970
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Granted.

Though it will depend on how well the exotic semiconductor holds up
under the daily thermal stress which is going to be non trivial with
agressive cooling on one side and 500x concentrated sunlight on the
other. I can see it working in the lab OK for a year or two. But for 25
years under the rigors of real world conditions...
The problem is the size of the lakes required. Pumped storage has to be
done on a big enough scale to replace a significant fraction of fossil
and nuclear during the night (or during a week of cloudy weather).

Nuclear goes to cover base load during the night and you use pumped
storage to cover short duration fast transients like everyone turning on
the kettle at half time in the world cup (World Series final) or
whatever. The pumped storage generators can go from a standby tickover
to 1MW synchronised output in under 16s which is impressive.

In countries at lower latitudes with significant daytime aircon load the
insolation and electricity demand are fairly closely correlated.

Until we have cheap and photostable organic semiconductors that are
screen or inkjet printable I think solar PV will always be a novelty
that is usable only in the sunniest locations or off grid. Having said
that market distortions have made it attractive for higher rate
taxpayers to install a PV array if they have the room. Where else can
you get a government guaranteed 8% ROI for 25 years today?

Regards,
Martin Brown
 
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Spehro Pefhany

Jan 1, 1970
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Granted.

Though it will depend on how well the exotic semiconductor holds up
under the daily thermal stress which is going to be non trivial with
agressive cooling on one side and 500x concentrated sunlight on the
other. I can see it working in the lab OK for a year or two. But for 25
years under the rigors of real world conditions...

Nuclear goes to cover base load during the night and you use pumped
storage to cover short duration fast transients like everyone turning on
the kettle at half time in the world cup (World Series final) or
whatever. The pumped storage generators can go from a standby tickover
to 1MW synchronised output in under 16s which is impressive.
<snip>

I hope you mean 1GW. 1MW is UPS territory. ;-)
 
D

Dirk Bruere at NeoPax

Jan 1, 1970
0
There was a headline in the late 1950s "ZETA! free power from the
sea". I still have a reference to it in a book from the time.

This was ZETA
http://en.wikipedia.org/wiki/ZETA

And we might well have had controlled fusion by now if all the money had
not been poured into Tokamak
 
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