Collaboration aims to harness the energy of 2,000 suns

Apr 22, 2013
Credit: IBM

Today on Earth Day, scientists have announced a collaboration to develop an affordable photovoltaic system capable of concentrating, on average, the power of 2,000 suns, with an efficiency that can collect 80 percent of the incoming radiation and convert it to useful energy. The proposed system can be built anywhere sustainable energy, drinkable water and cool air are in short supply at a cost of three times lower than comparable systems.

A three-year, $2.4 million (2.25 million CHF) grant from the Swiss Commission for Technology and Innovation has been awarded to scientists at IBM Research; Airlight Energy, a supplier of solar power technology; ETH Zurich (Professorship of Renewable ) and Interstate University of Applied Sciences Buchs NTB (Institute for Micro- and Nanotechnology MNT) to research and develop an economical High Concentration PhotoVoltaic Thermal (HCPVT) system.

Based on a study by the European Solar Thermal Electricity Association and Greenpeace International it would take only two percent of the 's land area to supply the world's electricity needs. Unfortunately, current on the market today are too expensive and slow to produce, require and lack the efficiency to make such massive installations practical.

The prototype HCPVT system uses a large , made from a multitude of mirror facets, which is attached to a tracking system that determines the best angle based on the position of the sun. Once aligned, the sun's rays reflect off the mirror onto several microchannel-liquid cooled receivers with triple junction photovoltaic chips—each 1x1 centimeter chip can convert 200-250 watts, on average, over a typical eight hour day in a sunny region.

The entire receiver combines hundreds of chips and provides 25 kilowatts of electrical power. The photovoltaic chips are mounted on microstructured layers that pipe liquid coolants within a few tens of micrometers off the chip to absorb the heat and draw it away 10 times more effective than with passive air cooling.

The coolant maintains the chips almost at the same temperature for a solar concentration of 2,000 times and can keep them at safe temperatures up to a solar concentration of 5,000 times. The direct cooling solution with very small pumping power is inspired by the hierarchical branched blood supply system of the human body and has been already tested by IBM scientists in high performance computers, including Aquasar.

"We plan to use triple-junction photovoltaic cells on a microchannel cooled module which can directly convert more than 30 percent of collected solar radiation into electrical energy and allow for the efficient recovery of waste heat above 50 percent," said Bruno Michel, manager, advanced thermal packaging at IBM Research. "We believe that we can achieve this with a very practical design that is made of innovative concrete trackers, primary optics composed of inexpensive pneumatic mirrors and structures made of concrete—it's frugal innovation, but builds on decades of experience in lightweight and high strength concrete elements used for building bridges."

An initial demonstrator of the multi-chip receiver was developed in a previous collaboration between IBM and the Egypt Nanotechnology Research Center.

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"The design of the system is elegantly simple." said Andrea Pedretti, CTO of Airlight Energy. "We replace expensive steel and glass with low cost concrete and simple pressurized metalized foils. The small high-tech components, in particular the microchannel coolers and the molds, can be manufactured in Switzerland with the remaining construction and assembly done in the region of the installation. This leads to a win-win situation where the system is cost competitive and jobs are created in both regions."

The solar concentrating optics will be developed by ETH Zurich. "Advanced ray-tracing numerical techniques will be applied to optimize the design of the optical configuration and reach uniform solar fluxes exceeding 2,000 suns at the surface of the photovoltaic cell," said Aldo Steinfeld, Professor at ETH Zurich.

With such a high concentration and a radically low cost design scientists believe they can achieve a cost per aperture area below $250 per square meter, which is three times lower than comparable systems. The levelized cost of energy will be less than 10 cents per kilowatt hour (KWh). For comparison feed in tariffs for electrical energy in Germany are currently still larger than 25 cents per KWh and production cost at coal power stations are around 5-10 cents per KWh.

Water Desalination and Cool Air

Current concentration photovoltaic systems only collect electrical energy and then dissipate the thermal energy to the atmosphere. With the HCPVT packaging approach scientists can both eliminate the overheating problems of solar chips while also repurposing the energy for thermal water desalination and cool air.

To provide fresh water IBM scientists and engineers are utilizing a world leading technology they developed for water-cooled supercomputers. With both the Aquasar and SuperMUC supercomputers water is used to absorb heat from the processor chips, which is then used to provide space heating for the facilities.

"Microtechnology as known from computer chip manufacturing is key to enable such an efficient thermal transfer from the photovoltaic chip over to the cooling liquid" explains André Bernard, head of the MNT institute at NTB Buchs. "And by using innovative ways to fabricate these heat transfer devices we aim at a cost-efficient production."

In the HCPVT system, instead of heating a building, the 90 degree Celsius water will pass through a porous membrane distillation system where it is then vaporized and desalinated. Such a system could provide 30-40 liters of drinkable water per square meter of receiver area per day, while still generating electricity with a more than 25 percent yield or two kilowatts hours per day. That is a little less than half the amount of water the average person needs per day according to the United Nations, but a large installation could provide enough water for a small town.

Remarkably, the HCPVT system can also provide air conditioning by means of a thermal driven adsorption chiller. An adsorption chiller is a device that converts heat into cooling via a thermal cycle applied to an absorber made from silica gel, for example. Adsorption chillers can replace compression chillers, which contain harmful working fluids, with water eliminating any impact on the ozone layer.

Scientists envision the HCPVT system providing sustainable energy and fresh water to locations around the world including Southern Europe, Africa, Arabic peninsula, south west of north America, south America, and Australia. Remote tourism locations are also an interesting market, particularly resorts on small islands, such as the Maldives, Seychelles and Mauritius, since conventional systems require separate units that have to be integrated, with consequent loss in efficiency and increased cost.

A prototype of the HCPVT is currently being tested at the IBM Research lab in Zurich, Switzerland. Several prototypes of the HCPVT system will be built up in Biasca and Rüschlikon, Switzerland as part of this collaboration.

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User comments : 18

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Whydening Gyre
2.7 / 5 (6) Apr 22, 2013
The direct cooling solution with very small pumping power is inspired by the hierarchical branched blood supply system of the human body and has been already tested by IBM scientists in high performance computers, including Aquasar.

Ahhh... Fractality... Ain't it great?
Telekinetic
2.6 / 5 (5) Apr 22, 2013
Who needs fusion reactors when you can lasso the sun and harvest its energy in your own backyard?
VENDItardE
2 / 5 (12) Apr 22, 2013
more bs to keep on the gravy, i mean grant, train
trekgeek1
4 / 5 (4) Apr 22, 2013
Wouldn't 100% efficiency in capturing 100% of our sunlight equal the power of one sun? Where the hell is the power fron the other 1999 suns coming from? Harnessing the power of 2000 suns? Is this some kind of starlight converter?
holoman
3 / 5 (6) Apr 22, 2013
I guess the great many sand storms don't account for much.
RealScience
5 / 5 (6) Apr 22, 2013
@trekgeek - it is just the silly headline writer that makes it sound as if the whole system harnesses more than just the sun. The overall structure receives one sun, but focuses all the light onto the receiver in the middle.

Those 36 circular membrane mirrors each focus the light (they are like drums, but with a partial vacuum behind them to pull the reflective surface into a quasi-parabolic 'Henky' curve), and they all focus onto the receiver in the middle. The receiver in the middles thus gets light concentrated to 2000 times the intensity of sunlight. This allows the use of very-expensive-per-area high-efficiency solar cells.
Pkunk_
1.8 / 5 (5) Apr 23, 2013
harness the energy of 2,000 suns

That headline is the biggest BS i've heard this year.
Forget 2000 suns , we are centuries away from harnessing even the power of our SINGLE sun. We're talking about a Dyson sphere or access to futuristic Antimatter Reactors to approach anywhere near the energy of our SINGLE sun.
Jo01
2.6 / 5 (5) Apr 23, 2013
It seems highly complex and maintenance prone.
One severe (sand) storm and all investment is gone.

J.
weezilla
5 / 5 (2) Apr 23, 2013
Wouldn't 100% efficiency in capturing 100% of our sunlight equal the power of one sun? Where the hell is the power fron the other 1999 suns coming from? Harnessing the power of 2000 suns? Is this some kind of starlight converter?


100% efficiency considers only the shell of radiation given off at the point the earth is from the sun. So, if you take, say, 3square meters, and harvest the available sun radiation at 100% efficiency, that's the most power you can get.
shagrabanda
2.6 / 5 (5) Apr 23, 2013
The sun outputs 3.846×10^26 watts (384.7 trillion trillion watts) so presumably one of these outputs 2000 times that amount. World consumption is only 1.44×10^17 (144 thousand trillion) so we'll only need one dish and we'll only have to turn it on for 1 second every 169443 years! Now to work on a battery that can smooth that out :-)
antialias_physorg
4.4 / 5 (7) Apr 23, 2013
Who needs fusion reactors when you can lasso the sun and harvest its energy in your own backyard?

Since solar energy is the direct result of a (rather big) fusion reactor...
And anyhow: We'll be needing a power source if we ever go interstellar (or even interplantary). The further out you go the less efficient solar becomes. So having fusion is a 'must' at some point.

shagrabanda, trekgeek1, Pkunk:
Don't be obtuse. If you really don't understand what is meant here you shouldn't be on this site. It's way over your heads.

I guess the great many sand storms don't account for much.

No they don't because there aren't a great many. In many arid/hot areas ideally suited for solar there are none at all.
(And those that do exist are predictable. A simple shutter system will protect your installation nicely for those few hours a year)
It seems highly complex and maintenance prone.

There are no moving parts (apart from the mobile base). Maintenance is minimal.
U V
1 / 5 (1) Apr 23, 2013

A misleading title. Replace "of" with "at".
Also the 80% conversion is more likely 65%.
When you convert 30% directly to electricity that leaves 70%. 1/2 conversion of 70% is 35%. 35% plus 30% is 65%.
I understand there is a marketing and political aspect to drawing readers but please try not to muddy the science while accounting for them.
Keep up the good work!
renergy
5 / 5 (1) Apr 23, 2013
The title is not the best, however it is common jargon to speak in the "sun" "unit" when discussing concentrator technology. 1sun = power density of the suns irradiation per unit area placed perpendicularly to it per second = cell without concentrator. 10suns = irradiation from (say) 10m^2 directed to 1m^2 cell. Numerically "one sun" is around 1kW/square meter on the surface of the Earth (corresponding to time around noon, given the sky is clear).

Another related term: "AM1.5 spectrum" - standard solar spectrum for Europe/US.1.5 because of oblique passage of sunrays through atmospehere, due to latitude. AM1.0 corresponds to the situation on equator during equinox, noon, clear sky.
TheGhostofOtto1923
2 / 5 (4) Apr 23, 2013
There are no moving parts (apart from the mobile base). Maintenance is minimal
Altazimuth mount with sensors and controls, plus all the pumps, valves, and controls of any boiler/chiller setup.
Pkunk_
1 / 5 (2) Apr 24, 2013
shagrabanda, trekgeek1, Pkunk:
Don't be obtuse. If you really don't understand what is meant here you shouldn't be on this site. It's way over your heads.

I think the article in question is way over the head of who came up with the headline.
Energy out of Sun/s = 3.8×10^26 W
Energy output of this "Photovoltaic" system = 2.5x10^4 W
The fact is the headline is sensationalist AND inaccurate by around 26 orders of magnitude.
antialias_physorg
not rated yet Apr 24, 2013
And if you had EVER read any article about solar before (especially a scientific one) in your life you would know that the factor refers to the relative concentration of ambient solar at Earth's surface.

It's not like the sentence "harness the energy of the sun" is continually misunderstood by people who then shout:
"Oh no, good sir. It's just the energy that impacts the Earth, which is X orders of magnitude less than the total power of the sun! Har, har."

So if you're capable of understanding
"harness the energy of the sun"
why are you incapable of understanding
"harness the energy of 2000 suns"?
antialias_physorg
5 / 5 (1) Apr 24, 2013
Altazimuth mount with sensors and controls, plus all the pumps, valves, and controls of any boiler/chiller setup.

Not exactly maximum high tech, is it? And it's not like we have similar setups already working in big, powerplant size solar setups without constant breakdowns, is it? (Heck, some people have constant watercooling in their computers without continually flooding their appartments. - and that based on the cheapest parts they can find. Oh no!)

Moaning about the complexity of something should be tempered by whether that something is already tried-and-true-and-reliable in the field or not.

TheGhostofOtto1923
1 / 5 (4) Apr 24, 2013
Not exactly maximum high tech, is it? And it's not like we have similar setups already working in big, powerplant size solar setups without constant breakdowns, is it? (Heck, some people have constant watercooling in their computers without continually flooding their appartments. - and that based on the cheapest parts they can find. Oh no!)

Moaning about the complexity of something should be tempered by whether that something is already tried-and-true-and-reliable in the field or not
-And how do you consider this an adequate defense of your initial statement, which was
There are no moving parts (apart from the mobile base)
-Erm?

I think the poster may have been implying 'relative complexity' as opposed to plain solar panels.