Clean Power Solar thermal IBM

Published on April 24th, 2013 | by James Ayre


High-Concentration Photovoltaic Thermal System From IBM Promises 80% Efficiency, Potable Water, And Air Conditioning

April 24th, 2013 by  

This article was originally published on Solar Love.

How does a cost-competitive photovoltaic system that is able to concentrate sunlight 2000 times and then capture 80% of the concentrated energy sound? Pretty good, right? Such a system is currently being developed by researchers at IBM Research, Airlight Energy, ETH Zurich, and Interstate University of Applied Sciences Buchs NTB, after winning a three-year $2.4 million grant from the Swiss Commission for Technology and Innovation.

Image Credit: © IBM

Image Credit: © IBM

And in addition to generating electricity, the system can itself desalinate water and provide air-conditioning, useful features for the sunny and remote regions that the system is designed for.

An economical High Concentration Photovoltaic Thermal (HCPVT) system, that in addition to supplying electricity can desalinate water and provide air conditioning, is the complete package as far as many regions of the world are concerned.

The prototype system makes use of a large parabolic dish, composed of a number of mirror facets, which are coordinated to a sun tracking system. The system automatically repositions itself to the optimum angle for power generation. The sunlight that hits the mirrors is reflected off of them onto a number of microchannel-liquid cooled receivers with triple junction photovoltaic chips. Every one of these 1×1 centimeter chips “can convert 200-250 watts, on average, over a typical eight hour day in a sunny region.” And there are hundreds of these chips in the design, providing a total of about 25 kilowatts of electrical power.

The press release notes:

The photovoltaic chips are mounted on micro-structured 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. An initial demonstrator of the multi-chip receiver was developed in a previous collaboration between IBM and the Egypt Nanotechnology Research Center.

“We plan to use triple-junction photovoltaic cells on a micro-channel cooled module which can directly convert more than 30 percent of collected solar radiation into electrical energy and allow for the efficient recovery of an additional 50 percent waste heat,” 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 lightweight and high strength concrete, which is used in bridges, and primary optics composed of inexpensive pneumatic mirrors — it’s frugal innovation, but builds on decades of experience in microtechnology.

By utilizing such a high concentration of sunlight, and the rather low cost of the design, the researchers think that they can realize a cost per aperture area under $250 per square meter — that is roughly 3 times lower than in similar systems. According to them, “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.”

One of the innovations of the new system is its collection and repurposing of the “waste heat” generated by solar thermal. By utilizing the heat instead of simply allowing it to dissipate, it becomes possible to cheaply desalinate water and provide cooling via a thermal-driven adsorption chiller, while also solving the overheating problems of solar chips.

In order to efficiently capture the waste heat, the researchers made use of an advanced technology that was already developed and in use, the water-cooling systems for very high-performance computers such as Aquasar and SuperMUC. While that heat is simply reused to provide space heating for the facilities, the captured heat in this instance will be used to heat salty water that is then distiller via vaporization. The researchers say that the system could provide up to “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 kilowatt hours per day.” So with a large array of these systems it would be very possible to provide enough water for a small city/town.

The system also possesses the ability to provide air conditioning, via 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, with water as working fluid, can replace compression chillers, which stress electrical grids in hot climates and contain working fluids that are harmful to the ozone layer.”

Researchers are currently testing a prototype of the HCPVT system at IBM Research — Zurich.

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • UncleB

    Slow progress? Restricted by the Oil plutocrats? The Enriched Uranium secrets crowd?

  • Andrew Miller

    Very interesting post. I suppose one might think that solar energy is a good source of energy to help save our envirnment from the effect of energy generated from coal. This project should be given more thought so as it to be perfected.

  • Lauren@GreenGlobalTrvl

    It would only take 2% of the Sahara desert’s land mass to power the entire world’s energy needs, amazing! What a great way to produce a greener way to air conditioning systems. Replacing compression with absorption chillers, genius! Way to go IBM. Thank you for sharing the details on this high-concentration photovoltaic thermal system.

  • I really need to see some numbers here as to the basis of their efficiency. As always, it should be total energy output divided by total solar radiation energy that falls into the entire footprint of facility. I don’t think it would reach that high.

  • iBM is behind 15 years in CPV. Solar Systems Pty has the most advanced CPV module which has one of the lowest cost per watt. It competes directly PV panel pricing of today. They have already implemented the technology in the Middle East and throughout Australia.

    • you have some documentation/links on that?

    • Ronald Brakels

      A worthy competitor in the conventrated solar PV sector and their design or something similar is more likely to succeed than IBM’s in my opinion. It has been put to good use in the outback for offgrid use, but it’s not really suitable for sticking on your roof. It’s not really deployed throughout Australia as we almost entirely don’t do the utility scale solar thing, but I suppose that might change in the future. I don’t know what their cost per watt is like, or what they could get it down to, but it looks like it could be a winner. But I guess we’ll have to wait and see.

  • Mohan Raj

    Wonderful concept and design.
    Hexagonal Dish with each segment having 6 cells for a total of 36 cells.
    It provides electricity, fresh water, cooling. This should be installed in Desert and high sunshine places.

    I hope its brought to market.

  • Does the levelized cost net out the value created by desalinization of water? What is a litre of drinkable water worth?

    • It is quite high already in arid regions and is getting higher continuously.

      The Arabs for example are already building desalination plants the question is only the power-source they use and solar can save them a lot of otherwise valuable oil/gas.

  • Wouldn’t this increase the amount of the sun’s energy retained on/by the Earth, effectively increasing the amount of insolation and thereby cause global warming?

    • Bob_Wallace

      Not likely. The incoming light would be captured and put to work. Eventually that work will create heat and some of that heat, unfortunately, will be trapped by our greenhouse gas blanket.

      If the light wasn’t put to use it would be changed into heat when it struck the ground. The result is roughly no different.


      If we put that energy to work before it gets turned into heat we can reduce our use of fossil fuels, reduce the amount of CO2 we’re pumping into the atmosphere, and slow global warming.

      • I think Zoe meant that the high albedo of the desert would cause a higher than 20% reflection (100-80) so actually more heat will be trapped compared to leaving the desert alone.

        While the above is likely true, fresh water, electricity and air.conditioning are very much needed in arid climates.

        • Bob_Wallace

          Yeah, that occurred to me later. I suppose the answer is to install these puppies over areas of black rock/sand. ;o)

          Desert sand can reflect out as much as 40% of the incoming light. Grasslands, around 25%. Water only 10%. We could stand up a whole bunch of them in the Salton Sea (as long as its water lasts).

          The big need is to reduce our greenhouse gas blanket.

        • agelbert

          Albedo is more complex than mere reflection. All energy that reaches our planet is radiated back out exclusively in the IR band. The issue is not the albedo but the gases now present that trap the IR heat before it can reach space. For example, the good negative feedback of white ice cover versus dark ocean would be made useless as a heat shield by a high enough concentration of CO2, H2O vapor and CH4 in the atmosphere. The ICE (internal combustion engine) is the problem because it adds heat and greenhouse gases simultaneously. The ICE has to go.

          • Bob_Wallace

            Isn’t light reflected back from the Earth’s surface sent back out into space as light? Yes, some may be converted to shorter band “heat” as it strikes molecules in the atmosphere, but a good deal of it gets through. Otherwise wouldn’t the Earth be invisible from space?

            (ICE has to go so that we hang on to some ice.)

          • agelbert

            “Otherwise wouldn’t the Earth be invisible from space?”

            Correct but that visible light reaching space is a tiny part of the Earth’s radiative profile. Anything that absorbs infra red light energy heats up the planet.

            From wikipeda:

            The various global temperatures that may be theoretically conceived for any planet in general in putative or theoretically conceived global radiative equilibrium are of considerable interest. Such temperatures include the equivalent blackbody temperature of a planet,[18] also called the effective radiation emission temperature of the planet.[19] Related putative or theoretical concepts include the global-mean surface air temperature,[20] which specifically considers the presence of an atmosphere.

          • I definitely agree on the ICE needing to go. Even if they can run on biofuel (which is much less effective than battery electric cars) they still release a lot of harmful PM2.5 into the air.

      • Michael Federoff

        Than you Air Force for help in trapping in the green house gases with your chemtrails.ASSHOLES!!

    • agelbert

      Since the Earth radiates energy in the IR band, we only have a heat budget problem as long as we have an excess of tri-atomic molecules like CO2 gas and H2O vapor in the atmosphere that have large IR radiation energy absorption bands. Efficient solar energy harvesting in devices like these will lead to the elimination of the ICE (internal combustion engine) which, because it is only 20% efficient, adds waste heat AND greenhouse gases simultaneously. As we move away from the ICE for transportation and industry, we will kill two planet heating “birds” with one stone, so to speak. The transparency of the atmosphere to IR radiation so it can escape harmlessly into space is a matter of obtaining the proper ppm reduction of CO2 and other gases like methane. The ICE HAS to go.

      • Increases in the planet’s ambient temperature is bad enough with the consequential weather pattern shifts– droughts, more and more powerful hurricanes, tornadoes, etc., other deleterious effects– rising sea levels? But all should be aware of the other effects of increases in atmospheric CO2. It’s not just the heat… Remember that 9th grade physical science experiment– blowing through a straw into a glass of water and then testing the pH level? A weak acid is formed as the CO2 in the exhaled air reacts with water. CO2 transforms to H2CO3– carbonic acid. This is essentially what’s happening with rising atmospheric CO2 across 3/4’s of the earth’s surface– the oceans. The oceans are sucking in the CO2 and acidifying. The heat rise is bad enough as well– as heat reduces the quantities of dissolved oxygen in water– but this acidifying effect is adversely affecting many marine ecosystems in other ways– things like coral reef formation, shell formation in the larvae of thousands of marine species, and many others too numerous to list. I could save typing by suggesting looking at what’s known about the Paleocene-Eocene Thermal Maximum (PETM) 55 million years ago… And of course, no one should infer that because what we’re experiencing now happened before “naturally,” then no worries about humans continuing to burn fossil fuels– which is the usual errant logic of the climate deniers…

        • agelbert

          Well said. The Phylum mullusca, with about 85,000 species, many of them with calcium carbonate shells, simply cannot “evolve” around ocean acidification. We HAVE TO get the excess CO2 OUT of the atmosphere so, as has been said here, renewables need to be about 120% of the energy so we can use that 20% to get back down below 350 ppm of CO2 (or lower if that is what is required to stop acidification).

  • pranjal sagar

    Very similar to REhnu 20Kw/hr CSP

    • Mariappan Sethu Pillai

      Tell us about REhnu

  • JMin2020

    Thant actually sounds pretty good

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