Two-For-One: A New Solar Dish Delivers Low-Cost Electricity Along With Fresh Water

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"Two-For-One: A New Solar Dish Delivers Low-Cost Electricity Along With Fresh Water"

(Credit: IBMSocialMedia)

One challenge that continues to hound solar power is the efficiency with which it converts sunlight into electrical power. Right now, that efficiency ranges from 10 to 30 percent, while much of the rest is lost as waste heat. But Swiss researchers associated with IBM have built a new solar dish, called the High Concentration PhotoVoltaic Thermal system (HCPVT), that tackles the waste heat problem by using it to generate fresh water.

The dish itself is covered in small mirrors, which concentrate sunlight on a small module of photovoltaic cells. That design puts the dish at the leading edge of efficiency, converting 30 percent of the received solar radiation into electricity and providing 25 kilowatts of power. But it also means the solar module faces an enormous concentration of heat. To keep it from melting, the HCPVT employs a liquid coolant system that IBM first developed for its high-performance computers, and that’s 10 times more effective than traditional passive air cooling.

The liquid keeps the solar cells operating safely at up to 5,000 times the normal solar concentration by drawing away the waste heat, after which the heated coolant is used to vaporize salty water in a desalinization system. As a result, the HCPVT is able to recover half the waste heat and put it to productive use.

According to IBM, the HCPVT is built from unusually low-cost materials, meaning the per area price of setting it up is significantly lower than comparable solar systems, as is the cost per kilowatt hour:

“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….

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.

Just one square meter of receiver area in the HCPVT system can provide 30 to 40 liters of drinkable water per day — about half the needed daily amount for the average person, according to the United Nations. The researchers think a large array of the dishes could produce enough fresh water to sustain a town. On top of that, the system can even provide air conditioning, using an absorption chiller rather than the standard compression chiller:

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, 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.

The prototype is being tested at IBM research facilities in Zurich, and the project was recently awarded a three-year, $2.4 million grant from the Swiss Commission for Technology and Innovation. The long-term vision is to build arrays in areas of southern Europe, Africa, the Arabic Peninsula, South America, Australia, and the southwestern United States — places that are remote, dry, and in need of both affordable sustainable energy and greater supplies of drinking water.

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14 Responses to Two-For-One: A New Solar Dish Delivers Low-Cost Electricity Along With Fresh Water

  1. Jason Miller says:

    “Just one square meter of receiver area in the HCPVT system can provide 30 to 40 liters of drinkable water per day — about half the needed daily amount for the average person,”

    30 liters is equal to about 8 gallons and 40 liters is equal to about 10.5 gallons. When these amounts are doubled they would be 16 and 21 gallons of drinkable water. If a person were to drink this much water daily, they would soon be dead.

    NIH says “A daily water intake of 3.7 L for adult men and 2.7 L for adult women meets the needs of the vast majority of persons.”

    • MightyDrunken says:

      The UN suggests that each person needs 20-50 litres of water a day to ensure their basic needs for drinking, cooking and cleaning.
      Source: World Water Assessment Programme (WWAP)

      • SqueakyRat says:

        Water for cleaning surely doesn’t have to be drinkable.

        • Chris Hernandez says:

          Water for cleaning utensils and other areas where contact is made with people needs to be done with potable water otherwise you risk contamination with bacteria.

        • Luke says:

          Yeah, what would the WHO know.

        • Julian Boche says:

          Really? T Do you wash your dishes in lake water, river maybe……perhaps ocean? How’s that working out for ya?

        • Maureen Mower says:

          Of course it does… do you want to wash your dishes with swamp water? Or take a shower with runoff from the storm drain?

          Having clean water for such tasks as showering, cleaning clothes and dishes and preparing meals is necessary for basic hygiene and safety from potentially deadly bacterial infections,

    • Jason Miller says:

      Concerning cooking and eating utensils – Add chlorine bleach to non-potable water. Concerning clothes – UV light is a great sterilizer. I think they should have used the word “potable” instead of “drinkable”. Also this would not work if there was no water available in the first place.

  2. fj says:

    Another indication that the great transition has the potential to be truly extraordinary.

  3. Cool. Double Duty Design = the cheapest and best solutions. (Other than Triple Duty Design, of course.)

  4. Brooks Bridges says:

    This sounds awesome and gives one hope for the future. Water and electricity – helluva twofer.

    Can you imagine what could be accomplished if fossil fuel companies spent money on such projects instead of looking for more fuel?

  5. Merrelyn Emery says:

    Wow! Who says we can’t do it if we put our minds into it? Shame we left it so late, ME

  6. irrefudiate says:

    I hope this technology proves out. The Earth needs a source of fresh water as much as it needs a source of clean energy.
    Another big plus is IBM is not a petrol-chemical company.

  7. Douglas Hvistendahl says:

    Do a search on “annualized geo solar” and you will find a use for the heat that does not require an ocean nearby, if you live in a cold climate. I live in North Dakota, and have been able to reduce my late fall heating bill with a DIY system, which hopefully will be improved and expanded. My crude system has already paid for itself. I add that is possible to use the hot end of an absorption system to produce the storable heat needed by AGS.