Innovation Down Under Could Mean Off-Grid AC

The serious heat of the summer is over for much of the country (sorry, Texas and SoCal). But the memory of what may well be the hottest summer on record has left a vivid impression on many of us. Sure, that air conditioning feels good when the mercury rises. What doesn’t feel so good is knowing that the very tech we’re using to keep indoor temps cool is contributing to the problem outside. More AC units pulling more electricity from the grid for more days out of the year means more greenhouse gas emissions, laying the groundwork for even hotter weather to come. It’s a vicious cycle a lot of people would like to turn around.

Slowly but surely, the technology behind solar air conditioners is starting to improve, improving our chances of cutting the carbon footprint of cooling. One design that caught our eye this summer comes courtesy of Paolo Corrada, a PhD science and engineering student in at the Queensland University of Technology in Queensland, Australia. Corrada’s solar air conditioning system, according to Green Optimist, cuts electricity consumption by 90 percent.

Paolo Corrada, QUT

image via Queensland University of Technology

Corrada’s design is based on the absorption chiller, a well-proven and efficient technology that has played a part in many greener cooling systems around the world. (For example, in Abu Dhabi.) Australian smarts have also played a part in other eco-friendly  variations on the absorption chiller, including the world’s first hybrid solar electricity/solar thermal cooling system, which is currently in use at a house constructed for the 2007 Solar Decathlon.

The absorption chiller uses a chemical process to reject heat. It’s more effective than the more common mechanical process of vapor compression at accomplishing this when used it’s in conjunction with waste heat or solar thermal heat. Corrada’s device is revolutionary because it also incorporates a desiccant wheel to remove moisture from the air, and because it makes use of the rejected heat from the absorption chiller to regenerate itself and to produce hot water for the house.

The combo of the two technologies together increases the unit’s efficiency by 40 percent as compared with current solar cooling systems on the market, according to Corrada. (It’s also quieter, as it employs a small pump, rather than the compressors used in standard split systems.) But Corrada’s not satisfied with that miserly energy profile — he wants to make this one a no-brainer.

“My target is to make it 100 per cent [more efficient than current AC systems] so that the system is self-sufficient to run…[without support from] the main grid, costing the home owners nothing to run,” Corrada said. “Heating and cooling account for about 65 per cent of energy consumption in a house, whereas cooking accounts for only 6 per cent so it is easy to see why air conditioning devices are the main targets to reduce our energy consumption.”

All of which, you’ll have to admit, is pretty cool.

Susan DeFreitas has covered all manner of green technology for EarthTechling since 2009. She is a graduate of Prescott College for the Liberal Arts and the Environment, and has a background in marketing green businesses. Her work on green living has been featured in Yes! Magazine, the Utne Reader and Natural Home.


  • Reply September 9, 2012

    Rod Francis

    Congratulations Paolo on a masterful piece of engineering and design.Your creativity and design take us beyond the “best of both worlds” to the solutions for four worlds-Cooling, Heating, affordable Energy and considerable reduction of greenhouse gas emission. I am anxiously awaiting progress reports and product availability, as I am sure that the world is too.

    • Reply September 11, 2012

      Paolo Corrada

      Hi Rod,

      Thank you very much for your comment. I am trying to do my best !!
      Hope I will provide the product soon !!


      • Reply November 21, 2012

        Rod Francis

        Hi Paolo:
        Looking forward to updates on development.
        Regards to you and family.

  • Reply January 17, 2013


    Keep up the good work mate,during the latest qld heatwave i was trying to come up with an adsorption based diy system.

    To no avail unfortunately.

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