Environment

Solar-powered air-con uses heat to cool shopping center

Solar-concentrating thermal collectors atop the Stockland Wendouree Shopping Centre
Solar-concentrating thermal collectors atop the Stockland Wendouree Shopping Centre
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The researchers believe that solar heat-driven desiccant air conditioning systems have the potential to significantly reduce the electric power needs for humidity controlled fresh air requirements for large commercial spaces
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The researchers believe that solar heat-driven desiccant air conditioning systems have the potential to significantly reduce the electric power needs for humidity controlled fresh air requirements for large commercial spaces
Solar-concentrating thermal collectors atop the Stockland Wendouree Shopping Centre
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Solar-concentrating thermal collectors atop the Stockland Wendouree Shopping Centre
The air conditioning system uses trough collectors to capture heat and then store it in a thermal oil tank
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The air conditioning system uses trough collectors to capture heat and then store it in a thermal oil tank
The two-stage dessicant air con system incorporates a heat cascading design
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The two-stage dessicant air con system incorporates a heat cascading design

Solar-concentrating thermal technology is being used to power the air-conditioning system of an entire shopping center in Australia solely from the rays of the sun. With around 60 percent of all energy used in shopping centers being consumed by heating and cooling needs, the new system could lead the way to significant power and cost savings in a range of large commercial spaces.

Installed in the Stockland Wendouree Shopping Centre in Ballarat, Victoria, the prototype system was developed by the CSIRO and partly funded by the Australian Renewable Energy Agency (ARENA) program, which aims to increase the supply and competitiveness of renewable energy in Australia. The same program helped support the CSIRO's world-record breaking solar-powered supercritical steam generator.

The new solar-powered system is a "closed-loop" air-conditioner, meaning it heats and cools air within the building without introducing any external air into the system, with a pair of "desiccant" (drying) wheels acting as dehumidifiers to remove moisture from the air. These operate at separate temperatures; the high-temperature wheel uses the captured solar energy for regeneration of the low temperature wheel, which operates without any external heat at all.

The researchers believe that solar heat-driven desiccant air conditioning systems have the potential to significantly reduce the electric power needs for humidity controlled fresh air requirements for large commercial spaces
The researchers believe that solar heat-driven desiccant air conditioning systems have the potential to significantly reduce the electric power needs for humidity controlled fresh air requirements for large commercial spaces

"CSIRO's energy research is driving down costs of renewable technologies, accelerating the transition to a lower-emissions future," said CSIRO Energy Director Peter Mayfield. "We are pioneering new technologies and this project is a world-first demonstration of a desiccant air-conditioning system using roof mounted concentrating solar thermal collectors."

The air conditioning system uses trough collectors to capture solar heat of around 150 to 200° C (302 to 392° F) and then store it in a 2,000-liter (528-US gal) thermal oil tank. Utilizing a heat cascading design, heat from the tank is used to heat the center's ambient air in the winter and power an indirect evaporative cooler to cool the center in summer. So compact is the system, that the whole solar air-conditioning unit is some 40 percent smaller than a comparable standard single-stage desiccant system.

The researchers believe that solar heat-driven desiccant air conditioning systems have the potential to significantly reduce the electric power requirements and costs related to supplying humidity controlled fresh air in large commercial spaces.

The team at the CSIRO intend to spend the next 12 months monitoring and assessing the new system and gauge its capabilities in a commercial environment. These observations will add to the long-term goal of the CSIRO to help contribute to a low- emissions future. ARENA contributed AUD$520,000 (US$386,000) to the project, with the remainder of the AUD$1.2 million (US$890,000) being provided jointly by the CSIRO and the Stockland Group using technology from NEP Solar.

Source: CSIRO

3 comments
JoelF
I wonder what the seer rating for this system will measure out to, and what is the efficiency of the solar concentrating part of the system? Will it be cost-competitive with flat panel PV driving central compression-type air conditioners, which are very efficient these days? Lennox makes a central AC unit, albeit for smaller installations, which is 25 seer and has solar PV electrical inputs. Also, there's an earlier concentrating AC system atop the Steinway factory in Queens, New York, using absorption chiller technology.
Timelord
It makes sense when one thinks about it. Shopping centers have enormous expanses of mostly unused roof real estate. Might as well do something with it, especially since they can't put anything else up there.
StWils
Since before the first Earth Day in the early Seventies I have said that solar heat is a problem that provides for it's own solution. This is just one incremental example. Almost all the pieces are now available or clearly on the horizon to essentially drop most commercial spaces and pretty much all housing off the grid. The goal is to essentially provide all-to-nearly-all energy for space heating, cooling, and lighting on site, with adequate storage of heat & electricity to pretty much completely bridge any weather driven interruption. Further system integration engineering is needed as much as further storage engineering is needed. This also has to be backed up by continuing and consistent public policy support, across the country and the world. Persistent major nation support is needed to spur industry participation and sustain consumer interest and investment as our economies shift from a carbon focused energy delivery & consumption economy to renewable energy focused economy. As CSIRO pushes this project along they need to extend it so that it provides for as much energy gain as can affordably be had, literally, this system could return more energy to it's local users than the stores themselves actually need. I look forward to a follow-on article from them in six months to a year from now.