Space Cooling » Thermally driven and solar air conditioning
Introduction
Solar cooling is a proven technology, but hasn’t been widely deployed to date. As of 2009, only 113 large-scale solar cooling systems and 163 small scale ones were installed worldwide. In total, the installed cooling capacity of the 286 systems was just 15.7 MW (Sparber et al., 2009). The capital costs of these systems are substantially higher than conventional electric air conditioners, but can, depending on system design, virtually eliminate electricity costs. Future cost reductions could see solar thermal be-come competitive in niche applications, particularly where there are simultaneous cooling and water heating demand and available waste heat.
Global number of installed solar cooling systems by country, 2009
Source: (Sparber, 2009)
Note: ”Other Countries” include: Armenia, Australia, Belgium, Denmark, Egypt, Japan, Kosovo, Lichtenstein, Malta, Mexico, Netherlands, Singapore, South Africa, Switzerland, Syria, Turkey, United Kingdom, United Arab Emirates and the United States.
Market
Solar cooling uses solar thermal collectors to provide the heat required to power thermally driven chillers. Both of these are established, proven technologies, but they are rarely combined to provide solar powered cooling. There were 113 large-scale solar cooling systems and 163 small scale ones were installed worldwide as of 2009. Most of the small-scale systems are installed in Spain, while the large-scale systems are more evenly distributed between France, Germany, Italy and Spain.
Around 28% of the small-scale systems are installed in residential buildings. Solar collectors like Flat plate and evacuated tube collectors dominate large-scale systems, but no data is available for the small-scale systems used in the residential sector. Thermally driven absorption chillers account for 71% of large-scale solar cooling systems and 90% of small-scale systems. The remaining 10% of small-scale systems use adsorption chillers (Sparber, 2009). The total number of installed systems has increased five-fold since 2004 and more than doubled between 2006 and 2009 (Sparber, 2009).
Thermal chillers using desiccant evapoartive cooling (DEC) systems are only just beginning to be deployed at any scale. Of the 113 large-scale solar cooling systems installed to date, 14% have included solid DEC systems and 2% liquid DEC systems. No DEC solar cooling systems have been installed in residential dwellings to date, although some DEC systems have been installed in conjunction with conventional air conditioners and there are undoubtedly more systems in place, but no data is available. There has been growing interest in developing DEC systems because of the efficiency gains possible. Large and some small-scale systems are available from Kathabar/Niagara Blower (United States), DuCool (Israel), Pax Streamline (United States), Menerga (Germany), Amercian Genius (United States), L-DCS (Germany), FICOM (Australia), Drykor (Israel) and Amercian Energy Exchange (United States) (Lowenstein, 2010). Desiccant wheels are available for small and large-scale applications (0.1 metre to 6 Metres in diameter) from Munters (United States and Sweden), Seibu Giken (Japan), Nichias (Japan), DRI (India), Klingenburg (Germany), PorFlute (Sweden), Rotor Source (United States) and NovelAire (United States) (Beccali, 2010).
Although the use of solar cooling is currently not high, it has several advantages against which the currently higher cost of solar air conditioning systems must be balanced. Advantages include:
- Solar
air conditioning reduces electricity consumption and reduces peak
electricity demand which may have significantly higher costs and CO2
emissions than off peak electricity
- Solar air conditioning
systems don’t use environmentally harmful materials and don’t use
refrig-erants with high greenhouse gas contents
- Solar air
conditioning systems, by significantly reducing or eliminating
electricity use for air con-ditioning reduces a household or businesses
exposure to price increases and volatility
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India
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