Street cooling
Street cooling is a technique used to cool the road surface of entire streets , special street sections or parking lots in summer. The use of road cooling systems can reduce heat-related damage to the asphalt , such as rutting , for example . The thermal energy extracted during cooling can be stored and used to heat the street in winter . It is also possible to use the heat directly, for example to heat domestic water in nearby buildings. If this application is in the foreground, the term asphalt collectors is often used, based on conventional solar collectors .
Technical implementation
functionality
Asphalt heats up to over 60 ° C when exposed to sunlight, benefiting from its dark color . To use this thermal energy and the associated cooling, plastic pipes laid in loops are embedded in the asphalt at a depth of a few centimeters, through which cold water is pumped. The water removes some of the heat from the asphalt and dissipates it.
The heat can be stored in the ground with the help of geothermal probes . To do this, boreholes up to a depth of 250 m are necessary. The direct use of the warm water, on the other hand, is advisable if buildings or systems in the vicinity have a correspondingly high demand. For example, it can make sense to cool a large parking lot, the heat of which is used to heat domestic water for office and commercial buildings.
Life of the asphalt
As a result of the bitumen binding agent, asphalt surfaces have the property of becoming harder and more brittle at low temperatures. At very high temperatures, on the other hand, asphalt becomes increasingly soft and plastic deformations such as ruts can occur . Street cooling reduces the heat peaks of the asphalt in summer so that the critical temperatures, at which severe deformations can occur, are not reached. The life of a road can therefore be extended by cooling.
Energy balance
Manufacturers of such systems put the achievable thermal output at 270 kWh per year and square meter of asphalt surface. Modern solar thermal systems achieve roughly twice the output, but the cost of street cooling is estimated at one twelfth of a solar thermal system.
Electric power is required to operate the pumps, but this is countered by a considerably greater heat gain. According to the manufacturer, one kilowatt of electricity can generate 25 kilowatts of heat.
Web links
- Arian de Bondt, Rob Jansen: Technical article: Energy from asphalt pavements - generation and savings. December 2006, (PDF, 5 pages, approx. 771 KB)
Individual evidence
- ↑ a b c Ice-free with geothermal energy - Munich researchers develop a bridge heating system. 3sat, accessed on August 2, 2013 .
- ↑ a b c d Energy from the asphalt. (No longer available online.) Allianz, March 20, 2009, formerly in the original ; Retrieved August 2, 2013 . ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
