Solar thermal energy is the utilization of energy obtained from shortwave solar irradiance, transferred to a heat carrier medium. It also offers large-scale possibilities, such as high-temperature hot water for steam production and power generation. Interesting applications for urban energy planning include installations at building level or a possible connection with district heating networks.
In the picture (wikipedia.com) above you can see the solar furnace at Odeillo in the French Pyrenees-Orientales which can reach temperatures up to 3,500°C.
Interesting Examples
There are three temperature levels through which this type of energy can be used; for each of them, a different technology is put into operation:
1. Low-temperature collectors with temperature levels around 65°C. Here, all individual hot water systems for buildings and houses are included.
2. Medium-temperature collectors: they concentrate solar radiation supplying useful heat at higher temperatures, usually between 100°C and 300°C.
3. High-temperature collectors: temperatures are higher than 500°C, and steam production is possible for power generation.
Solar thermal power generation systems collect and concentrate sunlight to produce the high-temperature heat needed to generate electricity. All solar thermal power systems have solar energy collectors with two main components: reflectors (mirrors) that capture and focus sunlight onto a receiver. In most types of systems, a heat-transfer fluid is heated and circulated in the receiver and used to produce steam. The steam is converted into mechanical energy in a turbine, which powers a generator to produce electricity. Solar thermal power systems have tracking systems that keep sunlight focused onto the receiver throughout the day as the sun changes position in the sky. Solar thermal power plants usually have a large field or array of collectors that supply heat to a turbine and generator.
State of the Art Switzerland
In addition to daylighting and passive solar heating, further opportunities could be investigated, such as advanced PV glazing: new solar cell technologies, the so-called dye solar cells might offer a chance to combine the generation of solar electricity in facades with window properties. They offer transparency and low-cost production.
Although the proportion of solar heat to overall consumption in Switzerland is still relatively low, its potential is considerable. If all existing buildings were to be optimally improved in terms of energy efficiency, it would be possible to meet the heating requirements of all Switzerland's households through the use of solar collectors.
Quiz
What's the example that represents the idea behind solar thermal energy the most?
A. a black paper heating up in the sun
B. seething water
C. evaporating alcohol
Vocabulary
Solar Thermal Energy: Unter Solarthermie versteht man die Umwandlung der Sonnenenergie in nutzbare thermische Energie.
Solar irradiance: Sonneneinstrahlung
Solar radiation: Sonnenstrahlung
Urban Energy: Städtische Energie
Sway Presentation
Look at our Sway Presentation (sway.office.com).
Sources
Solar Thermal Energy (en.wikipedia.org)
Solar Thermal (studentenergy.com)
Energy Innovation (publications.iadb.org)
This post was written by Kolja Schenker and Michael Stutz.