Snowmelt system

Road heaters are a technique to keep all streets or special road sections, such as severe slopes, and bridges in the winter permanently ice-free. Road heaters are powered by electricity or water, which is heated with geothermal energy. Two, the latter variant also allows in summer cooling of the street, the heat energy can be stored or used for other purposes.

Road heaters, as well as the turf heating in sports facilities to the outdoor heating counted.

Basic idea

Speak for the permanent heating of winter roads in addition to economic and ecological issues, and demands on the safety of roads:

Roads are generally exempt through the winter service with snow and preserved with road salt before freezing. The road salt, which empty into drains and roads adjacent forest and meadow areas is flushed with melted snow and ice, is a burden on the environment, which can be reduced with the use of road heating or avoided. The fact that a heated road section is temperature constantly above the freezing point (0 ° C), the formation of black ice is prevented, resulting in a significant increase in road safety. Another advantage is the increased durability of a heated line. The heating reduces the maintenance costs, as frost damage can not occur; in particular, it reduces the formation of potholes significantly.

Technical implementation with geothermal

Road heaters work almost the same as floor heating for homes. In the asphalt hose lines are laid in loops in a few centimeters deep, is circulated through the heat a liquid carrier ( eg water). To heat the water, geothermal energy is utilized, which can be opened up with several, usually about 100 meters deep holes. The method is therefore particularly well used in regions where geothermal energy is already reachable in less depth. Advantage of this technique is that only the water pumps require electricity and the actual heating with a renewable energy happens.

In Scandinavia and especially in Iceland road heaters have long been common through the geologically related very easily exploitable geothermal energy. For this is also introduced in waste water heaters road in Iceland, as it still has enough residual heat to 30-40 ° C. In Germany so far only a few pilot projects were carried out with geothermal energy, but the finalized with success. In the Bavarian Marktredwitz example, a 135 m long street heater was designed for a downhill section which, according to the plans should have paid for itself after nine years due to the lower maintenance costs of the road.

Technical implementation with current

The operation of road heaters with electrical current is also possible. These heating wires are also routed in loops in the asphalt.

This type of road surface heating, has, however, compared to a geothermal heating, a poor environmental record, especially if the current is not produced from renewable sources. So there is an electric walkway heating in Berlin on the Kurfürstendamm with a floor area of about 600 m², wherein the heating power is 400 watts per square meter, resulting in a total output of about 240 kW. On a snowy day is thus produced for heating a power consumption of 5760 kWh, which is equivalent to the annual electricity needs of two families. If one of the power mix of working in Berlin Basic utility Vattenfall based around 3 tons of carbon dioxide are released by the operation of heating per day. Overall, this system runs per year, approximately 250 hours.

Heating technology for other modes of transport

Aviation

Using the techniques of street heaters it would in principle be possible to keep the start and runways, as well as the apron of airports ice. In the 1930s, a runway heating for the landing site of the Hugo - Junkers -Werke was built. In modern airports such heaters are, however, not be obstructed, especially since the size of the area to be heated would lead to investment costs in the billions.

Rail transport

In rail transport, point heaters are widely used to protect the moving parts of a railway switch in freezing weather before icing. Unlike the road there are for switches only limited reliable alternatives, so in early 2011 about 72 percent of the approximately 69,000 points were fitted in the DB network with a point heating. 2008 90 percent of these heaters were operated electrically, wherein the heating power electric switch heaters of about five kilowatts ( small curve radii ) extends up to about 50 kilowatts at high-speed switches.