Our planet's natural heat is a virtually endless source of energy, as over 99.9 percent of the Earth's volume is hotter than 100 degrees. This warmth can be used for heating, cooling and electricity production.
With the right technology, a lot of heat can be extracted from the Earth
At a depth of 25 meters (82 feet) below the Earth's surface the temperature remains constant, regardless of the weather or location. For every 100 meters further down, it increases by 3 to 4 degrees Celsius (5.4 to 7.2 degrees Fahrenheit).
In Germany, utilizing the Earth's natural warmth for heating is quite widespread. The heat and power plant in Neubrandenburg, for example, channels hot water with a temperature between 55 and 80 degrees Celsius from a depth of around 1,300 meters to the surface.
The water passes on its heat via a heat exchanger to a district heating network and then flows back underground through another shaft. With the help of heat pumps and geothermal collectors, some houses are heated entirely with this natural method.
For generating electricity with steam turbines, temperatures of at least 150 degrees Celsius are needed. In Germany, these temperatures can only be found at a depth of 2,500 to 4,500 meters, which is why the country only has a few small geothermal power plants.
In order to test geothermal electricity production methods, experts from the GFZ German Research Centre for Geosciences in Potsdam are performing drillings up to 4,300 meters deep in a geothermal lab in Brandenburg.
This kind of energy production is much easier in regions with volcanic activity, such as Iceland, Italy and Kenya. For example, Kenya's Olkaria geothermal power plants are located in the Great Rift Valley - a long fracture zone running from Lebanon to Mozambique.
Here, water vapor at a temperature of 300 to 350 degrees Celsius is channeled to the surface from a depth of around 2,000 meters via several shafts to turn the steam turbines and produce electricity. The potential for this kind of power generation is huge, but only a fraction of it is being currently exploited.
Author: Antonia Roetger (ew)
Editor: Mark Mattox