Geothermal energy inexhaustible and emission-free
Our planet contains inexhaustible energy reserves. Day after day, quantities of energy flow out of the earth's interior into space that would be enough to cover humanity's entire energy requirements several times over. With the technologies developed today, it is in principle possible to use this environmentally friendly and climate-friendly energy source anywhere. Geothermal energy is therefore one of the most widely used sources of renewable energy in the world.
Geothermal energy - energy from underground
Geothermal energy or geothermal heat refers to all the energy stored below the earth's surface in the form of heat. While the temperatures in the upper 10 - 20 m are still relatively low at an average of 10 - 12 °C, the influence of the enormous heat flow from the earth's interior becomes noticeable with increasing depth. Temperatures rise by around 3 °C per 100 m depth. In the earth's core itself, temperatures of up to 6000 °C are recorded. Volcanoes or geysers are an expression of this heat, which we are all familiar with. On its way upwards, the heat warms water reservoirs, rock and earth layers, which in turn can be used to generate heat or electricity. And this is completely emission-free !!! The main aim of geothermal energy utilization is to transport the heat from the depths to the earth's surface with the help of suitable technologies. In some places, nature itself provides the necessary circulation system, e.g. thermal springs. Elsewhere, development wells with a feed pump or geothermal probes with a circulation pump must be used.
Advantages of geothermal energy
- Infinite energy source, which is available everywhere on earth and around the clock
- Guarantees permanently low operating costs with professional planning and implementation
- Conserves valuable resources and reduces CO2 emissions
- Also suitable for cooling with minimal additional effort
- Geothermal energy is independent of weather & climate
- Geothermal energy does not have to be transported over long distances. It is energy on site
- There are mature technologies for boreholes, probes & heat pumps.
Geothermal power generation
So-called zones of geothermal activity with temperatures above 150 °C can be used directly to drive a turbine. In Germany, however, the usual temperatures of geological hot water deposits are lower. For a long time, thermal water was therefore only used to supply heat to buildings.
However, newly developed technologies make it possible to use temperatures as low as 80 °C to generate electricity. These work with an organic medium that vaporizes at relatively low temperatures. This hot steam drives the electricity generator via a turbine.
The first geothermal power plant in Germany was commissioned in Mecklenburg-Western Pomerania in 2004 as an extension to the geothermal heating plant built in 1994.
The electrical output of the Neustadt-Glewe geothermal power plant is up to ~200 kW. Water at a temperature of around 97 °C is extracted from a depth of approx. 2250 meters and used to supply electricity and heat.
Design of geothermal systems
For the planning of geothermal systems < 30kW, as is common in single-family homes, guideline values are often sufficient to determine the required drilling meters. For geothermal systems > 30kW, the most precise knowledge possible of the geological and hydrogeological structure of the subsurface, i.e. the type, thickness and distribution of the rocks as well as the groundwater level and groundwater flow conditions, is required. Specialist software is used here to simulate the underground processes.
How a heat pump works
The heat pump function is provided by a closed cycle. It works according to the functional principle of a refrigerator, i.e. by supplying technical work / drive energy, heat is extracted from the circuit and the condensation heat available at the high temperature level is transferred to the heating and hot water circuit. The heat pump converts low-temperature heat into high-temperature heat even in sub-zero winter temperatures.
The working medium continuously changes its aggregate state, evaporates, is compressed, liquefies and expands. Working fluids (refrigerants) are substances that vaporize at low temperatures and at the same time have a high internal heat.