Natural gas is harmful to the climate and expensive since the war in Russia. Geothermal energy would be a cheap and environmentally friendly alternative. Is this the golden age of geothermal energy?
More than 6000 citizens in Neustadt-Glewe (near Schwerin) heat their houses with 98 degree hot water from a depth of 2400 meters
In the center of our earth it is as hot as the sun, around 6000 degrees . 2,000 to 5,000 meters below the earth's surface it is then still 60 to 200 degrees and in volcanic regions on the surface up to 400 degrees Celsius.
Geothermal energy has existed since?
Our ancestors had been using geothermal energy in some regions for a long time: In the first century, the Romans in Aachen and Wiesbaden heated houses and thermal baths with hot spring water, in New Zealand the Maori used geothermal heat for cooking and in Larderello, Italy, electricity was first generated from geothermal energy in 1904.
Bathing in hot springs has a long tradition worldwide, like here on the island of Bali
< h2>Volcanic regions generate electricity with geothermal energy
Around 400 power plants in 30 countries generate electricity with steam from the earth – the total output is 16 gigawatts (GW). This power generation is particularly important in volcanic regions along the Pacific Ring of Fire, in the USA, Mexico, El Salvador, Iceland, Turkey, Kenya, Indonesia, the Philippines and New Zealand – the global average, however, is only 0.5 percent of electricity from geothermal energy.
El Salvador generates almost 30 percent of its electricity with geothermal energy
Heating with deep geothermal energy possible everywhere
Geothermal energy is more important worldwide for heating swimming pools, buildings, greenhouses and urban heating networks. Water at a temperature of up to 200 degrees is pumped out of aquifers from boreholes up to 5000 meters deep, the heat is used and the cooled water is pressed back through a second borehole.
This heat generation is possible worldwide, cheap and is increasingly used in countries without volcanic activity. The United Nations Environment Program estimates in the “Status Report Renewables”, a report on the status of renewable energies, that the installed capacity of geothermal thermal power plants is currently 38 gigawatts worldwide. That's more than twice that of geothermal power plants used to generate electricity.
So far, China (14 GW), Turkey (3 GW), Iceland (2 GW) and Japan (2 GW) in particular have been pursuing the expansion of deep geothermal energy with great determination and are using it to heat more and more districts and greenhouses. In Germany, the city of Munich in particular heats cheaply with geothermal energy and wants to use this energy to become climate-neutral by 2035.
The new federal government is now also focusing on the expansion of deep geothermal energy for climate-neutral heat supply by 2045 and wants to promote the development of deep heat sources with numerous measures. According to studies, deep geothermal energy in Germany with an installed capacity of 70 GW could generate around 300 TWh/a of heat, which is more than half of the future heat requirement of all buildings.
Heating from the surface with heat pump
Geothermal energy is increasingly being used from the near surface of the earth in combination with heat pumps. In boreholes from 50 to 400 meters deep, water flows from top to bottom and back again in a closed pipe system and heats up to 10 to 20 degrees. A heat pump then uses this energy to produce hot water at 30 to 70 degrees, which can be used to heat buildings.
Researchers see a heat potential similar to that of deep geothermal energy in this near-surface geothermal energy . In Germany, the entire heat requirement for buildings could be covered with these two technologies alone.
What does heat cost with deep geothermal energy?
According to an analysis by six German research institutes, heat generation using deep geothermal energy costs less than three euro cents per kilowatt hour (kWh).
Before Russia attacked Ukraine, however, heat generation with natural gas from pipelines was cheaper for many public utilities in Europe, so investing in the construction of deep geothermal plants did not seem attractive. The situation has changed completely as a result of the war and the sharp rise in gas prices in Europe to over 12 cents per kWh. Municipal utilities are now showing great interest in deep geothermal energy for municipal heat supply.
So-called vibro trucks generate sound waves and measure the reflections in the subsoil
Can geothermal energy completely cover the heat requirement?
no The potential of geothermal energy is almost unlimited, and deep geothermal energy and near-surface geothermal energy in combination with heat pumps can cover the heat demand for heating buildings everywhere worldwide.
But in industry, temperatures of more than 200 degrees required. As a rule, they cannot currently be achieved with geothermal energy and heat pumps. For such high temperatures, heating with electricity, biogas, biomass and green hydrogen are the climate-friendly alternatives.
How quickly can heat be supplied with deep geothermal energy?
Globally, the oil and gas industry in particular has gathered expertise about the subsoil in the last hundred years, there are specialist personnel and mature technology for drilling. In an interview with DW, Rolf Bracke, head of the Fraunhofer Institute for Energy Infrastructure and Geothermal Energy (IEG), is confident that geothermal energy can be expanded quickly “if the oil and gas industry should turn to geothermal energy”.
However, if the companies continue to concentrate on the production of oil and gas because more money can be made with it, “then I'm pessimistic,” says Bracke. Because then there would be a lack of personnel and drilling technology for the rapid expansion of geothermal energy. According to Bracke, the development of heat sources in the depths takes two to three years with quick approval, in Germany it takes about three times as long due to bureaucratic delays. The federal government now wants to accelerate this process and increase heat generation from deep geothermal energy tenfold from the current one terawatt by 2030.
Indonesia wants to quadruple its geothermal electricity production to 8 GW by 2030
Can deep geothermal energy cause earthquakes?< /h2>
Yes. In regions with seismic activity, geothermal energy can trigger small earthquakes if water is injected into the subsoil at too high a pressure and releases existing stresses there. In some cases, the earthquakes led to cracks in buildings and as a result the technique was rejected.
According to Bracke, there is no experience with earthquakes in regions without stresses in the subsoil. In the meantime, geothermal use has also been improved: With lower water pressures underground and more sophisticated monitoring methods, earthquakes on the surface can be avoided.
However, compared to the extraction of oil, natural gas and coal, geothermal energy is much less risky, emphasizes Bracke and “by far the safest source of energy on earth”.