Geothermal energy, the use of heat stored in the Earth's crust, has great potential in Austria but is currently hardly utilized. This is despite the fact that geothermal energy can provide climate-friendly heating and reduce energy costs in the long term. In other words, geothermal energy supplies renewable energy and is independent of weather and season.
What is geothermal energy and how does it work?
Geothermal energy uses the Heat inside the EarthWater is directed downward, heats up there, and brings the heat back up. Like wind, water, and solar energy, it is a renewable energy source. But unlike wind and sun, geothermal energy provides constant heat. It is completely independent of the weather and season.
Where does the heat inside the Earth come from?
The heat in the Earth's interior originates from multiple processes. A portion comes from the residual heat from Earth's formation about 4.6 billion years originated. In addition, there is heat from the decay of radioactive elements such as uranium. This process is constantly occurring and continuously generates new heat. However, it should not be confused with the Nuclear fusion, as it occurs in the sun and other stars.
Unlike nuclear fusion, where light nuclei fuse into heavier ones, the atomic nuclei of radioactive elements decay spontaneously, generating heat. 99 percent the Earth's mass are hotter than 1000 degrees Celsius. Even the outermost ten kilometers of Earth's crust contain so much heat that it could meet all of Earth's energy needs could cover 100,000 times. In contrast, the comparatively cool temperatures we know on the surface only prevail over a very small part of the Earth's mass – namely 0,1 %.
Near-surface and deep geothermal energy
The heat in the Earth's interior can be utilized in various ways. Basically, a distinction is made between two types of geothermal energy: the near-surface and the deep geothermal. In both cases, holes are drilled into the ground and the heat from the earth's interior is transported upwards using pipes. The difference lies in the depth of the boreholes.
Near-surface geothermal
Near-surface geothermal energy comes in Heat pumps for use. The boreholes mostly only go a few one hundred meters deep. There the temperatures are around 10 to 25 degrees Celsius.
U-shaped pipes run through the boreholes, through which a heat transfer fluid flows. It usually consists of water with antifreeze and transports the heat upwards. A heat pump compresses the low heat from 10–25 °C to 40–60 °C operating temperature, so that buildings can be heated with it.
The U-shaped pipes are also called geothermal probes. One to two such probes are sufficient to heat a single-family house. However, electricity cannot be generated this way.
Deep geothermal
Deep geothermal drilling reaches several kilometers into the Earth. At this depth, temperatures are significantly higher. Geothermal power plants These use this heat to supply entire city districts. These power plants can generate both heat and electricity.
However, not all locations have the necessary geological conditions. While near-surface geothermal energy is almost everywhere On Earth, deep geothermal energy requires either underground thermal water or hot underground rock layers.
Hydrothermal Geothermal Energy: From Water to Heat and Electricity
Hydrothermal geothermics utilizes naturally occurring hot water underground. This water circulates in deep rock layers. A borehole brings hot water to the surface. There, it releases its heat or drives a turbine to generate electricity. Afterward, it flows back down through a second borehole. There, it heats up again and a closed loop.
This technique is proven and has been used since used for decades. The main countries include the USA, China, and Turkey. However, geothermal power plants for electricity generation are only located in volcanically active regions economical. Iceland, Indonesia, and the Philippines are particularly leading in this area.
There are also geothermal plants in Austria. And some of them have been around since the 1970s. Many are located in Upper Austria and Styria. Another significant region is the Vienna Basin. There, Wien Energie, Austria's largest regional energy provider, is planning several new facilities.
Petrothermal Geothermal
Petrothermal geothermal energy extracts heat from underground rock and does not require natural thermal water. Instead, water artificial pumped into underground rock. To do this, companies drill two holes several kilometers deep into the earth. They inject water under high pressure through one of them. The pressure creates fine cracks in the rock. This allows the water to spread out and heat up. It returns to the surface through the second borehole.
The procedure resembles frackingIn both cases, water is pumped into the solid rock under extreme pressure until fine cracks form. In fracking, however, sand and environmentally harmful chemicals mixed in. And of course, the procedures have different goals: in fracking, Oil promoted, only heat in the case of petrothermal geothermal energy.
Theoretically, this technique can almost everywhere implement. Experts therefore estimate the potential of petrothermal geothermal energy at a Multiple times higher than that of hydrothermal geothermal energy. In practice, however, there are problems. The technology is Elaborate and expensive. Changes in rock pressure conditions can trigger perceptible earthquakes. A well-known example is a project in Basel in 2006.
There, a geothermal project solved 3.4 magnitude earthquake. The drilling had to be stopped. Due to these risks, there are hardly any economically operated plants to this day. Therefore, when geothermics is generally discussed, hydrothermal geothermics is primarily meant, i.e., the use of naturally occurring hot water and steam reservoirs underground.
Geothermal energy in Austria
The potential for geothermal energy in Austria is greater than many assume. Three regions exhibit favorable geological conditions: the molasses basin in Upper Austria's Innviertel and Hausruckviertel, which Styrian Basin in southeastern Styria and what Vienna Basin. There are hydrothermal systems there, in which thermal water circulates at greater depths.
In Upper Austria and Styria has had geothermal projects for decades. In the city of Ried im Innkreis, there are already 60 % for all households heated with geothermal energy. Additionally, local energy provider Ried Energie also supplies 300 households in surrounding communities with heat from deep within the earth. Ried is therefore often referred to as the Austria's Geothermal Hotspot designates.
In the Southeast Styria region, in addition to the existing facilities, since 2026 seismic measurements instead of exploring the underground for new geothermal plants. The third region with high potential – the Vienna Basin – has been less utilized so far. In the meantime, Wien Energie is strongly focused on expanding geothermal energy and plans to use the „deeep“ project to reach up to 7 Appendixto build. From 2028 should 20,000 households to be supplied with green energy from the depths.
Anyone who wants to know where geothermal energy is generally possible in Austria will find information on the website Geothermal Atlas found it. Currently, data is only available for Vienna, but work is being done to expand it nationwide.
Cost: Is a geothermal heating system worth it?
For a single-family home, the costs for this usually range between 15,000 and 30,000 Euros. However, those who want to have a heat pump installed usually don't have to bear the entire cost themselves. This is because the state subsidizes the „heating boiler exchange,“ meaning the conversion to climate-friendly heating in private households. up to 30 %.
In contrast, the investment costs for deep geothermal plants are typically in the Millions. Due to the high initial investment, many energy providers have shied away from expansion in the past. However, a geothermal power plant is worthwhile in the long run: Once built, it delivers almost Unlimited energy.
