Geothermal energy – how it works and whether it can be an important source of energy in the future?

Geothermal energy – what it is and how it works

Geothermal energy, also known as geothermal power, is energy originating from the Earth’s interior, stored in hydrothermal systems or so-called hot dry rocks. It can come both from the decay of radioactive elements in the Earth’s crust and from processes leftover from the formation of the Earth’s structure and surface. For energy to be classified as geothermal, its temperature must be at least 20°C. While geothermal steam deposits have temperatures above 150°C, geothermal waters are characterized by lower temperatures.

To harness geothermal energy, wells up to 4,000 meters deep are drilled. Steam and geothermal water are extracted from these wells. Depending on pressure, reservoir shape, and terrain, there are:

• Artesian deposits, which allow water to flow naturally above the surface,
• Sub-artesian deposits, areas of low pressure where extraction requires equipment such as deep well pumps.

One of the installations that uses geothermal energy is a heat pump, which transfers heat collected from a lower source (ground or groundwater) to an upper source (a building, more specifically its central heating and domestic hot water system).

Geothermal energy in Poland – potential and current projects

Poland has abundant geothermal energy resources. Its potential is estimated at over 1,500 PJ/year, which corresponds to roughly 30% of the country’s heat demand. Areas with significant geothermal potential also coincide with densely populated regions, highly industrialized zones, and agricultural areas. Therefore, practical use of geothermal energy is relatively inexpensive.

Some of the main geothermal facilities in Poland include:

• Bańska Niżna
• Pyrzyce
• Uniejów
• Stargard Szczeciński
• Mszczonów
• Słomniki
• Klikuszowa
• Toruń

Work is also underway to establish additional heating and energy centers that utilize the Earth’s natural heat.

It’s worth noting that different types of renewable energy sources are increasingly combined to maximize economic benefits. An example is hybrid power plants that use both geothermal energy and biofuels. These plants can almost completely eliminate the use of fossil fuels, significantly reduce carbon dioxide emissions, and reduce dependence on the cost of primary energy sources—such as coal, which still dominates in Poland.

Advantages and disadvantages of geothermal energy as a renewable source

Using geothermal energy offers many benefits. Primarily, it is a resource whose exploitation poses far less threat to environmental biodiversity compared to coal or natural gas extraction. The carbon footprint of geothermal infrastructure is very small.

The potential of geothermal energy is immense because it is a renewable resource that will be available until the Earth is destroyed by the Sun—estimated by astrophysicists to happen in about 5 billion years. Unlike photovoltaics or wind power plants, geothermal energy is stable and highly efficient at all times, regardless of the time of day, season, or weather conditions. This stability makes it easier to predict energy output. With accurate data, a power plant can be designed to ensure its production meets the needs of a specific area.

Like any technology, geothermal energy has some drawbacks. Most importantly, it can only be utilized in areas where it occurs naturally. A specific risk associated with deep drilling is local collapses or even earthquakes.

Initial costs are also relatively high. A 1 MW geothermal power plant costs between $2 million and $7 million. The cost per kilowatt-hour is estimated at around $0.04–$0.06, while solar or wind energy can be up to six times cheaper. However, long-term cost-effectiveness should be analyzed.

Can geothermal energy be economically viable for companies and households?

According to the International Renewable Energy Agency (IRENA), the levelized cost of electricity (LCOE) from geothermal energy between 2010–2020 ranged from $0.049 to $0.085 per kilowatt-hour (0.19–0.33 PLN). By comparison, electricity generated from coal in 2024 cost around 1.50 PLN per kWh. The economic advantage is obvious.

It’s no surprise that countries with abundant geothermal resources use it extensively. Currently, geothermal energy covers a large portion of electricity demand in countries such as New Zealand, Iceland, Kenya, the Philippines, and El Salvador. In addition, Iceland meets over 90% of its heating needs from geothermal sources.

So, is it worth exploring geothermal energy? Absolutely—whether for companies or individual users—as long as you are located in an area with geothermal resources.

It’s also worth mentioning that IRENA supervises the Global Geothermal Alliance, an international initiative aimed at spreading knowledge about geothermal energy and promoting modern technologies in this field.

The future of geothermal energy in Poland and worldwide

One of the main directions in geothermal development today is Enhanced Geothermal Systems (EGS). These systems allow the extraction of geothermal energy not only where natural high-efficiency heat sources exist but practically anywhere in the world by stimulating underground layers through chemical, hydraulic, mechanical, or thermal methods.

Currently, there are only a few dozen EGS worldwide producing electricity, but their development is progressing rapidly. It is possible that within this decade, they will become a real competitor to conventional electricity generated from non-renewable sources. The lifespan of EGS is estimated at 20–30 years, with the largest facility having a 25 MW capacity located in Australia’s Cooper Basin. It has the potential to generate 5–10 MW of electricity.