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Geothermal Energy Production & Utilisation

Geothermal Energy Production

Geothermal energy can be found all over the world, how feasible its utilisation is, depends on the depth of the resource, the temperature found, the geological settings, the resource type, closeness to energy demand etc.

Today, geothermal energy is being utilised either in power generation (electricity) or directly in the form of heat (so called „direct use“). 

The resource type and temperature define the applications that can use the heat found in the subsurface. For power generation traditionally temperatures of more than 150 degrees Celsius or greater are necessary to produce electricity. There are though new technologies that can generate electricity utilising geothermal resource temperatures of down to around 70 degrees Celsius. How economically feasible this is, depends though on general market conditions. 

Lower temperatures can be used for a wide variety of uses, for heat in industrial applications, heating greenhouses, district heating systems or houses, heat swimming pools, pathways, aquaculture, food dehydration and many more. Ground-source heat pumps and exchange systems with addition of electricity can then expand the use geothermal energy for heating and cooling. 

An adaptation of the Lindal Diagram in the U.S. GeoVision report by the U.S. Department of Energy

Picture: An adaptation of the Lindal Diagram in the U.S. GeoVision report by the U.S. Department of Energy, p. 14 – source: [ ]

Production by Country

Today, 30 countries utilise geothermal energy to produce electricity. The top countries today represent around 93% of the total installed geothermal power generation capacity of 15,854 MW (as of January 2022). There are five countries that belong to the GW club with a geothermal power generation capacity of 1,000 MW or more. 

For an always up to date Top 10 Country List for geothermal power generation capacity, see our Research pages. (Leave out for the moment as we will have to add it to the research pages when we are getting to that)

The Top 10 list of countries with geothermal power generation capacity (Status as of year-end 2021, source ThinkGeoEnergy)

# Country Capacity (MWe)
1 United States 3,722
2 Indonesia 2,276
3 Philippines 1,918
4 Turkey 1,710
5 New Zealand 1,037
6 Mexico 963
7 Italy 944
8 Kenya 861
9 Iceland 754
10 Japan 603


The top 10 geothermal Countries 2021

According to the Global Update for Power Generation for the World Geothermal Congress 2020, the total electricity generated was 95,098 GWh for 2019.

For geothermal direct use (including ground-source heat pumps), the Global Update for Direct Use of Geothermal for the World Geothermal Congress 2020 reports that as of today 88 countries are currently utilising geothermal energy for direct use applications. The estimated total installed thermal generation capacity is about 107,727 MW thermal. With an increasing interest, as well as attention to the heat sector for decarbonisation of the energy sector, it is maybe not surprising that this sector of the geothermal industry is expected to see exponential growth exceeding that of the geothermal power sector.

Top 10 Geothermal Countries Direct Use (installed capacity) 2020

The top 10 Geothermal Countries Direct Usage

Geothermal Energy Electricity Production

The majority of countries generating electricity with geothermal today, are located in the hot regions of the world along the boundaries of tectonic plates, such as the Pacific Ring of Fire, often connected to volcanic activities. These high-enthalpy regions represent the most economic way of tapping geothermal energy. There are also an increasing number of countries not seen as “traditional geothermal countries” that only have access to low-enthalpy resources with lower temperature that are generating geothermal electricity today. The predominant example clearly is Turkey with an installed power generation capacity of around 1,663 MW (as of August 2021).

Today, there are roughly 400 geothermal power plants (often consisting of several units/ plants) and they can be found all around the world. ThinkGeoEnergy’s geothermal power plant map [LINK] provides an overview on the locations of these plants, and if you zoom in in the satellite view you can go down to the cooling towers of each plant. The plant is being updated on a regular basis.

Geothermal Power Station Global Map

In the figure below you can see the share of geothermal power generation in the overall electricity market in selected countries, highlighting the often very important role not only in the overall electricity supply, but also in the contribution of electricity generated by a renewable energy source in those countries.

Percentage of Geothermal in Total Electricity Generation

Maximum Production of Geothermal Energy

Depending on the resource quality, it can be said that no country in the world is fully tapping its available resource potential. While a country like Iceland, like no other, utilises geothermal energy to a rather wide extent, such as for heating swimming pools, district heating, industrial applications, and power generation, among others, there remain large untapped potential and only about 30% of the country’s electricity is generated by geothermal today.

Countries like Indonesia, Japan and the United States are only tapping a fraction of their resource potential. Indonesia alone has an estimated potential of up to 29,000 MW, yet has only used so far a geothermal power generation capacity of 2,133 MW. In Japan the same applies. 

With additional technological development, such as closed-loop systems, enhanced/ engineered geothermal system, or tapping very deep supercritical heat resources, the currently estimated geothermal power generation capacity (conservative) of 150,000 GW could be only a fraction what could actually be tapped in the future.

At the same time, geothermal resources of lower temperatures are likely a multiple of that for high temperature and for power generation. So here the opportunities are endless.

Electric Power Generation

Geothermal energy is being used for power generation by turbine-generator sets on the surface. Traditional steam turbines either dry-steam or flash are utilising high temperature resources of 150 degrees Celsius on the surface and more. 

The existing power plant technology uses the high temperature steam, either dry steam where available, or from steam water mixtures utilising flash technology. Both are using the steam that turns a turbine which generates electricity. The average size of dry steam and flash-condensing geothermal power plants is around 53 MW. 

For resource temperatures between 70 degrees and up to around 150 degrees Celsius, the use of a binary cycle technology turbine extends the opportunities of generating electricity from geothermal resource. 

This technology – in very simple terms – utilises a secondary fluid that boils at lower temperatures, and the steam generated there then turns a turbine generating electricity. This technology clearly is a bit more complex and has been more expensive, while being quite competitive also for higher temperature resources today. The average size for binary cycle geothermal plants is around 10 MW. At the same time, one can see a large number of new technology providers providing small binary-cycle power generation units with capacities such as 40 kW for very small units, as well as 150 kW units. The ranges though go all from 1 MW up to larger scale plants. The largest binary cycle geothermal plants have a capacity of 60 MW.

Geothermal Direct Use

The International Geothermal Association (IGA) defines geothermal direct use as utilising the energy of the earth (geothermal heat) directly as heat instead of indirect heat use for power generation. 

In geothermal literature, there is though made a distinction: direct use of geothermal is defined as using geothermal „resources“ using the heat energy or the fluid from geothermal resources without intervening medium as opposed to its conversion to other forms of energy such as electrical energy. Most direct use applications can be applied for geothermal fluids in the low to moderate temperature range 20 – 120°C. Low to medium temperature geothermal resources have been used for ages especially in a first time for bathing and later on for space heating and farming applications, as well as for cooling. 

The difference essentially is if one uses a water-based geothermal reservoir, or pipes/ wells for subsurface heat conduction and use above either directly as heat or through heat pumps.

Today, geothermal is mostly used for heating baths and swimming pools, as well as for space and greenhouse heating. Other applications are industrial uses utilizing heat, aquaculture pond heating, agricultural drying, cooling and snow melting. 

Geothermal Direct Use Production

Picture: Geothermal Direct Use Production in TJ/ year by application (2020)

Particularly, the use of geothermal energy for heating of swimming pools and heating for buildings (space heating) has grown in recent years.

Here a geographical overview over the heat production by year through geothermal direct use (excluding heat pumps)

Geothermal Direct Use Production Without Heat Pumps

Picture: Geothermal Direct use Production in TJ/ year by region (2020)

Geothermal Heat Pumps

HVAC applications have been around for decades. HVAC stands for heating, ventilation and air conditioning. HVAC heat pumps are devices that are being used to warm, but also cool buildings by transferring thermal energy from the subsurface (but also air and e.g. lakes) from either cooler or warmer space using a refrigeration cycle, similar to a normal household fridge. With electricity applied the performance of those heat pumps is then determined by a coefficient performance (COP). The higher the COP is the more efficient the heat pump is and less energy it consumes. So the higher the temperature in the ground is the less electricity it requires to expand thermal energy to higher temperatures for heating.

Ground Source Heat Pumps 

Ground source heat pump (also referred to as geothermal heat pump) are transferring heat to or from the subsurface, thereby taking advantage of the constant temperature of the earth throughout the seasons.  The heat pump as such is connected to a geothermal exchange set-up, which can be engineered using a closed-loop vertical or horizontal exchange, direct exchange, piles, utilising a loop in a pond, lake or the ocean, standing column wells or well doublets. They all have in common that the refrigerant is run through those pipes used to transfer the heat picked up from the subsurface to the heat pump. In the winter-time, the heat pump can use the thermal energy picked up to heat a building (or buildings in larger settings), or in the summer for cooling a building.


Direct use of geothermal energy for heating purposes is the largest form of utilising geothermal energy. The likely most classic and widest form of geothermal heat utilisation can be found in the traditional hot springs used for bathing, such as the Onsens in Japan, or the thermal baths going back to Roman times, but today heating swimming pools and baths around the world is the largest form of geothermal direct use. This is followed by the use of geothermal energy for space heating, e.g. in district heating systems. The largest district heating systems for geothermal energy can be found in Reykjavik/ Iceland, Paris/ France and in the incredible growth of geothermal district heating in China. But we see an increasing interest in Europe for the use of geothermal to decarbonise the heating (and cooling) market. Cities such as Munich, Helsinki, Copenhagen and others are betting big on the use of geothermal for their heating needs.

Another important use is also heating for greenhouses, which become a more and more important element in sustainable agriculture and the food sector. Here the example of the Netherlands is probably a good case study. A country with a large and thriving horticulture sector (greenhouse), Dutch operators were looking at ways to replace natural gas for their heating needs and started to explore geothermal as option, creating a now thriving market of both operators and suppliers utilising geothermal energy for heating greenhouses. Similar examples can be found in Turkey, Greece, Iceland, in the U.S. and elsewhere.


While sounding counterproductive, geothermal heat can though also be used for cooling. Using a process called absorption, heat from a geothermal resource is used as driving energy in a heat pump which then provides cooling to buildings, or even through district cooling systems. 

There have been examples of e.g. Masdar City in the United Arab Emirates where deep geothermal wells were drilled to extract heat to be used for district cooling systems. While initially not further developed, a district cooling utility is now revamping the project. 

At the same time ground-source heat pumps can also extract thermal energy at colder temperatures to be used directly for cooling and larger and smaller systems can be found all around the world.

Industrial Use of Geothermal Energy

Electricity production is the common “industrial” use of geothermal energy, but as indicated above there are a large number of industrial applications for activities requiring fluid at low-to medium temperature. Examples are processing heating, industrial space air conditioning and heating, food processing, food and fish dehydration, pulp and paper processing, washing and dyeing of textiles, chemical production and many more.

An interesting overview can be found in this figure showing “Temperature ranges for some industrial processes and agricultural applications”, as published by Jóhannesson, Th., Chatenay, C. “Industrial Applications of Geothermal Resources” (2014)


Industrial Geothermal Application temperatures

There are a large number of great examples of the various uses of geothermal, e.g. for the food & beverage industry. 

Geothermal energy is used today for salt production, pasteurization of milk, production of milk powder, production of algae/ spirulina, production of vegetables in greenhouses, fish dehydration, beer brewing, production of liquor, producing caviar, fish farming, the production of skin care products and so much more.

A good overview was presented by Luca Guglielmetti of the University of Geneva in Switzerland, showing what role geothermal energy can play in the food sector based on temperature.

Geothermal in the food sector