How can we benefit of the geothermal resource?

Geothermal energy harnesses the natural heat of the Earth, stored in the rocks beneath its surface. This heat is generated by the Earth’s core and increases in temperature as you move deeper into the Earth, following a geothermal gradient that varies based on the type of rock.

The endogenous fluid, after releasing its heat on the surface, returns to its deep geothermal reservoir and is continuously reheated by the Earth’s natural heat. This perpetual cycle enables energy production without interruption or the need for storage, 24 hours a day, all year round.

Did you know?

In contrast to traditional geothermal fields, medium-enthalpy projects such as the one in Ostellato are characterised by the fact that all geothermal fluid, in its liquid state, is kept in overpressure within a closed circuit so that doesn’t not change its aggregate state.

Types of geothermal power plants

After the endogenous fluid is extracted from the production wells, it is transferred through a series of advanced exchangers to a special "working fluid" that absorbs its heat. The now-cooled endogenous fluid is then injected back into the same geothermal reservoir from which it was extracted, at a depth of over 5,000 meters. This process, known as a binary cycle, maintains the same volumes and quality of fluid without releasing any components into the atmosphere and without creating any pressure imbalances in the subsoil.
The most common technology, it uses steam coming directly from underground at high temperatures, it feeds a turbine which is coupled to an electricity generator. At the generator's outlet, the steam is cooled and partly fed back underground, and partly discharged through cooling towers.
The boiling, high-pressure water reaches the surface, is transformed into cooler, low-pressure water; this increases the steam portion and can be used to power a steam turbine that generates electricity.

How does a medium-enthalpy geothermal power plant coupled with a closed-cycle thermodynamic cycle function?

Through the reservoir, the geothermal fluid is brought from the intake well to the heat exchanger of the ORC (Organic Rankine Cycle) turbine. The ORC process uses the geothermal fluid to transfer heat to a suitable organic process fluid that circulates within a closed loop and, as it heats up to vaporisation, drives a turbine coupled to a power generator, thus enabling the conversion of thermal energy into electricity.

The geothermal fluid is contained within the heat exchangers throughout the entire process until it is fully re-injected underground, ensuring that no atmospheric emissions are released. Additionally, the residual heat generated after electricity production can be utilized to provide heat to district heating networks. This closed-loop system allows for the sustainable cultivation of geothermal resources without any negative impact on the environment and ensures that the entire resource is returned into the geothermal reservoir of origin.

The benefits of the technology used in the Pangea project


Frequently asked questions

Geothermal energy has a low environmental impact compared to other forms of energy production. Geothermal plants have a small surface footprint and do not require the construction of large-scale infrastructure like dams or transmission lines, which can have significant impacts on the environment. The wells are typically drilled to depths of several kilometres and the plant components are located underground, minimizing their visibility, and reducing the impact on the surrounding landscape. Additionally, geothermal plants can operate continuously, providing a reliable source of clean energy without the need for fuel transport or storage.
Medium-enthalpy geothermal projects such as San Giovanni are designed to maintain a closed-loop system where the extracted endogenous fluid is circulated through a heat exchanger to transfer its heat to a special "working fluid."
This working fluid, which is circulated in a closed loop, vaporizes, and drives a turbine to produce electricity. After the heat exchange process, the geothermal fluid is injected back into the reservoir at a depth of more than 5,000 meters, maintaining the same volume and quality, without any emissions or pressure imbalances. The use of submerged pumps with ESP technology in wells enables the extraction of the well-defined level of fluid from the medium-enthalpy reservoir without the need to maintain pressure..
This process minimizes the environmental impact while harnessing the natural heat from the earth to produce clean energy.
High-enthalpy geothermal reservoirs are often associated with negative environmental impacts, including the need to inject water to maintain pressure inside the reservoir. This can lead to a significant waste of surface water resources and can also result in microseismic activity that does not align with the desired pore pressure parameters. However, these issues can be avoided with full reinjection technology at mid-enthalpy, which is used by Pangea. With this technology, the geothermal resource is completely returned to the subsoil, without consuming a single drop of water and without causing any pollution.

Geothermal energy is a silent source of energy as it operates without any combustion, which means it doesn't generate any noise pollution. The only mechanical equipment required for the geothermal power plants are the pumps, and they are typically located within enclosed spaces to minimize the noise levels emitted during operation. This makes geothermal energy an ideal solution for areas where noise pollution is a concern.
Geothermal energy is a renewable and sustainable energy source that can be exploited indefinitely without depletion. Regulatory authorizations for the development of geothermal resources are typically granted for a period of 30 years and can be renewed multiple times. Geothermal power plants that use ORC technology can operate for extended periods with minimal maintenance, ensuring a reliable source of electricity for decades.