All About Geothermal Energy

Geothermal Energy: A Sustainable Alternative for Renewable Energy Investment

As a responsible investment platform dedicated to renewable energy (RE), Enerfip aims to accelerate the energy transition. These energies include photovoltaic, wind, biomass, and geothermal energy. In this article, we focus on geothermal energy! Often less known than other sectors, it offers a stable, low-impact, and sustainable alternative. By harnessing heat naturally stored beneath the Earth’s surface, geothermal energy presents significant potential.

Let’s explore what geothermal energy has to offer!

What is the principle of geothermal energy?

Derived from the Greek words “gê” (earth) and “thermos” (heat), geothermal energy is a renewable energy production method that extracts heat from underground layers and aquifers to generate electricity or heating. With low greenhouse gas (GHG) emissions, geothermal energy is a promising solution for energy independence.

Types of geothermal energy

1. Very low to low energy geothermal
   This technique uses shallow heat sources, below 30°C, and is often applied for heating homes or buildings.Examples:
   • Horizontal networks: Pipes installed in loops at shallow depth (60 cm–2 m), ideal for individual houses.
   • Vertical closed-loop probes: A looped pipe filled with a heat-transfer fluid circulates underground, capturing heat and transferring it to the building’s heating system. A 100 m deep probe can heat approximately 120 m².
   • Groundwater-based systems: Water from aquifers is pumped, and its heat is extracted through a closed-loop system for building heating.
2. Medium-energy geothermal
   Targets intermediate-temperature aquifers (30–150°C) and can be used for district heating or other larger-scale applications.
3. High-energy geothermal
   Typically developed in volcanic regions, this method requires water temperatures above 150°C. Steam from these sources drives turbines to generate electricity.

How does a geothermal power plant work?

In France, two geothermal plants produce electricity:

• Bouillante, Guadeloupe: 15.5 MW
• Soultz-sous-Forêt, Alsace: 1.7 MW

Process:

1. Rainwater infiltrates underground and is stored in a hot aquifer (150–350°C).
2. The water is pumped to the surface via a subsurface well, where it cools and turns into steam.
3. Steam pressure spins a turbine and alternator, generating electricity transmitted through high-voltage lines.

Different plants operate differently:

• Flash plants: Located in volcanic zones with very high-temperature geothermal reservoirs. Steam and water are separated as they rise and then converted into electricity (15–50 MW).
• ORC (Organic Rankine Cycle) plants: Geothermal fluid transfers energy to an organic fluid that vaporizes at low pressure, ideal for medium or low-temperature resources (80–200°C).

Why geothermal energy matters

As a renewable energy source, geothermal energy actively combats climate change. According to ADEME, geothermal energy emits 55 g CO₂/kWh on average, 10 times less than a natural gas power plant.

If you want to invest in geothermal projects, visit Enerfip under the “Invest” section!

For more information, don’t hesitate to contact our Investor Relations team.