01 · DEFINITION
Geothermal is, literally, earth-heat
From the Greek geo – therme, heat is a form of energy — and geothermal becomes an energy resource when we can use this heat to our advantage. Most of the Earth’s heat lies deep inside the planet, beyond the reach of technology. At relatively shallow depths, depending on the temperature, the heat may be economically extracted and used — and the shallow Earth itself may serve as a heat reservoir.
02 · USES
Three categories of use
Geothermal resource uses fall into three categories. The use depends primarily on the temperature of the resource, but also on the need of the user.
Geothermal heat pumps
~ 10 – 38 °C
The lowest-temperature use: the ground serves as a storage reservoir, heating buildings in winter and cooling them in summer.
Direct use
~ 38 – 150 °C
Heat used without conversion — thermal baths, fish farming, greenhouses, food processing, drying, and district heating.
Electricity generation
≥ 121 °C
Water hot enough to produce a vapor phase turns a turbine to drive a generator — binary, flash-steam and dry-steam plants.
03 · HOW IT WORKS
The geothermal temperature continuum
Every temperature has a use — from ground-source heat pumps at 10 °C to flash and dry-steam power plants above 177 °C.
10 – 38 °C
Heat pumps · aquaculture
Geothermal heat pumps, fish farming, building heating and cooling.
38 – 95 °C
Direct use
Greenhouses, food processing, concrete-block drying and district heating.
121 – 177 °C
Binary power plants
Cement and aggregate drying; binary geothermal power generation begins.
204 – 371 °C
Flash & dry steam
Flash and dry-steam geothermal power plants; hydrogen production.
CHAÎNE DE VALEUR INDUSTRIELLE
De l’exploration aux industries d’utilisation finale
04 · DIRECT USE
Direct use & district heating systems
Using heat from the Earth without any temperature or energy-form conversion is classified as direct use. Direct-use temperatures overlap with ground-source heat pumps at the low end and with electricity generation at the high end — thermal baths, fish farming, greenhouses, food processing, drying and district heating.
05 · HEAT PUMPS
Geothermal heat pumps
Typically the lowest-temperature use — the ground acts as a storage reservoir for heat. A heat pump transferring heat into and out of the ground is a far more efficient use of electricity than producing heat directly.
Summer · Cooling
Heat is pumped out of the building; the ground absorbs it.
Winter · Heating
Heat is pumped out of the ground and into the building.
Geothermal electricity generation
For electricity generation, water must be hot enough to produce a vapor phase to turn a turbine and drive a generator.
DRY STEAM
Dry-steam plants
Steam from the reservoir drives the turbine directly — the earliest plant design, used where the resource produces steam alone.
FLASH STEAM
Flash-steam plants
High-pressure hot water is ‘flashed’ to steam in a separator; older steam plants may carry a small pollution component from volcanic gases.
BINARY
Binary plants
Geothermal fluid passes through a heat exchanger and is reinjected — no exposure to the atmosphere, no pollution. Clean, renewable, baseload, sustainable electricity.
07 · GEOTHERMAL EXPLORATION
How ONHYM explores the resource
Exploration progresses from reconnaissance mapping to detailed multidisciplinary surveys that characterise the thermal fluids, structures and reservoir before a well is sited.
Géologie
Reconnaissance begins with preliminary mapping of lithologic units and structures, relating thermal surface manifestations to structures or volcanism. Detailed studies map geothermal surface alteration, analyse alteration minerals by XRD, and record physical properties — temperature, flow rate, conductivity.
Remote sensing
Photogeological maps and remote-sensing images map geological structures during reconnaissance and detailed mapping. Optical, near-infrared and thermal-infrared imagery identifies surface expressions — sinter/tufa, hydrothermal alteration (clays, sulfates) and thermal anomalies with distinct spectral signatures.
Géochimie
Sampling, analysis and interpretation of thermal fluids discharged from geothermal manifestations characterises the fluids, establishes their origin and flow direction (upflow, outflow), evaluates mixing scenarios and estimates the equilibrium reservoir temperature.
Géophysique
Geothermal anomalies are linked to geophysical anomalies: changes in temperature and gradient alter subsurface physical properties observable from the surface, measured with different methods and instruments.
| PROPERTY | METHOD | EQUIPMENT |
|---|---|---|
| Electrical conductivity / resistivity | Electromagnetic / Electric | MT / TEM |
| Density | Gravity | Gravimeter |
| Magnetic susceptibility | Magnetics | Magnetometer |
| Elastic moduli / velocity | Seismics | Seismometer |
Heat flow measurements
The primary objective is to estimate the heat energy lost naturally, analyse the distribution of heat-loss features and locate hidden fracture zones. Heat is lost through conduction and convection; high heat-loss anomalies usually coincide with the structural trend and areas with thermal manifestations.
Conceptual model & well siting
A descriptive model unifying the essential physical features of the system — size, temperature, flow patterns (upflow, outflow, recharge), processes such as mixing, chemical buffering or boiling, internal flow barriers, the cap-rock and the nature of the heat source — guiding where wells are sited.
08 · GEOTHERMAL IN MOROCCO
Potential still to be unexploited
The Moroccan subsoil holds geothermal energy potential still unexploited — especially in the northeast, where the estimated installed capacity is around 5 MWe. Geothermal data from deep oil wells highlights a heat flux increasing northeastward across the eastern Rif, northeastern Morocco, the Alboran Sea, southeastern Spain and northwestern Algeria.
The highest geothermal gradient in Morocco is found in the northeast, reaching up to 50 °C/km. Temperature data recorded in a water borehole in the Berkane and Oujda areas revealed an average gradient exceeding 120 °C/km at depths greater than 300 m.
≈ 5 MWe
ESTIMATED INSTALLED
CAPACITY, NORTHEAST
CAPACITY, NORTHEAST
50 °C/km
HIGHEST GEOTHERMAL
GRADIENT
GRADIENT
>120 °C/km
BERKANE-OUJDA
BOREHOLES, >300 M DEEP
BOREHOLES, >300 M DEEP
Hydro-thermal basins
Studies of the country's geothermal potential subdivide Morocco into several hydro-thermal basins.
1
North-Eastern Morocco Basin
2
North-Western Morocco Basin
3
Tadla Basin
4
Tarfaya–Laâyoune Basins (Moroccan Sahara)
5
Basins of Errachidia – Ouarzazate – Boudnib
6
Agadir Basin
7
Doukkala Basin
Priority zones for a first step: the North-Eastern Morocco area and the sedimentary basins of the Southern Provinces (Tindouf and Tarfaya).
09 · ONHYM PROJECTS
Assessment studies across the hydro-thermal basins
Conscious of geothermal’s role as an affordable, sustainable energy, ONHYM has launched several assessment studies to evaluate the country’s potential.
| PARAMETER | AGADIR BASIN | TADLA BASIN | NORTH-WESTERN MOROCCO | NORTH-EASTERN MOROCCO | TARFAYA – LAÂYOUNE (SAHARA) |
|---|---|---|---|---|---|
| Wells number | 60 | 30 | 70 | 90 | – |
| Water temperature (°C) | 28 – 32 | 28 – 47 | 27 – 51 | 28 – 55.5 | – |
| Geoth. gradient GOSA | 35 – 60 | 30 – 60 | > 40 | 30 – 70 | 20 – 32 |
| Geoth. gradient Geau | > 48 | > 30 | > 35 | > 50 | – |
| Water table | Turonian | Turonian | Lias | Lias | Lias |
| Depth of the roof (m) | 120 – 600 | 200 – 500 | 400 – 1000 | 200 – 1000 | 500 – 2000 |
| Number of occurrences | 10 | 14 | 24 | 32 | – |
| Salinity (g/l) | 0.5 – 0.7 | 0.7 – 2.1 | 2.36 – 2.84 | 0.1 – 3.0 | – |
| Flow rate (l/s) | 15 – 30 | Artesian | Artesian | 2.5 – 40 | – |
| Classification | C | C | C | A | B |
GOSA: apparent superficial geothermal gradient · G1: gradient between the water body and the surface · G2: gradient between the water body and the bottom of the well · Geau: gradient between the water body and interception level. Temperatures in °C, gradients in °C/km.
up to 120 °C
Relatively high geothermal potential — a deep reservoir (~3000 m) reaching 120 °C, suitable for the broadest range of applications.
up to 100 °C
Average geothermal potential — a deep reservoir (~3000 m) reaching 100 °C.
30 – 90 °C
Lower to medium temperatures — direct use in domestic heating, horticulture, greenhouse heating and fish farming.
FLAGSHIP STUDY
North-Eastern Morocco assessment study
The project “Study of the Geothermal Potential in North-East Morocco” evaluates the resource over roughly 50,000 km² — a SW-NE trending area of recent volcanic activity, thinned crust and a heat flux exceeding 40 °C/km. Divided into five phases:
Analysis and interpretation of available data
Sampling and field campaign
Compilation and interpretation of collected data
Synthesis of results
Definition of a regional geothermal roadmap
A roadmap for geothermal energy
The study proposes integrated options to promote geothermal resources in the region:
- Integration of geothermal heat into regional development strategies for tourism, agriculture, industry and energy.
- Inclusion in the Nationally Determined Contributions (NDC) framework for the national climate change strategy.
- Creating the regulatory and legislative framework for geothermal energy.
- Setting up mechanisms to support investment in the sector.
10 · THE OPPORTUNITY
Why geothermal belongs in Morocco's new energy mix
Renewable, baseload energy
Binary power plants produce clean, renewable, baseload and sustainable electrical energy — with the geothermal fluid fully reinjected.
A use for every temperature
From 10 °C heat pumps to 371 °C steam plants, the resource serves heating, industry, agriculture and power across the whole temperature continuum.
An investor-friendly framework
Law n°33-13 of July 2015 and its 2016 implementing decree modernized the Mining Regulations. Morocco protects investors through a transparent, attractive tax framework.
Explore Morocco's New Energy Opportunities
Discover ONHYM’s exploration programs and partnership opportunities in natural hydrogen and geothermal energy.
