3.1 Temperature and wells

Understanding the temperature profiles of these geothermal areas is essential for effectively harnessing the diverse thermal resources available in north-eastern Morocco. It provides a foundation for strategic planning and the development of tailored geothermal projects in the region. Across Morocco, the average geothermal gradient stands at 23°C/km, with occasional variations ranging from 19 to 42°C/km. Notably, the highest values are concentrated in the northeast and the south of Morocco.

This temperature variation at depth is attributed to the ascending movement of water, particularly noteworthy due to the artesian behavior of the Fezouane block. Another example is from borehole (2952/12), which highlights the circulation of water originating from carbonate formations below the depth of 594 meters, and the observed thermal profile indicates a remarkable geothermal gradient of 56°C/km (Figure 4).

The southernmost part of Morocco mainly consists of the Tarfaya-Laayoune-Dakhla basin. The latter is delineated by various geological features. It is bounded to the east by the Precambrian Reguibat shield and encompassed by the Paleozoic Dhlou-Zemmour belt and Zag-Tindouf basin (Figure 1). The northern limit is defined by the Anti-Atlas belt (Figure 1), while the southern boundary is represented by the Ouled Dlim massif and the Senegalo-Mauritanian basins. The basin's western edge is bordered by the Atlantic Ocean. The basin's geological composition comprises a Precambrian crystalline basement from the Reguibat shield, featuring Tonalities-Trondhjemites-Granodiorites, gneisses, and granitic rocks. The Reguibat shield is characterized by a collision between its southwestern Archean terrane and northeastern Paleoproterozoic terrane during a NE-trending transpressive Eburnean event, along the E-trending Oued Lekrae-El Mdena fault zone, shaping the basin's intricate geological framework (El Amraoui et al., 2023).

Over 1200 boreholes have been documented in southern Morocco, featuring temperatures ranging from 16.5 to 104°C. The measured water temperatures in these boreholes range from 30.0 to 84.2°C, validating the upward trend in water table temperatures within the Lower Cretaceous. This trend is observed from east to west toward Boujdour, aligning with the burial of the aquifer roof (Berkat et al., 2023). The geothermal gradient in the south of Morocco generally varies between 20 and 60°C/km (Figure 5a). The involved aquifers in the region are those of Paleogene and Lower Cretaceous accessible at varying depths. Based on the dispersion of thermal springs, aquifer productivity, the configuration of the productive aquifer, and the proximity to an anomaly in heat flow density, there are at least five distinct geothermal zones that have been identified (Figure 5b).

Dakhla El Argoub area: This area comprises 87 relatively low-temperature wells, averaging 33.7°C. The exploited aquifers are from the Paleogene and Lower Cretaceous. Notably, 81 wells show artesian characteristics, indicating elevated pressures within confined aquifers (Berkat et al., 2023).

Bir Gandouz area: Exploiting the aquifers from the Paleogene and Lower Cretaceous, the Bir Gandouz area features two nonartesian wells with temperatures of 36 and 32°C. The aquifer recharge likely occurs at a considerable distance northeast of this area (Berkat et al., 2023).

Boujdour Lamsid area: This area encompasses 11 deep boreholes accessing the Lower Cretaceous aquifer, with an average temperature of 52°C. Artesian conditions prevail near the coastal area (Berkat et al., 2023).

Essemara area: Essemara hosts three nonartesian wells with an average temperature of 33.5°C, exploiting the Lower Cretaceous aquifer.

El Marsa Laâyoune and Tarfaya area: This area encloses numerous hot water wells, with temperatures ranging from 32 to 69°C. The exploited aquifer is Lower Cretaceous, with localized artesian conditions. This area extends northward to encompass the impact of the positive geothermal anomaly attributed to the Canary Islands plume.

3.2 Geology and geochemistry

Morocco, as a country situated at a triple junction between a continent (Africa), an ocean (the Atlantic), and an active plate collision zone (the Alpine belt system), has experienced noteworthy tectonic activity, particularly in its northern part. This is evident in the density of seismicity, with the most active seismic zone located in the Alboran Sea and the Rif. This aligns with the region's status as a contact zone between the Eurasian and African plates. The Moho isobaths (Tadili et al., 1986) revealed minimum crustal thicknesses of approximately 25 km along the Mediterranean coast in the northern part and less than 25 km north of Oujda (Figure 6). Studies by Vallejo Martin et al. (1996) in the Betic Cordilleras indicate mantle upwelling in this area to a depth of 15 km. Overlaying the geothermal gradient map of Morocco with the findings by Tadili et al. (1986) and Vallejo Martin et al. (1996) suggests that thermal anomalies observed in the northern part of the map are primarily linked to crustal thinning (Zarhloule, 1999).

Figure 7 illustrates a conceptual model of northeastern Morocco, demonstrating the circulation of thermal water. Hot reservoirs in this region are trapped in sedimentary formations, which intrinsically compact Liassic limestones and dolomites and thus form the most relevant aquifer; these carbonates contain water in fractures and show locally some karstic patterns (Muffler & Cataldi, 1978; Rimi, 2011). The most resistant formations might be transmissive but not very accumulative, so the estimation of each aquifer's thickness, porosity, and transmissibility can hardly be made (Barkaoui et al., 2012). However, it is previously assumed that the reservoir's thickness is up to 500 m, with an increasing geothermal gradient of 50°C/km (Barkaoui et al., 2012; Zarhloule, 1999).

The integration of multiple isotope tracers (mainly 18O and 2H isotopes) indicates that most Moroccan geothermal waters (springs and boreholes) originate from meteoric water recharge (Figure 7) combined with water–rock interaction (Barkaoui et al., 2012; Bouchaou et al., 2017). They are mainly HCO3–Ca–Mg type and flow through carbonate rocks (Figure 8). Geochemical data show that the dissolution of marine evaporitic rocks (halite and gypsum/anhydrite) is the principal source of solutes (Table 1) controlling the composition and the salinity of these thermal waters (Bouchaou et al., 2017).

The structure of the Laâyoune-Dakhla basin is a syncline with a NE-SW axis. The sedimentary basin contains significant groundwater resources of varying quality, circulating in an aquifer complex comprising shallow and deep aquifers. The deep aquifers in this complex are multilayered, circulating in the northern part of the basin in the Cretaceous, and in the southern part (Dakhla area) in the Paleogene and Cretaceous. These nappes are fossilized and nonrenewable, free in the eastern part (outcrop zone), and captive or artesian in the western part (El Kanti, 2018).

In general, the waters of the Laâyoune-Dakhla Aquifer Complex predominantly have a chloride–sodium chemical composition. In the northern basin zone, the sampled waters display a chloride–sodium chemical facies with a tendency toward the sulfate pole. Moving toward the central zone, the waters become more mineralized and maintain the chloride–sodium facies, with discernible trends toward the calcium and sulfate poles. In the southern zone, the sampled waters consistently show a chloride-sodium chemical facies (Edoulati et al., 2013).

4.1 Current status

Morocco has already started working on an action plan including every possible geothermal area with the overarching goal of enhancing knowledge about geothermal resources, mitigating uncertainties related to resource exploitation, and initiating geothermal projects tailored to the unique characteristics of each area and its socioeconomic profile.

As Morocco becomes increasingly interested in geothermal development, the need to place a deeper emphasis on exploration and data collection to characterize the perceived geothermal potential is of more urgency. The lack of comprehensive plans encompassing geological characterization and involving other sectors such as economy, tourism, and energy is clearly unsatisfactory and outdated. There are, however, several initiatives from the ministry and the National Office of Hydrocarbons and Mines to implicate the society and facilitate this long-awaited project. These attempts have also affected universities and colleges as they started focusing on geothermal energy, either by providing on-site courses, organizing seminars and conferences, or by facilitating international collaborations and internships.

4.2 Moroccan legal regulations concerning EnR

Concurrently, Morocco is in the process of instituting an independent National Electricity Regulatory Agency to facilitate the burgeoning expansion of the energy sector. The regulatory framework outlined in Law No. 13-09 meticulously defines renewable energy projects, promoting their development for both domestic consumption and export by public or private entities. Importantly, private entities are granted permission to produce and export electricity, albeit still obligated to utilize the national grid for electricity supply. The law accords any renewable energy power producer, whether public or private, the right to connect to medium-, high-, and very-high-voltage grids.

Under the stipulations of this law, a preliminary statement regime becomes mandatory for new or upgraded installations producing renewable energy between 20 kW and 2 MW owned by the same operator on one or multiple sites, or for those generating 8 MW or more of thermal energy. Projects with a capacity of 2 MW or more necessitate endorsement from ADEREE, with the applicant securing temporary authorization for construction, followed by final authorization for operation. Failure to activate the facility within a year after final authorization or suspension of electricity production for more than 2 consecutive years may result in the withdrawal of the final authorization, excluding cases of renewable energy below 20 kW provided by a sole promoter.

4.3 Comparative analysis with other countries and technological advancements

Morocco can learn from valuable practices from the advanced geothermal countries from Europe and Africa, like Iceland, Turkey, and Kenya, which have successfully harnessed geothermal energy. It can learn from these countries especially in terms of prioritizing research and development, elaborating supportive regulatory framework, fostering public–private partnerships, addressing environmental and social considerations, and ensuring robust infrastructure for geothermal exploration and exploitation. Morocco can also learn from Turkey in terms of promoting private sector participation and fostering investment to facilitate the growth of its geothermal industry.

Enhanced Geothermal Systems usually refer to advancements that hold promise for overcoming challenges associated with traditional geothermal development. Specifically, this involves the stimulation of existing hot rock formations by injecting water at high pressure to create artificial reservoirs, thus expanding the potential locations for geothermal energy extraction beyond natural hydrothermal systems. This technology could be particularly beneficial for Morocco, as it could enable the exploitation of deeper geothermal resources in regions where conventional hydrothermal systems may be limited.

Furthermore, calling for innovative drilling techniques, such as directional drilling and slim-hole drilling, may help the country hasten the exploration and development of its geothermal resources, promoting the deployment of geothermal power plants, and enhancing energy security. In addition, advancements in reservoir modeling and monitoring technologies may enable better characterization of geothermal reservoirs and allow Morocco to improve its reservoir performance.

4.4 Economic framework

Like any other green schemes, geothermal projects typically entail higher initial investment costs for exploration, drilling, and plant construction. The return on investment (ROI) for geothermal projects in Morocco varies based on resource quality, project scale, financing terms, and prevailing electricity market conditions. Projects situated in regions with favorable geothermal conditions may yield attractive returns over their operational lifespan (several decades at least). However, this may be influenced by other factors, including project development schedules and regulatory frameworks governing electricity tariffs and incentives.

4.5 Environmental impact considerations

The most highlighted critical point in the environmental impact considerations lies in managing water resources sustainably, as geothermal energy extraction requires significant amounts of water for drilling, fluid injection, and power generation. Implementing water recycling and conservation measures, along with monitoring groundwater levels and quality, can minimize the depletion of local water resources already inadequately managed and prevent contamination of aquifers and surface water bodies.

5.1 Geothermal power generation

Morocco has been actively investing in renewable energy projects to diversify its energy mix and reduce dependency on fossil fuels (Figure 9), and the share of renewables in the total installed capacity in Morocco in 2022 has already achieved 38% (Figure 9). In fact, Morocco has one of the world's largest solar power plants, called Noor Concentrated Solar Power (CSP) complex. Located near Ouarzazate and with multiple phases, it is a flagship project in the country's renewable energy portfolio.

In addition to hydropower, which Morocco has been historically using as a renewable energy source, the country has also been investing in wind energy projects and has established wind farms, such as the Tarfaya Wind Farm, contributing to its renewable energy capacity (Figure 9). The country has received support and cooperation from international organizations and partners for its renewable energy initiatives and aims to derive a significant portion of its energy from renewables by 2030, including geothermal energy.

Geothermal power generation is a crucial and distinctive technology for producing electricity. In Morocco, where we encounter medium to low enthalpy conditions, binary cycles such as Organic Rankine Cycle (ORC) and Kalina become particularly relevant. The areas with the highest temperatures are predominantly situated near volcanic regions in the northeast, specifically in Nador and Oujda and in the Laayoune area in the south. The presence of a positive geothermal anomaly in Nador and the Boujdour–Lamsid region provides a marginal possibility for power generation through binary power plants near Kariat Arekman and Lamsid areas. These binary power plants can operate efficiently even at lower fluid temperatures ranging from 100 to 120°C and play a significant role in producing base-load electricity, surpassing the output of solar photovoltaic or wind power generation. While the global geothermal electricity supply experiences annual growth, it is noteworthy that this growth tends to be at a comparatively slower pace when compared to the expansion rates observed in solar PV and wind technologies, but this has to be followed up with extensive and detailed studies.

5.2 Geothermal direct use

Hydrothermal resources with lower temperatures have permeable, layered aquifers and/or aquifers within fracture or karst systems, making them suitable for geothermal direct-heat applications. Globally, these technologies play a vital role in providing solutions for space heating (especially through geothermal doublets, applicable for district heating and, more recently, for cooling), as well as for bathing, swimming/wellness, industrial processes, agriculture (particularly in greenhouses), and aquaculture practices such as fish farming. The most recent global report on geothermal Direct-Use (TJ/YR), compiled by Lund and Toth (2020), indicates that prevalent applications of geothermal energy have increased significantly in the past 25 years, with a particular growing interest in geothermal heat pumps and space heating, along with bathing and swimming, in the last 5 years (Figure 10). Except for aquaculture pond and industrial uses, which have not attracted attention during the last decade (Figure 10), all the other direct applications have increased, including agribusiness applications (greenhouses and covered ground heating) and agricultural drying (such as agricultural crop drying and industrial process heat).

The current contributions of the new technologies, coupled with shallow Ground Source Heat Pumps, can have a great impact on geothermal development within the regions. It is worth noting that within this hydrothermal category, certain locations (Figures 2 and 7) have thermal springs that have autonomously been supplying hot water to the surface for centuries. In these hydrothermal systems, meteoric water infiltrates the earth's surface, penetrates to greater depths to absorb heat, and then ascends back to the surface, typically along permeable fractures. These occurrences stand as exemplary instances of geothermal sustainability, where the outflow and its temperature remain consistently sustainable over extended periods.

This study delves into the diverse applications of geothermal energy that have been investigated and assessed, encompassing aspects such as market potential, economic feasibility, regulatory frameworks, and related policies. Ground Source Heat Pumps (GHPs) harness the Earth's consistently moderate temperature to supply heating, cooling, and hot water for residential, educational, governmental, and commercial structures. A minimal amount of electricity is needed to operate a compressor, and yet, the energy output is typically three to four times greater than the input. These systems essentially facilitate the movement of heat from a lower to a higher temperature location, akin to a reversible refrigeration unit. These GHPs can hence be used in all geothermal areas, but especially where shallow water sources exist, such as Berkane, Nador, Oujda, and Dakhla areas.

Figure 11 illustrates typical closed- and open-loop GHP installations. In the closed-loop geothermal heat pump system, a continuous loop of plastic or copper pipe is buried horizontally or vertically in the ground or submerged in a water source. The loop is filled with a heat-transfer fluid, usually a mixture of water and antifreeze. This fluid absorbs heat from the ground or water in winter to warm the building and releases heat back into the ground or water in summer to cool the building. Closed-loop GHPs are highly recommended for the areas of Taourirt and Lamsid (Figures 12 and 13).

In an open-loop system, groundwater or surface water is pumped from a well or another water source, passes through the heat pump's heat exchanger, and then is discharged to a second well, surface water, or a drainage ditch (Figure 11). It extracts heat from the water source in winter and releases heat back to the water source in summer.

Agriculture plays a substantial role in the Moroccan economy, at a significant proportion (Figures 12 and 13). This sector involves various activities within the targeted geothermal areas that include the cultivation of spirulina, mugwort's flowering tops and onion farming in Taourirt-Guercif, Lasmid, and El Argoub areas, greenhouse cultivation of tomatoes and artichokes, production of cereals, and cultivation of melons, watermelons, and oranges in Berkane, Oujda, and Nador. The exploration of geothermal energy applications in the context of Morocco's agricultural landscape underscores the potential for sustainable and diversified energy solutions in support of key economic sectors.

Aquaculture involves the cultivation of fish and other aquatic organisms within a controlled environment, essentially constituting the farming of freshwater or marine creatures such as fish and shellfish. The utilization of geothermal water in aquaculture serves to maintain stable water temperatures, enhancing survival rates and promoting accelerated growth of aquatic species. Nador, Lamsid, and El Argoub areas (Figures 12 and 13), with their geothermal resources, present promising and advantageous locations for the implementation of aquaculture projects, leveraging the benefits of geothermal energy to support and optimize the aquacultural practices in these regions.

Geothermal desalination utilizes geothermal energy to convert saltwater into freshwater. This method is known for its cost-effectiveness. Although the overall environmental impact remains uncertain, it has the potential to be more environmentally friendly compared to traditional desalination methods. The process involves using geothermal energy to directly heat saline or brackish water in multiple-effect distillation units or indirectly generate electricity for reverse osmosis units. Lamsid area, with its geothermal resources, is poised to benefit significantly from this direct application of geothermal energy for desalination (Figure 13).

Balneotherapy is a therapeutic practice that entails bathing in mineral-rich water with additional therapeutic additives. Thermal water, which has health-promoting properties, is utilized in thermal establishments for its beneficial effects. Comprising mineral salts, gases, and sludge, thermal water offers effective health benefits. Morocco has nearly 120 thermal springs distributed across six thermal spa areas: Northeast, Rif and South-Rif, Center, Middle Atlas, High Atlas, and Anti-Atlas, including the Sahara region (Fikri-Benbrahim et al., 2021). Balneotherapy typically follows various therapeutic orientations, including rheumatology, dermatology, otolaryngology, phlebology, and more (Fikri-Benbrahim et al., 2021). These therapeutic orientations are primarily determined by the nature of thermal mineral products, as outlined in Table 2.

Geothermal energy in Morocco can be utilized for many other industrial applications. It can provide heat for industrial processes such as drying, distillation, pasteurization, and other manufacturing activities, depending on temperatures of available geothermal reservoirs and the specific industrial heating needs. Thus, methods for prospecting and exploiting geothermal energy should be expanded not only in Morocco but also neighboring countries eventually, providing many advantages.

6.1 Challenges

Limited data and knowledge: Insufficient information about Morocco's geothermal resources poses challenges in identifying suitable locations for development.

Lack of technical expertise: The scarcity of skilled professionals experienced in geothermal exploration and development, especially those with field expertise, is a notable hurdle.

High upfront costs: The substantial initial capital investment required for geothermal energy development presents a significant challenge financially.

Regulatory and policy issues: Slow progress in the formulation of regulations supportive of geothermal development complicates the landscape.

Environmental and social impacts: Despite lower environmental and social impacts compared to other renewables, careful management is essential to prevent adverse consequences to local communities and the environment.

Infrastructure challenges: Inadequate infrastructure, including roads, power transmission lines, and water supply, adds complexity to the development of geothermal resources in Morocco.

6.2 Opportunities

Interesting geothermal potential: The large undeveloped geothermal potential of Morocco offers many opportunities for investments in exploration and development sectors.

Favorable geological conditions: The geology of Morocco features geological and structural conditions most favorable for geothermal energy, including crustal faults, volcanic formations, and hot springs.

High energy demand: The growing energy demand in the country, especially in rural areas, creates an opportunity for geothermal energy to contribute significantly.

Supportive policy environment: Morocco's sustainable strategy demonstrates an obligation to support geothermal energy, as a promising renewable energy resource, through policies and regulatory frameworks. With suitable motivations, partnerships, and community engagement, geothermal energy has the potential to become a significant contributor to Moroccan's energy sector.