The African Development Bank (AfDB) is planning to provide a US$26.6 million grant to the Comoros for the first phase of the Karthala geothermal project. The bank published the appraisal report for the scheme in mid-December 2024.

The scheme aims to explore the geothermal potential of the Karthala area, estimated at 45MW, with the government looking to exploit the resource for baseload electricity generation. The project will be located across an area of 1,148 square kilometres on the country’s main Grande Comore Island (Ngazidja).

The first phase will target the mobilisation of resources to facilitate the construction of the geothermal plant. These include the drilling and testing of three exploration wells with depths of 2,500-2,900 metres. The data collected will be used to conduct the feasibility study to confirm the geothermal potential. An independent review of the testing results and the feasibility study will be conducted.

The first phase will also see the development of drilling platforms and technical facilities such as laboratories, as well as the drilling of five water wells and the establishment of a water transport and distribution network, including reservoirs, pipelines and pumping stations. A 15km access road will also be built between Bahani and Soufriere.

The first phase is expected to help determine the feasibility of building the geothermal plant, confirm the power generation potential and facilitate agricultural trade via the access road.

Between late July and mid-August 2024, a consultancy team undertook geophysical and hydrogeological studies to confirm the existence of underground water sources capable of ensuring water supply for geothermal drilling activities. Studies conducted in 2015 identified potential sources of water around the area where the boreholes are proposed to be drilled.

The power plant will be built in the second phase and is planned to add 15MW of renewables capacity to the power grid at a generating cost of US$0.11/kWh.

The project is planned to directly benefit the Grande Comores Island’s population of an estimated 520,000 inhabitants, improving the reliability of power supply and providing access to about 93,000 households. Government offices and businesses will also benefit from the increased power supply, which will improve the population’s living conditions and economic productivity.

The Comoros’ energy mix is largely dominated by thermal power generation, at about 93% on average over the 2021-23 period and the country's electricity tariff is among the highest in Africa at US$0.44/kWh. The cost of diesel-based thermal power generation is US$0.67/kWh.

Meanwhile, the country is experiencing an estimated supply deficit of 5.4MW due to operations and maintenance issues and the government has turned to purchasing diesel generators with relatively high production costs in order to meet demand.  

To reduce the dependency on imported oil products and thermal energy, the authorities aim to diversify the electricity mix by developing solar capacity and exploring and enhancing geothermal potential. The country currently has two 3MW solar plants built by France’s Innovent on the Grande Comoros Island. However, the technical challenge of integrating solar into interconnected electricity systems limits the use of this source. The government is looking to use geothermal energy as a baseload power source to offset the intermittent nature of solar power.

Analyses of project costs and assessments of alternative clean energy options have demonstrated that geothermal power could offer a cost-effective, long-term solution to provide a secure and reliable source of electricity on Grande Comores, despite the scale of the investment required.

The Karthala geothermal exploration project is one of the flagship projects of the Comoros Emerging Plan as well as the energy sector’s 2020-33 investment plan. Over time, it is expected to contribute to the construction of infrastructure for the generation of clean, reliable and affordable energy, which will boost the country’s socioeconomic development.

The Comoros Geological Bureau (BGC) will be the project’s executing agency. The scheme is planned to begin in January and be completed by December 2029.

The US$44.4 million project will be jointly financed by the AfDB, the African Union, the Global Environment Facility and the government.

Top photo: Karthala volcano (© Lolodevenelles | Wikimedia Commons)