As Africa seeks to close its massive electricity access deficit, the continent is relying on a handful of well-established technologies to do the heavy lifting. Solar power is stepping up to become the workhorse of the electrification drive. Energy think tank Ember estimates that 100,000 panels are being installed every day across the continent. When combined with battery storage, which has significantly declined in cost over the last two years, solar technology is undoubtedly key to Africa's energy future.

The continent is also investing billions of dollars a year in other conventional energy technologies, including gas-fired power stations, large-scale hydroelectric dams and wind farms.

But no single technology can meet all of Africa's needs. While the continent boasts generally excellent conditions for solar generation, there are nevertheless significant regional variations in the quality of solar resources.

As a result, significant research and development efforts are underway to tap into niche sources of power generation and storage. African Business looks into four areas where technological innovation could help Africa to achieve breakthroughs that will increase energy access, improve the reliability of power systems and help provide last mile connections to the hardest-to-reach communities.

From waste to energy

Generating power or heat from waste products offers a key opportunity to build a "circular" economy in Africa.

Conventional waste-to-energy facilities use long-established technology and function much like any other thermal power station by burning municipal waste to generate power. Several waste-to-energy projects are under way around the continent. In Freetown, Sierra Leone, for example, infrastructure development company Infinitum Energy is working on a 30 MW facility. Its CEO, Lindsay Nagle, told African Business last year that there is "monumental" potential to expand this model across Africa's cities.

But conventional waste-to-energy projects are controversial due to the pollutants released when waste is burned. Also, most plants are designed to burn dry waste, whereas most waste in African cities is made up of organic material.

Generating power from biomass - such as crop residues - may be better suited to Africa's needs. These projects can create a win-win outcome, allowing smallholder farmers to earn revenue from waste products, while also creating a new source of "baseload" power supply - running continuously to meet the minimum or base demand level.

One of the most prominent biomass projects in Africa is the Biovea Energie facility in Côte d'Ivoire, which began supplying electricity to the local grid last year. Funded by a consortium that includes French utility EDF and infrastructure investment firm Meridiam, the 46 MW plant is fuelled by waste from palm oil production. Speaking at the beginning of construction in 2023, Meridiam's CEO Thierry Déau said that Biovea would create "a virtuous circle of economic development" and "improve the productivity and income of local plantations and farmers".

Anaerobic digesters are another option for generating power from biomass. These can use feedstock ranging from crop residues to cattle manure and even human faeces. The waste products are digested by bacteria in an oxygen-free - anaerobic - tank. This results in the release of "biogas", which can be used as a cooking fuel, for heating or for power generation. An added benefit is that leftovers from the digestion process can be an excellent organic fertiliser.

These biogas plants vary hugely in scale. Many supply biogas to single households or communities, while facilities that operate alongside commercial farming operations - such as the 9.8 MW Bronkhorstspruit Biogas Plant in South Africa - are a significant source of electricity generation.

Asian countries such as India have led the way in installing biogas digesters, although Kenya and several other African countries are working to harness their potential on a greater scale.

Anne Mburu looks at vegetables that she enriches using slurry that runs off the adjacent flexibag biogas digester installed at her farm in Kiambu county. She has plans to use the biogas to generate electricity for her broiler chicken brooding project. (Photo by TONY KARUMBA / AFP)

Drilling deeper

Kenya also stands out as the only African country that has made developing geothermal power a priority. The East African nation boasts the world's sixth-largest geothermal power production capacity and relies on geothermal sources for almost half its electricity supply.

This is partly because of geology. A geothermal power plant works like a giant kettle, tapping into water deep beneath the surface of the Earth that is heated by hot rock or magma. Kenya is bisected by the East African Rift Valley, a "tectonic fault" where the African plate of the Earth's surface is splitting into the Somali plate and the Nubian plate, which are moving apart by about 8 mm a year, and hot rock is relatively close to the floor of the valley. It is therefore easier and cheaper here than elsewhere to drill boreholes from which superheated steam rises to turn turbines and generate electricity.

Other African countries have made negligible progress in harnessing geothermal power, including those that also sit astride the Rift Valley.

Advances in technology could, however, make it feasible for a much broader range of African countries to generate renewable baseload power from geothermal sources.

In an enhanced geothermal system (EGS), companies drill more than 5,000 metres below the surface to reach a layer of hot rock, using techniques similar to those of "fracking" in the oil and gas industry. Cold water is then injected into the system, where it is heated by the hot rock and returns to the surface as hot water or steam.

In theory, this means geothermal power can be harnessed from almost anywhere in the world, including parts of West and Central Africa that are far from major tectonic faults. The catch is that drilling deeper comes with a hefty price tag. For now, efforts to commercialise EGS technology focus overwhelmingly on the United States and Europe.

The good news is that drilling costs for some recent wells have been less than 20% of the historical norm - suggesting that EGS could soon become a more economically viable option for African countries looking to open new sources of power supply.

A plume of steam billows from a three-kilometres deep open well at the ol-Karia geothermal power generation complex that lies on the floor of the Kenyan Rift Valley. (Photo by Tony KARUMBA / AFP)

Redefining storage

To make greater use of intermittent renewable energy, such as wind or solar power, the ability to store energy is essential. Battery energy storage systems (BESS) have reduced significantly in cost in recent years. It is possible for solar power, when combined with BESS, to function more like a baseload source. For example, energy systems developer CrossBoundary Energy completed a project in August that uses solar and battery storage to guarantee a continuous supply of at least 30 MW to the Kamoa Copper mine in DR Congo. Richard Stanford, CrossBoundary's chief technical officer, told African Business then that he expects a "rush" of similar projects for industrial offtakers.

But BESS has limitations. While the technical capabilities of battery systems have improved, they still generally store only a few hours of electricity demand. There are also social and environmental concerns around sourcing battery materials, and question marks around fire safety.

For these reasons, many companies continue to explore alternative energy storage technologies. In Nigeria's Kano State, for example, British company Tree Associates is piloting a compressed air storage system that it says avoids the need for materials like lithium and is designed for use as an overnight source of baseload power. The system uses electricity generated by solar panels to mechanically compress air into storage vessels. When power is needed, the air is released through a turbine to generate electricity.

Another long-duration storage technology that may be particularly relevant in parts of Africa relies on gravity. At the Hendrina power station in South Africa, for example, California-based company Energy Vault is working with the state-owned utility Eskom to pilot a gravity energy storage system (GESS).

A conventional pumped storage hydro system uses off-peak electricity to move water uphill, then runs it down through a turbine to generate electricity when it is needed. In contrast, the GESS at Hendrina will use surplus solar power to lift heavy blocks - in this case, made of recycled coal ash. When electricity is needed, the blocks descend, pulling cables that spin generators. Unlike batteries, GESS can store power indefinitely without degrading. As South Africa moves away from coal and towards renewables, Eskom CEO Dan Marokane has said the technology can play a "pivotal role" in the country's energy transition.

Though this pilot is taking place beside a power station, there is considerable potential to build GESS systems in abandoned mine shafts throughout the continent where they can take advantage of huge vertical drops....

African Business

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