The world’s oceans cover more than 70% of Earth’s surface. Within them flow strong ocean currents—many more powerful than large rivers. Scientists now believe these currents can be used to generate clean, renewable electricity.
Unlike solar or wind power, which can be inconsistent, ocean currents are steady and predictable. They move constantly, day and night, making them a reliable source of marine energy.
A new study has revealed that the eastern and southeastern coasts of Africa are among the best locations in the world for harvesting energy from ocean currents. Researchers Mahsan Sadoughipour, James VanZwieten, Yufei Tang, and Gabriel Alsenas explored how this clean energy source could help meet electricity needs in African countries.
How Do Ocean Currents Produce Electricity?
Ocean currents contain kinetic energy—the energy of movement. This energy can be turned into electricity using underwater turbines, much like wind turbines convert wind into power.
These turbines would float on or just below the surface of the ocean. Power generated by the turbines could be sent to shore using cables laid on the seafloor, as is done with offshore wind farms. Another option is using the electricity offshore to produce hydrogen, which can then be transported and used as fuel—removing the need for underwater cables altogether.
What Did the Researchers Study?
The research team analyzed 30 years of data on ocean current speeds. They used information from 1,250 drifting buoys equipped with sensors that track ocean movement and report back via satellite. These buoys float with the currents and are not affected by wind, allowing accurate measurements of how fast and in which direction the water moves.
In total, the team examined 43 million measurements of ocean current speed and direction. From this, they calculated the energy density—the amount of energy in each square meter of ocean. This was a crucial step in identifying where ocean energy can be most effectively harnessed. This is the first time such detailed energy density data has been produced.
Where Are Ocean Current Turbines Being Tested?
Although prototype turbines have been tested at sea since 1985, none are currently connected to electricity grids. This is mostly due to technical difficulties with setting up turbines in deep, offshore waters.
However, progress is being made. Developers have improved underwater cables, turbine blades, and microcomputers that control the systems. Stronger anchors have also been created to secure turbines in place.
Today, advanced ocean current turbines are being tested in the waters off Florida and North Carolina in the United States, as well as in Japan and Taiwan. Engineers in South Africa and Mexico are also exploring the technology.
Which African Regions Show the Most Promise?
The study found some of the most energy-dense ocean currents on Earth in waters off Somalia, Kenya, Tanzania, and Madagascar. These currents hold even more energy than what is considered “excellent” for wind power sites. South Africa’s coastline also shows strong potential.
In some places, the power density ranges from 500 to 2,500 watts per square meter. Off South Africa, this zone stretches about 800 kilometers by 30 kilometers. Off Somalia, Kenya, and Tanzania, it extends about 2,000 kilometers by 30 kilometers.
To understand the scale, the average small household in South Africa uses around 730 watts of electricity. So, one square meter of high-density ocean current could power one such home.
Still, more research is needed. Indian Ocean current data only goes back to 1994, while Pacific Ocean data has been collected since 1979. Many of the strongest ocean current areas are also located in deep waters—sometimes over 1,000 meters deep—which presents installation challenges.
The good news is that some of these high-energy areas are also found in shallower waters, around 100 meters deep and closer to shore. These sites may become the first to generate ocean current electricity in Africa.
What Needs to Happen Next?
Scientists around the world are researching how to turn ocean waves, tides, and currents into energy. The next step is moving from research to development.
This usually begins with a project developer, local community, or electric company launching a project and securing investment. Technical studies then follow to pinpoint the best turbine locations and decide how to get the power to land.
Each project varies in size, cost, and required technology. Finding enough start-up funding can be a major hurdle.
Another challenge is that ocean current energy technology is not yet widely available for commercial use. But advances are being made quickly.
With the growing urgency of climate change, ocean current energy offers a promising, clean solution for Africa’s power needs.
