The global drive to transition to clean and renewable energy sources is rising. This increased drive requires identifying other sustainable energy resources beyond what is currently available. The ocean – which comprises 71 % of the earth – is one resource that has seen increased research into its renewable energy potential. Energy generation from tides is at the frontier of ocean exploration.
Tidal energy is a form of energy generated by the rise and fall of ocean tides. It occurs due to the gravitational interaction between the earth, the moon and the sun. The energy is produced when water passes through a constriction, causing the water to travel faster, creating kinetic energy, which is then converted to other energy forms. Countries across the world have made bold moves to harness this resource. Estimates for the global potential of tidal energy are over 120GW (1053TW/h per annum).
How is this energy harvested?
Tidal energy can be harnessed from Tidal Streams, which are fast-flowing bodies of water created by tides. It could be natural or man-made. When ocean water is partially enclosed by a natural barrier, the tidal stream pools to form tidal lagoons. Energy is continuously generated as the lagoon fills and empties.
For man-made harvesting, barrages are used. Here, energy is harnessed by using a large dam with turbines beneath. The barrage is opened as the tide rises and closes, creating a pool. The water is then released through the barrage’s turbines, producing energy.
One for the Future or Now?
Tidal energy is often regarded as a future energy source as not much research has been carried out. However, some countries have a few tidal projects in the construction and operational phases. For example, the Sihwa Lake Project on the west coast of South Korea is currently the largest tidal energy plant producing about 555.27GWh of electricity and contributing 2 per cent to the country’s energy mix. Also, there is the MeyGen tidal energy project in Scotland. This huge energy project is being developed in phases with a planned capacity of 398MW. Furthermore, in Europe, the Interreg France (Channel) England Programme (Interreg FCE) approved a mega Tidal energy project in 2020. The project, referred to as the Tidal Stream Industry Energiser Project (TIGER), aims to scale the development of tidal stream energy by installing about 8MW of new tidal capacity to become part of the energy mix in the UK and France.
What are the Opportunities for Tidal Energy in Africa?
Africa has enormous potential for renewable development. Particularly, Eastern and Southern Africa and some parts of Western Africa have been reported to have significant tidal energy potential. For example, Kenya has been reported to have the capacity to generate over 1.9GW of tidal energy from the Indian ocean. However, challenges including high capital costs, political instability and lack of technological access have hindered the exploration of this energy resource.
Finally, there are vast opportunities associated with tidal energy, and it has the potential to generate a large quantity of renewable energy. Therefore, efforts are required from development agencies and global leaders to provide finance for research institutes to develop cost-effective technologies to access this resource.