The amount of energy generated by tides and waves in the last decade has increased tenfold. Now governments around the world are planning to scale up these ventures to tap into the oceans’ vast store of blue energy.
Although in 2019 the total amount of energy produced by “blue power” would have been enough to provide electricity to only one city the size of Paris, even that was a vast increase on the tiny experiments being carried out 10 years earlier.
Now countries across the world with access to the sea are beginning to exploit all sorts of new technologies and are intending to scale them up to bolster their attempts to go carbon-neutral.
Blue energy takes many forms. One of the most difficult technically is harnessing the energy of waves with devices that produce electricity. After several false starts many successful prototypes are now being trialed for commercial use. Other experiments exploit the tidal range – using the power of rapidly rising and falling tidal streams to push water through turbines.
The most commercially successful strategies so far use underwater turbines, similar to wind turbines, to exploit the tidal currents in coastal regions.
More ambitious but along the same lines are attempts to capture the energy from the immense ocean currents that move vast quantities of water around the planet.
Also included in blue energy is ocean thermal energy conversion, which exploits the temperature differences between solar energy stored as heat in the upper ocean layers and colder seawater, generally at a depth below 1000 meters.
A variation on this is to use salinity gradients, the difference between the salt content of the sea and fresh water entering from a large river system. Some of these schemes are being used to produce fresh drinking water for dry regions rather than electricity. Read more…
