Ocean Energy ChallengesPublished on 03.05.2021
5 min read
Various techniques for harnessing the energy of oceans and wind have been the subject of many studies and experiments around the world. But the ocean environment isn’t very friendly.
Ocean Power Potential
Everyone knows what the of a wave, the pull of a current or a strong sea wind feels like. If you think about these forces and the sheer size of the ocean – 70% of the Earth’s surface, nearly 1.5 billion cubic kilometers of water – it’s easy to imagine the amount of locked within these naturally occurring phenomena.
According to experts, oceans could technically produce 150,000 terawatt-hours (TWh)1 of energy per year, which is well above current global
output of around 23,000 TWh. In theory, ocean energy could meet 650% of current electricity demand.
Obstacles to Overcome
These calculations are highly theoretical. At present, ocean energy accounts for barely 0.3% of global electricity generation.
To turn theory into practice – which isn’t entirely impossible – it would be necessary to:
- Install a large number of imposing, complex ocean/shore equipment requiring significant investment and energy.
- Maintain and care for the equipment amid harsh ocean conditions (seawater and microorganisms cause rapid , known as biofouling).
- Minimize the installations’ on landscapes and marine .
- Share the sea space with other marine activities, especially fishing.
The Rise of Offshore Wind
Offshore wind, which accounts for most of ocean energy’s 0.3% contribution to power generation, captures the energy of wind, rather than that of the sea. Since 2015, there has been a surge in offshore wind development.
Although 0.3% may seem small, this percentage could increase 15-fold by 2040, according to
experts2. The advantage of offshore wind is that it is deployed in large areas – usually more than 10 kilometers from the coast – and uses turbines that are significantly taller and more powerful than their
counterparts. In 2020, the world’s largest turbine had a 222-meter rotor diameter and a capacity of 15 megawatts, compared to an average of 2 megawatts for an onshore turbine.
Other Ocean Energies
- Tidal energy: Tidal barrages built on estuaries hold back huge amounts of water twice a day. When released, the water generates power. Only a few barrage stations exist in the world. They require major infrastructure and have a big environmental footprint.
- Ocean current energy: Ocean current energy can be harvested using tidal turbines, or large propellers that are usually moored to the seabed. While the number of projects is growing, production remains low.
- Wave energy: Using pistons, the force of waves can drive mechanical systems to generate power. Projects are still in the experimental stage.
- Ocean thermal energy: The sea is a vast reservoir of heat. The temperature difference between surface water and deep water is leveraged to
a fluid and produce electricity. The technology is still in the experimental stage.
- Osmotic energy: This technique – the most surprising – produces energy from the movement of water through a membrane between a saltwater reservoir and freshwater reservoir. A large-scale project is operating in Norway.
What About Biomass?
Of the hundreds of thousands of microalgae species found in nature, around 300 have been identified as having the ability to produce large quantities of oil. Currently, however, the production of algal biofuels and biomethane is still at the research and development stage.
Ocean energy shouldn’t be confused with hydroelectric energy, which uses flowing water in mountain lakes and large rivers to produce power. Hydropower has been around since ancient times (in the form of water mills) and is today by far the leading
source for generating electricity.
- Tera denotes multiplication by one trillion. Kilo means one thousand, mega one million, giga one billion and tera one trillion (one thousand billion).
- See the IEA report