Wave energy is a promising yet immature technology that harnesses the energy from waves and converts it into usable electricity.
It is safe, clean, and reliable, and unlike other renewable energies, its production occurs 24-hours a day, every season.
Although wave power is only used in a few locations worldwide, it is proving successful and profitable, and the movement is gaining momentum.
How Wave Energy Works
The wind blows across the ocean, releasing kinetic energy into the surface layer to create waves. The stronger the wind, the higher the rigorous vertical motion of the waves, creating greater amounts of kinetic energy.
The waves behave like a conveyor belt, carrying the energy along their surface to the shore.
Here, it hits a Wave Energy Converter (WEC), a simple chamber with an opening under the ocean.
Water levels rise and fall with the rhythm of the waves, creating high-pressured moving air in the upper region of the chamber.
It propels an internal turbine; the more intense the waves, the faster the turbine spins, producing more energy.
The rotation of the turbine spins a shaft attached to a generator which, in turn, produces electricity. It transports to the power grid for use in homes and businesses.
This type of wave energy is called Oscillation Wave Energy (OWC); there are four other technologies used to harvest energy from the ocean.
- Absorbers – A buoy is used to extract energy from the rise and fall of the waves. The power station sits on the sea bed and employs a linear or rotary generator to convert the kinetic energy into electricity.
- Attenuators – These bright red structures consist of a series of linked segments that sit perpendicular to the waves. They flex with the motion of the waves, harvesting the energy before it is sent to hydraulic pumps where conversion occurs. The Pelamis is a fine example; off the coast of Scotland, the snake-like structure takes advantage of the bigger waves further out at sea.
- Overtopping – The system employs a similar method to that of a hydropower dam. A wave lifts over a barrier to fill a reservoir that drains through a hydro turbine.
- Inverted-Pendulum Device – Wave motion drives a series of paddles back and forth; this system powers hydraulic pumps that drive electrical generators.
Wave Energy Advantages
Wave energy is renewable, it requires two things from the earth; ocean and wind. Both of these are sustainable and finite; they won't run out.
Wave energy is green and produces zero waste, pollution, harmful by-products, or gas. It is an ideal replacement for toxin-producing fossil fuels.
Oceans cover 71% of the earth; wave energy relies on their movement; it is a constant.
Solar power is ineffective at night; wind power needs high gusts to be productive and to even operate efficiently.
Even considerably low wave motions produce enough airflow to maintain turbine movements, thus enabling constant energy production.
Reliable weather forecasts allow us to plan and estimate the amount of energy a site will generate well in advance.
High Energy Potential
Every meter of a wave along a shore has an energy density of 30kW – 40kW.
Analysis by the Electric Power Research Institute discovered that in the US alone, wave energy harnessed from the continental shelf edge has a potential of 2640TW hours per year; A single terawatt is 1-trillion watts.
Offshore Wave Power
Ocean wave power plants can be anchored offshore for vastly increased energy yield. Deeper seas and larger waves carry greater production potential.
Offshore power also minimizes any possible harmful or negative environmental impact.
Wave Energy Disadvantages
Wave energy generators are more restricted in their positioning than solar panels or wind turbines; they are only located along a coastline.
Landlocked countries are unable to benefit from wave power.
Wave energy is still very much in its infancy, and as such, there is much uncertainty surrounding the expected lifespan of the technology and the equipment.
As it is still in the early stages, the costs of wave power is relatively higher than other forms. As development progresses, prices will undoubtedly decrease accordingly.
Much of the equipment used to harness wave energy spends most of its service life submerged. Not only does it require frequent maintenance, but specialist engineers have to carry out the work.
As a relatively new technology, training takes a long time and is expensive.
A Blot on the Landscape
Wave Energy Generators (WEG) are power plants that, due to their nature, need to be close to the shoreline. Some locals and visitors fear they are an eyesore that spoils an otherwise beautiful panorama.
As wave energy gains momentum, installations and facilities will have to meet more stringent size and location restrictions.
Due to the immaturity of wave energy, it is not yet fully clear the effects, if any, it has on marine life (migration patterns, aversion behavior, feeding and orientation of marine species, etc.).
Research on this topic is still on-going.
Is Wave Energy the Same as Hydroelectricity?
Hydroelectricity and wave energy both rely on the power of water but adopt different methods to generate electricity.
Hydroelectricity collects rainwater in dams or relies on falling or flowing water in rivers or streams to turn turbines.
Wave energy harvests kinetic energy from the wind transported inland by the ocean's surface waves.
While the eyes of the world focus on up-and-coming wave farm sites in Portugal, the UK, Australia, the United States, and others, there is little doubt that wave energy has huge potential.