The uninterrupted undulation of the ocean has formidable force, yet wave power is still a relatively unknown renewable energy source because it is not as readily available as others. According to the World Energy Council, the worldwide potential of wave energy is estimated at 2 terawatts (double the current global electricity production).
Furthermore, 25% of UK power needs could be supplied via wave energy, and Australian shores are hit by 1 million gigawatt hours of wave energy every year. Because wave energy represents the most concentrate form of renewable energy, and its impacts on the environment are close to none, more and more companies, like Pelamis Wave Energy, are investing in technologies capable of capturing wave power.
Today we would like to take a closer look at the pros and cons of wave power, its history, available technologies, and future.
What is Wave Power?
Wave power is the green form of energy that results from the kinetic energy of water interacting with wind and creating waves. The distinguishing factor between tidal power and wave power is the fact that the latter is generated by wind, while the former is derived from underwater equipment that is capable of capturing the ongoing movement of ocean currents from gravity and the Earth’s rotation.
Because wave power comes from the continuous rising and falling water, facilities capable of storing and transforming this renewable source must have exposure to the waves. At present, there is no dominant technology available for harnessing wave energy (Wikipedia actually lists over 20 experimental technologies) and there probably never will be, because of the differences in potential wave power across the globe. Nevertheless, three basic technological paradigms for wave power exist: oscillating body, oscillating water column, and over topping device.
Wave Power Definition
Wave power is a lesser known renewable energy source with tremendous potential.
“Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work – for example, electricity generation, water desalination, or the pumping of water into reservoirs. A machine able to exploit wave power is generally known as a wave energy converter (WEC).” – Wave Power Definition according to Wikipedia
The History of Wave Power
Wave power generation may not be a globally employed technology, but attempts to harness the power of waves have been made since 1890. Below is a short time-line for the history of wave power.
- In 1799, the first patent of a device designed for the use of ocean waves in power generation was created.
- In 1910, Bouchaux-Praceique created the first oscillating water column for powering a house.
- In 1940, Yoshio Masuda began experimentation with various wave energy concepts.
- In 2004, Wave power was delivered for the first time to an electrical grid.
- On January 2009, the Scottish government announced that it will construct the largest wave station off the Isle of Lewis.
- On September 2015, the world’s first zero-emission grid-connected wave power station was inaugurated in Australia.
Wave Power Pros and Cons
To better understand the potential of this renewable energy source we have to take a closer look at its advantages and disadvantages.
The Advantages of Wave Power
The pros of wave energy significantly outweigh the cons. Let’s take a deeper look at the advantages of harnessing the power of the ocean in wave farms:
- Incredible energy potential. As we already mentioned, wave energy has tremendous energy potential in comparison to wind and solar power. Because water is roughly 800 times denser than air, the amount of energy obtained from wave power is exponentially higher. According to Energy Informative, the energy density of wave power is around 30-40 kW for one meter of wave along the shore. As you venture further into the ocean, wave energy increases to 100kW for every meter.
- Extremely reliable. The ocean is always in motion, and so are the waves. Because of this, generating electricity from wave power is more reliable than generating electricity from the sun or wind, which rely on fickle weather.
- Area efficient. Like geothermal facilities, wave power stations occupy very little land mass. A wave farm with the capacity of 30 MW (used to power 20.000 British homes) occupies less than half a square mile of the ocean.
- Environmentally friendly & renewable. The most important benefit of wave power is the fact that it is renewable. Seeing as fossil fuel supplies are running short, wave energy represents a viable alternative for the future. Furthermore, the process of harnessing and converting wave energy to electricity is emission-free. This is also the number one reason companies are trying to develop new technologies for utilizing wave power.
The Disadvantages of Wave Power
There is no such thing as the perfect energy source. Like most renewable resources, wave energy also raises several red flags. It is imperative for interested parties to weigh down both pros and cons before making an investment. Here are the main cons of wave power:
- High development costs. Because wave energy is in infant stages of development, it’s difficult to estimate costs. There are a few factors that you must consider: wave resources, lifespan of technology, energy efficiency, maintenance (for underwater parts), and connections to the power grid, among others, that will affect the costs of a project. At present, the cost of wave power generation is extremely high.
- Environmental Impacts. Despite the fact that wave farms are emission free, there are several local environment impacts that you need to be aware of. First of all, power farms are visible from the land and may cause visual displeasure. Researchers also suspect that wave farms can affect marine life, but more data is required to reach a conclusion. According to researchers, there are two main concerns regarding Power Buys in ocean waters: the electromagnetic field emitted by power cables, and the mooring lines used to anchor devices to the ocean floor.
How is Wave Power Harnessed?
There are three basic ways through which scientists can capture the power of waves: surface services (power is harnessed from the movement of waves up and down the surface of the ocean), reservoirs (waves move into a reservoir on the coastline and are forced down through tube and into a turbine), and underwater devices (balloon type objects attached to the ocean floor that stretch over huge distances).
Modern Technology Used to Capture Wave Power
Wave power technologies are categorized according to the method used to capture the waves, power take-off system (elastomeric hose pump, pump-to-shore, hydroelectric turbine and linear electrical generator) and location (shoreline, offshore or nearshore). It’s imperative to understand how each technology works in order to distinguish between them:
- Point absorber buoys float on the surface of the water and are held in place with the help of cables. These devices use the rise and fall of the ocean waves to drive hydraulic pumps and produce electricity. The presence of buoys may affect marine life (cables can cause animals to become entangled).
- Surface attenuator works similarly to point absorber buoys. They use multiple floating segments that are perpendicular to incoming waves and connected to one another. Waves generate a flexing motion that swells and drive hydraulic pumps to generate electricity.
- Oscillating wave surge converters. They have one end in the water, free to move, and another one fixed to a seabed or structure. This technology usually comes in the form of floats, membranes and flaps and energy is collected from their relative motion.
- Oscillating water columns. Are generally situated on the shore or in deeper waters offshore. They have an inbuilt air chamber that swells compress air and forces it into an air turbine to generate electricity.
- Overtopping devices. Are longer structures that use wave velocity to fill water reservoirs to a greater level than that of the surrounding ocean. This energy is then captured with the help of low-head turbines and converted into electricity.
Wave Power Applications
To better understand this renewable energy source we should take a look at technologies and companies that have learned how to use the power of a wave.
1. Anaconda Bulge Wave Power Generator
The Anaconda wave energy generator is located on the coasts of Great Britain. The device consists of a long rubber tube, closed at both ends and filled with water that is anchored on the bottom of the ocean. Developed by Checkmate Seaenergy Ltd, the prototype is capable of converting wave power into electricity by utilizing bulge waves.
The biggest advantage of the Anaconda over another system, like Pelamis, is the fact that it is virtually inexpensive to make because it uses cheap materials and no joints and hinges that may break.
2. Pelamis Wave Power
Pelamis, a Scotland based company established in 1998, is one of the primary designers and manufacturers of wave energy. Their primary technology, the Pelamis Wave energy converter uses the motion of surface waves to generate electricity.
3. Pert’s Carnagie Wave Energy Project
The Carnagie Perth Wave Energy project proposes a buoy-like device that can harness power from incoming swells and convert it into electricity. Three submerged 240-kilowatt buoys are connected to one-another via hydraulic water pumps. As the system moves up and down with the waves, they power turbines (for electricity) and a desalination water system. This project was designed to demonstrate the commercial viability of wave power.
4. Major Players in the Wave Power Industry
Here is a list of companies that are active in the wave power industry:
- Columbia Power Technologies develops wave energy harvesting technologies through a partnership with the Oregon State University.
- Aquamarine Power is a Scottish based company that develops hydroelectric wave energy converters called Oysters. Their second generation technology, the Oyster 2, was recently unveiled.
- Australian-based Oceanlinx is the company behind the oscillating water column.
- AWS Ocean Energy is a Scottish company that also develops ocean energy technologies.
- Pacific Gas and Electric Company is currently advancing its WaveConnect program, a prototype wave energy converter device.
The Future of Wave Power
Many environmental organizations believe that wave power should catch up to solar and wind energy because it has incredible benefits and yield. So why hasn’t this happened yet? There are three reasons:
- The ocean is a harsh environment for machinery. Salt water corrodes equipment quickly, waves are violent, and the costs of building something below water are high
- The cost disadvantage is difficult to overcome, and if it cannot be justified in places were solar, and wind technologies make more sense, wave energy may never become a reality.
- Wave energy has never been a priority. Solar and wind energy have always received more media coverage, and therefore, more investors.
But things aren’t all bad! Despite these challenges, there is progress. Many prototypes are being installed in Australia, Scotland, the UK, and Portugal. If one of these prototypes proves efficient and cost-effective on the long-term, more attention may turn towards this form of renewable energy.
Recommended Read: Why Wave Energy has Lagged Far Behind as Energy Source