Imagine standing on the gently shelving beach, the little waves lapping at your feet. Did you ever imagine the power the waves held?
And have you ever stood on the shores of the sea and heard the raw power of the waves crashing on the cliffs?
Do you remember that terrible tsunami of Boxing Day, 2004? It killed almost a quarter of a million people. The wave that devastated countless homes, offices and swamped the land.
Wouldn’t it be great if we could harness and use that awesome power? If we could use that force in our homes, in our offices without destroying the land?
We do have the technology. But the financial and political will to develop wave power is sadly lacking.
What is wave energy?
Wave energy is the energy which the waves contain, as they race across the oceans, seas and Great Lakes of our world. One wave holds an enormous amount of energy. This is because the energy density carried beneath the surface of the water is around five times higher than that of wind energy 20 meters above.
In fact, if we had the will, wave energy could supply about 40% of the global demand for energy. A clean, renewable, non-polluting form of energy. (This equates with about 800 nuclear power plants).
Most waves are formed by the action of wind hitting the surface of the sea. The wave continues to gain energy as it travels, maybe hundreds of miles. The exceptions are the tsunami waves. These result from some form of land displacement beneath or into the sea – a landslide, volcanic eruption, earthquake or even meteor impact.
What is the Difference Between Tidal Energy and Wave Energy?
Many people confuse tidal energy with wave energy.
Wave energy is the energy contained in the waves.
Tidal energy depends upon the rise and fall of the level of the sea. This is influenced by the gravitational action of the sun and the moon. The movement of the body of the water up and down might be very small mid-ocean but this may be magnified by the shape and configuration of the coastline. Some places have very large differences between high and low tide where there is a huge potential for harnessing energy. Alaska alone has over 90% of the US resources. There is a huge potential for development. Although some progress has been made, there is still a huge amount of investment needed before America can extract cheap electricity from tidal energy.
But How Can We Harness Wave Power?
We can alter the configuration of the land and thus change the size and power of waves. We can force them into narrow channels and raise their height and power.
By the turn of the century, over 1000 ways to harness wave power had been patented. Most were found to be impractical. But of those 1000 ideas, three main methods have evolved and are being developed.
In brief, they can be called the duck, the sea snake and the limpet generators! You can see how they work in this short video.
The Duck. As you can see the duck floats on the surface and goes up and down with the wave. It is attached to a lever and magnet inside a metal coil. The electricity is generated by the movement of the magnet inside the coil.
The sea snake uses the movement at a joint between sections of a chain of pipes. A Scottish firm has led the way in this development and it is deployed as a massive affair off the coast of Portugal, at Aguçadoura. Known as the Pelamis Project, this was opened in 2008 and provides 2.5 MW of power.
The third method is an Oscillating Water Column (the limpet). Here the motion of the waves changes the level of water in the column. This alternately compresses and decompresses air in the upper part the column. This moves a rotor and the generator converts the energy to electricity.
How Are We Doing?
Here is a small table of some achievements. The figures will become outdated as more development, testing and applications are brought in. But it does give some indication as to what is happening in the world.
|Location||Country||Capacity in MV|
|Pelamis||Portugal and UK||2.4|
And what about the USA?
Several places in the USA have been developing wave power, off both east and west coasts as well as in Hawaii.
The Azura wave power device in Hawaii
This was the first wave power energy supplier to be connected to the grid in America. It can generate 20 KW (not MK) of power.
The Azura is an interesting model. It has been designed to extract energy from both the vertical and horizontal wave motions, unlike most wave converters. The power comes from the relative rotation between the hull and float. And since the float can rotate through 360 degrees it means it can work in a wide variety of conditions. Furthermore, this also enables it to survive more extreme ocean conditions.
This is the third largest of the Great Lakes and has been targeted as suitable for a series of buoys. A Cleveland based company have developed a converter which can be incorporated into buoys. It contains a magnet and induction coil which can induce electric current as the
What is Holding Back Development?
In short – cost, and the political vision needed to look long term. Once the infrastructure is in place and the system is working, then cheap and reliable energy, free from pollution, will be available to many Americans. It has been calculated that 66% of the US energy consumption could come from wave power, that is 2.64 trillion kilowatt-hours.
The cost of developing and laying down the infrastructure is high. It will take time for costs of electricity from wave power to compete with the energy prices at present obtained from non-renewable sources.
Furthermore, there is not yet effective Federal support for developing and marketing the early wave power projects.
And then there are environmental uncertainties. These can cause delays in the necessary permissions for development. There are also uncertainties about the whole process and a lack of experience.
So, America has a choice.
Let the rest of the world continue to take the lead and develop the experience, tools and technology. Or act now to develop policies to create a more sustainable, cost-effective model. This needs to include the environmental consequences of energy generation from wave power. It would enable a U.S. market for marine energy and its supply chain benefits.
What of the Future?
At present, the world-leaders in the development of wave power are not American. Unless practical political and financial support is given to the development of wave power, America will lag behind in getting the long-term benefits of a non-polluting, renewable energy source.
So, as you stand on the beach, listening to the crash of the waves, do you feel the power is being used to benefit you and your children and their children? Or do you just stand in awe and listen? Can you see a brighter future using his amazing source of power? Or will it just slip by?
We have the technology, we just don’t have the long-term vision or the political will to make it happen. Or do we?