Submitted to: Professor Kevin Cassell
For: Scientific and Technical Communication, Spring 2011
Written by: Matthew C. Carney
April 10 th
, 2011

Table of Figures ............................................................................................................................... 2
Abstract ........................................................................................................................................... 3
Energy as We Know It ...................................................................................................................... 4
Renewable Energy: The Energy of the Future ................................................................................. 6
Emergence of Wave Power ............................................................................................................. 7
Types of Wave Power ...................................................................................................................... 8
On-Shore: LIMPET System ........................................................................................................... 8
Near Shore: The Oyster Wave Power Device .............................................................................. 9
Off Shore: Pelamis WEC Technology ......................................................................................... 10
Current Wave Power Development in the U.S. ............................................................................. 11
References ..................................................................................................................................... 12
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Figure 1: The Pollution Releases in the Burning of Fossil Fuels [2]
Figure 2: Nuclear Energy Production 101 [4]
Figure 3: Types of Renewable Energy [5]
Figure 4: U.S. Energy Production in Quadrillion BTUs in 2009 by Sector [1]
Figure 5: U.S. Renewable Energy Production Broken Down by Source [1]
Figure 6: History of Renewable Energy Production in the U.S. (1949 to 2009) [1]
Figure 7: Wave Density Map [8]
Figure 8: Locations of U.S. Wave Energy [9]
Figure 9: Schematic of LIMPET System [13]
Figure 10: LIMPET System on the Scottish Shore [13]
Figure 11: Oyster Wave Power Device Location and Operation [14]
Figure 12: Oyster Wave Power Device in Use [14]
Figure 13: Pelamis Hydraulic System [15]
Figure 14: Pelamis System [16]
Figure 15: Wave Unit in Use (Hawaii) [16]
Figure 16: Wave Farm Underdevelopment in Oregon [17]
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The topic presented within this report will focus on the emerging field of wave power for energy production. Wave power is a way of harnessing the kinetic power from oceanic waves and converting it to electrical power. The main objective is to understand the need for a viable alternative to the traditional ways of power production and explore the abilities of an alternative means to meet growing energy demands. In order to understand the need for such a technology, the current ways of energy production will be examined, as well as, the current usage of energy in the United States. After exploring the need for a shift in the way energy is produced, the way in which wave power will be funded through government incentives and new developments will be researched. The focus of the new developments will be on the three main locations for wave power, on-shore, near shore, and offshore. A current wave harnessing system in each of these locations will be examined in detail to further explain the field of wave power. With a better understanding of the importance and need for the development of wave power, the United States will be able to establish a cleaner and greener energy future.
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To meet the demands of consumers, the power industry uses a combination of three main sources of energy production. Those three sources are fossil energy, nuclear energy, and renewable energy [1].
The production of fossil energy is notoriously known for being an inexpensive but dirty way of producing energy. Fossil energy accounts for approximately 83 percent of the energy consumed in the United States in 2009 [1].
Figure 1: The Pollution Releases in the Burning of Fossil
Fuels [2]
Fossil fuels such as petroleum, coal, and natural gas are found naturally on earth and are created by the decaying remains of plants and animals. These remains are allowed to decompose for millions of years under the earth’s surface. The decay of plant and animal remains, along with the pressure induced from being located under earth’s crust, releases the carbon necessary for the formation of fossil fuels [3].
In order to harness energy from fossil fuels, petroleum, coal, or natural gas is burned in order to heat water (creating steam), which then turns a turbine to produce electrical energy [3].
However, the burning of
Figure 2: Nuclear Energy Production 101 [4] fossil fuels releases harmful toxic materials into the air which pollute the atmosphere and leads to an increase in the effects of global warming.
Fossil fuels are also a limited resource which will run out.
A substitute for carbon based energy production is the use of nuclear energy. Nuclear energy is produced by a complex process called nuclear fission. Nuclear fission occurs when the bonds of atoms are released as they collide with one another [3]. The process of nuclear fission is conducted within a nuclear reactor. The energy that is released within the reactor is used very much in the same way as the energy released by fossil fuels. Nuclear energy accounts for approximately 9 percent of the U.S. energy consumed in 2009 [1]. The nuclear energy is used to heat water (creating steam) which turns a turbine, producing an electrical form of energy. A diagram is located below to provide a more in depth illustration of the nuclear energy production.
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The production of nuclear energy is much cleaner than that of fossil energy production.
However, the big hazard in producing nuclear power is the raw material needed, Uranium, is highly radio-active and therefore dangerous to those who work/live around the plant [4].
The third main source of energy in the U.S. is energy produced by renewable means.
Renewable or alternative energy comes from natural resources replenished or provided by nature such as sunlight, wind, rain, biomass, and geothermal heat.
Figure 3: Types of Renewable Energy [5]
The production of renewable of alternative energy accounts for only 8 percent of the energy consumed on the United States in 2009 [1].
Renewable energy is often the most expensive form of energy production. On top of being expensive, most alternative energy systems are far less efficient in the production of energy when compared to fossil energy and nuclear energy. Despite the disadvantages alternative/renewable energy sources are viewed to be the energy of the future.
Located in the figure below is the breakdown of the energy production from its supplying source
(fossil energy, nuclear energy, and renewable energy). The figure was generated with information provided by the Department of
Energy (DOE) and is a representation for the data collected in the 2009 calendar year [1].
The illustration is being used to display the
United States dependence on fossil energy and the need to invest and develop the fuels of the future.
Figure 4: U.S. Energy Production in Quadrillion BTUs in 2009 by Sector [1]
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As technology evolves is in the field of alternative energy, a paradigm shift in the way that the United States produces energy grows closer. The United States’ stance on the need to produce alternative energy is best explained in a speech given by U.S President Barack Obama on
March 30 th
, 2011. The President is quoted…
“The United States of America cannot afford to bet our long-term prosperity and security on a resource that will eventually run out.
Not anymore. Not when the cost to our economy, our country, and our planet is so high… It is time to do what we can to secure our energy future.” [6]
The energy source mentioned by the President to be running out is fossil fuels.
In order to guide the U.S. into a cleaner, greener energy future the President has created a
Blueprint for a Secure Energy Future. Among the goals set by the President in this document is to increase the production of renewable energy to 80 percent of the United States energy production by 2035 [6]. In order to reach this goal the U.S. will need to continue to invest in the development/advancement of renewable energy sources.
Currently alternative energy only represents 8 percent of the energy produced in the U.S [1].
In Figure 5 to the right, the production is broken down by the means in which the energy is produced.
Through history the United States has had continuing growth in the development of alternative energy as shown in Figure 6. To help meet the new goal set by the President the federal government will provide aid in the form of grants and tax incentives to promote growth in the field of renewable energy.
It will take both advancements in the current technology as well as the development of new technologies to meet this goal. One of the emerging technologies in the field of renewable energy is wave power. Wave power is a way of harnessing the kinetic power from oceanic waves and converting it to electrical power.
Figure 5: U.S. Renewable Energy Production Broken Down by Source
[1]
Figure 6: History of Renewable Energy Production in the U.S. (1949 to 2009)
[1]
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With the face of the earth being covered by over
139,397,000 square miles of sea water it stands to reason that the emerging field in alternative energy will come from the sea [7]. Shown below are locations in which the wave densities are ideal for the implementation of wave power systems worldwide.
Figure 7: Wave Density Map [8]
When focusing on the location in the U.S.,
Figure 8 highlights the areas that hold the most potential for wave power.
Figure 8: Location of U.S. wave energy resources with the most electricity generation potential [9]
The notion of harnessing power from the seas and converting it to a useful from of electrical energy is not a new idea. Techniques and patents on ways of collecting power from the sea date back to as early as 1799. The early leader in the development of wave power was
Girard & Son of France [10]. Wave energy was then and is now such a viable technology because of the high density of energy that sea waves hold. In fact sea waves have among the highest energy density when compared to all of the renewable energy sources [10].
It is this large amount of energy that waves hold that make them such an attractive alternative.
This is why in the last 25 years persistent research and development has been conducted around the world to take advantage of these power sources.
When attempting to harness the power of waves, the advantages and disadvantages must be weighted. It is always important to look at both sides of the coin when assessing the means in which energy is collected in non-traditional ways [11].
Advantages:

Waves are free and will not run out so the cost is in building the power station.

Wave power does not produce greenhouse gases.
 There are very few safety risks with wave power generation.

Already a viable energy source and has been tested in real world conditions.
Disadvantages:

Waves can be big or small so you may not always be able to generate electricity.

You need to find a way of transporting the electricity from the sea onto the land.

Generating electricity through wave power is expensive because of setup/equipment costs.

Can disturb or disrupt marine life including changes in the distribution and types of marine life near the shore.
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There are many different wave energy conversion devices in design around the world.
Due to the fact that harnessing wave energy is a reemerging technology, most of all these devices are in their prototype form. However a few systems have been tested and proven effective around the world. To date, the
Department of Energy has recognized 270 different designs for wave power systems [12].
With this wide diversity in designs the process in which wave energy can be converted into
The first system that will be reviewed is the onshore LIMPET System. The LIMPET or Land
Installed Marine Powered Energy Transformer is a shoreline energy converter . This technology is currently in use in Scotland on the Isle of Islay.
The LIMPET system uses the waves to create an oscillating column of water that drives air through a turbine and is located directly onshore [13]. A schematic of this system is shown below.
Figure 9: Schematic of LIMPET System [13]
The numbers seen on the diagram of the LIMPET technology correspond to different stages in harnessing energy from the waves.
At location one, the wave capture chamber is set into the rock face and acts to isolate the sea from the air column. At the second location, the opening in the base of the air column allows the electrical energy varies greatly. Adding to the diversity in the ways that power is converted is the location that the power is collected. There are three different locations within the sea that wave technology is implementing [12]. The three primary locations that systems are being designed for are on-shore, near shore and off shore locations. In the next part of this report a developed system from each location will be examined. waves to compress the air trapped in the chamber. The air column inside the chamber at location three is constantly undergoing compression and decompression as the water level oscillates due to the waves. The final stage in the process is that the compression and decompression of air drives a turbine which is used to generate electrical energy [13]. The
LIMPET system can generate 500 kilowatts which is about 250 homes [13]. The picture below shows the finished LIMPET system located on the Scottish shore.
Figure 10: LIMPET System on the Scottish Shore
[13]
The LIMPET system is just one of the possible on-shore systems that can be used to collect energy from the sea. To minimize the impact on on-shore ecosystems the LIMPET can be integrated into common sea side structures such as sea walls. [13]
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When collecting energy from the ocean near the shore it is common to collect the energy through the use of a hydroelectric wave energy converter. One of the more popular systems for the near shore application is the Oyster Wave
Power Device as shown below.
Figure 11: Oyster Wave Power Device Location and
Operation [14]
The Oyster wave power device is a buoyant, hinged flap which is attached to the sea floor at a depth that ranges between 10 and 20 meters, within two kilometers of the shoreline [76]. This hinged flap, which is almost entirely underwater, sways backwards and forwards in the near shore waves. The movement of the flap drives two hydraulic pistons which push high pressure water onshore to drive a conventional hydro-electric turbine [14]. In essence, the
Oyster wave power device is simply a large pump which provides the power source for a conventional on-shore hydro-electric power plant [14]. The first generation Oyster can generate up to 315Kilowatts under ideal conditions [14]. With advancements in the technology the new Oyster, the Oyster 2, can generate up to 2.4 Megawatts when operating under optimum conditions [14]. Several Oyster systems are in use around the world have provided a proven robust near to shore system that is capable of collect energy from oceanic waves. A picture of the Oyster in use is shown below in Figure 12. As displayed, the Oyster has a low profile above the water line. The Oyster 2 is currently undergoing testing and will hit the market as a viable wave power technology this year [14].
Figure 12: Oyster Wave Power Device in Use [14]
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When looking at the offshore application of wave power there are two main types of systems, point absorber and attenuator. The system that will be explored here is a type of attenuator system that utilized hydraulic fluid to generate electricity from waves. The system is called the Pelamis WEC. As mentioned, the
Pelamis uses a series of hydraulic motors which are located between buoys. A diagram of the pump is shown below in Figure 13.
Figure 13: Pelamis Hydraulic System [15]
From these hydraulic motors, electrical generators are driven to produce electricity. The power from the string of electrical generators at each joint are lined through a single cord which is fed down to the sea floor and back to shore
[15].
In order for the Pelamis system to force the flow of hydraulic fluid the sinusoidal nature of waves are used. A simple system consists of three pontoons as shown below in Figure 14. As the raft moves through waves, the outer pontoons are raised by the peaks of the waves as the inner section lowers with the troughs. As waves travel past the raft, this alternating position of pontoons can be converted from kinetic energy into electrical energy. The floats are attached to the ocean floor by an anchoring line which allows the floats to always point into the wave.
This allows for the maximum vertical travel of the system. Individual rafts could generate up to
2 Megawatts depending on size of the float unit
[15]. When the float system is arranged in a field as shown below in Figure 14, a wave field can generate enough energy to power 20,000 homes.
Figure 14: Pelamis System [16]
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With the continued advancements and testing of wave systems like those mentioned above, the United States is on the verge of harnessing energy from the sea. Currently there are active wave power projects under way in Hawaii and
Oregon. These projects will lead the way for future form of energy production in the United
States.
In Hawaii, the U.S. Navy has partnered with a
New Jersey based company, Ocean Power
Technologies, contributing $300,000 to funding this particular project [17]. Thus far the state of
Hawaii has installed three offshore systems off of its coast. In addition to the Navy’s contribution to the Hawaii project it has contracted Ocean Power to develop its
PowerBuoy for use in conjunction with data gathering and communications [17].
The Oregon project is still currently under construction. It is being funded by a number of partners including the U.S. Department of
Energy, Oregon tax credits and money from the
Pacific Northwest Generating Cooperative. This project will be the first major wave farm connected to the U.S. grid. Upon completion it is anticipated that the wave farm will provide power to 400 homes [18].
With projects like the ones taking place in
Hawaii and Oregon the United States is one step closer to being able to establish a cleaner and greener energy future.
Figure 15: Wave Unit in Use (Hawaii) [16]
Figure 16: Wave Farm Underdevelopment in Oregon [17]
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