Generating Energy from Boat Wake Using Ocean Buoy Technology

By: Jacy Craig

Abstract: This study explores the use of wave energy to create usable power. The waves that will be explored to generate power will come from boat wakes. The optimal wave energy will be produced by assuming that boats are traveling at a speed fast enough to create wakes in a shallow or intermediate area. In order to collect this energy, a buoy would be placed at a location affected by the boat’s wake. The buoy would collect energy from the waves on the basis of Faraday’s Law. Faraday’s Law states that a magnet moving through coils will create electromagnetic induction. This can be converted into usable power. The power will then be transferred from the buoy to an onshore power plant for its use. A row of buoys like this one could provide a sustainable way to create power, while allowing fast boat traffic in coastal areas. In the long run, energy extraction from wake waves could benefit a region with little impact on marine life.

Table of Contents Introduction…………………………………………….………………………………………...1 Energy from the Ocean…………….……………………………………………………...1 Boat Wake…………………………………….…………………………………………...2 Objective…………………………………………….…………………………………………....3 Hypothesis………………………………………….…………………………………………….3 Background………………………………………….…………………………………………...3 Faraday’s Law…………………………….………………………………………………3 Natural Heaving Frequency…………….…………………………………………………4 Power Law: Determining Power from Voltage…...……….……………………………...4 Past Ocean Buoy Technology …………………………….……………………………...4 Boat Wake…………………………….…………………………………………….…….5 Methods...……………………………………….…………………………………………….…11

Developing a Prototype…………………………………………….……………………11 Potential Future of Prototype…………………………………………….………………12

Results……………………………………….…………………………………………….…….12 Discussion……………………………………….………………………………………………15 Potential Future of Prototype …………………………………………….……………..15 Conclusion…………………………..…………….…………………………………………….18 References……………………………………….………………………………………………19

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Introduction Energy from the Ocean With the high demand for energy supplies and a push for sustainable methods, wave energy has shown to be a viable power supplier. Worldwide, wave energy potential is between 8,000 to 80,000 terawatt-hours (TWh) compared to the annual electricity production of 18,000 TWh. [1] Of the energy produced from waves, 2,000 to 4,000 TWh/year is estimated to be available for use from the world’s large hydroelectric power plants. [1] Waves are constantly being produced by forces deforming the water’s surface. These are typically found from the force of gravity and disruption of surface tension. Waves can be created as simply as by a rock breaking the surface or a gust of wind. [2] Out of the ways waves are created, wind has shown to be a main contributor. On average, wind can create 3 m high waves. In extreme wind conditions like tropical storms or hurricanes, wind can produce wave heights over 5 m high. [1] By using an ocean buoy technology, the wave energy can be absorbed and harnessed. One common way to harness wave power is through the motion of the waves. As the waves move under the buoy and push it up and down, a system for absorbing this movement can be harnessed. Through Faraday’s Law, an electromagnetic induction is created and can be converted into usable power. [3] This will be expanded in the “Background” section. Power can also be created from tidal turbines. The turbines are placed in inlets, most commonly attached to bridges. As the tide changes, the water movement spins the turbines and creates energy. These are two common forms of energy converters, with more information also being addressed in the “Background” section. Looking around the world, ocean waves vary in magnitude. Wave density for different locations can help determine how well the wave energy will be harnessed. For example, the North Atlantic, Pacific and Southern Oceans have a power density of 40 to 100 kW/m. Meanwhile, close to the equator the power density is only 10 to 20 kW/m. The northeastern part of America has values of 20 to 50 kW/m and the northwestern has values of 40 to 60 kW/m. [1] The greater the power density, the more available power will be to harness. [4] Boat Wake Boat wake is a form of water surface deformation. As a boat passes over the surface of the water, it deforms the water and propels it outward. This creates a wave with heights of 0.5 m or greater. [5] By harnessing this wake power, usable energy can be created for the surrounding area. Wake size is dependent on the size and speed of boats. A larger boat would displace the water more creating a larger wave. [6] Wave speeds create the largest wakes when they fall into the transition zone, related to the boat speed and the wave speed. This will be described later in the “Background” section, but the exact speed is different for every boat. Optimizing these two properties will create an ideal boat wake and power supply. The amount of boats in an area also affects the amount of wake produced. The more boats there are, the more wake there is. An example of a good location for harnessing energy from wake waves would be the water ways around Port Authority of New York, including the Hudson River. The bays, inlets, and rivers are typically used for shipping and at any time contains over a hundred ships. [7] Most ships going through are very large like cargo ships. They can contain weights up to 25,000 tons. and contain a lot of weight. The water will displace more from these

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ships compared to smaller vessels like recreational use boats. This will create larger wake waves. Figure 1 shows an example of one time within the water ways around Port Authority. At that time, there were 249 vessels in the harbor, most being large cargo ships that carry additional weights up to 25 tons. [7] Many studies have been conducted on boat wake. These studies have included the velocity needed to surpass the natural wave velocity of the water system, along with the maximum height produced from a boat. Since areas close to the shoreline will have lower boat speeds, the wake is expected to act as a small amplitude wave. For this wave type, it is assumed to be irrotational, inviscid and incompressible. The waves will not break when they come into contact with the buoys, so the properties of linear wave theory will be used. Laplace’s Equation will be applied as the governing equation. [2] The equation is as follows: !

"#!$"

+ !"#!&"

+ !"#!'"

= 0 (Eq. 1) 𝜙 =Velocity Potential

The Laplace Equation is the governing equation for linear ocean wave mechanics equations by showing the second order differential of the velocity potential in the x, y, z-axis will sum to zero. The equations for wave height, celerity and power will follow the shallow and intermediate water characteristics for this theory depending on their relationship of depth over wave length. For a ratio less than 1/20, the water body will be considered shallow. For a ratio between 1/20 and ½, the water will be considered intermediate. The water bodies are not expected to reach

Figure 1: Current time image of boats around Port Authority of

New York. [7]

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deep water depth, so this is not needed. Irrotationality and incompressibility in the fluid are assumed through conservation of mass, via the relationships: [2] ∇𝑥  𝒗 = 0 (Irrotationality Equation) (Eq. 2) ∇ ∙ 𝒗 = 0 (Incompressibility Equation) (Eq. 3) Since boat wake can be treated as a small amplitude wave, it can be harnessed like regular waves. Using buoy technology, the boat wake energy will be captured and transferred into usable energy. Since the wake waves tend to be smaller than ocean wave, more buoys can be placed in the water body to meet the power demand of the surrounding area. Faraday’s Law can be implemented in the water body to absorb the energy from a magnet passing through coils. [3] This will be further expanded on in the “Background” and “Discussion” section for harnessing boat wake and the impact of multiple buoys in one area.

Objective With the current challenges of energy generation and a push for sustainable methods, wave power has shown to be a potential solution. This study examines the potential for harnessing wave energy from boat wake. Boats can create enough wake to make small amplitude waves. This can then be converted into usable power from an energy-harnessing ocean buoy. The buoys would be small enough to keep within inlets, while using basic principles of linear wave theory to harness the motion of the waves from wake for power. This study had the two main objectives to:

1)   develop a prototype to harness wake wave energy; and 2)   explore the potential future for the prototype.

This study will show how the idea followed Faraday’s law and progressed into a usable prototype for the generation of power from boat wake.

Hypothesis The boat wake will produce a bobbing motion of the buoy. This motion will in turn move a magnet up and down through a set of coils inside the buoy and will create a magnetic induction. The magnetic induction can be converted into usable power following Faraday’s Law. [8]

Background Faraday’s Law The main theory for this paper is based on Faraday’s Law. It was discovered by Michael Faraday in the 1830’s. He was a British scientist who was well known for his work in physics. [9] One of Faraday’s major accomplishments was his discovery of Faraday’s Law, which states [3]: 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 = −𝑁 9

9:[𝐵𝐴] (Eq. 4)

Volt (or EMF): Voltage Generated

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N: Number of coil turns B: External Magnetic Field A: Area of coil

𝑡: Time The equation for Faraday’s Law shows the relationship of voltage to the number of coils and the area of coil. The more coil turns there are, the greater the voltage. In return, this creates a higher magnetic induction and higher power supply. The negative sign within the equation comes from Lenz’s Law. Lenz’s Law states that an EMF is generated by a change in magnetic flux. This change causes the polarity of the EMF to create a current that opposes the change of the magnetic field. [3] Natural Heaving Frequency In order to determine the time component of Faraday’s Law, the frequency of the up and down heaving motion of the wave can be used. Time is inversely proportional to frequency as shown in Equation 5: [10]

𝑓 = @A= @

BCDEFGHIJIG

(Eq. 5)

𝑓= Frequency (1/sec) T = Period (seconds)

𝜌 =Density of seawater (1,30 kg/  𝑚M) 𝑔 = Gravity (9.81 m/  𝑠B)

𝐴PQ = Waterplane area of the float 𝑚 = Mass of the heaving system

𝑚P = Mass of the water excited by the heaving motion = @R𝜌𝐷M

D=Diameter of buoy

Power Law: Determining Power from Voltage The Power Law equation can help to determine the power from the voltage. The equation states: 𝑃 = 𝑉 ∙ 𝐴 (Eq. 6)

𝑃  = Power (Watts) 𝑉 =  Voltage (Volts) 𝐴 = Amp (Amps)

The voltage is determined from Faraday’s Law, while the Amp is determined from the type of wire being used. The voltage can also be confirmed from a Voltmeter, which will read the voltage from the wires. Since copper wire is typically used, the amps will range between 14-75 amps for a wire gauge size of 18-6. [11] Past Ocean Buoy Technology Ocean buoy technology has been a topic of research for years. It has been difficult to find a best-fitting technology that would withstand environmental inclemencies, while also being affordable. Modern ocean buoy technology development started in the 1970’s mainly in Norway. In 1980, the concept of a point-absorber buoy was invented. [8] The point-absorber technology uses the same theory of Faraday’s Law, with a magnet moving through the system.

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The basic uses of ocean buoys have been successful, but still in progress to achieve an ideal design. One type of ocean buoy previously designed was the W1 demonstrator. It was implemented in the Canary Islands in 2014 and could generate around 200 kW of power. The design used the idea of heaving. Heaving acts like a point absorber by using the up and down motion of the waves to produce power. [4] Other ocean technologies have included tidal turbines. The tides change with relation to the movement of the Earth, Sun and moon. Depending on the time of day, the tide will be flowing from one body of water to another. Scientists thought to harness it using propellers similar to a bike wheel design, e.g., Figure 4. The world’s largest tidal power station is the La Rance Tidal Power Station, built in France in 1966. It has been very successful in collected tidal flow energy and has created power for the surrounding area. [14] Most of the buoys have shown to be successful in harnessing wave energy. However, the main issue with ocean buoys is storm endurance. In heavy storms, the buoys can be ripped from their anchors or damaged from the extreme wave conditions. Larger buoys cost more to make and repair, when they are damaged it is costly to fix. [10] Boat Wake Boat wake is produced from the disruption of a boat on the water’s surface. Depending on the boat speed, two types of waves are formed in this process: divergent and transverse waves. A divergent wave is produced from the bow of the ship, while a transverse wave is produced from the stern and propellers. Figure 4 illustrates transverse waves and divergent waves leaving a ship in deep water. [15]

Figure 2: Ocean Buoy design using similar principle. [Taken from 12]

Figure 3: Tidal Turbine model example. [Taken from 13]

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Figure 5 shows a real life picture of boat wake leaving a boat. It can be seen that the divergent waves are coming off the bow, while the transverse waves are coming from the stern and propellers. [16]

Figure 4: Diverging and transverse waves. [Taken from 15]

Figure 5: Real life image of Diverging and transverse waves. [Taken from 16]

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Figure 6 shows the relationships between boat speed and wave height of a boat. At lower speeds, the water is only displaced to the lowest wave heights. At average speeds, semi-planing (or transition speed) creates the maximum wave height. Semi-planing occurs when a ship’s speed starts to increase from the displacement range. The buoyancy and lift forces of the water push the bow of the ship upwards. This creates the largest waves and categorizes the boat speed as the critical speed. The last portion of the figure shows the planning phase. This is when the boat reaches high speeds and the wave heights level out due to the lift force not pushing up onto the boat as much. There is no set speed for all boats to fall into these three categories. The categories are mainly determined by the size and shape of the boat and especially their hull shape. [15]

Figure 6: Speed versus Wave Height Relationship. [Taken from 15]

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In an ideal setting, the boats will travel at transition speeds to achieve the largest wake height. However, to produce the largest wake, the speed of the ship must exceed that of the waters critical speed. To determine the speed that wake waves must exceed, the linear ocean wave’s theory for shallow water can be applied. Typically, the areas where the buoys will be deployed will be in shallow or intermediate water like inlets. This will lead to the equation for shallow water [8]: 𝑣QVWXYYZP = 𝑔 ∗ 𝑑 (Eq. 7)

𝑣QVWXYYZP = critical speed of water in shallow depths g = gravity, (≈9.81 𝑚/𝑠Bor 32.2 𝑓𝑡/𝑠B)

d = depth of water The Equation 9 determines the critical speed of the wave in intermediate water [8]: 𝑣Q_`:abIa9_X:a =

cA= cd

Atanh  (𝑘𝑑)

(Eq. 8) 𝑣Q_`:abIa9_X:a = critical speed of water in intermediate depths

L = Wave Length (m) 𝐿Z = Deep Water Wave Length (m)

k = Wave Number

Figure 7: Speed versus Wave Height Relationship boat view. [Taken from 17]

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The wave pattern can be calculated using the ratio of vessel speed to the critical water speed. This can help determine how the wave leaves the ship in order to achieve maximum height. The wave pattern is categorized through the depth Froude number for the relationship between ship speed and water depth. It is a non-dimensional relationship and is represented through the following equation: [6]

𝐹W =mE9

(Eq. 9)

𝐹W= Depth Froude Number V = Vessel Speed

The depth Froude number shown in Equation 9, is broken down into four categories. Each of the categories creates a different relationship with the type of waves produced and the most power available. Out of these options, the Critical category would be ideal for the buoy since it produces the most power. The breakdown is as follows: [6] Sub-critical (𝐹W < 0.75): The wake produces short-crested divergent waves and transverse waves. Trans-critical (0.75 < Fs < 1.0): The divergent wave angle increases with F, while the period of leading waves also increases. The waves flow at a right angle with the sailing line. Critical (Fs = 1.0): The waves flow perpendicular to the ship sailing line with the crest length growing laterally at a rate equal to the vessel speed. A large leading wave is found to contain most of the propulsive power as wave energy, with the speed being the maximum allowable speed for the waterway. Super-Critical (Fs > 1.0): At this point, the transverse wave merges with the divergent wave and can not be seen. This creates a long-crested and leading wave that is long periodic.

Figure 8: Model showing the different Froude Depth Numbers.

[Taken from 19]

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Determining the category the wave falls into for the Froude number will help determine the maximum energy that can be produced. Once this relationship is known, the wave height can be estimated for a given set of parameters. Ideally, a ship would be traveling within the critical relationship of 𝐹W. This would lead to the most energy produced combined with the maximum wave height for the most power than can be harnessed from the buoy. According to linear wave theory, the water level in shallow and intermediate water at any time will be found as [8]:

𝜂 = 𝑎 ∙ cos 𝑘𝑥 − 𝑤𝑡 (Eq. 10) 𝜂= water level variation at any point

a = amplitude of the wave = H/2 k = wave number

𝑥=horizontal displacement 𝑤 =angular frequency in terms of 2𝜋𝑓

𝑡  = time

Equation 12 can determine the wave height at any point. Ideally, the wave will reach the buoy at its crest, but since this is typically not the case, the water level can be calculated from that equation. Previous studies have been done on wake wave height. Table 1 shows the relationship of the type of ship, distance from sailing line and speed to calculate wave height. [5]

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The equation of wave energy per unit area is directly proportional to the wave height squared. Therefore, the most energy will be produced from the maximum wave height. This is shown in equation 11: [2] 𝐸 = 𝐾𝐸 + 𝑃𝐸 = @

�𝜌𝑔𝐻B (Eq. 11)

𝐸 = Total Energy KE = Kinetic Energy = @

@R𝜌𝑔𝐻B

PE = Potential Energy = @@R𝜌𝑔𝐻B

𝐼𝑛  𝐽𝑜𝑢𝑙𝑒/𝑚

The power per unit length of the wave can be determined from Equation 12. This equation shows that the power is directly proportional to the energy of the wave (𝐸) and the critical speed (𝑣Q) [10]

𝑃PX�a =DE�" E9

�= 𝐸 ∗ 𝑣Q (Eq. 12)

𝑃PX�a = Power of the Wave 𝜌 = Density of Water

H = Wave Height 𝐼𝑛  𝑊𝑎𝑡𝑡𝑠/𝑚

By using the equations shown in the “Boat Wake” section of this paper, the optimal boat speed to produce the maximum energy and wave height can be determined. The relationships between these equations are later represented in the results section as the prototype for the buoy is examined and determined for its best fitting data.

Methods Objective 1: Developing a Prototype to Harness Wake Wave Energy In order to develop a prototype, the basis for power generation had to be established. As stated in the hypothesis, the bobbing motion of the waves can produce a magnetic induction. [1] The up and down motion created by the waves was represented on a smaller scale. A “Shakable Flashlight” provides a smaller scale representation and uses Faraday’s Law of a magnet passing through coils to create energy to light a bulb. The flashlight is shaken back and forth and the energy is stored in a capacitor. The capacitor acts like a battery for the flashlight and holds the energy produced. The user can then turn the flashlight on and light is produced. Once the capacitor runs out of energy, the user can shake the flashlight again to recharge it. [20]

Table 1: Relationship between type of boat and wave height.

[Taken from 5]

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The buoy design was created using the Shakable Flashlight as an example. The design uses the same concept of a magnet going through coils to produce a voltage. This is done through Faraday’s Law, which was previously mentioned as equation 1 and described as [3]:

𝑉𝑜𝑙𝑡 = −𝑁∆(𝐵𝐴)∆𝑡

In order to produce the most power possible, past ocean buoys designs were used. Previous buoys only considered large amplitude ocean waves as a source of power. Boat wake has not been thought to have enough power. However, using a smaller scaled buoy, power can be harnessed in greater amounts. Wake is hard to avoid in high boat traffic areas. If this is harnessed, it can power the surrounding cities. By comparing the failure and success rates of different designs combined with the concept of harnessing boat wake, the best design would use Faraday’s Law to collect boat wake. [8] Potential Future of Prototype: The Design The design would include a strong magnet at its core. The cylinder holding the magnet would be wrapped in zinc-coated copper wire. Copper wire produces the most magnetic induction due to its high conductivity [21], while the zinc helps prevent the copper from corrosion from sea water. Zinc is used as a coating because of its protective properties. It is the first element to wear away, while protecting the metal that is inside it. It has a long life span and can stand sea water. Tests have proven that corrosion rates are 25 µm/year in the tropics. In colder temperatures, like North America, the corrosion rates are half that. [22] With these rates, the zinc will not erode for an average of 9-10 years. This would be optimal for the buoys to also be serviced. The outer casing of the buoy would be a light weight plastic. This would allow for the most buoyancy for the buoy to stay on top of the water. In order to keep it upright and prevent it from falling onto its side, the buoy would contain a weighted ring on the bottom around the center coil and magnet centerpiece. It would contain a track that would hold weighted balls, similar to marbles, that would move around the track with the waves. This would enhance the movement of the buoy for increased power, while also keeping it stable. The more coils that are wrapped around the middle the cylinder, the more power will be produced. Therefore, the middle cylinder will contain as many turns as possible. The magnet will pass through these turns to produce a voltage. This voltage will be converted into usable power through a transformer, resistor and a circuit board. The combination of the three will harness the current produced from the magnetic induction and convert it into a stable power source.

Results When designing the prototype, the main concern was finding an airtight system that would allow for the magnets, coils, and electrical equipment to be safely installed. The outer casing also needed to be able to float and not sink while holding the weight of the inside pieces. For the purpose of showing a smaller model in a classroom setting, an industrial-use bucket was used. An airtight lid was attached to it that could be screwed on and off to protect everything inside but still allow for work to be down on it. The picture below shows the bucket with the lid:

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The inside of the buoy contains a circular platform about 1/3 of the length from the bottom of the bucket. A circular tube lays around on top of the platform and contains mini spherical balls that move within it. The purpose of them is to promote movement of the buoy as it goes over the waves. The added weight of the balls would create motion in the direction the wave moves the buoy. In between the circular plate and tube, a whole is cut through the center to allow for a PVC pipe to go through it. The PVC pipe will connect to the bottom of the buoy as a way to stabilize the center. The copper coils will then be wrapped around it starting from the circular plate to the top of the container. It will also be blocked off inside of it at the circular plate and the top, near the top of the container. The springs will then be placed on the blocked off sections of the PVC pipe. A magnet will be placed between the springs in the PVC pipe. The magnet will be able to bounce off the springs to allow for additional motion. This will create more electricity as the magnet is able to pass through the coils an increased distance?. Before developing the prototype, a model was created with just a PVC pipe, magnets, and copper wire. The wire was wrapped around the pipe with the magnet placed inside and sealed. The wire was attached to a circuit board containing a light. When the whole system was put together and shaken, the light could be turned on and would light up. On average, a voltage of 2.90 Volts was produced, with a max being at 3.03 Volts. The wire used had a gage size of 18, giving it an amp reading of 14 amps. Using the power law equation, the power was found to be 42.4 Watts. The voltage was achieved from shaking the flashlight for 20 min, which would result in a power of 14.1 Wh. Assuming a normal regulatory buoy size of 1.52 m, the power can be increased from the handmade flashlight model. The same copper coil would be used for wrapping the center frame, along with the same size diameter pipe. This would keep everything the same in Faraday’s law except for the number of turns around the center. More turns would be applied to the new inner

Figure 9: Outside casing and lid of buoy.

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pipe length. The flashlight had a length of 0.31 m while the actual buoy would contain a pipe with a length of 1.21 m. The number of turns would increase by a factor of four to account for a length that is four times greater. The voltage is directly proportional to the number of turns in Faraday’s Law and directly proportional to the power in the Power Law. This would result in a power supply of 170 Watts, or 56.7 Wh, that is four times larger than the flashlight. Typically, there are about 10 regulatory buoys located in an inlet. At this number, the power collected would be 1.7 kW (566.7 Wh). In 2017 alone, the average residential customer used 10,399 kWh a year, and 866 kWh a month. [22] For a month with 30 days and 24 hours a day and the same 20 min time span, 240 Wh would be needed. The value from the buoy is about a ¼ of this supply, but would still cut down on the use of non-renewable energy production. This would be enough to provide power to a surrounding area and eliminate some need for fossil fuels. Figure 10 shows a typical inlet with the amount of buoys located in it. By increasing the magnet strength, the voltage would increase from the proportionality of voltage to the external magnetic field. This would create even more power for the buoy. To show

Figure 10: Example of channel marker locations along inlets. [23]

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this, Ponce Inlet in Florida will be used as an example for calculations. The inlet has an average depth of 14 ft (4.27 m). This is shallow water, but has boat traffic from fishing boats. The critical speed, 𝑣Q, would be calculated as 4.27  𝑚 ∗ 9.81𝑚/𝑠 = 6.47  𝑚/𝑠 (21.23 ft/s or 12.58 knots). Therefore, the boats going through this area would need to exceed this speed to create significant wake. Due to manatee protection laws in this area, boats typically travel between 15 to 25 mph, which is 22 to 36.67 ft/s. Assuming a lower speed, Froude’s depth number relationship gives a value of 𝐹W =

BBB@.BM

≈ 1.0. This puts the boats into a critical speed for maximum wave height. The inlet averages 450.6 m wide, Table 1 can give an estimate for the maximum wave height. This inlet is mainly used for recreation and fishing, so a Boston Whaler 15.24 m from the sailing line will be used. Considering the speed around 6.7 m/s, the maximum wave height will be around 0.22 m high. Plugging this into the energy equation, give an energy of 𝐸 =@�1029 �E

I��.�@  IV"

∗ 0.22  𝑚 B = 61.07  𝐽𝑜𝑢𝑙𝑒𝑠. This gives a power of 𝑃PX�a = 61.07 ∗R.��IV

= 395.1  𝑊𝑎𝑡𝑡𝑠/𝑚 These numbers show that significant wave height can be produced from smaller boats traveling at average speeds. The waves carry a significant power to them, with the example alone having a power of 395.1 W/m. The small design system itself could lead to a bigger model generation and a future for ocean buoy technology.

Discussion Potential Future of Prototype With the prototype design created, the next step is to implement it in a real situation. The best situation for the buoy would be to put it into a shallow inlet that has heavy boat traffic. This would create the most of wake waves, while providing power. The buoy would be placed along the shoreline, far enough away not to wash ashore, but close enough to allow for collection of power. For this, a cable would be connected to the buoy to transmit the power from the buoy to an onshore power supplier. The cable would connect from the bottom of the buoy and be anchored to the channel floor. The cable would then lay on the floor until it reached the shoreline and would resurface on land. This would allow for the easiest and most sufficient power collection so that the power can be transmitted to the surrounded area at a continuous rate. If the inlet allows for it, multiple buoys can be placed 20-30 feet from each other and all connected to the same power plant onshore. This would optimize all wave power and create more in the long run. The buoys can also become multi-purposeful as a power supply, but also as a channel marker. Channel markers are typically found in the same location as the buoys would be placed. By designing the buoy to reflect a typical channel marker, it would eliminate overcrowding within the area. [14] Examples of channel marker designs look similar to the following image:

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This can easily be translated to the sustainable buoy. The only difference would be the machinery inside. These channel markers are typically anchored to the channel bed. This would be the similar case for the power transmitting cable, with an extra connection to the shoreline. To provide another example of an ideal implementation situation, Port Canaveral Inlet can be examined. This inlet is one of the busiest in Florida and provides a major shipping route for cargo and cruise ships. The inlet has heavy traffic moving through it at all times with an average of 4.5 million people a year traveling from it. It is about 36.6 m wide on average with an average depth of 13.1 m and a length of 13 km. The boats that typically go through this area are large and travel at lower speeds. The speed would still produce enough wake to power the buoys and create a wave heights significant enough to produce a wake due to their large size and weight. Since the inlet is 13 km in length, multiple buoys can be deployed. The cables would be 14.3 m long in order to give the buoys extra movement range for larger waves during storm conditions. They would connect to a point at the center of the inlet onshore. [24] The buoys could provide more advantages than just power supply. A major issue within inlets with high boat traffic is the erosion the wake creates on the shoreline. The waves wash away the surrounding shoreline embankments. This leads to more inlet replenishments and higher costs. The buoys would not only absorb the shock of the waves to produce energy, but create a separation from some of the waves that would break on the shoreline. If multiple were put in along the shoreline, then even more wave energy would be absorbed to keep it from breaking

Figure 11: Example of channel marker designs with symbols and

meanings. [23]

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onto the land. This would save the costs of rebuilding the shore bank, while also saving money on energy from a sustainable method. [19] Even with the advantages presented, there have been concerns in the past about the use of ocean buoy technology on marine life. Previous designs, like tidal turbines, have created a barricade for some marine life. Since they are implemented under bridges to collect the flow in and out of the inlet of the tidal change from the back bays to the ocean, they block the movement of marine life from the area. [16] They have also had concern of marine life getting stuck in the turbines or the buoys. The buoy design presented in this study would not have similar issues to the previous designs. They would act similar to channel markers by floating on the surface with a cable to anchor them in place. They would not affect marine life movement or trap them. The only disruption would be the initial laying and anchoring of the cable from the channel bed to the shoreline. After it is already in place, marine life will not be affected further. As previously mentioned, depending on the area of implementation, multiple buoys can be installed. A main consideration is the surrounding area. By looking at the power required in one city with power produced by buoys, one can estimate how many buoys would be needed to make a difference. If the area is more of a city than a town, more power would be needed. Therefore, it would be ideal to implement more buoys. For example, an inlet like Port Canaveral Inlet has higher boat traffic, but a lower population density for a coastal area. Not as much energy would be needed to power the area. However, if the buoys were put in the Delaware River next to Philadelphia, Pennsylvania, much more power would be needed to make a difference in the power grid of the city. Therefore, a threshold can be created to determine the number of buoys needed. Looking at other buoy designs, as mentioned in an earlier section, they are normally used in the oceans or for tidal flow. They are meant to harness larger waves from the ocean. The buoy design discussed in this paper looks to harness manmade power. This small difference can help the buoys become more commonly used, while not relying on naturally generated waves. On a calm day, there will be no waves to produce power for ocean buoys. However, extreme weather conditions can destroy the buoys. By harnessing power in inlets, the buoys will be more protected from storms and will have a consistent power supply from boats.

From this point on, the goal is to test a model in an actual inlet situation that has boat traffic. Since the model can only represent a smaller scaled energy in a wave simulation model, the full potential of the buoy is not captured. Therefore, the future would require a larger buoy with actual boats to produce proper energy readings. The power would also need to be converted into usable energy rather than power to light a light bulb. It would then be connected to the cable in order to show how the transmission of power would take place. The future of the buoy can provide help to energy production and environmental protection. The heavy use of fossil fuels to power society is harming and polluting the environmental. It is polluting the ocean and the fresh drinking water, while harming wildlife. Therefore, sustainable methods like the ocean buoy design, would be a better option. It is constantly going to be replenishing itself without polluting the surrounding area. The effect on marine life was previously mentioned as being minor. Boat traffic is always going to be a constant. Boats and

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ships are a popular mode of transportation for people, supplies and for fun. Society has consistently relied on boats for movement and this will not go away. Harnessing it would promote transportation and recreational businesses while producing energy to power surrounding areas.

Conclusion This study has examined the use of boat wake to power ocean buoy technology. By combining Faraday’s Law with the mechanics of waves, power can be generated from the buoy and transferred to an onshore power plant. There are many advantages to this including its sustainability and low impact on marine life. The results have shown that Faraday’s Law for magnetic induction does produce power I a prototype buoy. The magnet slides up and down through a tube with copper coils surrounding it. The model shows that light can be produced from this. This small action shows that there is enough energy produced to create electricity. On a larger scale, the energy produced can power townships.

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