Viability Report: Converting Seawater to Fuel for Unmanned Vesselsby

Jabril Muhammad

NAVSSES

NREIP Intern

Philadelphia, Pennsylvania

Jasmine Richardson

NAVSSES

NREIP Intern

Philadelphia, Pennsylvania

TABLE OF CONTENTS

EXECUTIVE SUMMARY………………………………………………………………………………….E-1

1.0 INTRODUCTION………………………………………………………………………………………1

2.0 APPROACH……………………………………………………………………………………………..2

3.0 RESULTS AND DISCUSSION……………………………………………………………………..3

3.1 Carbon Dioxide Feedstock Process……………………………………………..6

3.2 Energy Sources……………………………………………………………………………7

3.3 Final Energy Sources: Buoy and Solar Thermal Energy Technologies…..10

3.4 Designing the Refueling Platform………………………………………………………...11

4.0 CONCLUSIONS………………………………………………………………………………………..16

5.0 RECOMMENDATIONS…………………………………………………………………………….16

6.0 ACKNOWLEDGEMENTS………………………………………………………………………….16

7.0 REFERENCES…………………………………………………………………………………………..17

FIGURES

Figure 1. Schematic of Electrochemical Acidification Cell………………………………………4

Figure 2. Commercial Fischer-Tropsch reactor………………………………………………………4

Figure 3. Carbon Dioxide Feedstock Process Flow Chart……………………………………….6

Figure 4. Floating Wind Turbines…………………………………………………………………………..7

Figure 5. Solar Panels…………………………………………………………………………………..8

Figure 6. Wave Aqua-buoys…………………………………………………………………………………..9

Figure 7. Tidal Energy…………………………………………………………………………………..10

Figure 8. OPT Mark 3 PowerBuoy…………………………………………………………………10

Figure 9. SunCatcher Stirling Engine……………………………………………………………………….11

Figure 10. Refueling Platform Interface Diagram……………………………………………………12

TABLES

Table 1. Mark 3 Specifications……………………………………………………………………………..10

EXECUTIVE SUMMARY

Throughout this project, the objective was to conduct a viability study on producing fuel at sea for unmanned vessels. In order to do so, the electrochemical acidification cell and the Fischer-Tropsch process were researched. Once completed, calculations for producing an amount of hydrocarbon fuel

(eventually 1 galday ) were performed. It was found that 0.45213513 moles H2 and 0.14627901 moles CO2

were needed to produce 1 galday of fuel. Next, energy sources for powering the fuel creation process

were researched. Since the fueling process was sea-based, it was decided to limit the energy choices to those with sea-based potential (e.g. no coal). After much research buoy technology (two OPT MARK 3 PowerBuoys) and solar thermal technology (one SunCatcher) were chosen. Next, the concept level platform was designed. A platform interface diagram was created, which showed all of the processes and mechanisms involved in the process. Also, a sizing process (incomplete) was undertaken in order to figure how large the refueling platform would be. At base level, it was found that the platform would be

37 times larger than the original set-up (produces 0.027 galday of fuel). However, further research needs

to be done on this matter. Lastly, a series of calculations were performed in order to determine the placement of the platform in the ocean. They were based on the situation of a DF-21D missile flying toward a ship with two countermeasures (SR SAM and LR SAM). Based on where the two countermeasures impacted the DF-21D, the platform would be placed behind the farther point. It was found that the platform would be between 125.91657953 km and 140 km from the UAV mission area. As for further work on this project, it was recommended that the researcher determine the full power usage of the refueling platform system, perform a complete sizing of the refueling platform and attain all dimensions of each component, scale the refueling platform up to service a particular UAV based on its fuel specifications, pick an exact location for the platform based on the distance from mission area calculation, and conduct a cost/benefit analysis of creating the refueling platform

1.0 INTRODUCTION

This project was an effort to examine the efficiency of producing fuel at sea to support unmanned vessels. The project required one to conduct a viability study that investigates if producing fuel at sea for unmanned vessels is a feasible idea or not. In order to create the final viability study, other required steps had to be done. Completing this viability study and providing the benefits of the electrochemical acidification cell and Fischer–Tropsch technology may allow for this project to move out of the laboratory and into a proof of concept. The experimentalists were required to research the electrochemical acidification cell (EAC) and Fischer-Tropsch (FT) methods. After researching these two methods, further investigation had to be done to see if any modifications would need to be made to efficiently produce enough fuel for the unmanned vessels. The aim for this project was to allow this to be a sea-based operating system; therefore, an appropriate energy source had to be used to support the different machinery. After researching and performing different calculations, the final step of this project was to create a concept level design of the refueling platform.

Being able to support the unmanned vessels with a sea based synthetic fuel production would offer the Navy significant logistical and operational advantages in four main areas: time, safety, costs, and future demands. In regards to time, this fuel production process would be servicing UXVs, which need to stay on mission for as long as possible. Seeing as this system would be unmanned, it could be placed closer to mission area as opposed to a manned fueling tanker. Thus, the UXVs would be able to stay on mission longer due to the relatively short distance to the refueling platform. In regard to safety, this fueling process would reduce the ships’ vulnerability while out at sea. By placing a lower risk target closer to the mission area, the odds of a manned ship (tanker) being destroyed is lowered since it will be farther out. Additionally, creation of fuel in this manner would allow the Navy to be independent of foreign embargos, and thus save money on fuel. Lastly, as new technologies become accessible, it is imperative for the Navy to meet the new energy demands that accompany them. This process is one step in the right direction.

Currently, technology exists to produce hydrocarbon fuel on land using the FT process and coal as its primary energy source. This process uses the carbon dioxide that is extracted by electrolysis from seawater as a carbon feedstock that is then catalytically reacted with hydrogen to produce hydrocarbon fuel. This process was tested by Naval Research Laboratories in Key West, Florida. NRL took the commercially available electro-deionization cells and modified that machinery to function as an electrochemical acidification cell. This modified technology was successfully tested in the laboratory which allowed more steps to take place. The EAC was scaled up and integrated into a mobile skid design. The skid was built and limitedly tested at Havlovick Engineering Services in Idaho Falls, Idaho before it was sent to NRL Key West in 2011 to be fully tested in a marine environment. Once down in Key West for full testing, the NRL created a two step process. The first test was to develop an iron-based catalyst that could achieve carbon dioxide conversion levels up to 60% and decrease unwanted methane production from 97% to 25% in favor of olefins. The second step requires the olefins to oligomerize into a liquid containing hydrocarbon molecules, which can be converted into jet fuel.

2.0 APPROACH

In order to complete the task of performing a viability study on converting seawater to fuel for unmanned vessels, strict guidelines were followed. This project was split into four main parts, which were to research and understand the EAC and the FT processes for fuel creation, to research methods for powering the fuel creation process, to design a waterborne UAV refueling station, and to compile all of our findings in a report. To begin, a four part technical report from the Naval Research Laboratory in Washington, DC was studied. The report explained the extraction of carbon dioxide from seawater by the EAC. Through this study, both the extraction process and the FT process were more readily understood. Toward the end of the report, it was found that at 100% extraction efficiency and an

applied current of 30 amps, NRL Key West was able to produce 0.027 galday of fuel. Before proceeding to

the powering step, it was decided that the series of calculations required to attain this value needed to be redone. It was realized that if the calculations could be performed and understood, they could be scaled up to the specifications for the UAV (See these calculations in Results section).

Throughout the readings, inconsistent calculations were recorded. They were inconsistent due to the fact that the final answer (gallons of fuel per day) that the author attained did not correlate with other answers throughout the packet. The significant figures for each step in the calculation were not consistent nor did they follow the rules used to determine the amount of significant figures. Due to the fact that the final answers and the numbers that were used in the problem did not follow the correct significant figure approach, it skewed the final answer. As a result, the calculations were performed again to compare the answers throughout the steps and the final answer. After redoing the calculations to see how much hydrocarbon fuel can be produced per a day, the results from the reports and the results from the experimentalist were different.

After this realization was made, the calculations were scaled up so as to produce 1 galday of fuel. Using a

whole number such as 1, it would be simple to scale up further to the appropriate UAV fuel

specifications. Furthermore, having scaled up to 1 galday , the calculations were performed in reverse in

order to attain the amount of H2, CO2, and power needed for this fuel production (See these calculations in the Results and Discussion section) .

Next, energy sources to power the fuel creation system were investigated. As a starting point, it was determined that the chosen energy source(s) should be renewable so as to limit harmful environmental impact, able to be safely stored so as to limit leakage, and efficient in its conversion of energy to power. As a result, solar, wind, wave, and tidal energy were chosen as possible candidates. Each of these energy sources was thoroughly researched on the internet and in textbooks.

Next, the UAV refueling station was to be designed. An interface diagram was created, showing the EAC, FT, energy sources, and other machinery and processes involved. Also, the entire refueling station

needed to be sized for production of 1 galday . Upon calculating the size, it could be seen whether the

system would be the size of a moving truck, the size of a small city, and so forth. In order to do this, it

was determined that increasing from 0.027 galday to 1

galday is a factor of 37. Thus, it was inferred that the

1 galday refueling station would be roughly 37 times larger than the 0.027

galday refueling station. The next

step would be to determine how the concept of “37 times larger” correlates to each individual component of the system. However, during this project, this step was not achieved. But, by doing so, it could be determined just how much larger each component would need to be, considering that each component has to increase in size to begin with. With this information, the actual dimensions of the entire refueling station could be discovered.

Furthermore, as an addendum to the design of the UAV refueling station, a series of calculations were performed in order to determine the refueling station placement in regard to the mission area. This was done by creating a situation where the DF-21D Chinese missile (arbitrarily chosen) was inbound from the UAV mission area to a U.S. navy ship at a certain speed. The navy ship had two counter measures, namely the SR (short range) and LR (long range ) SAMs. Based on the initial distance between the ship and the DF-21D, the speeds of the DF-21D, the SR SAM, and the LR SAM, and the impact distances from the UAV mission area, the refueling station distance from the mission area was determined.

3.0 RESULTS AND DISCUSSION

The first requirement was to research the current methods of the electrochemical acidification cell (figure 1) and Fischer-Tropsch process (figure 2). To complete this requirement, research was completed by reading and discussing several reports by the Naval Research Laboratories:

1) Extraction of Carbon Dioxide from Seawater by an Electrochemical Acidification Cell Part I- Initial Feasibility Studies

2) Extraction of Carbon Dioxide from Seawater by an Electrochemical Acidification Cell Part II- Laboratory Scaling Studies

3) Extraction of Carbon Dioxide and Hydrogen from Seawater by an Electrochemical Acidification Cell Part III- Scaled-up Mobile Unit Studies (Calendar Year 2011)

4) Extraction of Carbon Dioxide and Hydrogen from Seawater by an Electrochemical Acidification Cell Part IV- Electrode Compartments of Cell Modified and Tested in Scaled-Up Mobile Unit

5) Sea-based Fuel Synthesis Work at NRL from FY02 to FY07

Figure 1: Schematic of Electrochemical Acidification Cell

Figure 2: Commercial Fischer-Tropsch reactor

Other reports where information was gathered from was the Hydrocarbon Synthesis from Carbon Dioxide and Hydrogen: A Two-Step Process. The earlier reports provide the reader with the background knowledge that one must comprehend before moving forward on the project. The later reports in the series, provides the reader with an abundance of calculations and how the Naval Research Laboratory used the modified machinery to produce the hydrocarbon fuel from seawater with coal as its primary energy source.

The calculations that were provided in the aforementioned reports calculated the molar ratio of hydrogen to carbon dioxide and then found how much hydrocarbon fuel could be produced using the molar ratio that they previously calculated. With the Naval Research Laboratory calculations, it was

found that the machinery could only produce 0.027 galday . Since this number is so low, more calculations

were completed, to figure out how much hydrogen and carbon dioxide would be needed to produce 1galday . To find this answer, the experimenter worked backwards using the calculations that were used by

the Naval Research Laboratory. The first step was to convert the 1 gallon into milliliters (1 gallon equals 3,787.88 milliliters). Also, 3,787.88 milliliters is equivalent to 2,993.21 grams. The next equation in the problem converts grams into the amount of moles of hydrocarbon that would actually be produced in a

day. After completing this equation, the results show that to produce 1 galday requires 19.15 moles of

C11H24. After figuring out how many moles of hydrocarbon are produced per a day, the process can be taken further to figure out how many moles of hydrogen and carbon dioxide are necessary.

1 gald ayà (X)(Y)= 1

galdayà (3,787.87879

mlday )*(0.000264)= 1

galday

(Xml)*(0.000264)= 1 galday

Xml= 3, 787.87879 mlday

(Xg/ 1)*( 1 ml/ 0.79)= 3, 787.87879 mlday

(Xg)*(1.26582278)= 3, 787.87879 mlday

Xg= 2,993.21426 gramsday

(2,993.21426g/ 1)*(1 mole/ 156.31g)= 19.149218 molesday of C11H24

(X moles H2/1)*(1 mole C11H24 / 34 moles H2)= 0.01329809 molesmin C11H24

The calculations to figure out how much of each substance is needed to produce 1 galday of hydrocarbon

fuel are listed below:

[(X moles H2/1)*(0.02941176)]/ 0.02941176= (0.01329809 molesmin C11H24)/ 0.02941176

X moles H2= 0.45213513 moles H2

(0.45213513 moles H2)*(11 moles CO2/ 34 moles H2)=

(0.45213513)*(0.32352941)=

=0.14627901 moles CO2

After completing the above calculations, the results found that 0.45213513 molesmin H2 and 0.14627901

molesmin CO2 are needed to produce 1

galday of fuel. Now that it is known how many moles of each

substance are needed, calculations can be completed to figure out how much energy is needed to

power the system to be able and produce 1 galday

.

(0.5 moles H2/ 96,487 A-sec)*(60 sec/ 1 min)*(XA)= 0.45213513 molesmin H2

(0.0000518)*(60)(xA)= 0.45213513

(0.00031092xA)/ 0.00031092= 0.45213513/ 0.00031092

xA= 1,454.18477 A

(1,454.18477)(30)= 43,625.54 watts/ 1000= 43 kW

3.1 Carbon Dioxide Feedstock Process

The diagram below is a flow chart of the carbon dioxide feedstock process to help summarize the process (figure 3). The two components that are needed to produce hydrocarbon are hydrogen and carbon dioxide. 96% of carbon in the ocean is in the form of bicarbonate (HCO3), from which carbon dioxide cannot be extracted. In order to collect carbon dioxide from the seawater, the pH of the water, which typically is around 7, must be lowered to around 4.5. The pH of the water is lowered during its journey through the ion exchange channel in the EAC. Once the pH of the ocean is around 4.5, the bicarbonate transforms into carbonic acid (H2CO3). Carbonic acid is not stable and therefore, gaseous CO2 can readily dissociate from carbonic acid. Now you have CO2 and H2O (water). The process now requires one to perform electrolysis on H2O in order to break the compound down. After performing electrolysis, there is H2 and O2 (oxygen). Now, the two essential components can come together in the presence of a catalyst and produce a hydrocarbon.

Figure 3: Carbon Dioxide Feedstock Process Flow Chart

After performing the calculations for how much H2(g) and CO2(g) was needed to produce 1 galday of fuel

and the power associated with this process, the energy source(s) for this process was determined. To begin, research was done to find sea-based energy sources that were renewable, able to be safely stored, and able to be converted to power. With these criteria, wind, solar, wave, and tidal energy were chosen as candidates.

3.2 Energy Sources

WIND ENERGY

Wind energy is captured from different winds in the atmosphere. The winds are converted into mechanical energy and then electrical energy by way of wind turbines (figure 4). There are two main types of wind turbines, namely horizontal and vertical axis wind turbines (HAWT and VAWT). Wind

Pull out H2

Perform Electrolysis on H2O;

H2 + O = H2O

CO2 dissociatesPerform Electrolysis; CO2 + H2O = H2CO3

Carbon is in form of H2CO3

(Carbonic Acid)

Lower pH to ≈ 4.5

96% of Carbon in Ocean is in form of

HCO3 (Bicarbonate).

Typical ocean pH is ≈ 7.8

turbines work by the lift created by wind. Wind turbines are oriented so that incident winds turn the blades, which are connected to a rotor. The now spinning rotor is attached to a shaft which spins a generator, thus creating electricity. There are advantages and disadvantages associated with wind energy.

Advantages:

Cubic power to velocity relationship à 12𝝆𝘼𝙑3

No resultant environmental pollution Heavier winds at lower altitudes (good choice for sea level) Quiet energy

Disadvantages:

Varies in frequency Varies in Intensity

Figure 4: Floating Wind Turbines

SOLAR ENERGY

Solar energy is energy emitted from the sun’s rays. It can be in the form of heat and/or light. There are three main types of solar energy apparatuses, namely the active, passive, and photovoltaic types (figure 5 shows photovoltaic). Similar to wind energy and its HAWTs and VAWTs, there are advantages and disadvantages associated with solar energy and its variations.

Advantages:

Multiple typeso Active: collect thermal energy through the use of components such as pumps, and can

potentially track the sun’s movement

Flat plate Parabolic trough

o Passive: collect thermal energy through non mechanical means (e.g. large windows) Radiation and free convection

o Photovoltaic: can directly convert solar energy into electricity

Disadvantages:

Varies in availabilityo Cloudso Stormso Nighttime

Reflectivityo Active o Photovoltaic (solar panels)

Figure 5: Solar Panels

WAVE ENERGY

Wave energy is captured from naturally occurring ocean waves. Waves are created due to the wind as it blows across the water. Amongst other devices, buoys can be used to convert this wave action into useful energy. Buoys are devices that float on top of the water. They typically ride the waves in a bobbing motion. This motion drives a piston which powers a turbine, thus converting mechanical energy to electrical energy (figure 6). Furthermore, there are advantages and disadvantages associated with this energy type.

Advantages:

Enormous power potential à up to 100kWmeter

Area efficient

o A wave farm can occupy less than 12square mile

Generates 30+ MW of power Direct relationship between wave size and energy potential Wave power can be harvested near of offshore

Disadvantages:

Largely dependent on wind levels Can be a hindrance in corrosive environments

Figure 6: Wave Aqua-buoys

TIDAL ENERGY

Tidal energy is energy that utilizes the ebb and flow of tides to create electricity (figure 7). In high tide and low tide, a reservoir is charged and discharged. During this process, a wave turbine can be used to capture this motion, and thus energy to create electricity. Like each of the previous energy types, there are advantages and disadvantages inherent in the technology.

Advantages: Predictable (contingent on movement of the Earth and moon) Effective at low speeds

o Power can be generated at roughly 3 ftsec

Long life span

Disadvantages:

Needs to be constructed close to land Expensive, and will commercially profitable by 2020 at the earliest Not constant

o Tidal waves occur 2 ¿day while waves happen every few seconds

Disrupts regular tidal cycles Reduces kinetic energy in the ocean

Figure 7: Tidal Energy

3.3 Final Energy Source Choices: Buoy and Solar Thermal Energy Technologies

As can be seen, there was much research conducted on the type of energy source that would be employed on the refueling platform system. After this initial research was conducted, it was decided that solar and wave energy technology would be employed. Wave energy was the primary choice in that the ocean represents a theoretically infinite amount of energy potential. Also, choosing wave energy allows for the use of wind energy as well in that wind drives wave action. Solar energy, particularly solar thermal energy, was chosen as the second option due to the greater efficiency when compared to solar panel technology (usually 11-15% efficient).

As for the buoy technology, the OPT Mark 3 PowerBuoy from Ocean Power Technologies was chosen.

Figure 8: OPT Mark 3 PowerBuoy and Table 1: Mark 3 Specifications

Based on the scope of the research, in that the focus was on the effectiveness of the fuel creation system, it was decided that the most important specifications were the peak generation rating, the design life, the wave height, and the water depth. The peak generation of 866 Kw is drastically higher than the 43 kW needed to produce the hydrogen. As a precaution, two Mark 3 PowerBuoys were chosen so as to ensure that all of the system’s power needs would be met. The design life of 25 years is about half the time of the lifetime of a navy ship (40-50 years). Thus, the refueling system would only have to be replaced once during a specific ship’s lifetime, considering the system did not sustain any serious damages during that time. The 1 to 6 meter wave height and 55 meter water depth, gave crucial insight into placement of the system.

In the case of the solar thermal technology, the Stirling engine from Stirling Engine Systems was chosen.

Figure 9: SunCatcher Stirling Engine

The system is called the SunCatcher, which is composed of a large, mirrored dish that captures and redirects the sun’s rays onto a Stirling engine. There is a resultant temperature differential between the different sides of the engine, which powers pistons, and in turn generates electricity. The SunCatcher system has a peak generation of 25 kW of power. Although this is below the 43 kW necessary to

produce the hydrogen for fuel production, and thus the entire process, the system is fairly compact. More than one can be connected to produce greater amounts of power. The PowerBuoys are also there to compensate for this difference. Also, unlike other solar thermal technologies, the SunCatcher is less reliant on water. This means that there would be little to no interaction between the SunCatcher and the PowerBuoys. However, the SunCatcher is unable to store energy, and thus can only be used during the day.

3.4 Designing the Refueling Platform

Through the guidelines outlined by this project, the design of the refueling platform entailed determining the layout of the platform with each component accounted for (EAC, FT process, energy sources, etc) and determining the position of the platform with respect to a particular mission area. As for the layout, an interface diagram was created, showing the positions of each process and mechanism (figure 10).

H2CO3

H2CO3

Fuel Storage

Fuel Storage

HydrocarbCatalysis H2CO2

ElectrolysisH2O

CO2

HydrocarboCatalysis H2

Electrolysis

H2O

CO2

CO2

Seawater HSeawater HC

Seawater

H2CO3

Seawater

HCO3

Power Storage

Energy

Figure 10: Refueling Platform Interface Diagram

In addition to the basic layout of the system, it needed to be sized as well. It was noticed from “Extraction of Carbon Dioxide and Hydrogen from Seawater by an Electrochemical Acidification Cell Part

III- Scaled-up Mobile Unit Studies,” that the carbon capture skid was able to produce 0.027 galday . Since it

was determined that the new refueling platform would produce 1 galday , this corresponded to an

increase of 37 times. Thus, initial results showed that the carbon capture skid would be either 37 times larger or increased to a total of 37 units. Now, based on further investigation, that is not completely

true. In order to attain the true sizing, each individual mechanism (e.g. a 0.5 galmin pump) would have to

be researched in order to discover its particular dimensions. Upon doing so, the new dimensions could be determined by applying the 37 times multiplier to the original dimensions (see Recommendations section).

As for the position of the refueling platform, a situation was created where the DF-21D Chinese missile was inbound from the UAV mission area to a U.S. navy ship at a certain speed. The two counter measures considered were the SR (short range) and LR (long range ) SAMs. The idea was to calculate how far from the UAV mission area (DF-21D starting point) each counter measure would hit the DF-21D. Thus, the refueling station would be placed behind the two impact points.

The calculations are as follows:

Given information:

Initial distance between the ship and the DF-21D: 140 km* Ship radar horizon: 35 km

Speed of the DF-21D: 6,125.22 kmh

Speed of the SR SAM: 4,892 kmh

Speed of the LR SAM: 3,669 kmh

Max range of SR SAM: 55 km Max range of LR SAM: 167 km Ship reaction time for looking, detecting, and reengaging: 10 sec

Assumptions:

10 sec reaction time is for each individual countermeasure Refueling platform is of great importance to the Navy Refueling platform has no weapons Refueling platform has no radar Refueling platform is unmanned

UAV is on mission and can tell the ship when the DF-21D is launched

Calculations:

DF-21D speed = (5)(speed of sound at sea level)

= (5)(1,225.22 kmh )

= 6,125.22 kmh

6,125.22 kmh *

1h60min *

1min60 sec = 1.70145

kmsec

SR SAM speed = 4,892 kmh *

1h60min *

1min60 sec = 1.3588888889

kmsec

LR SAM speed = 3,669 kmh *

1h60min *

1min60 sec = 1.0191666667

kmsec

(10 sec)( 1.70145 kmsec ) = 17.0145 km

During the 10 sec reaction time, the DF-21D moves 17.0145 km

If the DF-21D starts 140 km out from the ship and moves 17.0145 km in 10 sec:

140 km – 17.0145 km = 122.9855 km

The DF-21D is 122.9855 km from the ship when the ship fires its first countermeasure (SR SAM)

If the DF-21D is starting at position 122.9855 km and moving at 1.70145 kmsec , while the SR SAM is

starting at position 0 km and moving 1.3588888889 kmsec , what is the impact distance from the mission

area?

122.9855 km – 1.70145 kmsec t = 1.3588888889

kmsec t

122.9855 km = 3.0603388889 kmsec t

40.186889251 sec = t

40.186889251 sec have elapsed upon impact

(40.186889251 sec)(- 1.70145 kmsec ) = - 68.375982716 km

The DF-21D has traveled 68.375982716 km since the ship responded

122.9855 km - 68.375982716 km = 54.609517284 km

The DF-21D is 54.609517284 km out from the ship when it is hit by the SR SAM

*The 140 km distance was chosen initially so as to get an impact point as close to the max range of the first countermeasure (SR SAM) as possible. Further selections could have been performed to get as close as possible to the max range, but 140 km was kept due to the closeness of the resultant distance to the max range (within 1 km) and the relative simplicity of calculations.

As of now, only one countermeasure has been accounted for. Here are the calculations for the LR SAM:

Assumptions:

10 sec reactions time starts as soon as the missiles make contact

Calculations:

During the 10 sec reaction time, the DF-21D moves 17.0145 km

If the DF-21D starts 54.609517284 km out from the ship and moves 17.0145 km in 10 sec:

54.609517284 km - 17.0145 km = 37.595017284 km

The DF-21D is 37.595017284 km from the ship when the ship fires its second countermeasure (LR SAM)

If the DF-21D is starting at position 37.595017284 km and moving at 1.70145 kmsec , while the LR SAM is

starting at position 0 km and moving 1.0191666667 kmsec , what is the impact distance from the mission

area?

37.595017284 km – 1.70145 kmsec t = 1.0191666667

kmsec t

37.595017284 km = 2.7206166667 kmsec t

13.818564645 sec = t

13.818564645 sec have elapsed upon impact

(13.818564645 sec)(- 1.70145 kmsec ) = - 23.511596815 km

The DF-21D has traveled 23.511596815 km since the ship responded

54.609517284 km - 23.511596815 km = 31.097921469 km

The DF-21D is 31.097921469 km out from the ship when it is hit by the SR SAM

What is the minimum distance of the refueling platform from the UAV mission area:

17.0145 km + 68.375982716 km + 17.0145 km + 23.511596815 km = 125.91657953 km

The refueling station should be between 125.91657953 km and 140 km from the UAV mission area

4.0 CONCLUSIONS

Based on the aforementioned results, a number of observations were made. Firstly, the calculations for the total power usage of the refueling platform were incomplete. The 43 kW value attained only pertains to the generation of the hydrogen gas. The power needed to produce the carbon dioxide gas is still needed. However, since both the hydrogen and the carbon dioxide are produced through the same process (degassed after exit from the EAC), an educated guess was made that the power needed would be at least another 43 kW. Thus, the minimum power needed for this process should be roughly 86 kW. This value is vastly lower than the peak generation of the buoy and Stirling engine technology combination, and thus would be easily accommodated. Also, the sizing of the refueling platform was incomplete, thus preventing the system from being scaled up. However, the process for attaining this information is clear, thus making the scale up definitely possible. Though not fully completed, it is clear from the information presented, that the creation of hydrocarbon fuel from seawater is a viable endeavor. It presents an innovative opportunity for the Navy to create a larger fuel density for the fleet in order to further sustain its ships and complete its missions.

5.0 RECOMMENDATIONS

A study has been conducted on the efficacy of producing fuel at sea for unmanned vessels. Though promising, the results are not fully conclusive, and thus require a greater amount of research and development. Here are a few recommendations for when this process is carried out:

Determine the full power usage of the refueling platform system Perform a complete sizing of the refueling platform and attain all dimensions of each

component. Scale the refueling platform up to service a particular UAV based on its fuel specifications. Conduct a cost/benefit analysis of creating the refueling platform. Pick an exact location for the platform based on the distance from mission area calculation.

6.0 ACKNOWLEDGEMENTS

This work is supported by the Office of Naval Research both directly and through the Naval Research Laboratory.

7.0 REFERENCES

1. http://newenergyandfuel.com/http:/ newenergyandfuel/com/2012/09/25/an-almost-endless- fuel-supply/electrochemical-acidification-carbon-capture-skid/2. http :// www.velocys.com/our_products_processes_ft.php

2. http:// www.trekearth.com/gallery/South_America/Brazil/North/Amazonas/Manaus/ photo179642.htm

3. http:// www.velocys.com/our_products_processes_ft.php

4. http://commons.wikimedia.org/wiki/File:US_Navy_100410-N-6110S- 194_A_suspected_pirate_skiff_burns_after_being_destroyed_by_the_amphibious_dock_landing_ship_USS_Ashland_(LSD_48). jpg

5. http:// www.fcc.es/energia/actividades/index.html

6. http:// www.elioowners.com/threads/i-am-reserved-what-do-you-spend-now.1590/page-2

7. http://newenergyandfuel.com/http:/newenergyandfuel/com/2009/04/16/exploring-a-new-gasification-process/fischer-tropsch-section-in-china /

8. Naval Research Laboratories

9. http:// finallygoodnews.net/wp-content/uploads/2014/06/Floating-Windmills.jpg

10. http:// www.conserve-energy-future.com/SolarEnergy.php

11. http:// www.lockheedmartin.com/content/dam/lockheed/data/ms2/photo/alternative- energy/wave%20and%20tidal/OPT%20Wave%20Energy.JPG

12. http:// www3.telus.net/subductionservices/wind.htm

13. http:// www.connect-green.com/wp-content/uploads/2010/08/windlens-2.jpg

14. http://inhabitat.com/worlds-first-floating-wind-current-turbine-to-be-installed-off-japanese- coast /

15. http://www.theenvironmentalblog.org/2012/03/suns-energy-sea-ups-downs-floating-shore- solar-farms /

16. http:// www.ecoplanetenergy.com/wp-content/uploads/2012/03/solar-PV-energy-origins.gif

17. http:// www.sigmahellas.gr/index.php?lang=2&thecatid=3&thesubcatid=423

18. http://inhabitat.com/wave-energy-aquabuoy-20-wave-power-generator /

19. http://inhabitat.com/united-states-investing-10-million-in-wave-power-projects /

20. http ://www.kollected.com/# UXV