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Solar Aeronautics Project

Integrating solar panels into the structure of airplanes to use as a secondary source of energy

Authors: Arnar Freyr Lárusson Andrés Gunnarsson Ásgeir Bjarnason

Campus Contacts: Emmanuel Boulet Intellectual Sponsor: Dr. Sveinn Ólafsson


Solar Aeronautics Project An Airbus: Fly Your Ideas Proposal March 31, 2009

Contents 1 Introduction

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2 Project Management

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3 Solar Panels for The Airbus A380 Aircraft

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4 Solar Cells 4.1 Overview of Solar Cell Technology . . . . . . . . . . . . . . . 4.2 Technical Description of Thin-Film CIGS Solar Cells . . . . . 4.3 Production Methods . . . . . . . . . . . . . . . . . . . . . . .

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5 Weight Evaluation of the Solar Panel System

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6 Installation and Maintenance 10 6.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2 Protection Layers and Maintenance of Solar Panels . . . . . . 11 6.3 Ground Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . 12 7 Economic and Environmental Impact 12 7.1 Cost Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.2 CO2 Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 Unresolved Design Issues 15 8.1 Power Inverters and Wiring . . . . . . . . . . . . . . . . . . . 15 8.2 Securing Lightening Strike . . . . . . . . . . . . . . . . . . . . 15 8.3 Commercial Impact for Airline Industry . . . . . . . . . . . . 16 9 Further Research and Development

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10 Conclusion

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1

Introduction

"What railways have done for nations, airways will do for the world." This vision by Claude Grahame-White in 1914 has most certainly come to be. The great expansion of the airline industry has indeed connected the globe. It has ushered in a new era which has made the world seem smaller and more accessible. However, our ever shrinking world consumes more energy every year. Scientists are presenting dreary data showing what the effects of increasing CO2 and other greenhouse gasses will have on our climate. That coupled with the projected 1 billion people to emerge out of poverty and the 3 billion people yet to be born in the next half century does not make the future any brighter. The strong correlation between energy consumption and quality of life makes the prospect of reducing our energy consumption in this time period unlikely. Therefore our challenge lies in coming up with new sources of energy which create bountiful, clean and efficient electrons. These new sources of energy will come from many directions and we believe one of these should be from the plentiful rays of the sun. Our project is aimed at powering the electrical equipment in the cabin of an Airbus A380 airplane with solar energy. As solar cell technology has greatly improved over the recent years it was only a matter of time until someone thought of running an airplane with the suns rays. We know of two such projects, the NASA Helios project to fly an unmanned airplane and Solar Impulse, a privately sponsored Swiss born project, which aims to fly a one-man airplane around the world. Both planes are solely sun-powered. As we will show, our proposed system could be an extremely practical and environmentally friendly option for the airline industry to consider. It is of course a priority for airlines as for all companies to make a profit but it is also not in the least less important for airlines to take every reasonable measure available to decrease their environmental impact on the earth. We will show that our proposal allows them to do both.

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Project Management

This exploratory project we are working on touches on many aspects of different technological fields. To ensure our productiveness we needed to come up with an efficient methodology. The first thing we did was to set up basic working guidelines. They were as follows: • Define design and research tasks • Divide between the members of the team • Work separately during the week

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• Recap and organize progress with Campus Contact These guidelines proved to be very useful. The project required a lot of research into solar cells, the solar cell industry and airplane structures. We gathered most of our information on the internet, searching through research papers, company websites and online encyclopedias. By dividing the tasks each member of the team could look more closely into a specified area. When we evaluated the progress together and exchanged ideas we managed to create an atmosphere that developed our project even further and come up with simple solutions to problems that once seemed complicated. Throughout the course of the project we were engaged in weekly phone calls with our campus contact, Emmanuel Boulet. These phone calls helped us to recap on the work already accomplished as well as organize the work yet to be done. We made contact with two companies, Icelandair and Global Solar. We made several trips to the former to see their hangar and inspect their aircraft as well as make use of their technical expertise. The latter company provided us with vital information regarding solar cells. The help from these experts in the field allowed us to advance our project further than we would have otherwise been able to on our own.

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Solar Panels for The Airbus A380 Aircraft

On the 27th of April 2005 in Toulouse, France, Airbus guided the aviation industry into a new era. The Airbus A380 maiden voyage marked the arrival of air transport as never seen before. Our project will focus on designing and evaluating solar energy panels to be fitted on the Airbus A380. A typical A380 cabin needs about 211 kW in-flight [1] which is 0.5% of the planes total fuel consumption per hour. This power is obtained by generators connected to each engine. We will show in this report that a substantial percentage of the fuel needed for cabin use can be saved by solar energy panels. The practical available area for mounting solar energy panels onto the A380 is 1277 m2 . This total was arrived at after careful consideration and calculations; it includes the top of the wing and the top of the fuselage. The following graphs show the power output obtained from this surface area with respect to 10%, 20% and 30% solar cell efficiencies (see figure 1). The graphs below also show the power output with varying angles of the sunrays (see Appendix III and figure 2).

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Table 1: Efficiency of solar panels 10% 20% 30%

Power generated by solar panels [kW ] 93 186 279

Figure 1: Comparison between power generation of solar panels at 90â—Ś incident angle of sun with cabin power usage.

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Figure 2: Ratio between solar panel power generation for different incident angles of sun rays.

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Solar Cells

The solar cell technology has existed for many decades. Most people have for instance used a solar powered calculator. However, until recently, the majority of commercial solar cells have been produced using very energy and labor intensive methods which require glass substrates and silicon wafers; high purity silicon is an element in high demand in the technology sector, but is in relatively low supply. These solar cells are fragile and very heavy. This has mainly been due to the fact that it is rather recent since scientists have begun investigating solar cell technologies based on thin films and structured on the nanoscale. The recent arrival of nano-technologies means that the manufacturing processes are not yet perfected; however we will discuss this further below. The solar cell industry appears to be heading in a direction where their products are smaller, lighter, more efficient, cheaper and more versatile. The corporate executive officers of these nano-technology companies talk of a day when there will be no need to install solar cells onto the roof of a building. They envision a time when the sunlight absorbing material in solar cells will simply be a part of every buildings structure creating plentiful green energy for all.

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4.1

Overview of Solar Cell Technology

Currently there are three main types of thin-film solar cells in production: Amorphous-Silicon (a-Si): The a-Si technology is very similar to conventional solar panels, only thinner. As such this technology is tested and proven, but is unfortunately not very effective for large scale use due to their dependence on a glass substrate and silicon wafers as we mentioned before [2],[3]. Cadmium Telluride (CdTe): The CdTe cell technology relies on the availability of the rare element Tellurium. It seems too uncertain if enough new Tellurium mines will be discovered to guarantee enough CdTe cell supply. Moreover, CdTe cells also need Cadmium which is a highly toxic substance and a possible environmental hazard. The most common production process of CdTe cells is within a vacuum chamber, which is both energy and labor intensive [5],[3]. Copper (Indium, Gallium) (di)Selenide (CIGS): CIGS rely mainly on very cheap and available elements and compounds, which have a wide variety of uses in the industrial sector. CIGS-on-foil can be manufactured by simply printing the semiconductor on to a foil substrate in an open-air environment. This creates a potential for inexpensive mass production [6],[3]. After researching these different solar cells we came to the conclusion that the most promising technology in relation to this project is the CIGS solar cells. From here on after we will focus entirely on them.

4.2

Technical Description of Thin-Film CIGS Solar Cells

The CIGS cells themselves are only 3 to 4 Âľm thick. However, with the metallic substrate which they are deposited on, the thickness becomes about 0.5 mm [6]; the diameter of an average champagne bubble. Figure 3 shows the structure of the CIGS module. A closer look reveals the following layer construction:

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Figure 3: Cross-section of CIGS solar cell on foil substrate [6]. Layer 1: Aluminum reinforced Zinc Oxide (ZnO : Al) is a reinforced semiconductor. ZnO has a wide range of industrial uses. Some of its key characteristics are good transparency, high electron mobility and a wide band gap. Its main purpose in the cells is to withstand greater force and pressure and provide protection from the elements while allowing the suns rays through. Its wide band gap of 3.2 eV allows about 90% of the energy to pass through without being absorbed [6]. Layer 2: Zinc Oxide (ZnO) is the same chemical as in Layer 1 except it is not reinforced with aluminum. Layer 3: Cadmium Sulfide (CaS) is a direct band gap semiconductor and has many applications in light detectors. Cadmium Sulfide has a large band gap of 2.4 eV , combined with it being very thin allows the energy to pass through without being absorbed [7]. Layer 4: Copper (Indium or Gallium) (di)Sellenide (Cu(In, Ga)Se2 ) is the thickest layer and serves to absorb the energy from the suns rays. The absorption depends on whether Indium or Gallium is used. CIGS containing Indium currently hold the laboratory efficiency record of 19.9%. The band gap of CuInSe2 is 1.02 eV whereas of CuGaSe2 of is 1.65 eV [6]. Layer 5: Molybdenum (M o) is a metal and is used to conduct the electrons captured by the solar cells. It has a wide range of industrial uses, including many aircraft parts. Although supply currently meets demand, this is the only element which could potentially see a fall in supply in the coming years [8]. 7


4.3

Production Methods

CIGS solar cells are manufactured in a variety of ways. Previous manufacturing methods depended on a vacuum chamber which is both time consuming and energy intensive. This method does not allow a fast throughput. However, new vacuum free methods have been developed that take care of this issue. Today the most efficient process seems to be the so called "roll-to-roll" printing [3] [4]. This process occurs in an open-air environment. Rolls of substrate foils are put through a specialized machine which is best compared to a modern day newspaper printing press. One of Nanosolars manufacturing plants produces 1 GW worth of solar cells annually with this technique [9]. The "roll-to-roll" process has some major advantages in reducing the time and cost of manufacturing, something that is vital if solar technology is to become a major contributor in the world energy supply. CIGS solar cells are currently only capable of being produced in scale with 8 to 12% efficiency [10]. However the future holds in store much more efficient panels, as previously stated the current laboratory record for CIGS panels is 19.9%. The difficulty today is to produce such panels in large quantities. Companies such as Global Solar and Nanosolar predict that they will reach 15% efficiencies in mass production in the near future [10]. Currently the price of CIGS solar cells are at about $3/Watt [11]. With improved manufacturing processes and increased efficiencies this price is expected to drop below $1/Watt in the foreseeable future.

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Weight Evaluation of the Solar Panel System

Airplane manufacturers work tirelessly to decrease the weight of their airplanes. As one of aircraft designs most important aspects is weight control we made sure that the weight of our solar panel system abides with this rule. Figure 2 shows a scenario of total weight added by the solar energy panel structure vs. the fuel saving and paint weight saved by the solar energy panel structure. The weight per square meter of the solar cells including the substrate is 0.316 kg/m2 [12] which makes the entire weight of the 1277 m2 surface area 403.5 kg. This weight is indeed slightly less when we take into account the paint which the solar cells replace. A surface area of 1277 m2 requires 230 kg of paint [13]. The solar cells require a number of additional supplements; extra wires and the inverter to convert the DC to AC. We were unable to find information on an inverter capable of turning out 140 kW of power and thus we had to rely on smaller domestic inverters with only 5 kW capacities used in the commercial solar industry [14]. We combined the weight of 28 individual inverters to obtain 140 kW . This brought us to an unrealistic weight of just less than 300 kg. We believe we can safely assume that using an inverter specially designed for flight and capable of handling 140 kW will result in 8


reduced weight. In our calculations we therefore assumed a total weight of additional electrical regulatory equipment to be 200 kg. Therefore we expect that the total added weight is 390 kg. Table 2: m2 )

Solar energy panel (1277 Wiring Electrical regulation equipment Paint reduction (1277 m2 ) Total:

Weight [kg] 400 20 200 -230 390

This additional weight is countered due to the power generated by the solar cells. This extra power will allow the airline to reduce the take-off weight of the planes due to less fuel need. We can observe this relationship by viewing the results in figure 4 showing the weight of fuel saved by the solar cells on a A380 flight ranging from 8 to 16 hours. The results in figure 5 where we show the total extra weight added due to the solar cells during flights ranging from 8 to 16 hours.

Figure 4: Weight of fuel saved per flight for varying flight times. The colors show different solar panel efficiencies.

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Figure 5: Total weight difference between an airplane using and not using solar panel system. Total weight added to the solar panels for varying flight times. The colors show different panel efficiencies. If we interpret these numbers for 10% efficiency we can see from the graphs that roughly 230 kg of fuel would be saved for a flight of 8 hours and 470 kg for a flight of 16 hours. The total weight of an airplane with the solar cell system would indeed be increased by 160 kg for a flight of 8 hours, but reduced by 80 kg for a flight of 16 hours. The latter result, which shows that the solar cells actually manage to decrease the total weight of the airplane over the course of its flight is truly a double bonus; not only are we saving fuel by using less of it to generate electricity, but we need less to power the aircraft itself.

6 6.1

Installation and Maintenance Installation

The thin nature of the solar panels makes it a viable option for us to attach them in a similar fashion as many company logos. By gluing the solar cells using specialized adhesives the process of installing the solar cells, repairing something under the solar cells or even replacing a defunct solar cell becomes quite simple. The installation of the solar cells would fit into the production cycle at the end. The surface required under the solar cells could be prepped beforehand with the necessary wiring needed to connect the solar cells to the main electrical grid. We have estimated that it would take about 3 working days to complete the installation (see assumptions in appendix II). 10


This is roughly the same amount of time needed to paint the same surface area on an A380 aircraft. It is hard to estimate at this stage of the project how much extra time might be needed for preparing the surface area required under the cells because some things are unknown, for example the exact routes of the necessary wires. However, during the cycle of putting an aircraft together many things are done in parallel and this could be just one of those processes which makes lengthening of the production time seem unlikely.

6.2

Protection Layers and Maintenance of Solar Panels

Airplanes undergo regular maintenance check ups, minor checks every few weeks and thorough inspections every 18 months [13]. During these inspections it would be necessary to mend any tears that might have appeared on the outer layer in order to increase the lifespan of the solar cells. It would be best to use a protecting spray or gel of a transparent nature so as not to affect the efficiency of the solar cells. The material must withstand air friction, debris, drastic temperature changes and condensation during flight. What we suggest is a Silicone or a Zinc-Oxide (ZnO) based material. Aluminum reinforced Zinc-Oxide (ZnO : Al) makes up the top layer of the CIGS [6]. It could be the most straight forward solution to fix damaged ZnO with ZnO. There are two techniques for applying ZnO based materials which we found most practical. Zinc-Oxide has a wide range of uses in the industrial world, ranging from adhesives to metal protecting coatings. ZnO based paint could be used to patch the solar cells. The application would be simple; however research could be necessary to come up with the correct composition of paint for applying to the solar cells. Thin ZnO films are manufactured using a spray pyrolysis technique. This method is relatively cheap compared to other techniques involving ZnO. However applying the pyrolysis spray directly to the surface of the solar cells might be inconvenient as it is a rather complicated procedure for fixing small tears and would require further investigation if put to use. An alternative would be to apply pre-manufactured ZnO based films [15]. These strips would be applied to the cells when required during check ups. They may be more expensive but the procedure of applying them is much more practical. Silicone, a see-through Silicon based product, has proved itself as a suitable compound for use as a protecting layer and is manufactured around the world for countless industrial uses [16]. Because of that the use of silicone as a protecting spray would not require a great deal of researching and developing. Another advantage of this substance is that it would not affect the aerodynamic properties of the aircraft as the strips of ZnO might; depending on their thickness. In case of necessary maintenance directly under the solar panels an adhe11


sive releasing agent would be used to detach the solar cell. Once the repair work is done, either the old cell could be glued back on or a new one could replace it. With the decreasing cost of solar cell manufacturing and their improving efficiency it would likely cost less to insert a new one which could be on hand at the airliner’s hangar. This would also allow the airlines to upgrade their solar cells to a more efficient model with relative ease.

6.3

Ground Cleaning

Airplanes undergo regular cleaning, as well as de-iceing before take-off, in order to decrease air friction created by the debris. According to our source at Icelandair, their airplanes undergo thorough cleaning every 4 to 5 days with pressurized water and soap as well as being sprayed with pressurized water after every flight. It is essential that the cells can endure this rigorous cleaning. The manufacturers of CIGS test their cells using a special lifetime accelerator in which they are subjected to drastic temperature and humidity changes as well as intense UV light exposure [17]. The results of these rigorous tests have given companies such as Nano Solar the confidence to ensure a 25-year warranty for their products.

7 7.1

Economic and Environmental Impact Cost Reduction

By producing electricity from the solar panels we will show that airlines could save money every year on fuel costs. By looking at the graph below we see that the amount saved varies according to the price of fuel. The fluctuating price of fuel makes it difficult to predict the payback time for a solar cell installation. At the time of writing, solar cells cost approximately $3/watt as previously stated. This makes the cost of the solar cells per plane approximately $300,000 (see appendix II for calculations). With an average flight time of 12 hours, panel efficiency of 10%, the most recent price of jet fuel, $1.07 per liter as well as added cost due to extra wires and the inverter (see appendix II for price assumptions) this translates into a 4 year payback time. It is an exciting prospect that the manufacturing cost of the solar cells is expected to decrease a great deal; some of our sources predict it going down to $0.30/Watt. Along with the decreasing manufacturing cost the increasing efficiencies will help to bring the payback time below 1 year sometime in the future. This is not a long time when looking at the lifetime of one airplane and similarly the lifetime of the solar cells. The solar cells are expected to last

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Figure 6: Shows the potential money saved annually with 10% efficient solar panels. The colors show different prices of fuel in $/l. for up to 25 years, giving the airline at least 20 years of free energy per solar panel unit. Like the saying goes "a penny saved is a penny earned." Currently, 10% efficiency generates enough power to cover one generator completely only when the sun directly above. For the solar panels to generate enough power to fully cover 2 generators they need to be at 20% efficiency. We refer to figure 6 for depictions of this phenomenon. However, the graphs also show that with efficiencies ranging from 11-19% the solar energy panels will be able to cover a single generator when the sun is lower in the sky. The panels could also cover more generators if single generators are not required to be used at full capacity. We have thus shown that there is money to be saved by implementing solar cells. Although a relatively small amount of fuel is saved per flight this sum adds up when looking at the amount of flights each plane undertakes each year. In the future the amount of fuel saved will only grow as more and more people take to the skies.

7.2

CO2 Reduction

The fuel saved due to the solar panels creates not only additional revenue for airline companies but more importantly contributes to the environmental health of our planet. With an average flight time of 12 hours and panel efficiency of 10% the solar cells would decrease the amount of fuel used by up to 434 l of fuel per flight; thus reducing the world fuel consumption by

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Figure 7: Different colors in the generator column represent one, two and three generators providing 90 kW each. The other columns show solar panel output at varying efficiencies and angels of the sun. 134,700 l of fuel per year for 1 A380. The fuel consumption by the cabin of an A380 is 44% (see calculations appendix II). The greenhouse gas emissions of the airline industry are remarkably little compared to other industrial sectors. This statement, although true in percentages, should not be taken lightly. Airplanes fly in or very close to the ozone layer, a very fragile and yet extremely important part of our atmosphere. The various chemicals in airplane exhaust have direct and indirect effects. Such chemicals as CO2 and H2 O have direct effects on the climate, whereas Nitrogen Oxide gasses (N Ox ) have indirect effects on ozone depletion. The reduced fuel a standard A380 aircraft needs per flight as a result of using the solar cells reduces these emissions by 304,668 kg of CO2 per year (see CO2 emission numbers in appendix II). To compare the reduced emissions to more tangible things in our daily lives we refer to the table below. Table 3: Number of A380 using solar panels 1 A380 using solar panels for 1 year 1 A380 using solar panels for 25 year 300 A380 using solar panels for 25 years

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Equivalent CO2 CO2 emmisions of 51 cars annually CO2 contained in 520 km2 of rainforest 1 year of Iceland’s CO2 emissions


8 8.1

Unresolved Design Issues Power Inverters and Wiring

The electricity is conducted through the panels via the Molybdenum layer (see figure 3). The electricity would be conducted to the base of the wing where it would feed into inverters converting the DC current from the panels to AC current. From the inverters the electricity would be conducted via silver or tin coated copper wires to the electrical core located close to the cockpit. It is also a possibility that the DC current could be used directly as some parts of the aircraft run on DC. This would require extra research, but could lead to a smaller inverter needed in the aircraft and thus reducing the added weight. A study would need to be conducted to come up with the most efficient load management system.

8.2

Securing Lightening Strike

A very important feature for airplanes is to be able to preserve their electrical potential in case of a lightening strike. With the increasing use of carbon based materials in the structure of airplanes, notably the wings, the ability to maintain the electrical potential becomes an issue. Engineers have long known about the Faraday cage which is a simple principle based on an enclosure or mesh of a conducting material that keeps the inside completely isolated to outside electrical fields. The airplane’s ability to evacuate the current through exits typically located at the tips of the wings or tail is critical. For the plane to be able to evacuate the current safely means that there can be no electrical arcing in the airplane. This means that the conducting materials in the aircraft need to be connected together in order to keep it at the same electric electrical potential. On traditional planes the outermost layer is made out of aluminum which is a great conductor and thus fulfills the need to evacuate lightening charges. However, carbon based materials are insulators, so the engineers at Airbus have come up with a mesh out of a conducting material that goes within the outermost layer which is a 2 to 4 mm thick foil. On the A350 for example, this mesh acts as the Faraday cage and so contributes to keeping the aircraft at the same potential. The solar cells we are promoting in this project are 0.5 mm thick including the substrate which they are printed on. Our only concern in this area, which cannot be confirmed in this report, is that the thickness is too great and would affect the conductance of the outer surface. If further research would show that the conductance is affected due to the added thickness, we propose that an adjustment of the underlying mesh could be a solution.

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8.3

Commercial Impact for Airline Industry

People have become increasingly aware of the global energy crisis. This growing trend in awareness has sparked some airline companies to compete very aggressively by using green standards. By taking up green standards companies can appeal to a broader range of customers, bringing in those that are environmentally conscious. Doing so they obtain a cleaner and more friendly image. The incentives for airlines to buy planes fitted with solar cells are thus not merely to increase their fuel economy. The commercial and operational gains airlines would stand to obtain are therefore very promising. With the positive attention such an aircraft would produce, airlines stand to obtain a larger market share. This can be very beneficial in a competitive environment such as the airline industry.

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Further Research and Development

Throughout the course of this project we have come across areas which need further research. Many of these areas involve intense R&D which is beyond the means of this project. We hope to assist in future development of this idea by highlighting some of these next hurdles. • Structural Research - Adhesives: Research into strong adhesives and an adhesive releasing agent. - Securing lightning strike: If further research would show that the safety is affected due to the added thickness, we propose that an adjustment of the underlying mesh could be a solution. • Power generation and conversion - Inverter: A study would need to be conducted to come up with the most efficient load management system. - Whether it is possible to adjust the power usage from the generators in a way such that it would reduce fuel consumption as well as allowing the solar cells to be used most efficiently.

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Conclusion

We have shown in this report that airlines stand to save 135,000 l of fuel annually per A380 with 10% solar panel efficiency. Thus each plane will be saving 44% of the fuel used to power the cabin. This annual saving translates into 315,000 kg of CO2 reduction or the equivalent of driving 51 cars for 1 16


year. Airlines also stand to gain a better image which will make them more likely to attract customers. Today, the efficiency record for a CIGS solar panel achieved in a laboratory is 19.9%. This is a promising sign for what the future holds in store for CIGS solar panels. This system will take a number of years to design before it can be implemented onto an airplane. During this time solar panel efficiency will undoubtedly increase. We want to see the developed world take the forefront in the energy revolution which is on the verge of erupting. The technologies which will define our future are now only in their infancies.

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Appendix I References [1] Airbus - Service information letter. Guidance concerning the use of ground power units (GPU). [2] Wikipedia. Amorphous silicon. http://en.wikipedia.org/wiki/ Amorphous_silicon. [last checked 30/03/09]. [3] How Stuff Works. How Thin-film Solar Cells Work. http: //science.howstuffworks.com/thin-film-solar-cell1.htm. [last checked 30/03/09]. [4] Nanosolar. Semiconductor printing. printsemi.htm. [last checked 30/03/09].

http://nanosolar.com/

[5] Wikipedia. Cadmium telluride. http://en.wikipedia.org/wiki/ Cadmium_telluride. [last checked 30/03/09]. [6] Wikipedia. Copper indium gallium selenide. http://en.wikipedia. org/wiki/Copper_indium_gallium_selenide. [last checked 30/03/09]. [7] Wikipedia. Calcium sulfide. http://en.wikipedia.org/wiki/ Calcium_sulfide [last checked 30/03/09]. [8] Wikipedia. Molybdenum. http://en.wikipedia.org/wiki/ Molybdenum [last checked 30/03/09]. [9] Nanosolar blog. Nanosolar Achieves 1GW CIGS Deposition Throughput. http://www.nanosolar.com/blog3/?p=10. [last checked 30/03/09]. [10] RenewableEnergyWorld.com Utility-Scale Thin-Film: Three New Plants in Germany Total Almost 50 MW. http: //www.renewableenergyworld.com/rea/news/article/2009/03/ utility-scale-thin-film-three-new-plants-in-germany-total-almost-50-mw? cmpid=WNL-Friday-March13-2009. [last checked 30/03/09].

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[11] Celsias. Nanosolar’s Breakthrough Solar Now Cheaper than Coal. http://www.celsias.com/article/ nanosolars-breakthrough-technology-solar-now-cheap/. [last checked 30/03/09]. [12] Global solar. Based on data received from Global solar through e-mail. [13] Icelandair. Based on data received from Icelandair. [14] InvertersRus. Xantrex 5000 Watt Power Inverter. http: //www.invertersrus.com/xantrex813-5000.html [last checked 30/03/09]. [15] A. Ashour, M.A. Kaid, N.Z. El-Sayed, A.A. Ibrahim. Physical properties of ZnO thin film deposited by spray pyrolysis technique. ScienceDirect. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi= B6THY-4HDG93G-6&_user=713833&_rdoc=1&_fmt=&_orig=search&_ sort=d&view=c&_acct=C000039878&_version=1&_urlVersion=0&_ userid=713833&md5=e7a3cecfe66e857d1fb9b7f78a33297a. [last checked 30/03/09]. [16] Wikipedia. Silicone. http://en.wikipedia.org/wiki/Silicone. [last checked 30/03/09]. [17] Nanosolar. Designed to last. http://www.nanosolar.com/ Designedtolast.htm. [last checked 30/03/09].

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Appendix II Total surface area of an A380: c 路 l + s = 4429.85 m2 (c = approximation of the circumference of an ellipse, l = length of the airplane & s = surface area of the wings). The width of this is from window to window.

installation time: We estimate that the time it will take to attach the panels to the surface of the aircraft is 2 minutes per m2 This is based on the following assumptions: 1 minute: to peal the protecting layer off adhesive and get the panel into position 1 minute: to connect the necessary wires These are estimations made by us after observing the time it takes to place one square meter of paper onto another surface plus estimated time of removing the protecting layer and connecting two wires. Hence this could be a drastic exaggeration or under estimation. Now by multiplying 2 minutes per m2 by 1277 m2 solar panel surface we get 2554 minutes or about 43 hours or about 3 days (15 working hours in a day).

Cost of solar cells per plane: Current cost of solar cells per power output 路 power output at current 10% efficiency = 3 $/Watt 路 93 kW = $300,000.

Fuel price: Airports within 50 miles of KPHT (Henry Country Airport, Paris) Average price: 1.07 $/L

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CO2 reduction calculations: 44% calculated by dividing 134700 liters by 85 l/hour · 12 hour/flight · 300 flights (85 is liters needed to power cabin on average per hour).

Key CO2 emissions numbers: CO2 emmisions Iceland’s CO2 emissions annually: CO2 capicity of km2 of rainforest Annual CO2 emissions of a typical car:

2,350,000,000 kg 304,668 kg 6,084 kg

Assumptions: Jet engine efficiency: 30% Electricity generator efficiency: 85% Energy density of Jet A fuel: 43.15 MJ/kg Mass density of Jet A fuel: 0.81 kg/L

Appendix III

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Integrating solar panels into the structure ofairplanes to use as a secondary source ofenergy