Comparison of Electric Aircraft and Electric Train on the Distance Stockholm-Gothenburg

DEGREE PROJECT IN TECHNOLOGY, FIRST CYCLE, 15 CREDITS STOCKHOLM, SWEDEN 2021

Comparison of Electric Aircraft and Electric Train On the Distance Stockholm-Gothenburg

THERESE BÄCKSTRÖM

KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES

Abstract

Commercial aviation accounts for 2,4% of the total carbon dioxide emissions. This number is expected to reach 25% in 2050. In contrast to flying, the most energy efficient transportation mode is rail. In Sweden, rail and air are the most competitive on the distance Stockholm- Gothenburg due to similar total travel time. The most popular high-speed train on this distance is X2000. X2000 is electrified, contributing to merely indirect carbon emissions. Considering electricity as an energy source, the corresponding air transportation mode with respect to X2000 would be electric aircraft. This study investigates if electric aircraft could compete with electric trains on the distance Stockholm-Gothenburg in the foreseeable future. The objective was to identify challenges regarding electrification of aircraft using X2000 as a benchmark. These challenges were determined through a comparison between electric aircraft and electric train. In general, the comparison contains an analysis of cost, environmental impact, safety, comfort and time. In particular, the ticket price, carbon dioxide emissions, fatality rate, interior and exterior noise and transportation time were studied. The comparison was performed through a literature study. The results depicted electric aircraft could in the best-case scenario be slightly cheaper than the corresponding high-speed train option. Conversely, electric aircraft have somewhat higher energy consumption than X2000, hence the indirect carbon dioxide emissions from the electricity production are higher. However, these emissions are significantly lower than those from conventional aircraft. Regarding safety, electric aircraft are predicted to be safer than conventional ones, and therefore even safer than trains. Furthermore, electric aircraft contribute to less noise pollution than X2000. Though, the interior noise level is lower in a train car of X2000 than in a cabin of an electric aircraft. Concerning time, electric aircraft would even in the worst-case scenario have the same transportation time as X2000. Therefore, it was concluded that electric aircraft could compete with electric trains for short travel distances such as Stockholm-Gothenburg, in the foreseeable future.

Keywords Electric Aircraft, X2000, Electric Train

Sammanfattning

Kommersiell luftfart står för 2,4% av de totala koldioxidutsläppen och förväntas nå 25% år 2050. Tillskillnad från flyg är tåg det mest energieffektiva transportsättet. I Sverige är konkurrensen mellan flyg och tåg som störst på sträckan Stockholm-Göteborg på grund av liknande total restid. Det populäraste snabbtåget på denna sträcka är X2000. X2000 är ett elektriskt tåg som därmed enbart bidrar till indirekta koldioxidutsläpp. Angående elektricitet som energikälla så skulle det motsvarande luftburna transportalternativet till X2000 vara elektriskt flygplan. Denna studie undersöker om elektriska flygplan kan konkurrera med elektriska tåg på distansen Stockholm-Göteborg inom överskådlig framtid. Målet var att identifiera utmaningar gällande elektrifiering av flygplan med hjälp av X2000 som riktmärke. Dessa utmaningar fastställdes genom en jämförelse av elektriskt flyg och elektriskt tåg. I allmänhet innehåller jämförelsen en analys av kostnad, miljöpåverkan, säkerhet, bekvämlighet och tid. I synnerhet studerades biljettpris, koldioxidutsläpp, dödlighet i trafiken, inre och yttre buller och transporttid. Jämförelsen utfördes genom en litteraturstudie. Resultaten tydde på att elflygplan, i bästa fall, kan vara något billigare än motsvarande snabbtågsalternativ. Dock har elflygplan något högre energiförbrukning än X2000, varför de indirekta koldioxidutsläppen från energiproduktionen är aningen högre. Däremot är dessa utsläpp betydligt lägre än de från konventionella flygplan. När det gäller säkerhet förutspås elflygplan vara säkrare än konventionella och således ännu säkrare än tåg. Dessutom bidrar elflygplan till mindre bullerutsläpp jämfört med X2000. Den inre bullernivån är dock lägre i en X2000-tågkupé än i en elflygplanskabin. Gällande tid så skulle elflyget även i värsta fall ha samma transporttid som X2000. Således blev slutsatsen att elektriska flyg skulle kunna konkurrera med elektriska tåg på korta distanser som Stockholm-Göteborg, inom överskådlig framtid.

Nyckelord Elektriskt flygplan, X2000, Elektriskt tåg

Content

1 Introduction ...... 2 1.1 Problem ...... 3 1.2 Purpose ...... 3 1.3 Objective ...... 3 1.4 Methodology ...... 3 1.5 Delimitations ...... 4

2 Technical background ...... 5 2.1 Electric Aircraft ...... 5 2.2 Electric Trains ...... 7

3 Method ...... 8 3.1 Research Method ...... 8 3.2 Comparison ...... 8

4 Results ...... 10 4.1 Cost ...... 10 4.2 Environmental Impact ...... 13 4.3 Safety ...... 16 4.4 Comfort ...... 18 4.5 Time ...... 23

5 Discussion ...... 26 5.1 Cost ...... 26 5.2 Environmental Impact ...... 26 5.3 Safety ...... 27 5.4 Comfort ...... 28 5.5 Time ...... 28

6 Conclusion ...... 29

Definitions

RPK = Revenue passenger kilometre.

Specific energy (Wh/kg): energy per unit mass.

Energy density (Wh/litre): energy per unit volume.

Noise contour: The noise contour is drawn as a line which represents the same noise level.1 dB(A): A-weighted decibel scale. Depicts the sound level with respect to the human ear’s sensitivity to different frequencies.2

1 Federal Aviation Administration (FAA), Fundamentals of Noise and Sound, 2020 https://www.faa.gov/regulations_policies/policy_guidance/noise/basics/ (accessed 23.05.2021) 2 Min Sanggyu, Lim Dongwook, N. Marvis Dimitri, Aircrafts noise reduction technology and airport noise analysis general aviation revitalization, Atlanta: Georgia Institute of Technology, 2016, page 3 https://www.doi.org/10.2514/6.2015-2389

1 Introduction

The aviation industry has relied on fossil fuels ever since the first powered flight in 1903. Fossil fuels are energy dense and cheap but is not a sustainable choice due to the carbon dioxide emissions related to the aircraft’s combustion of the fossil jet fuel. The acceleration of emissions from aviation has increased. Between 2013 and 2017 the global carbon dioxide emissions from commercial aviation grew with 21%, from 710 million to 810 million tons3. Commercial aviation worldwide accounts for 2,4% of carbon emissions and the International Civil Aviation Organisation implies this number will reach 25% in 20504. Additionally, Swedes fly about five times the global average and 10% of Sweden’s annual climate impact accounts for flying5.

To maintain the commercial flights, but decrease the emissions, electrification might be the answer. Electric motors require less maintenance as a cause of wires and magnets replacing combustion chambers6. Furthermore, electric motors are 90% energy efficient compared to gas- powered engines which are only 30% efficient7. However, one known issue with electrification is the low energy density of batteries compared to jet fuel. Even though the batteries limit the electric aircraft’s range to about 1000 kilometres, this represents half of all departures8. In fact, short-haul flights require more fuel per kilometre than long-haul flights considering the most fuel-intensive phase is the start of the trip, when taking off and climbing to altitude9. Electric motors and batteries are improving rapidly every year. Certified electric aircraft are already being used in pilot training10. These aircraft are two-seats-gliders though, far from commercial planes. Aircraft are extremely sensitive to weight, which distinguish them from grounded vehicles such as cars and trains, which have been electrified for decades11.

Trains in general, and electric ones in particular, are competitors to conventional airplanes. Almost all trains in Sweden are electrified and powered by renewable energy12. Swedish aircraft and railway are the most competitive on the route Stockholm-Gothenburg, with 32 tours by air

3 Jeff Overton, ”The growth in greenhouse emissions from commercial aviation”, EESI, 2019 https://www.eesi.org/papers/view/fact-sheet-the-growth-in-greenhouse-gas-emissions-from-commercial-aviation (accessed 20.02.2021) 4 Brandon Graver Ph.D, Kevin Zhang, Dan Rutherford Ph.D, CO2 emissions from commercial aviation, The International Council on Clean Transportation, 2018, page 1 https://theicct.org/sites/default/files/publications/ICCT_CO2-commercl-aviation-2018_20190918.pdf 5 Anneli Kamb & Jörgen Larsson, Climate footprint from Swedish residents’ air travel, Gothenburg: Chalmers University of Technology, 2019 https://research.chalmers.se/publication/508693/file/508693_Fulltext.pdf 6 NASA, ”Battery innovations power all-electric aircraft”, 2019 https://spinoff.nasa.gov/Spinoff2019/t_1.html#:~:text=Lithium%2Dion%20batteries%20are%20the,runaway%2 C%E2%80%9D%20ending%20in%20combustion. (accessed 29.03.2021) 7 NASA, 2019 8 A.W. Schäfer, S.R.H. Barrett, K. Doyme et al., “Technological, economic and environmental prospects of all- electric aircraft”, Nat Energy 4, 2019, page 160 – 166 https://www.doi.org/10.1038/s41560-018-0294-x 9 Tom Wills & Gianna-Carina Grün, ”Trains vs. planes: What’s the real cost of travel?”, DW, 2018 https://www.dw.com/en/trains-vs-planes-whats-the-real-cost-of-travel/a-45209552 (accessed 20.02.2021) 10 Daniel P. Raymer, Aircraft Design. A conceptual approach, 6 ed. California: American Institute of Aeronautics and Astronautics, 2018, page 737, ISBN: 978-1-62410-490-9 11 Dries Verstraete, “Climate explained: why don’t we have electric aircraft?”, The Conversation, 2019 https://theconversation.com/climate-explained-why-dont-we-have-electric-aircraft-123910 (accessed 23.02.2021) 12 Josefin Hallenberg & Jonathan Sundin, Development of supply and prices on Swedish railway lines 1990– 2018 (original title in Swedish: Utveckling av utbud och priser på järnvägslinjer i Sverige 1990-2018), Transportstyrelsen, 2019, page 66 https://www.transportstyrelsen.se/globalassets/global/publikationer/jarnvag/utveckling-av-utbud-och-priser-pa- jarnvagslinjer-i-sverige-1990-2018.pdf

and 34 by rail13. Planes are assumed to be faster, whereas trains are more environmentally friendly14. However, electric aircraft might change this, since the jet fuel would be withdrawn from the equation. This report aims to compare electric aircraft with electric trains considering efficiency and sustainability for short travel distances.15

1.1 Problem

One commonly known fact is that the train is more environmentally friendly than the conventional airplane16. However, the plane is more popular due to among several reasons a perceived shorter travel time17. Airplanes will always be compared to trains, primarily regarding environmental impact. Electric trains such as X2000 set a benchmark for low carbon dioxide emissions. What if electric aircraft replace conventional aircraft, how will the comparison turn out then? Should electric aircraft replace electric trains? Are these transport alternatives equal? It is thought that this thesis will investigate how electric aircraft stand in relation to electric trains.

1.2 Purpose

The purpose of this thesis is to answer the question:

Can electric aircraft compete with electric trains regarding cost, environmental impact, safety, comfort, and time, on the distance Stockholm-Gothenburg, in the foreseeable future?

1.3 Objective

The objective with this report is to determine challenges regarding future electrification of domestic aircraft using electric trains as a benchmark.

1.4 Methodology

The methodology used to answer the research question is a literature study. The motive behind this choice is the thesis’ aim to gather information about air- and rail travel, which intentionally establishes an overview of the field. This overview creates a solid base for a comparison of the transportation modes.

13 Jonathan Sundin, Traveling flow on Swedish rail network (original title in Swedish: Resandeflöden på Sveriges järnvägsnät), Transportstyrelsen, 2019, page 10 https://www.transportstyrelsen.se/4978e1/globalassets/global/publikationer/marknadsovervakning/resandefloden -pa-sveriges-jarnvagsnat20190411.pdf 14 Hallenberg & Sundin, 2019, page 12 15 Sundin, 2019, page 10 16 Wills & Grün, 2018 17 Hallenberg & Sundin, 2019, page 12

1.5 Delimitations

Only flights between Stockholm Arlanda Airport and Gothenburg Landvetter Airport are studied. This decision is based on the high probability of a future closure of Stockholm Bromma Airport18.

The enduring pandemic’s effect on trains and certainly aircraft is significant. Hence, numbers from earlier years, such as 2019, are used in most cases in this study.

Regarding the energy required to power the electric trains and electric aircraft mentioned in this study, it will be considered as originated from Swedish energy mix, despite other claims. This decision is further discussed in Section 4.2.

The parameters studied in this report is limited to the cost, environmental impact, safety, comfort and time. The reason to this selection is explained in Chapter 3.

18 André Orban, “The Swedish government wants to close Stockholm’s Bromma Airport”, Aviation 24, 2021 https://www.aviation24.be/airports/stockholm-bromma-bma/the-swedish-government-wants-to-close- stockholms-bromma-airport/ (accessed 12.05.2021)

2 Technical background

This chapter aims to explain why electric airplanes possibly can replace conventional domestic ones in the foreseeable future, in terms of a technical point of view. Additionally, it discusses electric trains in general and the high-speed train X2000 in particular.

2.1 Electric Aircraft

The state of the art implies the technology do exist to build smaller electric aircraft. Electric aircraft are already being used in pilot training. The aircraft in question is the Alpha Electro, a two-seat T-tail design developed by Pipistrel in partnership with Siemens, certified by the Federal Aviation Administration (FAA)19. Last year the largest electric plane ever to fly took off in USA Washington State and had seats for up to nine passengers20. Cessna 208B Grand eCaravan is the name of the plane and it is a modification of the fuel-powered version21. The companies behind it are AeroTEC and magniX. magniX’s CEO Roei Ganzarski said the company believes all flights off less than 1609 kilometres will be completely electric in 15 years22. Furthermore, magniX is in the process of attaining the FAA certification by 202223. Another nine-seater currently in testing, also with an electric motor by magniX, is the company Eviation’s aircraft Alice24. Alice is designed to fly 814 kilometres with a maximum speed of 407 km/h25. Even if these small nine-seaters are far from covering todays traffic flow, bigger planes come with higher battery energy density26.

Battery energy density is the greatest challenge regarding electrification of aircraft due to the direct proportionality between the aircrafts weight and its energy consumption. It is simpler to modify a land vehicle, since it can manage the extra mass the electrical propulsion power system is causing. In addition, aircraft travel further than land vehicles such as cars, and therefore need more energy. Furthermore, aircraft need to store all the energy for the flight onboard, in contrast to trains which constantly are powered by the electrical grid.27

19 Raymer, 2018, page 737 20 Chris Baraniuk, “The largest electric plane ever to fly”, BBC, 2020 https://www.bbc.com/future/article/20200617-the-largest-electric-plane-ever-to-fly (accessed 21.02.2021) 21 Jon Fingas, ”Modified Cessna is the ´largest´ electric aircraft to take flight”, Engadget, 2020 https://www.engadget.com/magnix-aerotec-fly-electric-aircraft- 180259260.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig= AQAAAICdwl5kyPxNTQtQCH3_svIE27oZoUrQLJ84CFrdVRwAglQnKq4xf7B7KdDT3BOR1vRBnEMTMlP UGGdpwiQ1fCPdrZW3lZk6iw6GsoKKpf6I0i_MP0llcNckGJOjHLAENxtsX_0TVYus8tSCPm_kHAfYxYHX UwGEB9zKIAANOwo6 (accessed 22.02.2021) 22 Damian Carrington, ”World's largest all-electric aircraft set for first flight”, The Guardian, 2020 https://www.theguardian.com/world/2020/may/27/worlds-largest-all-electric-aircraft-set-for-first-flight (accessed 23.03.2021) 23 Johnna Crider, “Eviation Is Closer To Launching Commercial Electric Airplane Service – Alice Gets An EPU”, Clean Technica, 2021 https://cleantechnica.com/2021/05/13/eviation-is-closer-to-launching-commercial- electric-airplane-service-alice-gets-an-epu/ (accessed 25.05.2021) 24 Charles Alcock, ”Eviation’s electric Alice aircraft catches fire during ground tests”, AIN online, 2020 https://www.ainonline.com/aviation-news/business-aviation/2020-01-24/eviations-electric-alice-aircraft-catches- fire-during-ground-tests (accessed 06.04.2021) 25 Loz Blain, “Eviation prepares to fly Alice, its stunning luxury electric plane”, New Atlas, 2021 https://newatlas.com/aircraft/eviation-alice-magnix/ (accessed 25.05.2021) 26 Baraniuk, 2020 27 Verstraete, 2019

The most suitable energy storage device for powering electric aircraft is lithium ion (Li-ion) batteries, due to their high efficiency, long life cycle and high energy density compared to other batteries28. This allows the Li-ion batteries to be light and small. Li-ion is a catch-all phrase for all lithium-based batteries using lithium plus other materials. The Li-ion batteries of today present a specific energy of 250 Wh/kg, which limits the range to about 600 kilometres29,30. One forecast of Li-ion specific energy shows it will reach 300 Wh/kg before 203031. This forecast is based on extrapolation of the present improvement rate, which currently appear linear. Another scientific paper suggests the specific energy of Li-ion batteries will reach 800 Wh/kg around mid-century, which could power an Airbus A320-sized-aircraft to 1111 kilometres32. This argument is supported by the prediction that a specific energy of 750 Wh/kg could be achieved through new technologies involving sodium- or magnesium ions. However, this is far from the jet fuel energy of 11890 Wh/kg33. Probably, it will take 20-25 years before small-scale aviation will be developed.34

Even though the battery-forecast is diffuse, the world agrees on approaching electric aircraft. In 2017, over 100 electric-powered aircraft projects initiated in the world. One of them was the Airline giant Boeing, who has invested in the company Zunum Aero, who expects to fly an electric 50-seater aircraft with a range of 1600 kilometres by 2027. Likewise, Airbus is planning for an electric aircraft with capacity for 100 passengers and a range of 1000 kilometres by 2030. In addition, one Swedish project from Elise’s commercial apartment Heart Aerospace strives to electrify a regional nineteen-passenger aircraft with a 400 kilometres range and certify it by 202635,36. This aircraft would only require a 750-metre runway37. Furthermore, Norway has promised all of their short-haul flights will be electrified by 2040, with the first one introduced in 2025. In Norway several flights are under 30 minutes considering the mountainous terrain which aggravates other transportation modes.38

28 Y. Ding, Z.P. Cano, A. Yu et al., “Automotive Li-Ion Batteries: Current Status and Future Perspective”, Electrochem. Energ. Rev. 2, 2019, page 1-28 https://doi.org/10.1007/s41918-018-0022-z 29 Tom Metcalfe, ”The largest electric plane yet completed its first flight – but it’s the batteries that matter”, NBC News, 2020 https://www.nbcnews.com/science/science-news/largest-electric-plane-yet-completed-its-first-flight- it-s-n1221401 (accessed 30.03.2021) 30 Peter Bjarnholt, Electric propulsion in passenger jet airplanes. Requirements to realize all-electric propulsion, master thesis, Stockholm: Royal Institute of Technology, 2017, page 18 31 Hans Anton Tvete, ”Are solid state batteries the holy grail for 2030?”, DNV https://www.dnv.com/to2030/technology/are-solid-state-batteries-the-holy-grail-for-2030.html (accessed 09.03.2021) 32 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166 33 Umair Irfan, ”Forget cars. We need electric airplanes”, Vox, 2019 https://www.vox.com/2019/3/1/18241489/electric-batteries-aircraft-climate-change (accessed 09.03.2021) 34 European Commission, Strategic Research Agenda for batteries, 2020, page 12 https://ec.europa.eu/energy/sites/ener/files/documents/batteries_europe_strategic_research_agenda_december_20 20__1.pdf 35 Cecilia Häckner, Precision of national interest in Stockholm Arlanda Airport (original title in Swedish: Riksintresseprecisering för Stockholm Arlanda Airport), Trafikverket, 2020, page 21 https://doc.taby.se/handlingar/Kommunstyrelsen/2020/2020-10-22/Handlingar/17.3%20Remissversion.pdf 36 Heart Aerospace, About https://heartaerospace.com/about/ (accessed 08.05.2021) 37 Heart Aerospace https://heartaerospace.com/ (accessed 08.05.2021) 38 Stephen Dowling, ”Norway’s plan for a fleet of electric planes”, BBC, 2018 https://www.bbc.com/future/article/20180814-norways-plan-for-a-fleet-of-electric-planes (accessed 14.03.2021)

2.2 Electric Trains

In Sweden most trains are electric39. The high-speed-train X2000 between Stockholm and Gothenburg are fully electric powered40. This railway belongs to the state-owned company SJ AB, who is the major operator of passenger trains in Sweden. The railway between Stockholm and Gothenburg, called The Western Main Line, was one of the first to be built in Sweden and was finished in 1864. This railway had a great impact on the development of the Swedish industry. In 1915 the electrification of Swedish railway began and in 1926 the inauguration of the electrification of The Western Main Line held place. The primary object of the electrification was to make the railways independent of foreign fuel. By now, most railways in Sweden have been fully electrified for ages. Regardless, the railways’ share of Sweden’s total electricity consumption is below 3%.41

The high-speed X2000 trains were introduced in traffic in 199142. SJ wanted these trains to substitute flights between major cities. The X2000 trains had a new design including radial bogies and a tilting system. This design was comfortable and safe even in high speeds up to 200 km/h on curved tracks. The trains were manufactured by ABB, who used Swedish stainless steel as the main material in the train frames. The trains’ electrical brakes have the ability to transfer back energy to the power supply system and further out to the auxiliary system, other trains on the line or even the general electric grid43. 44

The introduction of X2000 on the distance Stockholm-Gothenburg decreased the travel time from four to three hours. Due to the fact that trains are as fast as planes when the travel time is three hours, the introduction of X2000 increased the train’s markets share from 40 to 60%.45

39 Hallenberg & Sundin, 2019, page 66 40 Evert Andersson & Piotr Likaszewicz, Energy consumption and related air pollution for Scandinavian electric passenger trains, Stockholm: Royal Institute of Technology, 2006, page 1, ISSN: 1650-7660 41 Vattenfall, ”Electrified railways for 100 years” https://history.vattenfall.com/stories/the-revolution-of- electricity/electrified-railways-for-100-years (accessed 27.02.2021) 42 Bo-Lennart Nelldal, Possibilities for the train to compete with and substitute the plane (original title in Swedish: Möjligheter för tåget att konkurrera med och ersätta flyget), Stockholm: Royal Institute of Technology, 2007, page 14 https://www.kth.se/polopoly_fs/1.87154.1550158897!/Menu/general/column- content/attachment/Nelldal2007_SubstitutionTagFlyg.pdf 43 Piotr Lukaszewicz & Evert Andersson, Green train energy consumption, Stockholm: Royal Institute of Technology, 2009, page 15, ISBN: 978-91-7415-257-9 44 Outokumpu, Making of the X2000 high-speed trains, 2016 https://www.outokumpu.com/en/expertise/2016/making-of-the-x2000-high-speed-trains (accessed 27.02.2021) 45 Nelldal, 2007, page 4

3 Method

This chapter includes the steps which were taken to achieve the results presented in Chapter 4.

3.1 Research Method

The choice of research method was supported by an initial general literature review. The literature review implied that transportation modes earlier have been compared regarding costs, environmental impact, safety, comfort and time in multiple papers. Accordingly, information and numbers about these areas could be found in several case- and literature studies. Therefore, a literature study was performed in this report with the aim to gather information from previously done work.

3.2 Comparison

The comparison of electric aircraft to electric train was done with respect to the cost, environmental impact, safety, comfort and time. These subjects were chosen since they are prevailing today and are commonly studied factors in other similar comparisons of transportation modes. In the paper On the Environmental Impact and Efficiency of Travel, a similar investigation was carried out between Stockholm and Berlin, comparing travel by train and airplane46. This study completed an analysis of safety, time, cost, work environment and environmental impact47. In the master thesis Efficiency of regional travel, the same parameters were analysed48. Similarly, these parameters are central in the Case study on the Environmental Impact and Efficiency of Travel, a comparison of travel by train and airplane between Stockholm and Bordeaux49. These investigations compared ticket price, fatality rate, travel time, reliability, interior noise level, energy in kWh and carbon dioxide in kilograms for different transportation modes. Likewise, these factors appear in this study. Meaning, when cost was inspected the ticket-price was of interest. Considering environmental impact, the energy in kilo Watt hours, the carbon dioxide emissions and other related environmental issues were examined. Regarding safety, the fatality rate and the general known safety of the vehicle were investigated. For comfort, interior and exterior noise were of importance. Lastly, the time was studied with respect to the transportation time on-board, the additional time required for transfer and terminal and the transportation mode’s punctuality.

The most crucial factor regarding competition between rail and air is the travel time50. The train is as fast as the airplane when the travel time is three hours51. Three hours is also the travel time between Stockholm-Gothenburg with high-speed train52. Accordingly, Swedish aircraft and high-speed train are the most competitive transportation modes on this accurate route53,54. This

46 Hans Bodén et al., On the Environmental Impact and Efficiency of Travel, Stockholm: Royal Institute of Technology, 2019 47 Bodén et al., 2020 48 Cherine Coliander, Efficiency of regional travel, master thesis, Stockholm: Royal Institute of Technology, 2020 49 Evelyn Otero & Ulf Ringertz, Case Study on the Environmental Impact and Efficiency of Travel, Aerospace European Conference AEC2020, Bordeaux, France, 2020 50 Nelldal, 2007, page 4 51 Nelldal, 2007, page 4 52 Omio, Trains Stockholm-Gothenburg https://www.omio.com/trains/stockholm/gothenburg (accessed 02.03.2021) 53 Sundin, 2019, page 10 54 Hallenberg & Sundin, 2019, page 13

means, the greatest both rail- and air-supply of Swedish long-distance traffic exist on this distance55. The dominating train traffic operator is SJ, who owns 72% of the number of services56. Their high-speed train X2000 is the fastest way to travel Stockholm-Gothenburg by rail57. Intuitively, X2000 dominates the number of services on the accurate distance58. Furthermore, the airline SAS owns half the share of the Swedish commercial flight market59. Naturally, SAS dominates the number of services between Stockholm Arlanda Airport and Gothenburg Landvetter Airport60,61. The airplane SAS use is the Airbus A32062. This means the comparison was based on the train X2000 by SJ, and the airplane Airbus A320 operated by SAS. The Airbus A320 performed as a reference aircraft while discussing the electric point of view. This certain aircraft has earlier performed as a reference in a study which compared conventional and electric aircraft63. Additionally, the electric aircraft mentioned in the technical background, Alpha Electro, Alice and Cessna eCaravan, will be used for support. These electric aircraft are for instance used in the calculations of the energy consumption, which is computed as: E E = b (1) RPK R⋅ n Where is the energy consumption per RPK (kWh per RPK), is the energy stored in the ERPK Eb battery (kWh), R is the maximum cruise range (km) and n is the number of seats occupied. To confirm the results, the energy consumption of a theoretical electric aircraft was estimated.

Regarding the carbon dioxide emissions, they will be calculated for the distance Stockholm- Gothenburg as: total production (2) CO2 = ERPK ⋅ D ⋅CO2 total Where CO2 is the total carbon dioxide emissions per passenger on the whole distance (grams of CO2 per passenger), D is the transportation distance between Stockholm and Gothenburg (km), which vary with the transportation mode, and production is the carbon dioxide emissions CO2 per kWh from the electricity production (grams of CO2 per kWh).

55 Hallenberg & Sundin, 2019, page 123 56 Hallenberg & Sundin, 2019, page 40 57 Hallenberg & Sundin, 2019, page 100 58 Hallenberg & Sundin, 2019, page 99 59 Hallenberg & Sundin, 2019, page 40 60 Scyscanner, Flightinformation Stockholm Arlanda-Gothenburg Landvetter https://www.skyscanner.se/rutter/arn/got/stockholm-arlanda-till-goteborg-landvetter.html (accessed 23.03.2021) 61 Hallenberg & Sundin, 2019, page 18 62 SAS, Time schedule for Stockholm Arlanda Airport – Gothenburg Landvetter Airport the 3th of June https://www.sas.se/book/flights/?search=OW_ARN-GOT- 20210603_a1c0i0y0&view=LPC&bookingFlow=revenue&sortBy=stop (accessed 03.05.2021) 63 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166

4 Results

This chapter contains the results based on the literature study.

4.1 Cost

Regarding a ticket for the distance Stockholm-Gothenburg, the average price in 2018 was 508 kr for high-speed train, and 1674 kr for conventional airplane, according to Figure 1. This means the difference in 2018 between air and rail was 1166 kr. The ticket in question is a rebookable but non-refundable adult-ticket, booked one week in advance.64

Figure 1 Price of a rebookable but non-refundable ticket with high-speed train and conventional airplane Stockholm-Gothenburg, booked one week in advance 1990–201865

In contrast to the ticket price from 2018, today’s tickets (2021) are booked one month (instead of one week) in advance, non-rebookable, affected by the pandemic and only calculated with respect to the high-speed train X2000 and the airline SAS. Today a train ticket from Stockholm to Gothenburg with X2000 in second class, non-rebookable and non-refundable, costs 318 kr in average. This price is based on Table 1 which lists the price when booking one month in advance.66

64 Hallenberg & Sundin, 2019, page 36, Figure 11 65 Hallenberg & Sundin, 2019, page 36, Figure 11 66 SJ, Time schedule for Stockholm – Gothenburg the 3th of June 2021 https://www.sj.se/en/home.html#/tidtabell/Stockholm%2520Central/G%25C3%25B6teborg%2520C/enkel/avga ng/20210603-0500/avgang/20210603-1500/VU--///0// (accessed 03.05.2021)

Table 1 Time schedule of all X2000-trains Stockholm-Gothenburg when booking one month in advance (departure 3th June 2021)67

Number of the departure Transportation time X2000 (hours) Price 2:class (kr) 1 3:15 225 2 3:09 195 3 3:05 225 4 3:09 295 5 3:06 295 6 3:05 515 7 3:06 365 8 3:10 295 9 3:05 365 10 3:08 445 11 3:07 445 12 3:09 445 13 3:09 365 14 3:05 195

Today, a conventional airplane ticket between Stockholm and Gothenburg with SAS, in economy class, non-rebookable and non-refundable, costs 952 kr in average68. This price is based on Table 2, which lists the price when booking one month in advance. This means today’s difference between a ticket for the train X2000 and a flight by SAS is 633 kr. This calculation does not take the shuttle connection, between airports and cities, into account. The shuttle connection 2018, with airport bus at both ends, costed approximately nearly 200 kr69.

Table 2 Time schedule of all SAS flights Stockholm-Gothenburg when booking one month in advance (departure 3th June 2021)70

Number of the departure Transportation time SAS (hours) Price economy class (kr) 1 1:00 899 2 1:00 899 3 1:00 1249 4 1:00 759

Conventional airlines spend around 25 to 50% of all their costs on jet fuel and a switch to electric power could make the flight tickets cheaper71. The estimated cost for flying an electric airplane is 40-70% lower per flight hour than a conventional plane72. This is according to Roei Ganzarski, the CEO of magniX, which was one of the two companies behind Cessna 208B Grand eCaravan, the largest electric plane ever to take off. The 30-minute flight costed 6 USD (50 kr if currency exchange 07.05.2021), instead of 300-400 USD (2502-3336 kr if currency exchange 07.05.2021) which is the equivalent cost if conventional engine fuel was used73. Furthermore, according to Ivo Boscarol, the general manager of Pipistrel, their aircraft Alpha

67 SJ, Time schedule for Stockholm – Gothenburg the 3th of June 2021 68 SAS, Time schedule for Stockholm Arlanda Airport – Gothenburg Landvetter Airport the 3th of June 69 Hallenberg & Sundin, 2019, page 13 70 SAS, Time schedule for Stockholm Arlanda Airport – Gothenburg Landvetter Airport the 3th of June 71 Sophie Hand, ”When will electric aircraft really take off?”, Aerospace manufacturing, 2019 https://www.aero- mag.com/when-will-electric-aircraft-really-take-off/ (accessed 29.03.2021) 72 Carrington, 2020 73 Baraniuk, 2020

Electro could cut as much as 70% of the costs of pilot training74. Additionally, Swedish Heart Aerospace claims their electric aircraft could cut 50-75% of fuel cost75. Conversely, the electric propulsion system cost more than the combustion engine76. Though, the cost of building an electric plane is similar to that associated with a conventional one, as indicated by Ganzarski77. Costs such as environmental charges are small relative to the total airport charges. In 2016 the numbers were only 1% for short haul flights respectively 4% for long haul flights78.

If the cost for flying an electric airplane is 70% lower per flight hour in the best-case scenario, and 40% lower in the worst-case, one ticket with electric aircraft would cost between 502 kr and 1004 kr, if the price from Figure 1 is used as a reference. This is depicted in Figure 2. In contrast, if today’s average ticket price with SAS from Table 2 is used as a reference, one ticket with electric aircraft would cost between 286 kr and 571 kr. This is presented in Figure 3. The calculation of the ticket price for electric aircraft is based on the assumption that electric aircraft would be as fast as conventional ones, meaning flying Stockholm-Gothenburg in one hour, as depicted in Table 2.

Figure 2 Ticket price using numbers from 2018 in Figure 1 as a reference

Figure 3 Ticket price using numbers from today in Table 1 and Table 2 as references

Furthermore, conventional short-haul planes often operate for 11 to 12 hours a day with 15 minutes refuelling. Electric aircraft, such as the nine-seater Alice by Eviation, could only fly

74 Pipistrel, First Pipistrel’s Alpha Electro took flight in Australia, https://www.pipistrel-aircraft.com/first- pipistrels-alpha-electro-took-flight-in-australia/ (accessed 08.05.2021) 75 Heart Aerospace 76 Raymer, 2018, page 740 77 Adele Peters, ”How electric planes could revolutionize commercial aviation”, Fast Company, 2020 https://www.fastcompany.com/90490893/how-electric-planes-could-revolutionize-commercial-aviation (accessed 29.03.2021) 78 EASA, Environmental charges https://www.easa.europa.eu/eaer/noise/airports (accessed 02.04.2021)

for eight to nine hours a day, considering a half hour charging is required for every hour in air. Regarding Alpha Electro, it requires an hour charging for every hour in air79.80

Electric aircraft are estimated to require several generations of new batteries, which results in direct costs when financing batteries, and maintenance cost when exchanging them. The higher weight of the aircraft, due to batteries, may increase the need of maintenance and switch of landing gear. In contrast, electric aircraft do not require a fuel system, a gas turbine or engine starting, which makes the electric motor simpler and easier to maintain. Although, the high- temperature electric motor demands cooling.81

4.2 Environmental Impact

SJ claims their trains use 100% renewable energy from hydropower. According to them, the energy consumption of the high-speed train X2000 is 0,050 kWh per revenue passenger kilometre (RPK), assuming an average occupancy rate. The average occupancy rate in 2019 was almost 70% for all high-speed trains on the route Stockholm-Gothenburg82. Since X2000 is powered by electricity, the direct carbon emissions are zero83. Still, indirect carbon dioxide emissions come from the electricity production. SJ’s hydropower supplier is Vattenfall, who claims to have carbon dioxide emissions of 0,048 grams per kWh. Furthermore, SJ’s annual and sustainability report from 2019 reveals their largest source to carbon dioxide emissions are replacement services and leakage of refrigerant84. Lack of punctuality and rolling stock maintenance is causing the need of replacement traffic and refrigerant respectively85.86

However, the emissions from Vattenfall’s hydropower might seem unfeasible, as originally stated in the study On the Environmental Impact and Efficiency of Travel87. The official number for Sweden’s greenhouse gas emissions per produced kWh of 2018 was 13 grams of carbon dioxide per kWh88. The Swedish electricity is (2019) essentially generated by hydropower and nuclear power89. This number, from the Swedish electricity mix, will hereafter be used in this thesis. According to these emissions and the 455 kilometres railway between Stockholm and Gothenburg, X2000 corresponds to 0,30 kilograms of carbon dioxide per passenger, according

79 Raymer, 2018, page 737 80 Jeremy Bogaisky, ”Billionaire Richard Chandler takes control of Eviation, giving it funds to make electric passenger plane take flight”, Forbes, 2019 https://www.forbes.com/sites/jeremybogaisky/2019/02/20/eviation- gains-backing-from-billionaire-richard-chandler-to-make-first-electric-passenger-plane-take- flight/?sh=264b40866ebb (accessed 29.03.2021) 81 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166 82 Sundin, 2019, page 7 83 Andersson & Likaszewicz, 2006 84 SJ, Annual and sustainable report 2020, page 28 https://www.sj.se/content/dam/externt/dokument/finansiell- info/SJ-Ars-och-hallbarhetsredovisning-2020.pdf 85 SJ, Annual and sustainable report 2020, page 28 86 SJ, Climate smart (original title in Swedish: Klimatsmart) https://www.sj.se/sv/om/om-sj/klimatsmart.html (accessed 27.03.2021) 87 Bodén et al., 2020, page 78 88 European Environment Agency, Greenhouse gas emissions intensity of electricity generation in Europe, 2018 https://www.eea.europa.eu/data-and-maps/indicators/overview-of-the-electricity-production-3/assessment (accessed 03.05.2021) 89 SCB, Electricity in Sweden (original title in Swedish: Elektricitet i Sverige), 2019 https://www.scb.se/hitta- statistik/sverige-i-siffror/miljo/elektricitet-i-sverige/ (accessed 03.05.2021)

to Equation 290. This information is collected in Figure 4, composed with the equivalent energy in kWh per RPK for X2000.

For comparison, SAS’s annual and sustainability report from 2019 shows their carbon dioxide emissions are 95 grams per RPK91. This corresponds to 38 kilograms of carbon dioxide emissions per passenger on the 395 kilometres linear distance between Stockholm Arlanda Airport and Gothenburg Landvetter Airport, according to Equation 292.

Regarding electric aircraft, the direct carbon dioxide emissions are, similar to electric trains, zero. This is a result to the elimination of combustion emissions. Indirect emissions would be caused by electricity losses during battery charging and electricity distribution.93

The energy consumption for electric aircraft is calculated with respect to the three most prevailing electric aircraft mentioned in the technical background. These aircraft are Alpha electro, Alice and the Cessna eCaravan. The calculations are made as depicted in Equation 1. These electric aircraft are still far from standard-sized aircraft, and because they only have capacity for a few people, in comparison to trains, the calculations are done with respect to full planes. The energy requirement is higher if considering take-off and climbing to altitude, due to the fact that these are the most energy consuming phases94.

The computation of Equation 1 results in the following numbers. The first FAA-certified electric aircraft, Alpha electro, has a cruise range distance of 139 kilometres, capacity for two people and a 21-kWh battery95,96. This gives a 0,076 kWh per RPK, when it travels with the maximum capacity. Alice has a battery pack on 820 kWh, ability for nine passengers and a range of 814 kilometres97,98. This results in 0,11 kWh per RPK, when it travels with the maximum capacity. The Cessna eCaravan has a range of 161 kilometres, takes nine passengers and has 907 kilograms Li-ion batteries with the specific energy of 250 Wh/kg, which gives a 227 kWh-battery99. This corresponds to 0,16 kWh per RPK, when traveling with the maximum capacity. These numbers are gathered in Table 3.

90 Railway Technology, ”MTR launches commercial service on Stockholm-Göteborg route in Sweden”, 2015 https://www.railway-technology.com/uncategorised/newsmtr-launches-commercial-service-on-stockholm- gteborg-route-in-sweden-4538868/ (accessed 04.04.2021) 91 SAS, Annual and sustainability report – fiscal year 2019, page 132 https://www.sasgroup.net/files/documents/Corporate_governace/annual-reports/sas-sas-annual-and- sustainability-report-fiscal-year-2019-200130.pdf 92 Travelmath, The flight time from Gothenburg Landvetter Airport to Stockholm Arlanda Airport https://www.travelmath.com/flying-time/from/GOT/to/ARN (accessed 21.03.2021) 93 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166 94 Wills & Grün, 2018 95 Pipistrel, Technical data Pipistrel Alpha Electro https://www.pipistrel-aircraft.com/aircraft/electric- flight/alpha-electro/#tab-id-2 (accessed 31.03.2021) 96 Shane Dowling, “6 electric aviation companies to watch”, GreenBiz, 2019 https://www.greenbiz.com/article/6-electric-aviation-companies-watch (accessed 31.03.2021) 97 Eviation, Alice Specifications https://www.eviation.co/aircraft/#Alice-Specifications (accessed 25.05.2021) 98 Blain, 2021 99 Metcalfe, 2020

Table 3 The input and output of Equation 1

Range Capacity Battery energy Energy consumption Electric aircraft (km) (-) (kWh) (kWh per RPK) Alpha Electro 139 2 21 0,076 Alice 814 9 820 0,11 Cessna eCaravan 161 9 227 0,16

According to these calculations, an electric aircraft has an average energy consumption of 0,11 kWh per RPK. Considering the energy as originated in Swedish energy mix and the 395 kilometres between Stockholm Arlanda Airport and Gothenburg Landvetter Airport, the carbon dioxide emissions per passenger are 0,56 kilograms, according to Equation 2100. These quantities are collected in Figure 4. Though, since both Alpha Electro and Cessna eCaravan do not actually have the range to cover the distance between Stockholm and Gothenburg, they might require more batteries to extend their range. This would imply a higher weight and therefore a higher energy consumption101.

Figure 4 Energy consumption and carbon dioxide emissions

The energy required for a theoretical electric aircraft can be calculated with respect to a conventional one. A conventional aircraft burns 0,05 litres per RPK on the distance Stockholm- Gothenburg102. The average load factor 2018 was around 63-65% for all domestic flights in Sweden103. The energy density of jet fuel is 34,5 MJ/litre104. This gives 1,73 MJ per RPK. Only 30% is used for propulsion, whereas 70% is lost during combustion105. This results in 0,52 MJ per RPK for propulsion. Moreover, 0,52 MJ per RPK corresponds to 0,14 kWh per RPK. Considering the energy as originated in Swedish energy mix and the 395 kilometres between the airports, the carbon dioxide emissions per passenger are 0,72 kilograms, according to Equation 2106.

100 Travelmath 101 Verstraete, 2019 102 Chalmers, “When will aircraft go green?” Chalmers Magazine, 2012 https://www.chalmers.se/en/news/Pages/green-flights.aspx 103 Henrik Petterson, “Slower passenger growth for Swedish civil aviation in 2018”, Transport Analysis, 2019 https://www.trafa.se/en/civil-aviation/slower-passenger-growth-for-swedish-civil-aviation-in-2018-8254/ (accessed 07.05.2021) 104 Michelle Kocal et al., Sustainable Aviation Fuel. Review of technical pathways, U.S. Department of energy, 2020, page 12 https://www.energy.gov/sites/prod/files/2020/09/f78/beto-sust-aviation-fuel-sep-2020.pdf 105 NASA, 2019 106 Travelmath

As stated, Alpha Electro, Alice and Cessna eCaravan are small aircraft. This is not a disadvantage since smaller planes need smaller runways and therefore enables smaller airports107. Swedish Heart Aerospace claims their nineteen-passenger aircraft, launching in 2026, merely requires a 750-metre runway108. This can be compared to one of Stockholm Arlanda Airport’s runways, which is 3300 metres long109. Smaller planes and smaller runways could result in a new air traffic flow management, an increased ability outside the main cities and less noise110.

In contrast to electric aircraft, electric trains do not have batteries111. Batteries will inevitably decline over time. Both due to calendar age, and the number of times charge and discharge. Every fifth to eighth years a total battery pack replacement is required. Even the materials in the batteries cause environmental hazards.112

One of the materials in Li-ion batteries is obviously lithium. The lithium process is water consuming, meaning one ton of lithium consumes 1900 tons of water. In fact, in one major lithium centre in Chile´s Salar de Atacama, the process consumed 65% of the whole water supply. Regarding the remaining water, the risk of it being contaminated, due to toxic chemicals from the lithium process, is high. Chemicals are required to extract minerals, such as lithium. In Nevada, researchers found the lithium process impacted fish 240 kilometres downstream the lithium extraction. Regardless, the lithium-demand is increasing exponentially, partly because of electrification of vehicles.113

Another material the Li-ion batteries contain is cobalt, which merely can be extracted across the Democratic Republic of Congo and central Africa. From 2016 to 2018 the price on cobalt quadrupled. Cobalt is toxic while extracting it, and during the unethical circumstances it is often handled using child labour without protective equipment.114

4.3 Safety

Comparison of fatality risk for passengers in EU indicates that the safest transportation mode is airplane followed by rail. Rail is safer than bus/coach and cars in terms of the fatality risk. The fatality risk for a railway passenger in EU was in average equivalent to 0,10 fatalities per billion passenger-kilometres, between 2011 to 2015. Meanwhile, the risk of commercial flight passengers in EU was 0,06 fatalities per billion passenger-kilometres. These numbers are depicted in Figure 5. In EU, most train accidents are caused by suicides and represents 73% of significant accidents. The second largest share represents by accidents due to an unauthorized person and serve as 17%. The third largest share on 7% belongs to level-crossing accidents.115

107 Stephen Dowling, 2018 108 Heart Aerospace 109 Swedavia Airports, For neighbors (original title in Swedish: För grannar), 2021 https://www.swedavia.se/arlanda/grannar/#gref (accessed 03.04.2021) 110 Häckner, 2020, page 21 111 Bodén et al., 2020, page 17 112 Raymer, 2018, page 741 113 Amit Katwala, ”The spiralling environmental cost of our lithium battery addiction”, Wired, 2018 https://www.wired.co.uk/article/lithium-batteries-environment-impact (accessed 30.03.2021) 114 Katwala, 2018 115 European union agency for railways, Railway safety in the European union: Safety overview 2017, Luxembourg, 2017, page 16, 22 and 28 https://www.era.europa.eu/sites/default/files/library/docs/safety_interoperability_progress_reports/railway_safet y_performance_2017_en.pdf

Figure 5 Number of fatalities per billion passenger kilometres in EU between 2011-2015

Every year in Sweden, there are 85 to 100 deaths linked to railways. Around 80% of all Swedish railway accidents are caused by suicides. Several railway crossings lack gates or warning lights. This led directly to 20 deaths at Swedish railways crossings during 2018.116

Concerning electric motors, they have no fuel to catch fire, no carbon-monoxide emissions and are therefore safer than fuel-based engines. Nor can ice form in the carburettor or fuel tanks. Electric motors are smaller than combustion engines. In opposite to fuel cells, the power in electric motors do not decrease with altitude.117

However, electric aircraft create other challenges. In contrast to electric trains, electric aircraft require batteries118. Li-ion batteries can short-circuit and cause thermal runaway leading to combustion119. Thus, it is crucial to ensure a chain reaction is not caused by one cell burn in the battery pack. Moreover, it is critical the batteries reliably maintain power as the flight system depend upon power at all times120. As earlier mentioned, Li-ion batteries are the only batteries for the moment which are really practical for aircraft. They present a fire hazard, particularly when shorted or charged to promptly121. This fact was confirmed by Eviation’s aircraft Alice, which caught fire during testing. Eviation said the fire was caused by a fault in the battery system122. The fire in lithium batteries is caused by harmful structures named as dendrites and whiskers, which can emerge with possibility to breaching separators123. Fire hazard is not the only danger. Electric motors radiate electromagnetic energy with the risk to interfere with other electronic components, such as radio signals including the ability to turn off the motor124.

116 The Local, ”Railway crossing deaths set to hit 10-year high in Sweden”, 2019 https://www.thelocal.se/20190930/railway-crossing-deaths-set-to-hit-10-year-high-in-sweden/ (accessed 12.03.2021) 117 Raymer, 2018, page 739-740 118 Bodén et al., 2020, page 17 119 NASA, 2019 120 Mohd Tariq et al., ”Aircraft batteries: current trend towards more electric aircraft”, IET Electrical systems in tranportation 7, 2017, page 93-103 https://doi.org/10.1049/iet-est.2016.0019 121 Raymer, 2018, page 746 122 Alcock, 2020 123 Pacific Northwest National Laboratory, ”Scientists pinpoint cause of harmful dendrites and whiskers in lithium batteries”, Phys org, 2019 https://phys.org/news/2019-10-scientists-dendrites-whiskers-lithium- batteries.html#:~:text=Dendrites%20are%20tiny%2C%20rigid%20tree,patio%20or%20a%20paved%20road. (accessed 06.04.2021) 124 Raymer, 2018, page 741

4.4 Comfort

The number of tours with high-speed train and conventional aircraft between Stockholm and Gothenburg is depicted in Figure 6. There are, and have always been, more air-services than rail-services. However, the rate of train-services is increasing faster than for air-services. 125

Figure 6 Supply of services per day and direction by high-speed train and conventional airplane Stockholm- Gothenburg 1990–2018126

Noise from aircraft is experienced as more disturbing than noise from trains. The reason might be the aircraft noise come from above and the noise is harder to predict, in contrast to railway- noise.127

Though, according to Figure 7, the number of people exposed to railway noise over 55 dB(A) during day and evening, respectively 50 dB(A) during night, are significantly higher than the corresponding number of people exposed to the same level of noise originating from airports.

125 Hallenberg & Sundin, 2019, page 36, Figure 9 126 Hallenberg & Sundin, 2019, page 36, Figure 9 127 Transportstyrelsen, “Is aircraft noise perceived as more disturbing for the humankind than noise from other sources?” (original title in Swedish: ”Upplevs flygbuller mer störande för människan än buller från andra källor?”), 2012 https://www.transportstyrelsen.se/sv/luftfart/Miljo-och-halsa/Vanliga-fragor-och-svar/Upplevs- flygbuller-mer-storande-for-manniskan-an-buller-fran-andra-kallor/ (accessed 04.04.2021)

Figure 7 Total number of people exposed to railway, airport and industrial noise, in Sweden (2012)128

Furthermore, Figure 8 shows which noise levels these people are exposed to. This figure emphasises how much more disturbing railways are in contrast to airports, in Sweden. 129

Figure 8 Number of people exposed to different noise levels at day and evening (Lden) respectively at nigh (Lnight) (2012)130

128 European Environment Agency, Noise in Europe. 2017 overview of policy-related data. Sweden, 2017. page 2 129 European Environment Agency, 2017, page 1 130 European Environment Agency, 2017, page 1

The measurements in Figure 7 and Figure 8 are done with respect to Stockholm Arlanda Airport, Gothenburg Landvetter Airport, Stockholm Bromma Airport and the major railways, including the rail between Stockholm and Gothenburg131.

One of the cities X2000 passes between Stockholm and Gothenburg is Falköping132,133. The average noise contour X2000 creates in Falköping is depicted in Figure 9134.

Figure 9 Maximum noise level from the X2000 train in Falköping135

The railway between Stockholm and Gothenburg is stretching over 455 kilometres, and Figure 9 depict the area with a noise level over 65 dB(A), 720 meters perpendicular to the railway136. This means that the total area affected by a noise level over 65 dB(A) from X2000 is approximately 328 km2.

Airlines are always on the mission to circumvent noise pollutions restrictions at night, which have made the noise motive the greatest one regarding exchanging the propulsion system to

131 European Environment Agency, 2017, page 1 and 3 132 SJ, Traffic information Stockholm central - Gothenburg central (original title in Swedish: Trafikinformation Stockholm central – Göteborg central) https://trafikinfo.sj.se/sv/stracka/Stockholm%20Central/G%C3%B6teborg%20C/tag/431/431/2021-05- 27T11:30?date=2021-05-30&type=departure (accessed 25.05.2021) 133 SJ, Rail network map (original title in Swedish: Linjekarta), 2021 https://www.sj.se/content/dam/externt/bilder/ovrigt/kartor/sjlinjekartahelasverige-2021.pdf (accessed 25.05.2021) 134 Trafikverket, Report about noise (original title in Swedish: Underlagsrapport Buller), 2017, page 10 and appendix 3 https://www.trafikverket.se/contentassets/a6cf36110ff24079bcb4807162c4faa9/bullerutredning_1140_kb.pdf 135 Trafikverket, 2017, appendix 3 136 Railway Technology, 2015

electric137. At Stockholm Arlanda Airport the maximum noise level at night is 70 dB(A), and at day and evening 80 dB(A)138. The noise contour for Arlanda is illustrated in Figure 10.

Figure 10 Stockholm Arlanda Airport, noise contours for maximum noise level at day and evening139,140

The annual traffic (2017) at Gothenburg Landvetter Airport is about 3,4 times less than at Stockholm Arlanda Airport141. The difference between the noise contours for the airports is shown in Figure 11.

Figure 11 Noise contours for Gothenburg Landvetter Airport (left hand side) and Stockholm Arlanda Airport (right hand side)142

137 Philip E. Ross, ”Hybrid electric airliners will cut emissions – and noise”, IEEE Spectrum, 2018 https://spectrum.ieee.org/aerospace/aviation/hybrid-electric-airliners-will-cut-emissionsand-noise (accessed 13.04.2021) 138 Swedavia Airports, For neighbors, 2021 139 Charlotta Eriksson et al., Long-term aircraft noise exposure and body mass index, waist circumference, and type 2 diabetes: A prospective study, Stockholm: Karolinska institute, 2014, page 6 and 29 https://doi.org/10.1289/ehp.1307115 140 Google maps https://www.google.com/maps/@59.6741227,17.907527,10.62z (accessed 03.04.2021) 141 European Environment Agency, 2017, page 3 142 European Environment Agency, 2017, page 3

According to Figure 10, Stockholm Arlanda Airport has a noise level over 65 dB(A) on approximately 16,7 km2. As stated, Gothenburg Landvetter Airport’s annual traffic is 3,4 times less than Arlanda’s. Figure 11 shows the noise influenced area is about the same number of times smaller than the noise influenced area of Arlanda. This corresponds to 4,9 km2. Meaning, the total area affected by a noise level over 65 dB(A) from the airports results in approximately 22 km2.

The noise contour for the aircraft Boeing 737-800 is depicted in Figure 12. Boeing 737-800 is the same size as Airbus A320, which is one of the reference planes in this study143,144.

Figure 12 Example on noise contour for take-off and landing with Boeing 737-800145

An electric aircraft with a battery-pack on 800 Wh/kg contributes to 36% reduction in noise contour area during take-off and landing, compared to the conventional best-in-class current generation short-haul aircraft. To comprehend the electric aircraft’s reduction of noise contour, Figure 12 performs as a reference. As a result, electric aircraft could extend airport operation hours. Considering the take-off specifically, the reduction of the noise contour area is expected to be more than 50%, due to the absences of combustion and thrust of engines. In contrast, the landing results in a 15% larger noise contour area, compared to the conventional best-in-class current generation short-haul aircraft, because of the higher weight of the electric aircraft.146

143 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166 144 Johanna Bailey, ”The Boeing 737 vs Airbus A320 – which plane is the best?”, Simple Flying, 2020 https://simpleflying.com/boeing-737-vs-airbus-a320/ (accessed 03.04.2021) 145 Swedavia Airports, Stockholm Arlanda Airport. Environmental effect description for application concerning new licence according to the Swedish environmental code (original title in Swedish: Stockholm Arlanda Airport. Miljökonsekvensbeskrivning för ansökan om nytt tillstånd enligt miljöbalken), 2011, Figure 5.5.2 https://www.swedavia.se/globalassets/arn/miljo-arlanda/5-flygbuller.pdf 146 Schäfer, Barrett, Doyme et al., 2019, page 160 – 166

Regarding interior noise; the noise level inside a train car of X2000 is approximately 60 dB(A)147. The noise level in an average conventional aircraft cabin is about 84 dB(A)148. This is the same noise level as in an Airbus A320149. These numbers are gathered in Figure 13. Moreover, the loudest phase of the flight is the take-off150.

A comparison of electric and a conventional aircraft have been made by magniX, the company who provide the Cessna eCaravan with its electric propulsion system. They discovered the electric version had a decrease in noise level of 16 to 22 dB(A). Another paper suggest electric aircraft could reduce the noise level by only 10 dB(A)151.152

This means the electric system, in the best-case scenario, contributes to a noise level reduction of 22 dB(A) from the original 84 dB(A), which results in a noise level of 62 dB(A). In the worst-case scenario, the reduction is 10 dB(A), resulting in a noise level of 74 dB(A). These results are illustrated in Figure 13.

Figure 13 Interior noise level

4.5 Time

The time it takes for X2000 to travel the 455-kilometres long railway between Stockholm and Gothenburg is in average 3 hours and 4 minutes, according to Figure 14153,154. This correspond to the speed of 148 km/h. Furthermore, Figure 14 declares that the corresponding time for an average conventional airplane to fly the linear distance of 395 kilometres between Stockholm Arlanda Airport and Gothenburg Landvetter Airport is 59 minutes155. The flight endurance is

147 Bodén et al., 2020, page 78 148 C.D. Zevitas, J.D. Spengler, B. Jones et al., “Assessment of noise in the airplane cabin environment”, J Expo Sci Environ Epidemiol 28, 2018, page 568–578 https://doi.org/10.1038/s41370-018-0027-z 149 Reinhard Müller & Joachim Schneider, Noise exposure and auditory thresholds of German airline pilots: a cross-sectional study, BMJ Open, 2017 https://www.doi.org/10.1136/bmjopen-2016-012913 150 Scott McCartney, ”The noisiest parts of the plane”, The Wall Street Journal, 2019 https://www.wsj.com/articles/the-noisiest-parts-of-the-plane-11556703001 (accessed 13.04.2021) 151 Sanggyu, Dongwook, Dimitri, 2016, page 9 152 magniX, ”magniX continued flight testing reveals electric aircraft significantly reduce noise pollution”, Cision PR Newswire, 2021 https://www.prnewswire.com/news-releases/magnix-continued-flight-testing-reveals- electric-aircraft-significantly-reduce-noise-pollution-301264765.html (accessed 13.04.2021) 153 Railway Technology, 2015 154 Hallenberg & Sundin, 2019, page 100, Figure 4.11 155 Travelmath

calculated with respect to the average speed for a commercial airliner of 805 km/h and 30 minutes for take-off and landing156.

Figure 14 Travel time with train and conventional airplane Stockholm-Gothenburg 2018. The transfer is the shuttle connection between airport and city, on both ends.157

In contrast to fast conventional airplanes, the speed record for an electric aircraft is only 338 km/h, reached in 2017. Though, Eviation’s aircraft Alice is intended to have the maximum speed of 407 km/h158. Considering Alice’s speed and adding an extra 30 minutes for take-off and landing, this would result in a transportation time on less than 1,5 hours on the 395 kilometres linear distance between the airports159. This is presented in Figure 15 as the best- case scenario. Additionally, another company has a new record in process for an electric aircraft on 482 km/h. The performance of electric aircraft is not limited as a cause of the motors, but the battery technology160.161

Considering Pipistrel’s aircraft Alpha Electro, it travels with the speed of 150 km/h. If time for take-off and landing is taken into account, it would travel the linear distance between the airports in about 3 hours162. This is presented as the worst-case scenario in Figure 15. Though, this is not yet possible since the maximum flying time for Alpha Electro is one hour.163

156 Travelmath 157 Hallenberg & Sundin, 2019, page 100, Figure 4.11 158 Blain, 2021 159 Travelmath 160 Raymer, 2018, page 736 161 Nick Lavars, ”Rolls Royce taxis the world’s fastest electric aircraft to-be”, New Atlas, 2021 https://newatlas.com/aircraft/rolls-royce-taxis-worlds-fastest-electric-aircraft-to- be/#:~:text=We%20first%20caught%20wind%20of,set%20by%20Siemens%20in%202017. (accessed 29.03.2021) 162 Travelmath 163 Raymer, 2018, page 737

Figure 15 Transportation time

Regarding punctuality; trains are considered as in time when arriving in a five-minute window from appointed time, for airplanes this window is 15 minutes164. According to SAS, 80% of all flights were on time 2019165. For SJ, this number was 83% (for all long-distance services)166.

Considering the accurate distance Stockholm-Gothenburg, and 15 minutes allowed delay for both transportation modes, the train was in 2019 punctual in 86-87% of the cases, the plane in 77%. At 5 minutes allowed delay, the train was in time in 76% of the cases, the plane in 59%.167

However, the Swedish high-speed trains are the least punctual in Europe. Only 66% of all high- speed trains on the routes Stockholm-Gothenburg and Stockholm-Malmö arrived on time between 2008 and 2015. The high-speed train in question is the X2000. In Spain and France, the corresponding punctuality was 98% and 92% respectively. One of the main reasons to the bad punctuality is the 150 years old railway and the poorly maintained tracks. Another is the increase in traffic flow. The train traveling has doubled the last 25 years, without any extension of the railway. One third reason is the Swedish high-speed trains share the same railway as slower regional- and freight train.168

164 Helle Kikerpuu, “The train is more punctual than the plane” (original title in Swedish: “Tåget är punktligare än flyget”), Vagabond, 2020 https://www.vagabond.se/artiklar/nyheter/20200203/taget-punktligare-an-flyget/ (accessed 12.05.2020) 165 SAS, Annual and sustainability report – fiscal year 2019, page 153 166 SJ, Annual and sustainable report 2020, page 17 167 Per Sydvik, “The train is more punctual than the plane to Stockholm” (original title in Swedish: “Tåget är punktligare än flyget till Stockholm”), Göteborgs Posten (GP), 2019 https://www.gp.se/nyheter/gp- granskar/t%C3%A5get-punktligare-%C3%A4n-flyget-till-stockholm-1.19890831 (accessed 26.05.2021) 168 Tomas Augustsson, ”Swedish high-speed train the worst in Europe” (original title in Swedish: ”Svenska snabbtåg sämst i Europa”), Svenska Dagbladet (SvD), 2016 https://www.svd.se/svenska-snabbtag-samst-i- europa (accessed 01.03.2021)

5 Discussion

This chapter discuss both the achieved results and the observed limitations.

5.1 Cost

Electric aircraft cost is, in the best-case scenario, 70% less per flight hour than conventional ones. This means one ticket would cost 502 kr, if the price from 2018 in Figure 1 is used as a reference. This is approximately the same price as one ticket for a high-speed train in 2018 on 508 kr. If the electric aircraft only has the ability to cut 40% of the cost per flight hour, the price for one ticket 2018 would be 1004 kr, which corresponds to the price of two high-speed train- tickets.

In contrast to the ticket price from 2018, today’s ones are booked one month (instead of one week) in advance, non-rebookable, affected by the pandemic and calculated only with respect to the high-speed train X2000 and the airline SAS. If today’s average price for a conventional airplane ticket with SAS on 952 kr from Table 2 is used as a reference, one ticket with electric aircraft would cost 286 kr in the best-case scenario and 571 kr in the worst. Compared to today’s average ticket price for X2000 on 318 kr from Table 1, the electric aircraft would be cheaper if it is able to cut at least 66%.

To summaries, both Figure 2 and Figure 3 illustrate how electric aircraft could (in both best- case scenarios) cost slightly less than the high-speed train respectively the X2000, despite of the differences between the circumstances of the booking.

Though, the calculation of the ticket price for electric aircraft is based on the assumption that electric aircraft would be as fast as conventional ones, meaning flying Stockholm-Gothenburg in one hour, which is not yet achievable. Today’s slower electric aircraft would increase the ticket price as they require more time in the air.

Furthermore, electric aircraft might entail transfer between the airports and the cities, which price has not been taken into account here. Though, the electric aircraft could change the traffic structure and land closer to cities, which erase the need of transfer. Regardless, the electric propulsion system is more expensive than the combustion system. Even the batteries have a price, which is estimated to increase in the upcoming years. Moreover, the batteries require to be exchanged regularly.

However, the reduction of cost per flight-hour might not affect the ticket-price at all. Airlines might use this opportunity to earn more per passenger.

5.2 Environmental Impact

The energy required to power the train is less than for the electric aircraft. This is a cause of the train being grounded. In addition, the train does not have batteries, and is therefore not in need of unsustainable minerals such as lithium and cobalt.

The average energy consumption of electric aircraft of 0,11 kWh per RPK is confirmed by the theoretical electric aircraft, which requires 0,14 kWh per RPK with respect to the average occupancy rate.

The energy consumption for X2000 is 0,050 kWh per RPK compared to the three mentioned electric aircraft with an energy consumption of 0,076 kWh, 0,11 kWh and 0,16 kWh per RPK, respectively. All these electric aircraft require more energy individually than X2000, even though the calculation for the X2000 is made with respect to it traveling with only approximately 70% of the payload, in contrast to the electric aircraft flying with the maximum payload.

The total carbon dioxide emissions on the distance from electric aircraft of 0,56 kilograms per passenger are almost twice the ones from X2000 of 0,30 kilograms per passenger. These numbers are still low compared to a conventional aircraft’s total carbon emissions per passenger on the linear distance, which corresponds to 38 kilograms.

As mentioned, both Alpha Electro and Cessna eCaravan do not actually have the range to cover the distance Stockholm-Gothenburg. An extension of the range might result in more batteries, implying a higher weight, causing a higher energy consumption. Paradoxically, Alice’s energy consumption is slightly lower than Cessna eCaravan’s, even though Alice’s range is 5 times greater than Cessna eCaravan’s. However, Alice has not left the ground yet.

This study does not cover enough aspects of environmental issues to make a sufficient analysis in depth in that question. In a potential extension of this study, that area would be central. For instance, transportation does not merely impact the climate, moreover it interrupts wildlife169. Railway has a direct impact on wildlife through train-collision, and indirect mortality can occur as a result to electrification170.

Furthermore, electrical power sources need to be charged by energy, and if this energy is created by burning hydrocarbon coal or oil, the electric power is not as sustainable as predicted.

The calculation of the energy consumption in this study might be insufficient as the electric aircraft entail more energy during take-off and landing. Moreover, these aircraft are rather small in contrast to their combustion counterparts. However, if the structure of the travel system changes, these calculations may be prevailing. The new structure could mean electric aircraft would be used more as cars, carrying as many passengers, allowing travel from city to city, without the need for transfer or even security checks.

5.3 Safety

Conventional aircraft are safer than trains considering fatalities per billion passenger- kilometres, shown in Figure 5. Furthermore, electric aircraft are stated as even safer than conventional, and therefore significantly safer than trains. However, for electric aircraft to be this safe, the battery pack must be constructed with caution. Otherwise, the batteries represent a fire hazard.

As a cause to the lack of existing and certified electric aircraft, it is difficult to predict their degree of safety. Moreover, if the air traveling increases due to electric aircrafts possibility to operate without, or with smaller airports, the fatality rate is feasible to rise, as more planes might increase the probability for accidents.

169 Luís Borda-de-Água et al., Railway Ecology, Switzerland: Springer International Publishing, 2017, page 26 https://doi.org/10.1007/978-3-319-57496-7 170 Borda-de-Água et al., 2017, page 26

5.4 Comfort

The number of services per day and direction are 31 with air and 26 with high-speed train, according to Figure 6. With electric aircraft the number of tours might decrease due extra needed time to charge the batteries. Alternatively, the batteries could be changed in a few minutes, but this entails doublets of batteries. The number of tours would also decrease if the electric propulsion system does not have the ability to reach the speed produced by a combustion engine. Today the maximum speed of an electric aircraft is about half the average speed of a conventional one.

Less people are influenced by the exterior noise from conventional aircraft compared to that from trains. Electric aircraft are even quieter than conventional, which means they would disturb even fewer people. Likewise, the total area affected by a noise level over 65 dB(A) is significantly larger for trains than for conventional aircraft. Electric aircraft generate a noise contour reduction of 36%, which would result in an even smaller noise influenced area. Though, additional planes might be required to enable for the small electric aircraft to handle the traffic flow. As a result, the number of people disturbed by electric aircraft may increase.

As stated, the cabin of an electric aircraft is quieter than of a conventional one. In the best-case scenario, the electric aircraft cabin has a noise level of 62 dB(A), and 74 dB(A) in the worst. Still, an electric aircraft cabin is not quieter than a train car of X2000 of 60 dB(A).

5.5 Time

According to Figure 14, the total travel time from Stockholm city to Gothenburg city is a few minutes shorter with the X2000 than with the airline SAS, if considering the time for terminal and transfer between cities and airports. Additionally, the train is more punctual than the conventional aircraft. Regarding the transportation time on-board, the conventional aircraft is three times faster than X2000. Electric aircraft do not have the speed to match conventional aircraft. The current speed record for an electric aircraft is 338 km/h, which is less than half the average speed of a conventional aircraft on 805 km/h. The transportation time between the airports with electric aircraft is in the best-case scenario nearly 1,5 hours, and in the worst-case just over 3 hours, according to Figure 15. Hence, electric aircraft would even in the worst-case be as fast between airports as X2000 is between city centres. Though, this scenario builds upon the fact that Alpha Electro could manage 3 hours in the air, which is not possible today. In addition, the best-case scenario depends on the accuracy of Alice, an aircraft which has not yet left the ground. However, even if electric aircraft would be as fast as conventional, they would still just be approximately as fast as X2000 in total, considering the distance from city to city, including the time required for transfer and terminal. Though, electric aircraft could use potentially smaller airports, perhaps closer to the cities, due to smaller manageable aircraft and less noise pollution. In that case, the electric aircraft may be the faster option.

6 Conclusion

An investigation has been carried out comparing electric aircraft and electric trains for the distance Stockholm-Gothenburg regarding cost, environmental impact, safety, comfort and time. As presented, the ticket price for electric aircraft could be slightly lower than for the corresponding high-speed train option, in the best-case scenario. Regarding the energy consumption, it is almost as low for electric aircraft as for X2000. Considering safety, electric aircraft are predicted to be safer than conventional ones, and therefore even safer than trains. Additionally, electric aircraft contribute to less noise pollution than X2000. Though, the interior noise level is lower in a train car of X2000 than in a cabin of an electric aircraft. Hypothetically, electric aircraft would even in the worst-case scenario have the same transportation time as X2000. Therefore, it was concluded that electric aircraft could potentially compete with electric trains for short travel distances such as Stockholm-Gothenburg, in the foreseeable future.

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