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Electric aircraft are getting closer to practical use. Rolls-Royce of the United Kingdom will carry out the first flight of a small electric aircraft in the summer of 2021. Small electric aircraft are expected to be practical in 2023 and are expected to become popular as the economy recovers from the COVID-19 pandemic.
Electric aircraft replace jet engines and gasoline engines with electric motors. Various drive methods have been developed, such as "hybrid" types that combine engines and motors. This can reduce energy consumption during flight and reduce greenhouse gas emissions.
According to the Air Transport Action Group (ATAG), in 2019, aircraft emitted 915 million tons of carbon dioxide, accounting for 3% of the world's total emissions, an increase of 40% in 20 years. The carbon dioxide emitted by an airplane for transporting one passenger is twice that of a bus and six times that of a railway.
There are three main types of electric aircraft. The smallest is a "flying car" that takes off and lands vertically and does not require a runway. The second is a small aircraft that carries a few to a dozen people and takes off from a runway. The third is a medium-to-large aircraft that carries dozens of people or more. Generally speaking, electric aircraft need to increase the energy density of the battery and the output power of the motor while reducing the weight, so the larger the aircraft, the more difficult it is to put into practical use.
Flying cars are expected to become practical by 2023. Joby Aviation, a US startup funded by Toyota, has developed a five-seater flying car that can fly more than 240 kilometers at a speed of 320 kilometers per hour and will begin commercial flights in 2023.
German startup Lilium is developing a seven-seater aircraft that can fly at a speed of 280 kilometers per hour and will be commercialized in 2024. The aircraft uses Toray's carbon fiber to reduce the weight of the fuselage.
The small electric aircraft has entered the full-scale test flight stage. Rolls-Royce will conduct the first test flight in the summer of 2021. The company's goal is to achieve a world-high flight speed of about 480 kilometers per hour. The characteristics are that it is equipped with about 6,000 batteries with "the highest energy density for aircraft use" (Rolls-Royce) and an independent cooling system. The small electric aircraft will be provided for domestic routes in Norway in 2026.
Some companies have successfully conducted manned test flights. MagniX, an American startup, successfully carried out a single-person flight in 2019. It is reported that by optimizing the combination of motor magnets and coils, the reducer that changes the propeller speed was removed.
MagniX installed electric motors on the seaplane. It is reported that when one motor is installed, it can fly up to 160 kilometers, and when two motors are installed, it can fly up to 815 kilometers at a speed of 407 kilometers per hour. The goal is to carry 11 people for a test flight in 2021 and obtain passenger permission in 2023.
Some companies do not use batteries, but choose to use fuel cells that generate electricity using hydrogen.
Startup ZeroAvia used fuel cells to fly a small aircraft in the fall of 2020. If the hydrogen tank is lightweight, fuel cells will become a power source to reduce weight. It aims to achieve commercial flights of about 800 kilometers with a 10-20-seat aircraft by 2024.
The Delft University of Technology in the Netherlands and paint company Akzo Nobel are working together to launch a small aircraft using fuel cells by 2023. The earliest test flight is expected to be this summer. Airbus in Europe is also discussing a medium-to-large aircraft with 100 to 200 seats powered by hydrogen.
To launch medium and large electric aircraft, the motor output power is believed to be more than 5 times the previous level, and the battery capacity is expected to be 4 to 5 times, which requires innovative technology.
According to a survey by the Japan Aircraft Development Association, electric aircraft with 10 seats will be put into practical use in the first half of the 2020s. It is also expected that models with 50 to 100 seats will not be put into practical use until the second half of the 2020s, and models with more than 100 seats will not be put into practical use until the 2030s.
The energy density of existing batteries is only about 1/50 of that of jet fuel, and the output power is also low. The Japan Aircraft Development Association estimates that in order for Boeing's "737 series" aircraft to take off, it would take about 50 tons of batteries based on calculations alone.
Although there are technical issues, the trend of pursuing electrification of aircraft is expected to progress due to environmental protection measures. In 2018, Avinor, a Norwegian aviation and airport management company, announced that it plans to convert all short-haul flights taking off and landing in Sweden to electric aircraft by 2040. In 2019, a trend of avoiding flying, known as "flight shame," emerged in Europe. The International Civil Aviation Organization (ICAO) has set a goal of not increasing total emissions after 2020.
The COVID-19 pandemic has led to a sharp drop in air passengers. Although it is difficult to accurately predict the recovery of demand in the future, the Japan Aircraft Development Association expressed its expectation in its market forecast released in March that "if the vaccine is widely used, (air passenger demand) will recover to 90-95% of 2019 by 2023 and exceed 100% by 2024."
If economic activities become active, it is necessary to respond to climate change. Just as the French government has provided 15 billion euros in environmental protection measures for aircraft, it is expected that governments around the world will provide support.
Electric aircraft face cost issues
The popularization of electric aircraft faces cost issues. It is estimated that the body of electric aircraft will be cheaper than previous aircraft, but because of the large number of batteries and motors, the passenger and cargo space will become smaller, and profitability will deteriorate.
Flying car developed by Joby Aviation in the United States
Estimates by Japan's International Aircraft Development Fund (IADF) show that electricity costs about $0.12 per kilowatt-hour to fly the same distance, which is about 1.7 times the cost of jet fuel.
In terms of aircraft's response to climate change, the use of renewable fuel SAF has also been discussed. It is reported that the power cost of electric aircraft is cheaper than using SAF fuel, making it competitive.
If fuel cells are used, the cost of hydrogen fuel is as high as about $0.39 per kilowatt-hour. Compared with fuel cells for automobiles, if they are used in aircraft, the output per unit weight needs to be 2 to 3 times higher. At the same time, it is necessary to achieve lightweight fuel tanks and master cheap methods for producing hydrogen.
Electric aircraft are expected to become popular by replacing propeller aircraft. The International Joint Development Promotion Fund for Aircraft estimates that the cost of an electric aircraft to transport a passenger one kilometer is $0.18, which is 40% lower than that of a propeller aircraft.
According to statistics from MarketsandMarkets, an Indian market research company, the global market size for aircraft electrification is expected to reach US$3.4 billion by 2022 and US$8.6 billion by 2030. First, in the field of short-distance transportation, the demand for using electric motors to compensate for the required output power during takeoff and climb will increase.
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