Are commercial electric planes possible?

      Are commercial electric planes possible?

commercial electric planes
Electric Plane - Wikimedia

You may have heard about Tesla cars which run on electricity and have zero emissions. Ever wondered can the same be possible with planes? Well, the concept of electric aviation is not new. You may be astonished to know that the world’s first electrically powered flight took in 1883. Albert and Gaston Tissandier showcased the world’s first electrically powered aircraft by coupling an electric motor to an airship.

Why are electric planes needed?

The main reason for the development of electric planes is the adverse impact on the environment caused by conventional plane emissions. It is found that out of total Global Greenhouse emissions aviation CO2 emission is 2%. The amount of CO2 emission from aviation is growing by 3-4% per year. US-based aircrafts are responsible for 29% of all greenhouse gas emissions from commercial aircraft worldwide according to EPA. Also, the penalties on greenhouse gas emissions are increasing and stricter emission regulation standards are pushing electric aircraft development.

The European community has set pollution reduction targets of 75% CO2, 90% NOX, and 65% for noise. Electric planes are better because they have no direct emissions. Electric planes are also quieter in operation. There will be no noise produced by electric planes in airports and inhabited areas. The other fact is that the optimum performance of a jet engine is decreased when there is an increase in altitude and temperature. Electric plane’s performance does not depend on environmental factors. Since electric planes work on electricity they don’t carry flammable fuel and thus are safer than conventional planes.

How electric planes work?

In conventional planes, the jet engine sucks the air which is compressed or squeezed in a compressor. This increases the temperature and pressure of air which makes it suitable for mixing with fuel. The fuel is injected from injection holes in the combustion chamber which mixes with the incoming air. This air-fuel mixture is then lit. Now, this high-pressure, high-temperature mixture (fluid) passes through a turbine which reduces its pressure. Due to the reduction in pressure of this fluid, it's velocity increases and it leaves the jet engine with high velocity. This high velocity is responsible for generating the thrust and makes the plane move forward.
Jet Engine
    Jet Engine-Wikimedia
On the other hand, the working of electric planes is rather simple. When it comes to electric planes the power source need not be compulsory batteries. Solar power can be used as power source. In case of battery powered planes, the batteries run an electric motor that spins a propeller. This spinning produces the thrust required. Yup as simple as that! Electric engines are thus mechanically simpler than the jet engines. This reduces their maintenance and performance monitoring requirements.

Problems with electric planes

            The question now arises that even though electric planes have so many advantages why don’t we see any flying over our heads? The main problem is weight. Let me put it in this way. When you travel by train you don’t have limitations on the weight of luggage you carry. In the crowded country like India, people travel by sitting on train roofs. Although you cannot travel by sitting on plane wings, the fact is there is a limitation on the maximum weight of luggage for traveling through planes. Why is this so? 

Planes have a maximum takeoff weight. If the weight is more than this it cannot take off and will keep running on the runway (actually it may damage the plane and is dangerous). So how is this related to electric planes? As mentioned earlier electric planes can be powered by

  1. Battery Power
  2. Solar Power

The thrust required for the plane is very large and thus will require more numbers of batteries. This concept is related to energy density. Energy density is the amount of energy stored per unit volume. The energy density of batteries is far less than fuel. It means that for the same amount of energy generated more numbers of batteries will be required than the fuel. As more battery packages are needed to be installed the weight of plane increases. Li-ion battery energy density is 300 Wh/kg or 1.08 MJ/kg while the energy density of typical aviation fuel is 44.65 MJ/kg. Research is being done to develop batteries having energy density of 400 Wh/kg.

The other problem is that airplanes also have a maximum landing weight. In conventional planes the fuel is burnt till it reaches its destination and thus the weight of the plane is reduced. Also a plane on its way to the destination burns fuel due to which the weight of fuel carried by the plane gradually goes on reducing while in air until it completes its journey. This reduction of weight due to burning of fuel also increases the efficiency of jet engines.

This is not possible in case of batteries. Batteries once used remain in planes and contribute to the overall weight of the plane and as a result of this the plane has to fly with the weight of used batteries.

The other method of powering the electric plane is by solar power. The batteries generate power by solar energy and thus drive the motor. But we cannot fully rely on this as weather conditions are different throughout the year.

Attempts made by companies for electric planes

The disadvantages of electric planes haven’t stopped some companies to develop one. Although electric planes do exist but their weight carrying capacity is less which is mostly upto 2-4 persons per flight only. This no is far less than that of commercial conventional plane flights which has a to take on an average 150 passengers per flight.

German company Siemens has developed propulsion system for Extra 330LE electric plane. The plane has a very powerful drivetrain. The motor which weighs only 50 kilograms develops a power of 260 kw which is equivalent to 350 horsepower. The aircraft is able to reach a world record breaking speed of 340 km/hr. Although these numbers don’t sound impressive but the important thing is the plane burnt no fuel and emitted zero emissions.
  Siemens Extra 330LE electric plane
  Siemens Extra 330LE electric plane - siemens
Solar Impulse 2 is another such aircraft financed by Swiss businessman and pilot Andre Borschberg. As the name suggests this aircraft runs by power generated through solar cells. The batteries are used to store the power generated. It is a single seater aircraft and contains 17000 solar cells. These cells are mounted on the wings of the plane. The plane is still under testing.

 Solar Impulse 2 - Wikimedia
 Solar Impulse 2 - Wikimedia
The Airbus Group’s E-Fan is a two-seater electric aircraft and first took flight in 2014. It has a top speed of 220 km/hr. The E-Fan has been upgraded to E-fan Plus version which has a hybrid configuration for longer flight endurance. Hybrid implies that it uses an internal combustion engine in addition to its on-board lithium-ion batteries.
Airbus Group’s E-Fan - Wikimedia
With the current developments in technology will we be able to travel in commercial electric planes? 

Probably not so soon. As mentioned earlier the Solar Impulse 2 uses solar power. However its flight is made possible only because it is light in weight. The technology is still not ready to power commercial planes which are more heavier. In order to have electric planes in the commercial market, we need better batteries. The current batteries in the market are lithium-ion batteries which have replaced the lead-acid batteries. To power a plane we need batteries which deliver more power simultaneously being small and light in weight. Scientists say that those kinds of power delivering batteries will be available in a decade and only then we will be able to travel in electric planes having tickets cheaper than those running on fuel.

Thanks for reading!  

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