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Electrification of Commercial Airliner is a Long Way to Go

Crawling out of the challenges below is only the tip of the iceberg.

CFM International’s LEAP gas turbine engine mock-up during the 2018 Singapore Airshow. Image by Author.

First of all, jumping from the current internal combustion engine straight to a fully electric propulsion system does not make any sense. It requires a tremendous amount of money, time, evaluation, and lots of analyses for the preparation alone.

But that does not mean the aviation industry is not heading that way to eliminate carbon emission.

As for now, the industry is investing heavily in reducing fuel consumption by introducing new technology and aerodynamic tweaks to be as efficient as possible. Such practices consisting of new winglets, geared turbofan engine, the usage of composite material, and many more.

If it’s not enough, some major airlines are sprinting to cross the sustainable-fuel-finish-line that incorporate synthetic jet fuel into the mixture, while others are using biofuel from renewable biomass to accomplish the goal of carbon neutrality.

These efforts are baby steps compare to what the car industry had done in the past years, but it is not an apples and oranges comparison.

Heading for electrification certainly is a good move. Imagine if an electric commercial aircraft flying hundreds of passengers daily between one of the most popular air routes, unsurprisingly between New York and London.

Several hundred tons of fossil fuel will not combust and releases the gas that we are struggling to reduce.

The Problems

When talking about aviation, the majority would spontaneously think about the commercial aircraft flying high above the sky, speeding through the cloud approaching the speed of sound, transporting thousands of businessmen and leisure families from one continent to another. It’s not their fault as commercial aviation is the backbone of all air transportation.

What I’m saying is if we could electrify the industry, particularly the airliner, it will be a breakthrough and an engineering feat for humanity, and as in the same league as space exploration and medical fields.

Imagine if the Boeing 777 or the double-deck Airbus A380, flying from Kuala Lumpur to Auckland with an electrical propulsion system, that will be super cool.

But to achieve such an engineering marvel, a ton of investment, researches, and developments are necessary to work on like there’s no tomorrow to tap on this seems-impossible market. Here are some of the challenges:

1) Fuel is too good

Battery technologies nowadays are limited for a limited power in kilowatts hour. The storage is not there to constantly supply enough electrical generation for propulsion to develop concerning the size of today’s airliner. Let’s take a look at the difference between fuel and current battery storage.

Fossil fuel, in this case, Jet A1, releases a significant amount of energy per unit weight compared to the mass production lithium-ion nowadays. In other words, fuel is too good.

To put it in perspective and roughly manner, the energy released from a bottle of fuel equals several dozens of ‘bottles of batteries’ needed to match the power output.

It takes a significant amount of cells to churn out as equal energy output as possible in contrast to fossil fuel (thanks dinosaurs). The differences in energy density between these two are so huge that it is impractical to install them in aircraft economically.

In this case, battery manufacturers should scramble all their resources to meet the aircraft propulsion system demand and leapfrogging from the current battery capacity.

Sure, why not put all the necessary batteries inside the aircraft to power up the propulsion engines? That will lead to point number 2 below.

2) Weight

As point number 1 specifies, it takes a notable amount of battery cells to supply the same amount of energy compared to fuel. You can point out that we are facing the subsequent problem, which is the weight.

The design of aircraft is to be as light as possible to be efficient.

These additional weights contradict the design philosophy of commercial aircraft that engineers are scramble to solve. If it’s carrying an enormous weight itself, the economy seems faded and far-fetched for airlines to operate. It also means adding up unnecessary weight the aircraft need to piggyback.

3) Lithium-ion battery testing and reliability

Currently, the best battery that is being used widely on cars and some specific aircraft is lithium-ion. It is economically viable plus has a higher energy density compared to others but it came with a price.

The lithium-ion battery can have a condition where an uncontrolled rise in temperature within the cells could lead to a blazing fire. This phenomenon is also known as thermal runaway.

To store a significant amount of said battery in aircraft is a disaster waiting to strike (assuming lithium-ion is the only choice to produce electricity for aircraft in this era).

Remember the two incidents where Japanese airlines, Japan Airlines and ANA, experienced these thermal runaway issues back in 2013 from one of their Boeing 787s? Both were categorized as serious incidents that prompted the authority to ground the 787. It is only a medium-sized battery for powering up essential systems in case of an emergency.

The safety of passengers and crews is the utmost priority for this industry. Therefore, thorough reliability testing and hazard mitigation on lithium-ion battery usage as the primary power source should be the authorities’ next agenda.

Currently, both the International Air Transport Association (IATA) and International Civil Aviation Organization (ICAO) limit the transportation of lithium batteries as cargo for some degrees and even prohibited them on passenger aircraft.

A screenshot shows the guidance put on airlines and cargo operators in transporting lithium-ion batteries. Image from the IATA’s 2021 Lithium Battery Guidance Document.

A crucial reshuffle on guidelines and testing data along with risk mitigation for both the aircraft fire suppression system and the batteries itself should be called for before an electric commercial aircraft could take off.

4) Lack of regulation

Regulation and guidelines are vital to standardize the design configuration for the manufacturer to comply before it is certified to fly and ahead of transporting the flying public.

Title 14, Code of Federal Regulation Part 25 and 33 from the US, and Certification Specification from their European counterpart are the regulations that manufacturers must obey. Although they are extensive guidelines, it missing an adequate and appropriate set of rules for implementation on the electrical motor for propulsion purposes.

As per the FAA, electrical propulsion technology is substantially different from the previous certification processes for gas turbine engines and reciprocating engines. They are quoted as;

The FAA has not previously type certificated an engine that uses electrical technology for propulsion of the aircraft

and;

The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature.

It will take some time for the authorities to do research and analyses before implementing it into the existing regulation. As we all aware, safety is the utmost priority, and they should not rush to certify it as it will induce unnecessary pressure and human error.

In Progress…

A problem is not an obstacle as long as it has an answer. It is a matter of when, not if, for the electrification of commercial airliners. Regarding this issue, numerous company are now undertaking their parts in testing and experimenting with much smaller aircraft like electrical vertical take-off and landing (eVTOL) and propeller aircraft.

The FAA has granted special conditions for firms to develop and demonstrate the reliability and safety of electrical propulsion prototypes to the authority. One of them is magniX USA, which is currently undergoing testing of several electrical powerplants designed for smaller propeller aircraft.

It is a start for something bigger ahead, the beginning of managing other hindrances like controlling the battery temperatures, maintenance, charging times, and others. Not to mention the existing fire protections on aircraft have to be reviewed and modified when needed.

All in all, the world could only see electric commercial airliner decades ahead. The importance of all the investors, authorities, manufacturers, and the government hand in hand in realizing this dream cannot be overstressed.

From now onwards, the industry has to wait for the result of the immense number of trials until it is proven to be reliable and safe enough to transport the flying public economically, along with suitable technologies to arrived such as the usage of solid-state batteries.

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