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Electric planes generate significant climate gains.

Newswise — Aviation has grown significantly in recent decades and each year accounts for about 2 percent of global carbon dioxide emissions and about 4 percent of all climate change impacts. Although aviation is a significant contributor to climate change and other environmental issues, electrification is an option to reduce these environmental impacts. The first electric aircraft are already in service today and are mainly small aircraft used for pilot training and short flights in the immediate vicinity. This is the type of aircraft that was studied in the life cycle analysis.

“In the short term, battery-powered electric planes will probably be mainly used for shorter distances, such as what is called in Norway “fjord-hopping”, i.e. shorter flights between fjords deep. From a broader perspective, the study shows that battery-powered electric aircraft have the potential to significantly reduce the environmental impacts of aviation,” says Rickard Arvidsson, the lead author of the Chalmers study.

The study: same plane, but different

The team examined a commercially available two-seat battery-electric aircraft, the ‘Pipistrel Alpha Electro’, as part of the life cycle assessment. The same plane is also available as a model powered by fossil fuels, allowing researchers to make a direct comparison. The team studied the full impact of each aircraft, from “cradle to grave” – from raw material extraction to end of life – with a functional unit of one flight hour. The aircraft manufacturer’s data and records contributed significantly to the study.

A wide range of impact categories were considered, with a focus on global warming due to greenhouse gas emissions (e.g. carbon dioxide), scarcity of mineral resources due to use of rare minerals (e.g. lithium for batteries), formation of particles from particle emissions, acidification. from acidic emissions (e.g. nitrogen oxides) and from the formation of tropospheric ozone from emissions of nitrogen oxides and hydrocarbons.

“The key point of this study is that small electric planes can have significantly lower climate impact – up to 60% less – and other types of environmental impacts than equivalent fossil fuel planes. However, there is a trade-off regarding the scarcity of mineral resources – around 50 percent more, even in the most favorable scenario, mainly because of the rare metals present in the batteries of electric aircraft,” explains Rickard Arvidsson.

As with electric cars, the electric plane is comparatively worse from a climate point of view when the plane is new, because the production of the battery consumes a lot of energy and resources. Then, over time, the relative impact diminishes as the electric aircraft is used and its benefits are realized, namely emissions-free electric propulsion. The longer the electric aircraft is used, the better it is for the environment, and ultimately a “break-even point” is reached.

After about 1,000 hours of flight, the electric plane surpasses the fossil fuel plane in terms of less climate impact, after which the electric plane is better for the environment. This is measured in kg CO2 eq/h – carbon dioxide equivalents per flight hour and is true under optimal conditions, where green energy is used. Any use thereafter thus becomes a “climatic benefit”, compared to the classic plane. The estimated life of the aircraft is at least 4,000 hours, four times longer than the break-even point.

“However, the lifespan of lithium-ion batteries would need to be approximately twice as long for the scarcity of mineral resources to be approximately the same for electric aircraft and for fossil fuel aircraft. Alternatively, double the energy storage capacity, so that only every other pack is needed on board for the same flight time,” says lead researcher Anders Nordelöf, one of the other authors of the study.

New and improved batteries for a greener future

In the study, researchers discuss the further development of batteries as a major step toward reducing the life cycle impacts of electric aircraft. Already today – but after the study was carried out – the manufacturer of the aircraft model has managed to extend the life of the batteries up to three times. New battery technologies could further improve both climate impacts and mineral resource scarcity.

“There is a constant development of lithium-ion batteries that can improve the environmental performance of electric aircraft and make it even more preferable to fossil fuel ones. There are also new battery technologies that could be developed and applicable to electric aircraft in the longer term, such as lithium-sulfur batteries, although they are still in an early phase of technological development,” explains Rickard Arvidsson.

Learn more about the research:

The research is presented in the article, “Life cycle analysis of all-electric two-seater aircraft”Published in The International Journal of Life Cycle Assessment.

The researchers involved in the study are Rickard Arvidsson, Anders Nordelöf and Selma Brynolf. The researchers are active at Chalmers University of Technology in Sweden.

This work was supported by open access funding provided by Chalmers University of Technology.

About the plane

The electric plane studied is a Pipistrel Alpha Electro manufactured in Slovenia. The wings have a span of just over 10 meters and the plane weighs 550 kg fully loaded. Maximum flight time is approximately one hour, plus reserve. The battery is a 21 kWh NMC (nickel-manganese-cobalt) lithium-ion battery and the motor produces 60 kW of power. The Alpha Electro was a pre-production model and was replaced by an advanced mass-produced model.

The fossil fuel plane compared in the study has the same basic structure as the electric plane. The differences mainly lie in the aviation gasoline engine and fuel tank, instead of the electric motor and batteries.



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