Slide

Electric planes could be here sooner than we think but might do little for noise

By John Stewart

In less than 20 years electric planes could be using our airports, although we doubt there could be electrification of large aircraft. A report (1) from the CAA (Civil Aviation Authority) in the UK suggests some short-haul flights could be using electric aircraft by the early 2030s. However, the larger long-haul planes are not expected to be electrified until at least 2050.

Electric aircraft would reduce the air pollution and climate emissions coming out of each plane. But there is much more doubt about their noise benefits

The report says “There is still a clear need to undertake noise measurements of the full scale commercial electric planes once they are available to fully understand their noise characteristics” adding “it is still unknown whether the noise exposure from electric aircraft will be an improvement from conventional aircraft.”

The CAA report identifies the main sources of the potential noise from a fully electric plane

The battery systems, the motor and air frame. Early modelling suggests the planes may be quieter on departure than current aircraft but noisier on arrival. But, because of their batteries, they will be heavy and are expected to climb more slowly after take-off which might off-set any noise gains at source.

 

All of this would be problematic for communities under flight paths

The technology which could clean up the industry could make things worse for them. They will be concerned that, driven by the need to cut emissions, the aviation industry may rush into a technology which may do little or nothing for noise.

 

Developing new aircraft, whether or not they are electric, often means noise and emissions are at odds with each other

It’s a tough challenge for the aviation industry which aims to develop technologies and operational practices which will reduce aircraft CO2 emissions per passenger kilometre by 75%, noise by 65%, and NOX by 90%, by 2050, benchmarked against a typical new aircraft in 2000.

The industry body Sustainable Aviation says (24): “Achievement of any one of these three targets would be challenging, but to achieve all three simultaneously will require considerable ingenuity and a clear understanding of the inter-dependencies between these three key drivers”.

The CAA summed it up like this (25): “Concerns in relation to climate change, carbon dioxide emissions, and local air quality could also have an impact on noise performance. Although there is not a direct correlation, and noise performance has previously been reduced alongside emissions reductions, as gains become more marginal in future, the potential requirement to trade off emissions and noise performance is likely to increase……the Sustainable Aviation Noise Roadmap22 for example, highlights that there are two conceivable paths for future aircraft design, low-carbon designs and low-noise designs. Whilst low-carbon designs may be quieter than existing aircraft, they may not be as quiet as low noise designs”.

References:

(1) http://publicapps.caa.co.uk/docs/33/CAP1766EmergingAircraftTechnologiesandtheirpotentialnoise impact.pdf

(2). Sustainable Aviation 2017 Progress Report: https://www.sustainableaviation.co.uk/goals/noise/

(3). https://publicapps.caa.co.uk/docs/33/CAP%201165%20Managing%20Aviation%20Noise%202.pdf