Electric airplanes are set to decarbonise the aviation industry, making the environment greener - but when can we expect to see full-electric airplanes in the sky, asks Susan Fourtané.
The global aviation industry produces about 2% of all human-induced carbon dioxide (CO2) emissions. Aviation is responsible for 12% of CO2 emissions from all transport sources, compared to 74% from road transport, according to the US Air Transport Action Group (ATAG).
In 2018, flights produced 895 million tonnes of CO2, worldwide. Globally, humans produced more than 42 billion tonnes of CO2.
Aviation has brought great benefits to humanity; it has connected people and businesses across the world contributing to globalisation and the expansion of international commerce.
More recently, aviation and low-cost travel have opened the world to thousands of remote workers and location-independent individuals - also known as digital nomads - who enjoy the marvels of travelling the world at a low-cost while delivering their work digitally.
However, recent discussions on the implications of climate change and how carbon emissions are affecting the environment have prompted more initiatives focused on reducing carbon emissions. One of those initiatives involves decarbonising the aviation industry.
There has been a significant improvement from the fuel consumed by jets in the 1960s to the present day. Jet aircraft today are more than 80% more fuel-efficient per seat kilometre than the first jets in the 1960s, according to the Air Transport Action Group.
In the same way, urban mobility has experienced an evolution towards vehicle electrification, we will soon start to see the transformation of the aviation industry into the development of large electric air vehicles that will be cruising the skies in just a few years' time.
One of the most significant initiatives for electric air vehicles that has been initiated by a world-class higher education institution is the Cambridge Zero, which combines a full range of research and policy expertise in order to help create a zero-carbon future.
Cambridge Zero: an initiative from Cambridge University
The University of Cambridge has launched an ambitious new environment and climate change initiative with the goal of scaling the process of turning ideas into new technologies in the aviation and power industries.
https://youtu.be/pCebfIeV48o
This could result, for starters, in covering about 80% of the United Kingdom's future aerodynamics technology needs.
Cambridge Zero is not just about developing greener technologies but combining the university’s top-class research and policy expertise in favour of developing actionable solutions that work for the citizens' lives, society, and the biosphere as a whole.
Electrification: electric air vehicles (EAVs) perhaps ready by 2024
For small and medium-sized aircraft, electrification is a way to decarbonise. Currently, more than 70 aviation companies are planning the first flight of electric air vehicles (EAVs) by 2024.
Unfortunately, larger aircraft have to continue relying on the jet engine, for now. However, this is going to change in the coming years thanks to hybrid-electric engines that will come first.
As the path to fully electric aircraft continue to evolve initiatives such as the Cambridge-MIT Silent Aircraft Initiative and the NASA N+3 Project are developing novel aircraft architectures with the potential of reducing CO2 emissions by about 70%.
According to the N+3 Technology Level Reference Propulsion System Project's Abstract (PDF), an N+3 technology level engine, suitable as a propulsion system for an advanced single-aisle transport, was developed as a reference cycle for use in technology assessment and decision-making efforts. This reference engine serves three main purposes:
- It provides thermodynamic quantities at each major engine station
- It provides overall propulsion system performance data for vehicle designers to use in their analyses
- It can be used for comparison against other proposed N+3 technology-level propulsion systems on an equal basis
This reference cycle is meant to represent the expected capability of gas turbine engines in the N+3 timeframe given reasonable extrapolations of technology improvements and the ability to take full advantage of those improvements.
Meanwhile, at the Whittle Lab in Cambridge, the researchers are working on applications that include the development of electric and hybrid-electric aircraft, the generation of power from the tides and low-grade heat like solar energy, and hydrogen-based engines.
According to Professor Rob Miller, director of the Whittle Laboratory, world leading turbomachinery research lab at the University of Cambridge, the researchers are also working on existing technologies as a way of reducing the carbon emissions, like wind turbines, and developing the next generation of jet engines such as Rolls-Royce’s UltraFan engine, which will enable CO2 emission reductions of no less than 25% by 2025.
Prof Miller’s research is aimed at reducing the emissions of both air travel and land-based power production. He has worked extensively with industry; he is currently undertaking research in collaboration with Rolls-Royce, Mitsubishi, Siemens, and Dyson.
Rolls-Royce UltraFan engine: the next generation of jet engines
The UltraFan is a new architecture of Rolls-Royce for civil engines. Phil Curnock, chief engineer, Civil Future Programs, Civil Aerospace Rolls-Royce, explains how the progress and technologies at play within the UntraFan bring a new era of jet engines closer to reality.
https://youtu.be/auk-LRqtFs8
Curnock says the UltraFan is different from today's engines because it incorporates the power gearbox into the gas turbine, which allows a larger diameter fan, more flow for the engine which makes the engine more efficient.
The power gearbox is introduced between the fan and the intermediate pressure compression. This ensures that the fan, compressors, and turbines all continue to run at their optimum speed. It also incorporates a composite fan in the front of the engine, which allows for a lighter turbine.
Meanwhile, in Gloucestershire, Rolls-Royce introduces Accel
Accel, Rolls-Royce powered new electric demonstrator aircraft's flight testing is scheduled to begin rather soon in 2020. The zero-carbon emissions is set to become the world's fastest electric-powered aeroplane after breaking the current record.
The first flight will be targeting a new air-speed record of more than 300mph (480km/h) flying 200 miles (320km) (from London to Paris) on a single charge. The current speed record for an aircraft powered by electricity is 213mph (343km/h) and was set in 2017 by Germany's Extra Aircraft 330LE powered by a Siemens electric motor.
Accel, powered by "the most powerful battery ever put in an aircraft", according to Rolls-Royce and reported by industry editor Alan Tovey at 'The Daily Telegraph', is partly funded by the UK government and it involves a host of partners including electric motor and controller manufacturer YASA as well as aviation startup Electroflight.
The electric plane, which targets the record books, was unveiled for the first time at Gloucestershire airport, in the UK recently.
https://youtu.be/_3fFMFddep0
Electrical propulsion system: building the aircraft of the future
Dr Chez Hall, has been developing research into the areas of aero-engine design for reduced carbon emissions, engine-installation interaction, and low-noise turbomachinery since 2005.
Together with his research team at the Whittle Lab, they are working on how a potential replacement for the 737 could work.
The futuristic aircraft architecture would count with an electrical propulsion system which would be embedded into the aircraft fuselage; this would allow up to 15% reduction in fuel burn. According to Prof Miller, a key element of meeting the decarbonisation challenge is to accelerate technology development.
Focusing on the process itself during the past five years, they now can develop technology at least 10 times faster and 10 times cheaper.
"Our solution is to merge the digital and physical systems involved. In 2017, we undertook a pioneering trial of a new method of technology development. A team of academic researchers and industrial designers were embedded in the Whittle Lab and given four technologies to develop.
"The results were astonishing. In 2005, a similar trial took the Whittle two years. In 2017, the agile testing methods took less than a week, demonstrating a hundred times faster technology development," wrote Prof Miller on the Whittle Lab blog.
"We describe it as tightening the circle between design, manufacture, and testing," he says. "Design times for new technologies have been reduced from around a month to one or two days using augmented and machine-learning-based design systems.
"These make use of in-house flow simulation software that is accelerated by graphics cards developed for the computer gaming industry.
"Manufacturing times for new technologies have been cut from two or three months to two or three days by directly linking the design systems to rows of in-house 3D printing and rapid machining tools, rather than relying on external suppliers. Designers can now try out new concepts in physical form very soon after an idea is conceived."
He also explains that testing times have been reduced from about two months to a few days by undertaking a value stream analysis of the experimental process.
Each sequential operation was analysed, in order to remove more than 95% of the tasks, producing a much leaner process of assembly and disassembly. According to Prof Miller, test results are automatically fed back to the augmented design system, allowing it to learn from both the digital and the physical data.
"There’s a natural human timescale of about a week whereby if you go from idea to result then you have a virtuous circle between understanding and inspiration.
"We’ve found that when the technology development timescale approaches the human timescale – as it does in our leaner process – then innovation explodes," he says.
Decarbonising the aviation and energy industries
The New Whittle Laboratory will house the National Centre for Propulsion and Power, which is due to open in 2022 with funding from the Aerospace Technology Institute.
The National Centre for Propulsion and Power is designed to combine a scaled-up version of the agile test capability with state-of-the-art manufacturing capability to cover about 80% of the UK’s future aerodynamic technology needs.
The Whittle Laboratory counts with very strong industrial partnerships which have lasted for more than 50 years with manufacturers such as Rolls-Royce, Mitsubishi Heavy Industries, and Siemens, as well as a partnership with Dyson for about five years.
According to Prof Miller, another component of the new development is going to be a Propulsion and Power Challenge Space where teams from across the University of Cambridge will co-locate with industry to develop the technologies necessary to decarbonise the propulsion and power sectors.
Thanks to these strategic partnerships and their many benefits it has been possible for the researchers to enable technology strategy that can be shared at the highest level also triggering the start of new projects that can be kicked off rather quickly, and without the need for contract lawyers.
Joint industry-academic technology transfer teams move seamlessly between industry and academia, ensuring that technologies are successfully transferred into product.
According to Prof Miller, the partnerships provide a source of real high-impact research projects. "It’s these long-term industrial partnerships that have made the Whittle the world’s most academically successful propulsion and power research laboratory.
"We are at a pivotal moment, in terms of both Cambridge’s history of leading technology development in propulsion and power, and humanity’s need to decarbonise these sectors.
"Just 50 years ago, at the opening of the original Whittle Laboratory, research and industry faced the challenge of making mass air travel a reality. Now, the New Whittle Laboratory will enable us to lead the way in making it green."
Electric aircraft propulsion technology evolution
In the video, Dr Duncan Walker, senior lecturer in applied aerodynamics at Loughborough University, and a member of the Rolls-Royce UTC in Combustion System Aerothermal Processes since 1994, explains all about the changes expected in aviation in the coming years, including the electrification of future aircraft propulsion technologies.
Dr Walker specialises in experimental and computational study of gas turbine aerodynamics and combustion system aerothermal processes.
https://youtu.be/FXVOsDd6YIo
According to Dr Walker, the big changes are not going to happen for the first 10 to 20 years, However, after that, "we're going to see electric powered aircraft coming along".
First, and pretty much as we have seen it with electric vehicles, it is going to be a hybrid type aircraft with at least one jet engine or gas turbine. That will produce most of the thrust required for cruise. He explains that to help the aircraft off the ground it will have big electric fans powered by batteries.
Battery technology is not good enough at the moment, says Dr Walker. The development of better batteries and better energy storage will be happening in the next 20 or 30 years. The combustion system also has to change, obviously, since that is where the fuels are burnt and where the emissions are produced.
There are exciting times ahead for the aviation industry. We all hope that in a few decades' time electric airplanes will be as common as the aircraft that cruise the skies today.
This article was written by Susan Fourtané and is reproduced with kind permission from InterestingEngineering.com. Find the link to the original article here.