Can Flying Go Green?

Justin Rowlatt BBC journalist in front of a plane

Can Flying Go Green? Panorama, BBC One

With BBC Panorama questioning if airlines are doing enough to go green, the University of Bristol We are Engineering blog asked Bristol’s engineers how they’re making aviation greener. We republish a shortened version below.

Viewers of BBC’s Panorama programme Can Flying Go Green? last week would have seen how our passion for flying is warming the planet. Aviation is a major contributor to global carbon dioxide emissions, burning more fossil fuels per passenger than any other form of transport. In the show, Justin Rowlatt investigates how the airlines are trying to clean up their act, but what is being done outside of the commercial sector to make aviation greener? Here’s what our engineers are doing to pave the way to a greener future for the industry.

Making aircraft lighter

For every extra kilogram, more fuel is needed to fly the same distance, and more fuel means increased carbon emissions. Reducing the weight of aircraft is hence a crucial part of making aviation more environmentally friendly.

A major contributor to the overall weight is the airframe itself. Parts of the airframe such as the wings, which are often where the fuel is stored, need to be particularly strong. Traditionally, the reinforcement of these structures has also meant an increase in their weight, but carbon-fibre composite materials could hold the key. Every kilogram of carbon fibre is stronger and stiffer than materials that have traditionally been used for airframe fabrication, such as aluminium alloys, which is why they are the focus of our Bristol Composites Institute’s research.

Dr Rainer Groh and his colleagues have developed new manufacturing techniques that enable carbon fibres to be steered in curved trajectories, which allows the creation of blended structures capable of redistributing internal loads much more smoothly, in a way only previously seen in biological structures. These carbon fibre composites will allow the weight of existing airframe structures to be reduced without reducing their strength and enable the production of entirely novel airframe structures given that designs will no longer be dictated by the constraints imposed by traditional materials.

But this is only part of the picture, as Panorama states it’s important that airlines introduce further weight-saving initiatives across fuel, luggage and internal fixtures and fittings if aircraft are going to be as light as possible. A key aspect of this will be discouraging the practice of fuel tankering in which planes are filled with extra fuel, usually to avoid paying higher prices for refuelling at destination airports. After the airframe, the fuel is the biggest contributor to the weight of an aircraft, which is why it’s so important for other airlines to follow the lead taken by British Airways, which since the programme aired has pledged to review its use of fuel tankering.

In the future we could see the advent of aerial refuelling, which will allow smaller, less fuel-hungry aircraft to fly longer distances more efficiently. Another change we could see is commercial aircraft flying in a V-formation, like migrating birds, which would increase lift and reduce drag. Safety is paramount in the aviation sector, which is why our aerospace engineers Dr Tom Kent and Dr Steve Bullock have been investigating the routing, sensing and automated control developments needed to make aerial refuelling and formation flight possible.

Tow-steered carbon fibre

Improving aerodynamics

It’s not only the weight of the aircraft that impacts on the amount of fuel you burn during a flight, how streamlined the aircraft is also plays a huge part. During flight, the aircraft’s engines propel it forwards through the air, but at the same time the air is pushing against it slowing it down, this is known as drag, or air resistance. The higher the drag the higher the amount of fuel that is burned.

To make it more complicated, the air pushing against the aircraft producing drag is also producing the lift needed to keep the aircraft in the air. At the same time the aircraft is flexing, changing shape, as a result of all these aerodynamic forces acting upon it. The amount of lift and drag depends on the size and shape of the structure the air is pushing against. It’s not always possible to just decrease the size of certain airframe structures but it is possible to change their shape to make them more aerodynamic.

Our engineers in our Fluid and Aerodynamics Research Group, led by Dr Dorian Jones, are working to optimise designs for airframe structures from aeroplanes to helicopters to make them as aerodynamic as possible. Using our supercomputing and wind tunnel facilities, they examine how air moves across their designs to make them more aerodynamic so that aircraft can achieve greater fuel efficiency by reducing drag but keeping the lift.

As part of this work the group uses high-performance computing and high-fidelity simulation and optimisation codes for drag reduction and aerodynamic design that have been used by Airbus, Leonardo Helicopters and BAE Systems. This is the most active research area for high-performance computing use, but it’s not the only area in which this form of supercomputing is playing a role in transforming aviation.

Researcher using the University of Bristol Wind Tunnel Lab

Simulating with supercomputers

Researchers in our High-Performance Computing Research Group are also using supercomputers to make designing and prototyping of new jet engines through simulation viable for companies in the aviation industry.

Developing new engine models for market has traditionally required the prototype to be built and physically tested, often passing through several iterations each of which requires the components to be remanufactured. This activity contributes to the aviation industry’s carbon footprint.

Using supercomputers, our computer scientists are developing advanced modelling software and simulation programmes that can produce a jet engine simulation so accurate that designs will be able to be signed off by the civil aviation authorities without the need to build multiple prototypes. This will save the industry millions of pounds, which could then be allocated to funding the development of emission-reducing technology.

They have also developed software that can accurately model the physical effects of thermo-mechanics, electromagnetics and computational fluid dynamics and simulation-based design programmes, which enable much more rapid development of new engines and radical new techniques to achieve greater engine reliability and fuel efficiency.

A close up of a jet engine

Jet engine design

Developing electric aircraft

With the exception of people flying less, the electrification of propulsion in aircraft will have the single greatest impact on reducing the aviation sector’s carbon emissions.

Traditionally fuel handling, cabin air pressurisation systems and actuation, the link between the flight controls and the rudders and flaps on the wings and tail, were all powered through hydraulic, pneumatic and mechanical means but these are gradually being replaced with electrical systems. The next major breakthrough will be where the propulsion will be driven electrically and distributed across the aircraft wings and body to improve aerodynamic efficiency.

Researchers in our Electrical Energy Management Group, led by Professor Phil Mellor, are working on innovations to distribute and power propulsion electrically that can be both lightweight and energy efficient. The key here is to use distributed electrical propulsion to improve the efficiency of aircraft through hybridisation, this means the aircraft will function like a hybrid car where there is still a fuel engine.

It is difficult to find alternatives to the energy density of kerosene fuel, but further hybridisation will allow for alternative fuels such as biofuels to be used. These hybrid aircraft will lead to cleaner operations, with the potential for zero emissions taxiing from gate to runway, which would help to reduce air pollution levels in and around airports.

The Snitch, what an electric aircraft could look like in the future

Altering flight paths

But it’s not just about reducing carbon emissions, in order to achieve greener aviation, we also need to look at the damaging effects of water vapour and soot emissions.

When released in the sufficiently cold and humid conditions of the upper troposphere, the emitted water vapour condenses around the soot particles due to the high humidity and then proceeds to freeze due to low temperatures, leading to the formation of a type of ice cloud in the wake of the aircraft known as a contrail.

These contrails often dissipate within minutes and have very little effect on the climate. However, when aircraft fly through ice super-saturated regions (ISSRs), where the ambient conditions are sufficiently cold and humid, the contrails can persist for up to 10 hours, transitioning into cirrus clouds that have the potential to spread over hundreds of kilometres.

As these clouds are more effective at trapping heat within the atmosphere than they are at reflecting inbound sunlight, they produce a net warming effect. One way to tackle this is to develop sustainable aviation fuel that produces less soot, the other is to look at where in the atmosphere this soot is being emitted.

Aerospace student Kieran Tait is using emissions estimation software and atmospheric modelling to investigate how current flight paths can be altered, in terms of route and flying altitude, to avoid ISSRs most sensitive to contrail formation, which tend to be found in the tropics at high altitudes and the extratropics at lower altitudes. In some cases, these flight path alterations may increase flight time causing more fuel to be burned and therefore an associated increase in carbon emissions, but by avoiding sensitive regions, overall the flight will actually be less damaging to the environment.

Contrails forming from the exhaust fumes of an aircraft

Reducing noise pollution

Contrails streaking across our skies are a visible sign of the growing number of flights but they’re not the only noticeable sign of this expansion. Those living underneath flight paths or in proximity to large airports will be all too aware of the level of noise generated by aviation.

Although reducing the level of noise generated by aircraft doesn’t contribute to reducing the carbon emissions, it is an important consideration given that, as Panorama says, the aviation sector is set to continue to expand. Noise has significant effects on society, impacting on health, productivity and ecosystems.

The World Health Organisation estimates that up to 1.6 million healthy life years are lost each year in western European because of exposure to high levels of noise, with a social cost of between £60 billion to £100 billion per annum. In almost every environmental noise report produced for the UK and EU governments, aerodynamic noise, which includes aircraft-generated noise, is recognised as one of the most intrusive types of noise pollution, with major public health implications.

Considering the current growth rate of commercial aviation and the emergence of new technologies, such as air-taxi and drones, noise is expected to remain an important problem facing the industry. Researchers in our Aeroacoustics Research Team, led by Professor Mahdi Azarpeyvand, work on better understanding noise from different aero-components and are developing novel passive and active methods to reduce the noise at its source through testing in the National Wind Tunnel Aeroacoustic Facility based here in our Faculty.

A man in a room where the walls and floor are made of soft spikes

Researcher using the University of Bristol’s Anechoic Chamber

A matter of time

It’s not so much a matter of how but when. We are developing the right solutions to aviation’s emissions problems, but as Panorama highlights it is a case of the timescale needed to make these solutions commercially and practically viable and to roll these out across the global aviation sector. The work we are doing within aerodynamics, flight paths, simulation-based design and carbon fibre fabrication means that we can start mitigating the detrimental impacts of aviation whilst we work towards better electrification of aircraft.

Read more about the Faculty of Engineering on the original blog post.

The ‘5 Ts’ of policy engagement: PolicyBristol’s approach to supporting academics

Supporting academics across the University of Bristol to achieve policy impact from their research is a diverse and fascinating job. In the process of doing this, our team at PolicyBristol is constantly learning about new topics; from the value of NHS managers to refugee rightsenhancing peace processes to the role of universities. Continue reading

Motivated to succeed? Attitudes to education among native and immigrant pupils in England

Perhaps the central policy question for those of us studying education is: how can we raise levels of attainment? For long, the focus was almost solely on cognitive skills, but a line of recent research has looked at the interaction between such skills and non-cognitive factors (also called psychological traits), motivations, and culture in generating higher student achievement. Continue reading

Setting the priorities for advanced heart failure research

by Dr Rachel Johnson
Clinical Research Fellow
Centre for Academic Primary Care

This week sees the launch of the James Lind Alliance Advanced Heart Failure Priority Setting Partnership Survey to gather research ideas from those living or working with advanced heart failure. Continue reading

Five lessons for researchers who want to collaborate with governments and development organisations but avoid the common pitfalls

The appeal of collaborating with a government agency, or an organisation funded by one, seems obvious. It provides researchers with much needed resources and information, while also offering practitioners and policymakers a way of generating the evidence needed to design better programmes. Continue reading

Food and drink options in NHS settings; new questionnaire prompts changes


Photo Credit: Christopher Gross/Released

Dr Fiona Lithander, Senior Research Associate, NIHR Bristol Biomedical Research Centre.

Fiona explains how a new questionnaire could be used to increase healthy food and drink options in hospital retail outlets

At the National Institute for Health Research (NIHR), Bristol Biomedical Research Centre we are interested in the role the NHS plays in promoting good nutrition and health in children. Recent reports have shown a quarter of children in the UK are overweight or obese; a worrying statistic in itself, and the problem doesn’t appear to be getting any better.

NICE guidelines say that retail outlets in hospitals such as shops, cafes, restaurants and vending machines should offer healthy food and drink options, and that these options should be prominently displayed. They also say that nutritional information about the foods on their menus should be available. These guidelines do not refer to foods served to patients, although patients may have access to foods and drinks for sale onsite.

At NIHR Bristol Biomedical Research Centre we developed a new questionnaire to help NHS Trusts assess how healthy their food and drink options are. This differs from other questionnaires in that it allows Trusts to compare their findings with the NICE guidelines. Trusts can use this questionnaire to measure how healthy prepared foods for sale are, and can make changes accordingly. These changes may involve, replacing sugary drinks with sugar-free options such as water, and replacing chocolate bars with more healthy options such as unsalted nuts.

Using this questionnaire, we measured how healthy the foods and drinks were in two Trusts, and how closely they followed NICE guidelines. Our findings showed a lack of healthy food and drink options for sale in vending machines. Nutritional information on menus was minimal, and there was limited promotion and advertising of healthy foods and drinks. Since the findings were published, both of the Trusts have made improvements.

Our plan is to further develop the questionnaire in conjunction with the NICE guidelines, so that it can be used more widely in NHS Trusts and in local authority settings, such as leisure centres. Making it easier for parents to direct their children to healthier choices should be a central element of our healthcare system.

Disclaimer: This study was supported by the NIHR Biomedical Research Centre at the University Hospitals Bristol NHS Foundation Trust and the University of Bristol. The views expressed in this article are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health.

This blog was originally published by the National Institute for Health and Care Excellence (NICE)

How do we teach clinicians to talk about the end of life?

Image of Doctor and patient

Image credit: Doctor and patient – Government of Alberta. Creative Commons License 2.0 (Non-commercial No Derivatives). Source: Flickr

By Dr Lucy Selman Research Fellow (Qualitative Research in Randomised Trials) Centre for Academic Primary Care  University of Bristol

In a systematic review published this month, we identified 153 communication skills training interventions for generalists in end of life care. In randomised controlled trials, training improved showing empathy and discussing emotions in simulated interactions (i.e. with actor patients) but evidence of effect on clinician behaviours during real patient interactions, and on patient-reported outcomes, was inconclusive.

The global increase in the proportion of older people and length of life means providing end of life care is now increasingly the responsibility of generalist as well as specialist palliative care providers. But many clinicians find communicating about end of life issues challenging: how do you best discuss imminent mortality, limited treatment options, what to expect when you’re dying, or a patient’s preferences for end of life care?

When this communication is done poorly, or not done at all, patients are confused and less satisfied with their care, experience inadequate symptom relief, and have worse quality of life. Staff who feel insufficiently trained in communication skills are more likely to provide depersonalised care and suffer from burnout.

While research in clinical communication has grown in recent years, there is little consensus on optimal training strategies and the most effective teaching methods. Continue reading

Using administrative data for labour market research: getting the balance right

Isabel Stockton, PhD Student, School of Economics, Finance and Management, and panel participant in Research without Borders 2017

Administrative data: it’s one of those phrases that can generate much excitement among economists and some other social scientists, but will never make for scintillating party conversation in any other setting.

However, the possibilities and limits on the use of administrative data for research can have a big impact on the policymaking process and raise tricky ethical questions, so it is important that the conversation is as broad as it can possibly be.

What is administrative data?

Administrative data is collected by the government for a non-research purpose.

For example, as part of my doctoral research I analyse national insurance data on jobs, wages and commuting distances in Germany.

Whenever someone starts or leaves a job, starts to claim unemployment benefits, is assigned to a jobseekers’ training programme or goes on parental or sick leave, this leaves a paper trail.

Economists in particular are very interested in this information: Many of us still subscribe to the traditional credo “Believe what people do, not what they say”. Continue reading

Why healthcare services have a problem with gambling

Image of electronic gambling machines.

“I have a problem with gambling. There’s not enough of it.”

Dr  Sean Cowlishaw, Research Fellow at the Centre for Academic Primary Care, University of Bristol

That was the admission from billionaire Steve Wynn, a major figure in the casino industry, speaking at a recent gambling research conference in (where else?) Las Vegas. And sure, it made for a good quote. But it’s also a rather glib dismissal of a serious issue that affects many thousands of people across the world.

The UK certainly has a problem with gambling. At least it has since 2007, when laws were changed to allow for huge growth in gambling opportunities and exposure. It has been hard to ignore the subsequent explosion in industry advertising, which increased by around 500% between 2007 and 2013. By contrast, you may have missed the increased numbers of high intensity electronic gambling machines, called Fixed-Odds Betting Terminals (FOBTs), which now occupy the high street (within betting shops) and allow punters to wager up to £100 every 20 seconds.

Yet Britain doesn’t have much insight into its problem with gambling. Compared to most other addictive behaviours, involving drugs or alcohol for example, gambling is largely ignored by health services and public health agencies. This is partly because gambling is a hidden concern. It does not manifest with physical warning signs. Indicators are usually visible in extreme cases only, and generally following major life crises such as extreme debt or relationship breakdown. Continue reading

Research, Impact and the UK Parliament – Event Report

Katie Drax, Honorary Research Assistant at the Tobacco and Alcohol Research Group (TARG)

Science can inform how society is run so research can have implications for public and private policy. But how? How can research feed into policy-making, i.e. evidence-based policy? For those who don’t have a clue about parliamentary actions or how they relate to academics’ work the “Research, Impact and the UK Parliament” event series is a good way to get to grips with Parliament and research.

Starting at 10 a.m. we pinned name badges to our shirts and busied ourselves by riffling through the Houses of Parliament tote bags placed on our seats. Thankfully the event did not require much prior knowledge since it was assumed the majority of attendees were ignorant about the workings of Parliament and so the first presentation was a 30 minute crash course on the subject. Continue reading