Thousands of aircraft were grounded during the pandemic. Now research is showing people might fly less. JetKat/Shutterstock
Tens of thousands of aircraft have been grounded for well over a year due to the pandemic. In April 2020 air travel around the world was cut by 94% from April 2019. By June 2021 it was still 60% down on June 2019 thanks to holidays being cancelled, work trips shelved, and long-planned journeys to see family and friends moved to another time.
Some people who live close to an airport may also have welcomed the drop in noise. But many others will be worrying about the effect the long-term reduction in air travel may have on their community’s economy.
But will the air industry even bounce back in five years? Research our team conducted in early 2021 in Bristol, an English city with an airport and a century-old aviation industry, found that close to 60% of those surveyed expect to fly less in the future. Many of our respondents gave climate change and the pandemic as equally important reasons. Other polling has shown that many elsewhere remain wary of flying in the future too.
Businesses may also operate differently. Polling has found that four in ten business travellers are likely to fly less in the future. Business-class seats are an important part of airline income – on some flights corporate travel can represent 75% of revenue.
Setting aside ideas about electric planes for now, it seems obvious that we will need to fly less to move to a zero-carbon economy. Two-thirds of people want a post-pandemic economic recovery to prioritise climate change. This means fewer planes, and fewer jobs for crew and baggage handlers and so on.
Rebuilding communities
The decline of older industries such as mining, textiles or pottery resulted in high unemployment in towns which were massively dependent on one of them. We are all familiar with how the closure of a local pit or car plant caused the decline of once vibrant towns, leaving a generation to struggle with unemployment and the need to retrain.
Steel mills were nestled deep in the fabric of nearby communities. Their closure removed the pivot around which lives, work and leisure were based. So with the pandemic, whole communities are at risk of a similar economic decline.
In summer 2020 the rate of those jobless (be it unemployed or on furlough) was higher in areas near UK airports. In Hounslow (near London Heathrow) this was 40% of the population – with an estimated £1 billion loss to the borough’s economy. At Gatwick airport in 2020, there were job losses for 40% of its workforce, many of whom live in nearby towns such as Crawley.
Towns like Hounslow are highly dependent on the nearby airport for employment. BasPhoto/Shutterstock
Many towns and communities are economically dependent on nearby airports. Luton Airport is estimated to have sustained over 27,000 jobs (directly and indirectly) and is a major employer in the region. The decline of the sector has broader effects on subsidiary industries too, such as taxis, maintenance, catering and hotels.
So what is to be done? The Green Jobs Taskforce, an industry and government initiative set up in 2020 to look at future employment, has called on the UK government to invest in jobs related to wind turbines, electric trains and replacing gas boilers.
Any version of a green new deal is necessarily a job-heavy economy, with a great deal of work needed to alter the infrastructure that powers our current lifestyle. The UK government’s Ten Point Plan for Green Industrial Revolution pledges 250,000 green jobs. The political question here is whether politicians and policymakers will be brave enough to resist a bounce back for aviation and invest in a longer term future for these airport towns, to avoid them suffering a decade of decline.
This is likely to see aviation jobs lost, and will require very targeted support for cities or regions reliant on airport employment. To build back better, a green recovery must seek to support these communities and provide them with new opportunities and livelihoods.
Is hydrogen the lifeblood of a low-carbon future, or an overhyped distraction from real solutions? One thing is certain – the coal, oil and natural gas which currently power much of daily life must be phased out within coming decades. From the cars we drive to the energy that heats our homes, these fossil fuels are deeply embedded in society and the global economy. But is the best solution in all cases to swap them with hydrogen – a fuel which only produces water vapour, and not CO₂, when burned?
Answering that question are six experts in engineering, physics and chemistry.
Road and rail
Hu Li, Associate Professor of Energy Engineering, University of Leeds
Transport became the UK’s largest source of greenhouse gas emissions in 2016, contributing about 28% of the country’s total.
Replacing the internal combustion engines of passenger cars and light-duty vehicles with batteries could accelerate the process of decarbonising road transport, but electrification isn’t such a good option for heavy-duty vehicles such as lorries and buses. Compared to gasoline and diesel fuels, the energy density (measured in megajoules per kilogram) of a battery is just 1%. For a 40-tonne truck, just over four tonnes of lithium-ion battery cells are needed for a range of 800 kilometres, compared to just 220 kilograms of diesel.
With the UK government set to ban fossil fuel vehicles from 2035, hydrogen fuel cells could do much of the heavy lifting in decarbonising freight and public transport, where 80% of hydrogen demand in transport is likely to come from.
A fuel cell generates electricity through a chemical reaction between the stored hydrogen and oxygen, producing water and hot air as a byproduct. Vehicles powered by hydrogen fuel cells have a similar driving range and can be refuelled about as quickly as internal combustion engine vehicles, another reason they’re useful for long-haul and heavy-duty transport.
Hydrogen fuel can be transported as liquid or compressed gas by existing natural gas pipelines, which will save millions on infrastructure and speed up its deployment. Even existing internal combustion engines can use hydrogen, but there are problems with fuel injection, reduced power output, onboard storage and emissions of nitrogen oxides (NOₓ), which can react in the lower atmosphere to form ozone – a greenhouse gas. The goal should be to eventually replace internal combustion engines with hydrogen fuel cells in vehicles that are too large for lithium-ion batteries. But in the meantime, blending with other fuels or using a diesel-hydrogen hybrid could help lower emissions.
It’s very important to consider where the hydrogen comes from though. Hydrogen can be produced by splitting water with electricity in a process called electrolysis. If the electricity was generated by renewable sources such as solar and wind, the resulting fuel is called green hydrogen. It can be used in the form of compressed gas or liquid and converted to methane, methanol, ammonia and other synthetic liquid fuels.
But nearly all of the 27 terawatt-hours (TWh) of hydrogen currently used in the UK is produced by reforming fossil fuels, which generates nine tonnes of CO₂ for every tonne of hydrogen. This is currently the cheapest option, though some experts predict that green hydrogen will be cost-competitive by 2030. In the meantime, governments will need to ramp up the production of vehicles with hydrogen fuel cells and storage tanks and build lots of refuelling points.
Hydrogen can play a key role in decarbonising rail travel too, alongside other low-carbon fuels, such as biofuels. In the UK, 6,049 kilometres of mainline routes run on electricity – that’s 38% of the total. Trains powered by hydrogen fuel cells offer a zero-emission alternative to diesel trains.
The Coradia iLint, which entered commercial service in Germany in 2018, is the world’s first hydrogen-powered train. The UK recently launched mainline testing of its own hydrogen-powered train, though the UK trial aims to retrofit existing diesel trains rather than design and build entirely new ones.
Aviation
Valeska Ting, Professor of Smart Nanomaterials, University of Bristol
Of all of the sectors that we need to decarbonise, air travel is perhaps the most challenging. While cars and boats can realistically switch to batteries or hybrid technologies, the sheer weight of even the lightest batteries makes long-haul electric air travel tricky.
Single-seat concept planes such as the Solar Impulse generate their energy from the sun, but they can’t generate enough based on the efficiency of current solar cells alone so must also use batteries. Other alternatives include synthetic fuels or biofuels, but these could just defer or reduce carbon emissions, rather than eliminate them altogether, as a carbon-free fuel like green hydrogen could.
Hydrogen is extremely light and contains three times more energy per kilogram than jet fuel, which is why it’s traditionally used to power rockets. Companies including Airbus are already developing commercial zero-emission aircraft that run on hydrogen. This involves a radical redesign of their fleet to accommodate liquid hydrogen fuel tanks.
An artist’s impression of what hydrogen-powered commercial flight might look like. Airbus
There are some technical challenges though. Hydrogen is a gas at room temperature, so very low temperatures and special equipment are needed to store it as a liquid. That means more weight, and subsequently, more fuel. However, research we’re doing at the Bristol Composites Institute is helping with the design of lightweight aircraft components made out of composite materials. We’re also looking at nanoporous materials that behave like molecular sponges, spontaneously absorbing and storing hydrogen at high densities for onboard hydrogen storage in future aircraft designs.
France and Germany are investing billions in hydrogen-powered passenger aircraft. But while the development of these new aircraft by industry continues apace, international airports will also need to rapidly invest in infrastructure to store and deliver liquid hydrogen to refuel them. There’s a risk that fleets of hydrogen aeroplanes could take off before there’s a sufficient fuel supply chain to sustain them.
Heating
Tom Baxter, Honorary Senior Lecturer in Chemical Engineering, University of Aberdeen & Ernst Worrell, Professor of Energy, Resources and Technological Change, Utrecht University
If the All Party Parliamentary Group on Hydrogen’s recommendations are taken up, the UK government is likely to support hydrogen as a replacement fuel for heating buildings in its next white paper. The other option for decarbonising Britain’s gas heating network is electricity. So which is likely to be a better choice – a hydrogen boiler in every home or an electric heat pump?
First there’s the price of fuel to consider. When hydrogen is generated through electrolysis, between 30-40% of the original electric energy is lost. One kilowatt-hour (kWh) of electricity in a heat pump may generate 3-5 kWh of heat, while the same kWh of electricity gets you only 0.6-0.7 kWh of heat with a hydrogen-fuelled boiler. This means that generating enough hydrogen fuel to heat a home will require electricity generated from four times as many turbines and solar panels than a heat pump. Because heat pumps need so much less energy overall to supply the same amount of heat, the need for large amounts of stored green energy on standby is much less. Even reducing these losses with more advanced technology, hydrogen will remain relatively expensive, both in terms of energy and money.
So using hydrogen to heat homes isn’t cheap for consumers. Granted, there is a higher upfront cost for installing an electric heat pump. That could be a serious drawback for cash-strapped households, though heat pumps heat a property using around a quarter of the energy of hydrogen. In time, lower fuel bills would more than cover the installation cost.
Replacing natural gas with hydrogen in the UK’s heating network isn’t likely to be simple either. Per volume, the energy density of hydrogen gas is about one-third that of natural gas, so converting to hydrogen will not only require new boilers, but also investment in grids to increase how much fuel they can deliver. The very small size of hydrogen molecules mean they’re much more prone to leaking than natural gas molecules. Ensuring that the existing gas distribution system is fit for hydrogen could prove quite costly.
In high-density housing in inner cities, district heating systems – which distribute waste heat from power plants and factories into homes – could be a better bet in a warming climate, as, like heat pumps, they can cool homes as well as heat them.
Above all, this stresses the importance of energy efficiency, what the International Energy Agency calls the first fuel in buildings. Retrofitting buildings with insulation to make them energy efficient and switching boilers for heat pumps is the most promising route for the vast majority of buildings. Hydrogen should be reserved for applications where there are few or no alternatives. Space heating of homes and buildings, except for limited applications like in particularly old homes, is not one of them.
Electricity and energy storage
Petra de Jongh, Professor of Catalysts and Energy Storage Materials, Utrecht University
Fossil fuels have some features that seem impossible to beat. They’re packed full of energy, they’re easy to burn and they’re compatible with most engines and generators. Producing electricity using gas, oil, or coal is cheap, and offers complete certainty about, and control over, the amount of electricity you get at any point in time.
Meanwhile, how much wind or solar electricity we can generate isn’t something that we enjoy a lot of control over. It’s difficult to even adequately predict when the sun will shine or the wind will blow, so renewable power output fluctuates. Electricity grids can only tolerate a limited amount of fluctuation, so being able to store excess electricity for later is key to switching from fossil fuels.
Hydrogen seems ideally suited to meet this challenge. Compared to batteries, the storage capacity of hydrogen is unlimited – the electrolyser which produces it from water never fills up. Hydrogen can be converted back into electricity using a fuel cell too, though quite a bit of energy is lost in the process.
Unfortunately, hydrogen is the lightest gas and so it’s difficult to store and transport it. It can be liquefied or stored at very high pressures. But then there’s the cost – green hydrogen is still two to three times more expensive than that produced from natural gas, and the costs are even higher if an electrolyser is only used intermittently. Ideally, we could let hydrogen react with CO₂, either captured from the air or taken from flue gases, to produce renewable liquid fuels that are carbon-neutral, an option that we’re investigating at the Debye Institute at Utrecht University.
Heavy industry
Stephen Carr, Lecturer in Energy Physics, University of South Wales
Industry is the second most polluting sector in the UK after transport, accounting for 21% of the UK’s total carbon emissions. A large proportion of these emissions come from processes involving heat, whether it’s firing a kiln to very high temperatures to produce cement or generating steam to use in an oven making food. Most of this heat is currently generated using natural gas, which will need to be swapped out with a zero-carbon fuel, or electricity.
Let’s look in depth at one industry: ceramics manufacturing. Here, high-temperature direct heating is required, where the flame or hot gases touch the material being heated. Natural gas-fired burners are currently used for this. Biomass can generate zero-carbon heat, but biomass supplies are limited and aren’t best suited to use in direct heating. Using an electric kiln would be efficient, but it would entail an overhaul of existing equipment. Generating electricity has a comparably high cost too.
Swapping natural gas with hydrogen in burners could be cheaper overall, and would require only slight changes to equipment. The Committee on Climate Change, which advises the UK government, reports that 90 TWh of industrial fossil fuel energy per year (equivalent to the total annual consumption of Wales) could be replaced with hydrogen by 2040. Hydrogen will be the cheapest option in most cases, while for 15 TWh of industrial fossil fuel energy, hydrogen is the only suitable alternative.
Hydrogen is already used in industrial processes such as oil refining, where it’s used to react with and remove unwanted sulphur compounds. Since most hydrogen currently used in the UK is derived from fossil fuels, it will be necessary to ramp up renewable energy capacity to deliver truly green hydrogen before it can replace the high-carbon fuels powering industrial processes.
The same rule applies to each of these sectors – hydrogen is only as green as the process that produced it. Green hydrogen will be part of the solution in combination with other technologies and measures, including lithium-ion batteries, and energy efficiency. But the low-carbon fuel will be most useful in decarbonising the niches that are currently difficult for electrification to reach, such as heavy-duty vehicles and industrial furnaces.
Here is a blog to accompany the video to give you more detail on the biggest issues that the university (and other similar organisations who rely on air travel) are facing as it works towards making itself carbon neutral by 2030. Caboteer Eleni Michalopoulou, who features in the video, explains more…
The effects of climate change now have almost a daily mention in the news as they become all the more frequent and evident by various studies, reports, blogs and pictures from all over the world. And as the climate crisis escalates, it was of course a matter of time before scientists pointed out the irony of flying to a conference in order to discuss the urgency and issues related to climate change. Of course, there is here an irony within the irony that led to a lot of finger pointing of scientists that do fly and a narrative of ‘unethical scientists’ that ‘don’t practice what they preach’ but we will come back to that a little later when we explore some of the reasons that people (not just scientists) fly.
I must admit that before I attended the workshop organized by the University of Bristol Sustainability Team with support from the Cabot Institute on the 10 June 2019, I had never really considered the actual facts and figures related to the aviation industry. So, I started doing some research and these are only some of the numbers I came across:
Over 65.5 million jobs are supported worldwide in aviation and tourism, out of which, 10.2 million people are working directly in the aviation industry.
If the aviation industry were a country, it would rank 20th in the world in terms of gross domestic product (GDP), and sixth in terms of carbon emissions.
Someone flying from London to New York and back generates roughly the same level of emissions as the average person in the EU does by heating their home for a whole year. and more than the average person does in a year in 56 countries of the world
On the 17 April 2019, the University of Bristol became the first university in the UK to declare a climate emergency and joined a long list of organizations and institutions across the world in the fight against climate change. This announcement came to highlight the university’s commitment to become carbon neutral by 2030.
Bike servicing and repair at the University of Bristol
As part of this efforts to accelerate action on its own climate impacts, the University is now developing a plan to address academic and other business travel and in particular air travel. The first task has been to assess the carbon footprint of the thousands of journeys made each year on University business by academics, postgraduate students and professional services staff.
Business travel emissions lie outside the scope of mandatory carbon reporting required in the higher education sector and are not included in the University’s carbon neutral goal. Nonetheless for the past few years the University has collated emissions data on flights and other forms of business travel, alongside those from energy use in buildings and the fuel used by its own vehicle fleet.
In order for the University to monitor and report carbon emissions, it uses three different ‘scopes’.
Scope 1 – Emissions are direct emissions from activities owned or controlled by the University, such as University owned vehicles and the fuel they use.
Scope 2 – Emissions are indirect emissions from electricity owned or consumed by the University that we do not own or control.
Scope 3 – Emissions are other indirect emissions that are related to the University’s activities, such as waste, water and business travel.
Analysis of these data for the business travel plan suggest that emissions from air travel have more than doubled since 2010/11 and now account for nearly one fifth of the University’s total known operational carbon footprint. This growth has occurred against a backdrop of declining emissions from the University’s estate achieved through investment, for example, in improved energy efficiency in buildings.
This was the context for the workshop on ‘Air travel: Drivers, impacts and opportunities for change’ in order to explore the most efficient way to develop a business travel plan for the University including the constraints and opportunities for managing the impacts of air travel for academic and other business reasons. The Vice-Chancellor for Global Engagement, Dr Erik Lithander, was present in this workshop and highlighted the need to maintain our global impact as a leading university while managing our environmental footprint and remaining committed to our strong sustainability agenda.
One of the most interesting parts of the workshop was the discussion around the reasons behind air travel in the University of Bristol. So, what is academic and business travel usually linked to according to the most recent staff travel survey? This found the most common reasons (for business or academic travel) were to attend a conference or other forum for sharing research; take part in collaborative projects with other academic or industry partners; and go to other types of meetings on University business. Travel for fieldwork and training purposes was less frequent, followed by attending trade shows and recruitment.
Discussions during the workshop considered the reasons why flying might be the first choice over video-conferencing or other travel modes)’. The following five responses emerged from the roundtable discussions as the key determining factors in the choice of air travel over other alternatives:
Time
Costs
Technological limitations (e.g. quality of videocalls)
The importance of face-to-face interaction, and
Air travel being the default option in funding requirements or travel management companies.
I suppose when I walked into the workshop, my thinking regarding air travel was overly simplistic. I had not realized the complexity of this issue especially for an institution as big as the University of Bristol. During the discussions around the reasons behind flying, three were the reasons that really troubled me in terms of a complex problem that potentially requires a complex solution.
Time
Perhaps the most important issue is the issue of time. A direct flight from Bristol to, for instance, Edinburgh is approximately one hour while the same distance if covered by train is six hours in a best-case scenario. And while for most of us this could be an opportunity to relax and enjoy a lovely trip by train, what about cases where there are caring responsibilities involved, or even an extremely busy workload? This question brings us back to the irony of the irony that I briefly mentioned in the beginning. While climate scientists care, of course, about the environment and their own environmental footprint, in a lot of cases they have families, children, or are responsible for the care of a relative or an individual and increasing the duration of their business trip by 10 or even 20 hours might not be a realistic goal to set.
Costs
Similarly, while a direct flight from Bristol to Edinburgh can cost from £23 pounds, the train from Bristol to Edinburgh ranges between £140 and £280 pounds. Of course, for the biggest part these expenses are not covered by the individual researcher but even so, a very simple question to ask would be ‘why use a substantial amount from the budget to cover a train ticket and not use the cheap option of a plane ticket?’
Physical presence
What was perhaps discussed the most during the workshop was the culture and beliefs behind the idea that an academic’s physical presence would be much more beneficial and could better achieve the purpose of their visit (e.g. research, collaboration, securing funding, networking) rather than the e-presence of the same individual. Can our physical presence be replaced with the help of technology? Can we achieve the same goals through an e-conference than we would if we were there? What can replace a handshake?
I should at this point highlight, that I am not writing the above in defense of flying. I am writing it as a way to reflect on my own thoughts and discussions with colleagues both during the workshop but also afterwards. Afterall, if there was one thing that was evident from the IPCC report was the fact that our lifestyle would have to go through ‘unprecedented changes’ in order for our planet and the climate to have a chance. Perhaps, while a train trip might seem as an inconvenience or disruption to us right now it will be nothing compared to future “inconveniences and disruptions” of a much-deteriorated climate.
I truly believe that it is extremely courageous for the University to start quantifying and addressing its own emissions related to air travel. This effort to explore both the limitations but also the opportunities, by consulting and talking to members of staff is the University’s best bet in order to both meet its very ambitious sustainability goals but also maintain a strong global presence and agenda. Following the workshop in June, a program of wider staff engagement is due to take place continue in the autumn to help develop the University’s approach to air travel. Like many other colleagues, I look forward to the opportunity to contribute to this important response to the climate emergency.
