Beautiful

 The Lockheed Constellation.  A beautiful, elegant, shapely plane.  And a technological marvel of its time.

The true climate impact of aviation

From Carbon Brief

 

Data for 2018 shows the global population flying more frequently – and over longer distances than ever before – with nearly 38m scheduled flights, carrying 4.3bn passengers over a total of 54bn km. Aviation has been growing at around 5% per year before 2020.

But what is the climate cost of all these flights? The oft-quoted figure is that aviation accounts for around 2% of global CO2 emissions. Yet, the impact of aviation on the climate goes beyond just CO2 and its emissions have complicated interactions in the atmosphere that can reinforce the warming impact.

Aviation’s climate impacts have been studied for many years, including a special report by the Intergovernmental Panel on Climate Change (IPCC) in 1999, but rarely are all the results pulled together to produce such a comprehensive analysis and assessment based on the best available science.

Published in the journal Atmospheric Environment, we – along with 19 other scientists around the world – recently produced an updated analysis of the present-day climate impacts of aviation.

We find that, when all its impacts are taken into account, aviation represents around 3.5% of the warming impact caused by humans in the present day.

Below, we unpack this headline result of the study and describe a little of the context.

[Read more here]

For simplicity, I will assume in future that the GHG emissions from aviation are ~4% of the total.  Of course, as emissions from other sources fall, the percentage will increase.

Europe's 5 largest airports emit more than Sweden

 

From TransportEnvironment

Europe’s five biggest airports combined pollute more CO2 than the entire Swedish economy with emissions that are almost entirely untaxed, a new airport tracker shows. 

The online airport tracker created by ODI, Transport and Environment (T&E) and the International Council on Clean Transportation (ICCT), uncovers, for the first time, precisely how much CO2 is released from planes leaving airports.

Passenger flights departing London Heathrow, Paris Charles de Gaulle, Frankfurt, Amsterdam Schiphol and Madrid Barajas emit[1] 53 million tons of CO2 which is exempt from fuel tax and of which less than 15% is priced into the EU and UK’s cap and trade schemes. These schemes include domestic and EU flights only, meaning flights leaving Europe are not covered.

Jo Dardenne, aviation manager at T&E, said: “Unlike cars or power stations, most flight emissions are released outside of Europe’s borders, leaving the vast bulk of emissions from European airports scandalously overlooked. All flights should be included in the emission trading system, not just the ones within Europe.”

80% of Paris Charles de Gaulle’s emissions, for example, come from long-haul flights, whereas the majority departing from smaller airports, such as Krakow, are short-haul. Pollution from smaller airports is therefore taxed more than those from larger ones which cater for longer, higher-emitting flights.

These undocumented and untaxed carbon emissions are important when considering airport expansions, says the coalition of NGOs. Emissions from the aviation sector grew 5% per year from 2013 to 2018 reaching 2.5% of global CO2 emissions – the 7th biggest emitter globally if it were a country. 

Jo Dardenne concluded: “We can now see the alarming extent of airport emissions and it is clear that the aviation sector isn’t doing enough to curb its pollution. We cannot justify airport expansion in this time of climate crisis.”

All of the major airports mentioned have plans for expansion, most notably Heathrow. Heathrow airport – whose planned expansion has recently been delayed due to Covid –  is responsible for the second largest airport emissions in the world. Its 16.2 million tonnes of CO2 each year is equivalent to that of 8.1 million cars.

Fly, drive, or take the train?

 From the BBC

What are aviation emissions?

Flights produce greenhouse gases - mainly carbon dioxide (CO2) - from burning fuel. These contribute to global warming when released into the atmosphere.

An economy-class return flight from London to New York emits an estimated 0.67 tonnes of CO2 per passenger, according to the calculator from the UN's civil aviation body, the International Civil Aviation Organization (ICAO).

That's equivalent to 11% of the average annual emissions for someone in the UK or about the same as those caused by someone living in Ghana over a year.

Aviation contributes about 2% of the world's global carbon emissions, according to the International Air Transport Association (IATA). It predicts passenger numbers will double to 8.2 billion in 2037..

And as other sectors of the economy become greener - with more wind turbines, for example - aviation's proportion of total emissions is set to rise.

How do emissions vary?  

It depends where passengers sit and whether they are taking a long-haul flight or a shorter one.

The flight figures in the table are for economy class. For long haul flights, carbon emissions per passenger per kilometre travelled are about three times higher for business class and four times higher for first class, according to the Department for Business, Energy and Industrial Strategy (BEIS).

This is because there's more space per seat, so each person accounts for a larger amount of the whole plane's pollution.

Taking off uses more fuel than cruising. For shorter flights, this accounts for a larger proportion of the journey. And it means lower emissions for direct flights than multi-leg trips.

Also, newer planes can be more efficient and some airlines and routes are better at filling seats than others. One analysis found wide variation between per passenger emissions for different airlines.

For private jets, although the planes are smaller, the emissions are split between a much smaller number of people.

For example, Prince Harry and Meghan's recent return flight to Nice would have emitted about four times as much CO2 per person as an equivalent economy flight.

The increased warming effect other, non-CO2, emissions, such as nitrogen oxides, have when they are released at high altitudes can also make a significant difference to emissions calculations.

"The climate effect of non-CO2 emissions from aviation is much greater than the equivalent from other modes of transport, as these non-CO2 greenhouse gases formed at higher altitudes persist for longer than at the surface and also have a stronger warming potential," Eloise Marais, from the Atmospheric Composition Group, at the University of Leicester, told BBC News.

But there is scientific uncertainty about how this effect should be represented in calculators.

The ICAO excludes it, while the BEIS includes it as an option - using a 90% increase to reflect it.

The EcoPassenger calculator - launched by the International Railways Union in cooperation with the European Environment Agency - says it depends on the height the plane reaches.

Longer flights are at higher altitude, so the calculator multiplies by numbers ranging from 1.27 for flights of 500km (300 miles) to 2.5 for those of more than 1,000km.

In the chart above, the high-altitude, non-CO2 emissions are in a different colour.

How does travelling by train compare? 

Train virtually always comes out better than plane, often by a lot. A journey from London to Madrid would emit 43kg (95lb) of CO2 per passenger by train, but 118kg by plane (or 265kg if the non-CO2 emissions are included), according to EcoPassenger.

However, the margin between train and plane emissions varies, depending on several factors, including the type of train. For electric trains, the way the electricity they use is generated is used to calculate carbon emissions.

Diesel trains' carbon emissions can be twice those of electric ones. Figures from the UK Rail Safety and Standards board show some diesel locomotives emit more than 90g of C02 per passenger per kilometre, compared with about 45g for an electric Intercity 225, for example.

The source of the electricity can make a big difference if you compare a country such as France, where about 75% of electricity comes from nuclear power, with Poland, where about 80% of grid power is generated from coal.

Can driving be better than flying?

Yes, if the car's electric - but diesel and petrol cars are also in many cases better options than flying, though it depends on various factors, particularly how many people they're carrying.

According to EcoPassenger, a journey from London to Madrid can be done with lower emissions per passenger by plane, even accounting for the effect of high altitude non-CO2 emissions, if the car is carrying just one person and the plane is full. If you add just one more person into the vehicle, the car wins out.

Coaches also score well. BEIS says travelling by coach emits 27g of CO2 per person per kilometre, compared with 41g on UK rail (but only 6g on Eurostar) - though again this will vary depending on how full they are and the engine type.

Tourism responsible for 8% of global emissions

 From Carbon Brief

Worldwide tourism accounted for 8% of global greenhouse gas emissions from 2009 to 2013, new research finds, making the sector a bigger polluter than the construction industry.

The study, which looks at the spending habits of travellers in 160 countries, shows that the impact of tourism on global emissions could be four times larger than previously thought.

The findings suggest that tourism could threaten the achievement of the goals of the Paris Agreement, a study author tells Carbon Brief.

However, the results may still be underestimating the total carbon footprint of tourism, another scientist tells Carbon Brief, because they do not consider the impact of non-CO2 emissions from the aviation industry.

The global tourism industry is rapidly expanding. Fuelled by falling air travel prices and a growing global middle class, the number of international holidaymakers is currently growing at a rate of 3-5% per year.

The new study, published in Nature Climate Change, explores how the recent growth of global tourism has impacted greenhouse gas emissions.

Tourists contribute to climate change in a number of ways – through travel by air, rail and road, for example, and by consuming goods and services, such as food, accommodation and souvenirs.

For the new analysis, the researchers considered all of these factors together in order to calculate tourism’s “global carbon footprint”, explains study author Dr Arunima Malik, a lecturer in sustainability from the University of Sydney. She tells Carbon Brief:

“Our analysis is comprehensive and, hence, takes into account all the upstream supply chains to quantify the impacts of tourist spending on food, clothing, transport and hospitality.”

The research finds that, between 2009 and 2013, tourism’s annual global carbon footprint increased from 3.9 to 4.5bn tonnes of CO2 equivalent.

This figure is four times higher than previous estimates and accounts for 8% of global greenhouse gas emissions, the research finds. The rise is largely driven by an increased demand for goods and services – rather than air travel, the research finds. [Total emissions of greenhouse gases from air travel are twice the CO2-only emissions]

[Read more here]

Rooftop solar refinery makes jetfuel

 From Anthropocene.

Scientists have made a pilot-scale solar refinery that efficiently turns carbon dioxide and water plucked from air into liquid fuels. The system takes us one step closer to making carbon-neutral fuels for flying and shipping pretty much anywhere in the world.

The global aviation and shipping industries together produce about 8 percent of manmade carbon dioxide emissions. Battery-powered electric ships and airplanes are one way to reduce emissions, and are already being tested on small scales. But batteries are large, heavy, and expensive especially for long-haul international travel.

A promising near-term solution is to make fuels like gasoline, diesel and kerosene from water and carbon dioxide using solar energy. Of the several ways to do this, an efficient process with high fuel-production rate involves using concentrated sunlight as a source of high-temperature heat.

Aldo Steinfeld and his colleagues from ETH Zurich in Switzerland used this technique for their solar fuel plant. As an added benefit, they use carbon dioxide absorbed directly from air for truly carbon-neutral fuels. And their system also extracts water from air, which means it could produce fuel in desert regions or areas with limited access to water resources.

Their system, reported in the journal Nature, makes fuel in three steps. First, a direct air capture unit absorbs carbon dioxide and water from air using a sorbent bed. Then a solar unit uses solar heat to convert the carbon dioxide and water into a mixture of carbon monoxide and oxygen. This unit consists of a sun-tracking curved reflector that focuses the sun’s energy onto the chemical reactor. Finally, a third unit turns the syngas into a liquid hydrocarbon such as methanol or kerosene that is used as fuel.

The researchers tested their system successfully on a rooftop, where it produced 32 milliliters of methanol over 7 hours a day. They propose a design for a commercial solar plant made of ten solar towers, with each tower containing an array of solar reactor modules. Such a plant would produce about 95,000 liters of kerosene a day.

All the solar plants needed to produce enough kerosene for the global aviation industry—which used about 414 billion liters in 2019—would have a total land footprint of roughly 45,000 square kilometers, they calculate. That’s 0.5% of the area of the Sahara desert.

Such solar fuels would be more expensive than conventional fossil fuels, however. An analysis of the entire process showed that the fuel would cost 1.4 to 2.3 USD per liter if it were produced on a commercial scale. Regular kerosene jet fuel typically costs about 0.50 USD. The researchers say that the solar fuels would need policy support for widespread use.

Virgin Galactic's supersonic jet

 From Space.com

The private spaceflight company Virgin Galactic and Rolls-Royce have teamed up to create a supersonic jet for high-speed passenger flights.  

The Spaceship Company (TSC), Virgin Galactic's aerospace-system manufacturing arm that builds the company's SpaceShipTwo space planes, is now working to develop a high-speed commercial aircraft capable of flying at Mach 3, or three times the speed of sound.

Today (Aug. 3), TSC announced the completion of a mission concept review and unveiled the initial design concept for a high-speed aircraft. They also announced that they have signed a memorandum of understanding with Rolls-Royce to collaborate in design and development for the craft. 

Rolls-Royce might seem like an odd choice, but the company, known for its luxury cars, previously developed the turbojet that powered the famed supersonic airliner the Concorde, which flew at Mach 2.04, or just over twice the speed of sound. 

Concorde certainly isn't the only commercial supersonic jet for TSC's ambitious aircraft to contend with.

Boom Technology, which partnered with Virgin Galactic in 2017, has been developing the XB-1, their supersonic vehicle, set to debut Oct. 7. Spike Aerospace is also developing a supersonic business jet. Meanwhile, NASA and Lockheed Martin are developing the X-59 X-plane, a supersonic jet aimed at quieting sonic booms. All these projects follow in the high-speed footsteps of the Concorde, which flew from 1969 to 2003, the Soviet supersonic passenger airliner Tupolev Tu-144 flew from 1968 to 1999. 

[read more here]

Virgin Galactic has experience building suborbital supersonic aircraft, with its SpaceShip 1 & 2, which in fact can't reach orbit.  And with SpaceX's rapid progress, it must be obvious to Richard Branson that the potential market for space tourism will be dominated by SpaceX.  

The largest electric plane ever

The eCaravan could be adapted to seat a grand total of nine passengers, but on its test flight it had just one seat for the pilot

 From the BBC

At a large airfield surrounded by farmland in central Washington State, an electric aeroplane recently made history. It is the biggest commercial plane ever to take off and fly powered by electricity alone. For 30 minutes on 28 May, it soared above Grant County International Airport as crowds of onlookers clapped and cheered.

The biggest electric plane ever, huh? Well, it was a modified Cessna Caravan 208B – which can take a maximum of nine passengers. And the test aircraft only had a seat installed for the pilot.

It’s a far cry from the 200-300-seater jet that takes you on weekend city breaks or work trips, never mind the huge double-decker planes that cross continents. But the “eCaravan” test flight was a success. The two companies behind it, AeroTEC and magniX, which supplied the electric motor, are chuffed with the results. Roei Ganzarski, chief executive of magniX, pointed out in a statement that the price of flying the Cessna clocked in at a mere $6 (£4.80). Had they used conventional engine fuel, the 30-minute flight would have cost $300-400 (£240-320).

It builds on previous experiments with smaller aircraft also fitted with an electric motor built by magniX. And is raises the question: when will you and I be able to fly on a larger passenger plane powered by electricity rather than fossil fuels?

The first thing to note is that long-haul flights by large aircraft are not going to become fully electric any time soon. Certainly not within the next 50 years – and the jury’s out as to whether that will even happen this century. The reason is energy density.

Energy density is usually defined in terms the number of watt-hours (Wh) you get per kilogram (kg). A current lithium-ion battery’s energy density might reach 250 Wh per kg, while the energy density of jet fuel, or kerosene, is roughly 12,000 Wh per kg.

Put like that, it might seem like electric planes stand little hope of catching up. However, the difference isn’t quite as stark as it seems because electrical propulsion systems can be designed to be more efficient, meaning that they can cover more miles on less energy. But, at present, this still leaves fossil fuel systems about 14 times more energy-rich than battery-powered alternatives. Batteries, not being fluids that merrily slosh around, are also awkward in terms of their shape and bulk. “Right now the fuel nicely fits into the wing,” says Susan Liscouët-Hanke, an aerospace engineer at Concordia University in Montreal.

Plus, a further hitch is that the weight of a battery stays the same even when it’s dead. As a traditional aircraft flies, kerosene gets used up, making the aircraft lighter. That in turn reduces the amount of fuel it needs to stay in the air.

Engineers are currently trying to build a 180-seat fully electric jet that can fly for around 500km. The budget airline EasyJet has partnered with the aviation start-up Wright Electric to design and develop such a prototype plane that, if successful, could enter commercial service as early as 2030. Its travel routes would be limited – Paris to London for instance, not much further – but narrow-body aircraft that fly short-haul routes of 1,500km or less make up around a third of aviation emissions, according to management consultants Roland Berger. By gradually introducing electric planes that could replace conventional aircraft on these short-hop trips, the environmental impact of flying could be significantly improved.

It couldn’t come too soon because, as Roland Berger also notes, aviation is the only major industry in the EU in which CO2 emissions are increasing significantly. While the industry accounts for just 3% of global CO2 emissions today, by 2050 commercial aircraft could be churning out up to 24% of worldwide emissions due to predicted growth in the sector.

Flying fully electric 180-seater aircraft commercially by 2030 is “very ambitious”, says Robert Thomson, a partner at Roland Berger. The more sober view is that by 2030 we will more likely see hybrid electric aircraft being rolled out. In these planes, propulsion is provided by batteries and electric motors alongside traditional combustion systems. “A 50-seater aircraft would become viable as a hybrid, maybe 2030, late 2020s – I think that’s the sort of timescale which is plausible,” says Thomson.

He adds that his firm has counted more than 200 electrically powered aircraft in development and the number of these projects increased by 30% between 2018 and 2019. Many of these aircraft are hybrid models. They come in all sorts of “flavours”, says Thomson, wherein electricity might provide as little as 10-20% of the plane’s propulsion. Still, in principle, these designs might be easier to develop using existing aircraft bodies.

[Read more here--the BBC's piece is a lot longer than the excerpt above]

The most likely route to long-distance zero-carbon air traffic for the next few decades will be green jetfuel.  (See previous articles about this, here, here, here, and here)  But electric planes are much cheaper to run, as the article points out.  So there will be an incentive to switch where it's feasible.

Emissions from air travel vs coal

A nice chart showing emissions from Victoria's 3 (brown) coal power stations vs national emissions from Australia's 3 main airlines, for fiscal year 2019 (from 1st July 2018 to 30th June 2019, in other words, pre-covid) from Simon Holmes à Court

In normal times, aviation is a significant source of greenhouse emissions. not wanting to downplay its carbon footprint, but let's use that sector as a yardstick.

Here's how emissions from Victoria's 3 coal power stations stack up against Australia's domestic aviation sector.

 This chart emphasises just how important it is to get coal out of our energy supply.

World recession deepens

We have at this stage only a few countries which have released March 2020 industrial production data.  The big falls started happening (outside China) in March.  So here's a chart of the year-on-year percentage change in the average of industrial production for China and the USA (which have released March data) compared with the the year-on-year percentage change in my calculation of world industrial production (only available to February).

Numerous indicators have shown that the world economy had started a new upturn, which the covid crash has aborted.  You can see this in the slight uptick in world IP in February.  The USA and China together make up 32.1% of the world economy, and you can see how close the correspondence between world and US/Chinese IP is.  We are clearly heading towards GFC lows.  Because the covid crash has been a rolling affair, by which I mean it's hit different countries at different times and scales, and because lockdown also has been imposed at different times, the recovery will lag.  That's also before we consider that international borders will remain closed affecting air travel, hotels, and restaurants.  The covid crash affected services first.  Now its impact will spread into industrial production.  It still seems likely to me that the low point of year-on-year change in IP and GDP could be as bad as or (probably) worse than during the GFC.

This is a very unusual recession.  But as always in economics, feed-back happens.  The supply shock of lockdowns is leading to a demand shock as businesses close and lay off or furlough workers which will in turn lead to financial shocks as over-extended companies go bankrupt, as workers default on mortgages, as developing countries default on their debt.  In "normal" recessions it is more usual for financial shocks to lead to demand shocks which feeds back into more financial crises.

I do not think it will be  a V-shaped recovery.  The USA is floundering, their management of the covid crisis has been abysmal, and fiscal stimulus has been too little, too late.  The Fed gets it; the administration doesn't.  Developing countries in which I include India, Russia and Brazil, as well as other less developed countries, make up more than 20% of the world economy.  Their health systems are too basic to deal with the coronavirus well; they are too poor to borrow vast sums to stimulate their economies; they have too many heavily indebted companies and governments which have borrowed in US$, debts which will not be repaid.  Europe is squabbling about a stimulus package.  Foolishness on the part of the German bloc, but alas all too reminiscent of the follies of the 2011 Euro crisis.  So the European recovery will be slow, the agony of developing countries is far from over, and the US will struggle to get off its knees.   And a big chunk of services will remain way below normal.  More than half the world economy will flounder along in the shallows.  Some of it will drown.

Improving my China alternate GDP index

I mentioned in my last piece that I needed more services compnents in my alternate China GDP  index.  I've decided to add the number of passenger-kilometres travelled to the index.

This is a chart of passenger-km seasonally adjusted.  Note the sharp plunge in 2003 with the SARS virus, analogous to the new SARS virus now.  Fortunately, SARS is much less infectious than COVID-19, so the downturn was confined to China.  Now it is global, so the economic damage will be much worse.

The new calculation of alternate GDP, which includes civil aviation passenger-kilometres, is a better fit to GDP  than the old one.  It now has two service indicators included in its calculation—the volume of retail sales and air travel.  It also tracks published GDP more closely for the last few years than the old index did.

I first introduced my alternate GDP index here.

A hydrogen-powered plane

From TriplePundit

The clean energy revolution means more than simply replacing fossil fuels with low-carbon alternatives. Clean technology can also provide extra benefits for companies in terms of productivity, comfort and convenience. A case in point is the hydrogen plane startup ZeroAvia. The company has just emerged from “stealth” mode to offer the world’s first commercial aircraft with a hydrogen fuel cell powertrain as its exclusive means of locomotion.

ZeroAvia’s business model is based on the premise that its hydrogen fuel cell powertrain will reduce the cost of flight on small, 10-20 seat aircraft, targeting short-haul journeys of up to 500 miles.

With the ability of the company's hydrogen plane to compete on cost for passengers against large conventional jets, ZeroAvia is anticipating that business travelers will be attracted by the opportunity to fly into smaller regional airports.

Ideally, the increased flexibility in choice of destinations will reduce the potential for delayed flights and long security lines that often bedevil larger airports.

Hydrogen fuel cell passenger cars have been slow to take off, partly due to their relatively high cost and lack of a mature fuel distribution network for motorists.

Those two issues are not significant barriers for ZeroAvia’s hydrogen fuel cell aircraft, however.

The company is anticipating a per-flight cost savings of about 50 percent for its powertrain compared to conventional jet aircraft. Higher power train efficiency is one key difference. Lower fuel and maintenance costs will also factor in.

To help reduce costs farther, ZeroAvia has adopted a “power-by-the-hour” engine lease model commonly used in the aircraft industry, in which customers pay only for the hours that they use the powertrain. The cost of fuel and maintenance will be picked up by ZeroAvia as part of the lease.

Hydrogen fuel cells produce no airborne pollutants. The only emission is water, resulting from the interaction of hydrogen with oxygen in the fuel cell.

Still, the supply chain for hydrogen is front-loaded with pollutants and environmental impacts because the primary source for hydrogen today is natural gas.

Air Liquide has committed to decarbonizing hydrogen production for energy-related applications through its Blue Hydrogen initiative.

For its short-term goal, the company has pledged carbon-free production for at least 50 percent of hydrogen in the energy category by 2020 -- in other words, by next year. Biogas, water-splitting (using electricity sourced from renewables) and carbon recycling are the three main pathways identified by the company.

Air Liquide’s timetable for renewable hydrogen improves the prospects for ZeroAvia to reduce its supply chain emissions.

ZeroAvia is looking at the year 2022 to introduce its new fuel cell aircraft to the market, and earlier this year Air Liquide announced it would ramp up carbon-free hydrogen production at an existing facility just across the border from the U.S. in Canada.

[Read more here]

Brown hydrogen is made from coal, blue hydrogen from natural gas and green hydrogen via electrolysis using green electricity.  The supporters of a hydrogen economy say that supporting blue hydrogen will lead to economies of scale which will then allow the introduction of green hydrogen.  For example, this page from Oz gas producer Woodside. 

I'm not altogether convinced.  The problem with blue hydrogen is not economies of scale.  It's cost, because the chemical bonds between oxygen and hydrogen in the form of water are so strong it requires lots of energy to break them apart during electrolysis.   ZeroAvia's relative cheapness, I suspect, depends on blue hydrogen, not green. 

That's doesn't mean ZeroAvia's project is completely pointless.  Green hydrogen produced by renewable electricity that would otherwise be curtailed because there is surplus electricity in the grid is cheap.  Curtailment will increase rapidly as we increase the percentage of renewables in the grid.  And it may be possible that the CO₂ produced as a by-product of the production of blue hydrogen could be dissolved in water and pumped into basalt where it turns into rock.  On the other hand, compressing and delivering the CO₂ to far-off locations increases the cost and energy usage.

For now, blue hydrogen is more efficient and much less polluting than petroleum or jet-fuel, so it is half a step forward.  Air Liquide's commitment to producing 50% green hydrogen as part of its total hydrogen production is good news.  Progress comes from small steps, as long as they're all in the same direction.

Carbon-friendly jet fuel

Vapour trails.  Source: Transport & Environment

Electricity generation is transitioning to renewables.  Not fast enough, but it is happening.   There are no technological or economic barriers to achieving a 100% green grid--though there are, it's true, technical and organisational issues to be faced.  Similarly, over the next 15 or 20 years, it will be inevitable that our land transportation fleet will be electrified.  I'm not saying we should relax--fossil fuel interests will do their best to delay or prevent these transitions, but the economics has turned (or soon will) unambiguously in favour of the green alternatives.

That leaves air travel, sea transport, iron and steel, cement production, agriculture and land clearing.  Each of these is more complicated and difficult than transitioning generation to renewables and our ICE fleet to EVs.

Aviation is responsible for 5% of global warming and its rapid growth puts it on track to consume a quarter of the world’s carbon budget by 2050. There is a way to avoid this outcome but we need to act fast, a green transport NGO has said. By driving out the use of fossil kerosene fuel through carbon pricing and requiring aircraft to switch to synthetic fuels, the climate impact of flying can be reduced dramatically, according to a new report by Transport & Environment (T&E).

While high profile promises such as short-haul electric aircraft or more efficient aircraft designs every 20 years won’t be sufficient to solve aviation’s climate problem, new near-zero-carbon electrofuels can be produced today and deployed immediately using existing engines and infrastructure. Electrofuels are produced by combining hydrogen with carbon dioxide, but to do this sustainably the hydrogen must be produced using renewable electricity and the CO2 captured directly from the air.

Synthetic fuels have been used in the past to power aircraft but are significantly more expensive than aviation kerosene, which is tax free. Running aircraft entirely on synthetic fuels would increase the cost of a plane ticket by 58% assuming kerosene remains untaxed, or 23% if a proper carbon price would be levied on kerosene, the report finds. Biofuels produced from wastes and residues can make a limited contribution to replacing fossil kerosene. 

Andrew Murphy, aviation manager at T&E, said: “This report confirms that we need to decarbonise aviation if we want to avoid catastrophic global warming. The good news is that radically cleaner aviation is possible even with today’s technology. Getting to zero starts with properly pricing flying, and progressively increasing the use of sustainable synthetic fuels. There is a cost to this, but in light of how cheap subsidised air travel has become, and the incalculable cost of runaway climate change, it’s a price worth paying.”

To facilitate the progressive switch to electrofuels, demand for kerosene must start to be cut and carbon pricing must gradually be increased to the equivalent of €150 a tonne, the report finds. Taxing aircraft kerosene – currently exempt – and a strengthened EU ETS can help achieve this as can strict CO2 efficiency standards for planes and greater incentives for fleet renewal.

A leaked version of the European Commission’s strategy to decarbonise the EU’s economy by 2050 highlighted the potential role of synthetic fuels. Earlier this month the IPCC also emphasised the importance of synthetic jet fuel. Meanwhile, governments are pursuing a controversial UN offsetting scheme for aviation, known as Corsia. There are serious doubts over the environmental effectiveness of carbon offsets and the UN’s plan only caps airlines’ emissions at 2020 levels.

Andrew Murphy concluded: “Putting aviation on a pathway to zero won’t be easy but this report shows it can be done. If we want to succeed we need to stop pursuing false solutions. It’s crystal clear that the UN’s plan to let airlines offset their emissions is a distraction at best. We need governments to focus on the things that matter: proper pricing and cleaner fuels. The European Commission has a unique opportunity to commit to this in its 2050 decarbonisation strategy.”

[Read more here]

If we aimed to transition jetfuel for air travel to 100% synthetic kerosene over 20 years, the cost impact would be spread out and small.  For example, we could require that each year the percentage of synthetic kerosene in the fuel mix could be lifted by 5%.  That would mean that, ceteris paribus, jetfuel prices would rise by just 3% per annum.  And in 20 years, air travel would not be adding any new CO2 to the atmosphere.

There's another consideration.  The synthetic jetfuel would be produced by a variant of the Sabatier reaction.  This takes H2 from electrolysing water  and CO2 from the atmosphere and blends them at high temperatures and pressure in the presence of a catalyst to produce methane.  Once you have methane, other hydro-carbons can be made.  It seems inevitable that we will need to install more renewable capacity than we might on require on average to cater for consecutive days when the wind doesn't blow and the sun isn't shining strongly.  Ensuring grid stability with 100% renewables will likely require excess capacity as well as storage.  But that will mean that on days when the sun is shining and the wind is strong there will be excess electricity potentially available.  To stop the grid burning out, that surplus output will either have to be spilled, or output from wind and solar farms will have to be curtailed.  Which means, in effect, that that electricity will be free.  So the cost of producing synthetic jetfuel and synthetic natural gas could be much lower, given that their costs are high because the process is so energy intensive.  It's a win-win: surplus renewable power could be used to produce carbon-friendly jetfuel.