This is a long post, around 5,000 words, wherein I go down many rabbit holes. Perhaps at the end, though, there is a little pot of genuine climate gold.
At any given time there are more than half a million people in the sky, a veritable city about 11 kilometres up, strapped into seats in pressurised tubes atop gigantic flying tanks of kerosene. Looking forward, numbers of air travellers are increasing by 5% each year.
By the Rule of 72 the numbers could double and double again by 2050. Flights currently account for about 2% of anthropogenic CO2 emissions. This percentage will increase dramatically as emissions are eliminated from other areas of activity. While the 5% annual increase will probably taper, the likely prospect is that by 2050 emissions from flying will form a troublesome residue, difficult to eliminate.
So should people drastically cut down on air travel? The New Scientist recently took a look in an article by Paul Marks Our addiction to flying is ruining the climate, but it doesn’t have to:
- From simply flying planes in straighter lines to sucking fuel from thin air, a raft of new technologies that could help us fly guilt-free are in the offing
Now is this all just hand-waving, or are the possibilities real? I’ll try to assemble some information; you can make up your mind. It’s important that we know what might or might not happen.
Some basics about air travel.
Marks says that an average return plane ticket in 2017 was about 60 per cent cheaper in real terms than it was in 1995, which has driven much of the expansion in numbers. One would think that air fares are unlikely to become cheaper. Already the cost of air travel, say from Brisbane to Sydney, which is about 950 km, would be cheaper than other forms of transport if you place any value on time, and count accommodation and meals as appropriate.
A disproportionate amount of the energy used and the CO2 emissions caused comes in the take-off, so length of trip is critical. Wikipedia differentiates three categories of trips in terms of emissions per passenger kilometre:
- Domestic, short distance, less than 463 km: 257 g/km CO2
- Domestic, long distance, greater than 463 km: 177 g/km CO2
- Long distance flights: 113 g/km CO2
Wikipedia cites a 2013 study which found that the carbon footprints of business class and first class are three-times and nine-times higher than economy class.
Wikipedia also says that about 60 percent of aviation emissions arise from international flights, and these flights were not covered by the Kyoto Protocol and its emissions reduction targets. From the reference, that statement refers to the situation in 2010. Wikipedia then links to an October 2016 news item indicating that the United Nations’ aviation arm overwhelmingly ratified an agreement to control global warming emissions from international airline flight:
- The agreement, adopted overwhelmingly by the 191-nation International Civil Aviation Organization at a meeting in Montreal, sets airlines’ carbon emissions in the year 2020 as the upper limit of what carriers are allowed to discharge. Airlines that exceed that limit in future years, as most are expected to do, will have to offset their emissions growth by buying credits from other industries and projects that limit greenhouse gas emissions.
Participation is voluntary until 2028, when it becomes mandatory. Initially only 65 countries indicated they would participate, including the United States, China, and the European Union’s 44-nation aviation conference. Marks says make that now 72 countries. This now covers about 75% of international flying.
Countries must still act on their own to put the agreement’s limits into effect, and they are still responsible internally for internal domestic flights under the Paris Agreement. The article says that $181 billion was spent on fuel in the previous year, and that emissions were expected to treble between 2005 and 2050. Also if aviation were a country it would currently be the world’s seventh largest carbon emitter — larger than Canada or South Korea, but not as big as Germany.
The agreement is not expected to reduce emissions, simply limit their growth:
The International Council for Clean Transportation said its analysis shows the agreement will offset only about three-quarters of the growth in emissions from international aviation above 2020 levels.
Clearly, this situation is unsatisfactory.
I believe there are three general approaches to cleaning up the air industry – aircraft design and operation, alternative fuels (including a subset called ‘hybrid’), and offsets.
Aircraft design and operation
Marks was told that designing planes with better aerodynamics is ongoing, but the record over the last decade shows that a 1% improvement per annum is probably what we could expect.
A further gain could be made by reviving propeller-driven aircraft, which use fuel more efficiently, but are slower. Perhaps for freight handling. Generally speaking for personal travel people are in a hurry.
Planes stay in service for decades, so improvements in plane and engine design are too slow for the climate change agenda.
Then there is flight path control:
- Flight corridors are gradually being swept away by a new approach, called free route airspace, enabled by technologies like GPS and constant satellite tracking of planes. Each flight publishes its planned route in advance, then, as long as air traffic controllers monitor traffic, they can avoid clashes.
In Europe they say this will save 150,000 tonnes of CO2 per year. However, that’s only 0.02% of European emissions.
Better outcomes come from changing the practice of how planes reach maximum altitude. Aviation systems designers have found that cruising smoothly to full altitude rather than ascending in steps could save 10% of fuel. The concept is illustrated below:
Which brings us to the root cause, the use of fossil fuels. Most planes run on Jet A, an oil-derived chemical composed of carbon and hydrogen, which is basically kerosene.
First, lets look at electric planes powered by batteries. This is the bottom line:
- Large passenger planes that fully avoid kerosene are a long way off though, barring a huge tech breakthrough. Paul Peeters, a former aviation engineer now researching sustainable transport at the University of Breda in the Netherlands, has analysed the battery requirements of a 60-seater electric aircraft. “The battery, with current lithium technology, would have to be literally bigger than the whole aircraft,” says Peeters.
Yet Norway in June 2018 show-cased a two-seater plane (probably pay-walled) which took a few laps around Oslo airport. Norway hopes to electrify all air travel by 2040, but if it does it will be with more dense energy storage than is currently available. Battery technology would need to improve by an order of magnitude (at least).
Nevertheless, Airbus in the E-Fan X project is working with Siemens and Rolls-Royce:
- on converting a four-engine jet into a hybrid-electric plane, where one engine is replaced by an electric fan. A small engine hidden inside the plane will charge the batteries that run the electric motor, “like a Toyota Prius in the sky”, says Stein. The plan is for a test flight in 2020.
Boeing has a similar venture in Zunam Aero, a 50-seater with a limited range of 1100 km. This is how far you would get from London:
Boeing is claiming its plane will burn half the fuel of a similarly sized standard jet.
German firm E-Volo in Karlsruhe is working on a Volocopter, an electric two-seater vertical take-off and landing (eVTOL) aircraft that looks like an over-sized drone. A test flight is planned in Singapore this year, the first in a built-up environment. This development is seen as a real possibility for urban transport, so the EU and the Americans have begun a consultation on standards needed to certify eVTOLs.
Perhaps the most influential development came in 2008 when Joris Melkert at Delft University of Technology in the Netherlands flew a test jet with a fuel made from 95 per cent synthetic kerosene derived from natural gas. Melkert’s flight was not, I think, an eco-friendly development as such, but this is what followed:
- That fuel was synthesised from natural gas, but, in principle, synthetic kerosene from any source would be safe. That prompted ASTM International, which sets the standards on jet fuel, to rule that blends of up to 50 per cent synthetic kerosene could be used on flights. That in turn got the airline industry developing synthetic kerosene from crops. (Emphasis added)
There has been quite a lot of activity in using biofuels in the aviation industry, and some airlines offer customers the option of paying extra for biofuel when they make a booking. However, Marks reports that only 143,000 passenger flights have used biofuel blends in the past decade, a tiny fraction compared with the 39 million scheduled flights in 2018.
One of the more interesting is the BP Biojet project, which has been used in several airports in Norway and Sweden from 2017, and for a single day at Chicago O’Hare, one of the busiest airports in the world, in November 2017 as part of a proof of concept. In October 2018 the New Scientist reported on the project in an article How to make jet fuel from used cooking oil. BP does in fact collect cooking oil from restaurants, which would otherwise end in land fill where it produces methane emissions as it decays.
While there is more cooking oil available than you might imagine, they know that at best it could only provide a fraction of the fuel used by the whole industry. The BP project is part of their Advancing low carbon program. There BP advises that their Biojet blend reduces greenhouse gas emissions by more than 60% in comparison to the industry average fossil jet fuel. A footnote claims:
- A Life Cycle Analysis (LCA) was performed by SkyNRG (an independent certified operator, as a member of the Roundtable on Sustainable Biomaterials), on both SJF blends (BP-SPK-003 and -004), evaluating every step in the supply chain on its Green House Gas (GHG) emissions, up to and including blending at ST1 Terminal. It was taken into account that part of blend BP-SPK-003 was reused for making blend BP-SPK-004. Includes generation, use, disposal and re-use.
I’ll just point out that when they come to use sources other than cooking oil a new life cycle analysis would need to be done.
Of major interest is this comment in the NS article from Tom Parsons, Biojet commercial development manager at Air BP:
- It’s not yet possible for an aeroplane to fly solely on aviation biofuel. Instead, it has to be blended with conventional fuel. “You can have a one-to-one ratio of the biofuel with the conventional jet fuel,” says Parsons. This limit arises because aviation fuel needs to contain a small amount of ring-shaped organic molecules called aromatics. “The aviation biofuel doesn’t have any.”
I have never heard of this before. If true it places a cap on the utility of biofuels. There is also a question as to whether that same cap applies to synthetic hydro-carbon electro-fuels, where the inputs are air and water and green power, or to fuel made from the direct capture of CO2 from the atmosphere, I do not know. I suspect it does.
- Even if biofuels were widely used, there is concern over the impacts of growing the feedstocks. Would it displace food crops? And how much carbon is emitted generating the energy used to turn crops into fuel?
Boeing has a number of projects investigating the best sources of biofuel, including forestry waste in Canada, nicotine-free tobacco in South Africa and seawater irrigated plants in the United Arab Emirates. These all produce small amounts of fuel.
Better would be to make a synthetic fuel using carbon sucked from the air, so no net carbon is released when it is burned. This was first demonstrated by a company called Air Fuel Synthesis in 2014. In June 2018, a Canadian firm, Carbon Engineering, showed that it had got the cost of removing 1 tonne of CO2 from the atmosphere down to between $94 and $232, at least a third cheaper than previous estimates. But the challenge is to emit less carbon making the fuel than you save by avoiding oil-derived kerosene. And that’s tough. Tellingly, Air Fuel Synthesis quietly folded in 2016.
The first two links are to NS articles, no doubt pay-walled. In the first we are told that the promise of ‘carbon capture and use’ (CCU) is a burgeoning industry that has attracted billions of dollars in investment, some of it from major oil and gas companies.
There are two very basic problems. Firstly, it is hard to break the bond between the C and O atoms, so the search is on for the appropriate catalyst.
Secondly, there is no significant existing market for CO2. The global demand for CO2 was reckoned in 2011 as about 80 million tonnes each year, a mere 0.2% of emissions at that time. The fizz in drinks does not need a lot of CO2. However, here’s an image of Sunfire in Dresden, Germany, using water and CO2 to make liquid fuel:
With the co-electrolysis of Sunfire, CO2-neutral synthetic crude oil can be produced from water in combination with carbon dioxide and green electricity via syngas. The so-called e-Crude consists of various hydrocarbons and can replace crude oil in conventional production processes. Existing infrastructures can continue to be used with renewable resources. Industries that cannot be electrified, such as long-distance transport, aviation and shipping or even the chemicals sector, thus become more climate-friendly without adjustments and restrictions.
Marks’ article, which began with the title Our addiction to flying is ruining the climate, but it doesn’t have to (emphasis added), actually ends with no satisfactory answers at all. His final para quotes Paul Peeters, who said above that batteries would need to be literally bigger than the whole aircraft:
- He thinks the only solution is to find a way of limiting the number of flights, perhaps through an international agreement that goes far beyond what the UN has brokered so far. “We cannot count on these measures,” he says. “It is way too late.”
What this says to me is that the only way forward is through offsets – offsets that genuinely offset the carbon emitted in a more or less immediate time frame. My beef with using tree planting as offsets is that it takes around 50 years to offset the carbon emitted, long enough to cook the planet. Before I deal with offsets, however, I need to refer to two papers that have a major bearing on the subject which have been referred to in the long discussion of green flying on Climate clippings 229. The first is:
Twenty-First Century Snake Oil: Why the United States Should Reject Biofuels as Part of a Rational National Security Energy Strategy, by Captain T. A. “Ike” Kiefer, January 2013
We need to be clear that Kiefer’s focus in not on climate change mitigation, it’s on national energy security and in particular the effectiveness of the US Military program of funding biofuel research and development. He does have a short section on CO2 and climate change (11.2), wherein he mainly says that it is smarter to sequester CO2 in plants than to burn those plants for energy.
However, when you consider Kiefer is writing 6 years after James Hansen told us we must take CO2 out of the air to reach concentrations of 350 ppm, not having that front of mind cannot be excused. Moreover, if security is his thing, he should have been aware of Gwynne Dyer’s book Climate Wars (2008), which sees climate change as an existential threat, having written it after consulting leading climate change and security experts.
It’s a while since I’ve looked at biofuels in any comprehensive way, certainly well prior to 2013. My default view has been that only sugar cane returned sufficient energy for the energy invested in producing it. The world would benefit by consuming less sugar, so the common conflict with food production did not apply in the same way. Still there were questions about the large scale environmental effects of devoting so much fertile land to fuel production. Kiefer certainly blows sugar out of the park.
Without going into the full deal, biofuel from sugar is commonly produced from bagasse, the waste straw left after sugar production, which is very different from sugar. However, if you produce sugar solely for biofuel you still come against the problem of turning solid cellulose into a liquid. Sugar performs not much different from the rest.
His measurement tool is ‘energy return on investment’ (EROI), a ratio derived from dividing the ‘energy usable in newly produced fuel’ by the ‘energy consumed in producing the new fuel’ having regard for life-cycle factors as well as storage and delivery infrastructure. Here’s the formula courtesy of a screenshot:
One would think that if the ratio was greater than 1:1 then we would be in front. Not so. Our economy and lifestyle depends on a high EROI. He finds the US EROI is 12:1. Historical studies show that when the ratio dips below 6:1 the economy slides into recession. At 3:1 basically we starve.
Corn ethanol comes in at 1.25 to 1. Brazilian sugar was thought to be 8:1, but more thorough measurement brought that down to less than 2.
What it means is that our energy economy under biofuels would have an efficiency somewhere between the Stone Age and Roman society.
Kiefer is not keen on algae. Its a complicated story, and there may be some role for algae-based liquid fuel as a byproduct if the algae is used for other things. In the end liquefying cellulose takes considerable energy, and it’s better to shovel the stuff directly into a furnace.
Kiefer has a fascinating Section 13: Can a Technology Breakthrough Save Biofuels? Firstly he says the EROI of biofuels is limited by the maximum theoretical performance of photosynthesis.
It happens that the very latest issue of the New Scientist has an article Fixing a flaw in photosynthesis could massively boost food production. The print version has the title Evolution’s biggest mistake gets fixed.
Photosynthesis is notoriously inefficient. However, scientists at the University of Illinois have used GM modification to boost photosynthesis efficiency by 40%. For some reason they were working on tobacco, but are now trying the same technology on food crops like cowpeas and soya beans.
I’m not smart enough to work out what difference that would make.
Secondly, he says that if you are going to use fossil fuels to grow plants and then convert them into biofuels you are always going to be chasing your tail. Those were not his words, he says:
- Converting fossil fuel hydrocarbons into plant carbohydrates and then back into hydrocarbon fuels is a futile attempt at perpetual motion in chemistry.
However, he also says:
- The way out of this dilemma is to have a plentiful supply of hydrogen from a non-fossil fuel source, and the only prospect for doing this in sufficient quantity is to electrolyze hydrogen from water using nuclear power.
- However, if we had such a surplus of nuclear power electricity and hydrogen, we would use these directly for energy and fuel and not mess around with the inefficient middleman of biomass. This litany is the inescapable Catch-22 of biofuels.
Fair enough, but nuclear powered aeroplanes?
Section 14: Conclusions and Recommendations is worth a look. Inter alia, he says that military dependence on petroleum is less of a national security risk than dependence upon biofuels. He states that proven reserves for petroleum are robust and growing. If, however, we look like running out of oil:
- the government should ensure there is excess electrical capacity from non-oil and gas power plants to electrolyze sufficient quantities of hydrogen from water for transportation fuel purposes.
That’s para 12 of Section 14, p54 on the pdf counter. If he had seen burning fossil fuels as verboten, as he should have done, he would have been talking up a very different story. In the same year, our John Davidson, who did understand that burning fossil fuels would have to cease, outlined the potential of liquid fuels from air, water and renewable power.
Certainly the cost in dollars is another matter. But if the burning of fossil fuels must stop, is there any alternative? In my view the cost in dollars must be paid, even if it means lowering our standard of living, or we have to arrange our affairs to do without aeroplanes. That seems socially and economically close to impossible.
Turns out there is at least one alternative, as we turn to the report for the EU:
Novel carbon capture and utilisation technologies, Scientific Opinion 4/2018 by the Group of Chief Scientific Advisors
. The aim was “to provide scientific advice on the climate mitigation potential of CCU [carbon capture and utilisation] technologies, in particular CCU technologies that are environmentally safe and that may offer substantial climate benefits.”
The big question for me is, were they seized by a sense of urgency appropriate to an existential climate emergency? Clearly not. The approach is to do what is currently economic, to gradually transition to a virtuous future, as long as we get there about mid-century that will be OK. So when they contemplate capturing CO2 from flues from existing processes on its way to the atmosphere, that’s OK for now, while noting that it is really just making a second use of molecules that really shouldn’t be going into the atmosphere in the first place. In the end we’ll get to sucking free ranging CO2 molecules out of the air, but that would be more expensive than going for CO2 spewing out of industrial processes, which are still licensed to dump their CO2 into the air. And yes, there are still technical challenges, and basically no market for using CO2 as noted earlier.
They do address the important issues of accounting and accountability, and recognition as to how long any CO2 molecule is held (bound) before it escapes again.
In relation to transport, there was this in Chapter 6 Statements and recommendations:
- In the medium (2030/40) and long term (2050 and beyond) – [CCU] may contribute to the de-fossilisation of the energy and transport systems [by using excess variable renewables] to store in fuels for the use in high energy density needs (long haul flights and long distance shipping) as well as possible storage medium for power system.
In other words, CCU is worth spending research and development money on, maybe also subsidies, for its potential in the future. They’ve spotted that renewable energy is sometimes available in excess of power needs for limited periods. Readers of this blog will no doubt know that already on the NEM there are times when spot prices have been reduced to zero or lower, especially in South Australia.
We’ve reached a point, then, when we know that there no fully green answers to the airline industry at large available now. Perhaps there never will be, if a 50% mix is the maximum allowable technically. In that circumstance I believe we are bound to fully offset GHG emissions caused by aeroplanes. It should be in the price of the ticket or the freight charge.
Of course you can indeed opt to offset an air flight now. I tried Carbon calculator, which told me a trip to Sydney and back would produce 0.24 tonnes of CO2, which could be offset for £1.81. The CO2 sounds about right from the figures at the top of the post, but the cost is literally unbelievable.
Happens there is a commercial venture Carbon Engineering, with a demonstration plant in Squamish, BC, Canada which has developed a Direct Air Capture (DAC) process. This is the summary from Fortune magazine:
- With DAC, air is filtered through a non-hazardous chemical absorbent that captures about 80% of the air’s carbon dioxide content. The chemical substance drops to the bottom, while the cleaner air is released.
The collected CO2 then goes through a series of purifying processes, eventually producing a pure version that can be stored underground, turned into a carbon-based product, or-as clean energy company Carbon Engineering suggests—synthesized into cleaner transportation fuels.
Purified carbon dioxide fuel would create a circular system of emissions: your car runs on fuel made from the air’s CO2 (emitting CO2 back into the air), and a facility captures this CO2 again to make more fuel.
“So the net CO2 emission is zero,” Steve Oldham, CEO of Carbon Engineering, told Fortune. “It’s all working, we’ve made fuel. The next step for us to is scale up.”
A fourth option for disposing of collected carbon dioxide is enhanced oil recovery, or using atmospheric carbon in the oil drilling process. Oil drilling already uses CO2, but using a purified version from the atmosphere buries the carbon dioxide below ground, while also supporting oil-based economies.
Frankly, I don’t understand the scientific and technical process. However, the claim is that CO2 can be captured from the air for less than $US100 per tonne.
- enables the production of synthetic transportation fuels – such as gasoline, diesel, or Jet-A – using only atmospheric CO₂ and hydrogen split from water, and powered by clean electricity.
They say they can produce fuels for less than $1.00/L once scaled up, making them cost-competitive with biodiesels.
The scientific paper water cost them 10 cents per cubic metre. Water costs can vary, but they say as an upper bound, seawater desalination would only add roughly 5$/tCO2.
It all seems too good to be true. Is there a catch somewhere?
The firm received considerable support from government agencies and foundations. Occidental Petroleum Corporation and Chevron have now made equity investments into the company.
Looking at the Brisbane-Sydney trip, offsets at $100/ton converted at $US70 cents to the AUD, I make the added cost of a return trip about $34. Google told me the cost of a one-way ticket was “from $148”. That is no doubt a budget carrier. Given first class, business class etc I’d guess that airlines could incorporate offsetting with a 10% increase of fares, or perhaps less.
To save the planet, that would seem a reasonable price to pay, and would not greatly inhibit air travel. However, that is definitely outside my area of expertise.
Then we have the really cheap airlines, like Tiger, which I’m told will charge $60 to $70 for a ticket from Brisbane to Sydney. For those customers a $17 increase may well be too much. Surely they have as much right to visit friends and rellies as anyone else.
I can only say, it is not the airlines job to solve inequality issues in the world. In a just world, they should be able to fly.
The bottom line is that there is indeed a catch. It’s this.
Carbon Engineering’s prime aim is to make shitloads of money. When the carbon is removed from the air it needs to go somewhere. Turning it into fuel puts it back into the air, but not in a completely carbon neutral manner, even if renewable energy is used to power the process. Carbon used for other purposes does not always lock up the carbon forever as noted by the EU group above.
David Roberts has had a close look at this issue in
- Sucking carbon out of the air won’t solve climate change But it might fill in a few key pieces of the clean energy puzzle.
The problem with my Brisbane-Sydney example above is that the captured carbon must be used or buried. Roberts says what he calls Carbon Engineering’s A2F provides, by a fair measure, the lowest carbon fuel around:
Carbon Engineering’s commercial strategy is to sell low carbon fuels into the sizable market in California, which has introduced:
- a low-carbon fuel standard (LCFS) that requires fuels sold in the state to steadily decline in carbon intensity. In practice, that means companies that sell fossil-based fuels have to source some lower-carbon fuels to offset them, through a credit trading system.
Right now, credits under the LCFS are trading for $150 per ton of carbon. That is meant to be the source of Carbon Engineering’s initial financing, funding its effort to scale up.
Ultimately CE will make bucket loads by licencing its technology.
Currently no-one pays anyone to put the carbon into the ground. In a couple of decades, when governments wake up to the fact that CCS is actually necessary for the future of the planet, CE will be in prime position.
Roberts says he know of one other competitor to Carbon Engineering. It’s Climeworks, with demonstration facilities in Zurich and Iceland.
Carbon Engineering’s commercial strategy is based on doing climate change mitigation at a doddle, overshoot on our Paris targets, and then suck carbon out of the air later. That is recklessly dangerous and playing dice with the future of our progeny and a living planet. It is in their interests that the necessary changes come over a few decades, not urgently ASAP.
James Hansen in Climate change in a nutshell p45 says that CO2 can be buried for about $20/ton. If so that would add about 2% to the example I gave above, which is not a game changer.
An advantage with DAC is that you can do it where you intend to bury the carbon, as long as there is water and renewable power. No transport of massive amounts of CO2 is necessary.
If we want to act urgently, faster than the market solution currently being contemplated, two things need to change. We need political will and international co-operation. Mandate genuine offsets and have the airlines put it into the price. The money collected goes into developing and implementing the genuine carbon capture industry, by whatever means is appropriate.
Hansen’s figure, which seem in the ball park, see us spending trillions of money on capturing and storing carbon from the air. These figures seem large, but are roughly commensurate with what the world spends in defence, and a fraction as a proportion of GDP of what we spent saving the world from fascism in World War 2.
Time to act, not just for the airline industry, but to keep the third rock from the sun in a goldilocks state for life.