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The third runway by the numbers

Last week the project proposal for a third runway at Heathrow in London was put on hold after a successful court challenge based on climate concerns. The courts sided with the plaintiffs who argued that the proposal did not adequately demonstrate how its overall emissions impact would be managed given that the UK has now adopted a target of net-zero emissions in 2050. While the emissions from the project itself are modest, with cement probably being the largest component, the ongoing emissions from aviation expansion as a result of the project could be considerable on a cumulative basis over many years.

At this point I should note that the third runway at Heathrow has been a contentious project since it was first proposed and there are many reasons put forward as to why it should or should not be built. My focus here is on the expected expansion of aviation in and out of the United Kingdom and the resultant emissions. Aviation has grown rapidly over the half century since the introduction of the widebody Boeing 747 (by which point it had grown considerably since the first intercontinental jet services some twenty years prior), to the extent that there are now over four billion passenger flights per year globally.

Of course airlines, airports and aviation companies are responding to a strong demand signal from consumers (the UK is an island). In order to drive change consumers also need to understand their own externalities and be prepared to manage them, most likely by a cost passed through with the ticket purchase.

A 2017 UK Department of Transport assessment of aviation showed growth for both capacity constrained and unconstrained scenarios, with the low constrained case showing a 60% rise through to 2050 and the high unconstrained case showing a doubling of demand.

Heathrow consumes about 20-25 million litres of Jet-A1 every day, so a third runway would increase this by 50%, or some 10-12 million litres per day.

A double check based on aircraft efficiency and expected distance of travel gives a similar number. If we assume that the runway operates for 18 hours per day with a flight interval of 90 seconds, with 50% of the time being used for take-off, that implies 360 additional departing flights every day. If we then assume that every flight is dedicated to longer haul, say New York or Dubai, then that means about 37,000 litres of fuel per flight based on the improved efficiency for modern aircraft of about 2.2 litres per 100 km per passenger, 300 passengers and some 5,500 km of travel, or a total of just over 13 million litres per day.

The consumption of 13 million litres of Jet A-1, 365 days a year, will result in the release of about 12 million tonnes per year of carbon dioxide when combusted. So the question that needs to be asked is how the mitigation of 12 million tonnes per year will be organised such that it has reached net-zero by 2050.

The answer lies with the sector itself, not just the airlines that own the planes or the companies that make them or the airport that is building the runway or the fuel providers that sell Jet A-1. All these parties will have to collectively own the problem and set about solving it. There are already the beginnings of some answers, but efforts will need to be accelerated such that the question posed through the court in relation to the net-zero goal of the UK can be confidently answered. For example;

All the above are still in their early stages of development and deployment, with bioJet looking to be the most promising immediate option. Nevertheless, over the coming thirty years it should be possible to bring UK aviation emissions to net-zero through some combination of the above.

But who should be responsible for implementing the strategy? Within the aviation industry, a framework already exists under which all this could be managed.

The airlines have already agreed and are now beginning to implement the CORSIA framework under the auspices of ICAO. This sets out a journey through to 2035 which will see global aviation emissions limited to current levels. It includes a facility to balance emissions through a trading arrangement where they cannot be directly mitigated through fuel changes, although the final rules of this have yet to be agreed and will involve Article 6 of the Paris Agreement. In almost any aviation scenario there will be unmitigated aviation emissions in 2050. CORSIA will need to evolve further after this first phase to be aligned with the emerging net-zero goals in many countries with major aviation hubs. The trading arrangement will eventually need to focus on removal of carbon dioxide from the atmosphere in combination with geological storage.

This form of emissions challenge to projects and development may well become more frequent, not just from campaigners but also from regulators, as the governments they represent grapple with the task of getting to net-zero emissions. There will likely be a real shift in focus from the projects themselves and their subsequent operation (i.e. Scope 1 plus Scope 2 emissions), to the broader impact they have on societal emissions (i.e. Scope 3 emissions). That will place more onus on project developers to think through and then manage the broader implications of their actions.

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