Airlines’ Net-Zero Pledges Fly on Fumes

by Ed Cropley (Reuters) ... Last month the International Air Transport Association (IATA), the airline industry body, said it wanted aviation’s net carbon footprint to fall to zero by 2050. That’s as it should be. Its own forecasts assume emissions grow 3% every year, meaning roughly 2 billion tonnes by 2050. Because other sectors are decarbonising rapidly as they move to zero-carbon technologies, aviation’s relative proportion of global emissions will increase. The catch is that cutting from 2 billion tonnes requires solutions that right now are expensive, futuristic, or both.

The first port of call is biofuel, one of the sustainable aviation fuel (SAF) options. The CO2 benefits derive from feedstocks like reused cooking oil or agricultural waste being part of the atmosphere’s existing carbon cycle, rather than fossil fuels that have trapped carbon underground for millions of years.

The good news is biokerosene is a near-perfect substitute, requiring minimal engine tweaks. Biofuel blends are already in limited commercial use. By 2023, Rolls-Royce’s (RR.L) new long-haul engines will be able to run on 100% biokerosene.

The bad news is that, overall, they still produce some CO2, reducing emissions by at best 80%. They’re also expensive. At three times the price of normal kerosene, biofuels upend aviation’s economics.

Availability is an even bigger challenge. Airline bosses have rightly red-carded feedstocks like palm oil or soybeans that endanger forests or food security. But there’s only so much old cooking oil lying around, and efforts to get SAF off the ground so far haven’t amounted to much – 100 million litres of annual production. IATA’s roadmap points to that soaring to 450 billion litres, a staggering 4,500-fold increase.

That said, a 25% biofuel blend would shave a fifth off CO2 emissions, bringing mid-century CO2 output to just over 1 billion tonnes. But it would add 50% to aviation’s fuel bill.

From a pure carbon perspective, biofuel’s chemical cousin e-kerosene scores higher. Its base ingredients are water and CO2 captured from the air. The water is split into oxygen and hydrogen using electricity from renewable sources; the hydrogen is then combined with the CO2 to create a hydrocarbon.

Again, price and availability are problematic. With no existing commercial production, it’s hard to say what e-kerosene will cost. But if it was cheaper than biofuels, it would already be in use. And the energy input is colossal. Brussels lobby group Transport & Environment thinks Europe’s 2050 fleet would require 535 terawatt hours of green electricity, 1.6 times Britain’s entire electricity consumption last year.

Assuming complete carbon efficiency, adding a 25% e-kerosene blend to the mix would take aviation’s emissions down to 780 million tonnes, but inflate its fuel bill by another third.

Yet batteries’ weight remains problematic. Barring an Elon Musk-style technological breakthrough, electric planes will thus be confined to city- or island-hopping for a few dozen passengers, generating negligible CO2 savings.

Hydrogen is theoretically promising, but entails a major rejig of the traditional airframe – in liquid form, it is at minus 253 degrees Celsius and takes up three times the space of kerosene with the same amount of energy.

The outlook, for airlines, is therefore not encouraging. In the absence of a technical hack, flying demand will have to fall. That may come from sharply higher operating costs feeding through to higher ticket prices. But governments may also feel the need to impose punitive taxes or regulation.

As during the pandemic, business travellers can probably make do with remote substitutes, especially given the inevitable telecommunications advances. Barring the advent of an airborne deus ex machina, the days of mass-market leisure aviation look numbered. READ MORE