Flying Isn’t Going to Become “Green” or “Sustainable” Anytime Soon - Don’t Believe the Aviation Industry’s Hype
The aviation industry talks a lot about how flying is going to become “sustainable” or “green” in the near future. This is presented as an alternative to limiting passenger numbers and stopping airport expansions, as recommended by the government’s expert advisers on the Climate Change Committee. Meanwhile, the government has committed to cutting UK greenhouse gases by 78% by 2035 and scientists on the Intergovernmental Panel on Climate Change say we must make radical emissions cuts in the next 10 years. So the big question is: can flying become “sustainable” in the next 10-15 years? In a word: no. In a sentence: “Zero-carbon aviation is highly unlikely to be feasible by 2050.” Climate Change Committee, 24 September 2019.
But what about…?
More efficient planes?
By using better technology in newer aircraft, the aviation industry has, as recently as 2016, said it expects efficiency gains of around 1,5% per year in its kerosene (fossil fuel) use. However efficiency gains make flying cheaper, which encourages even more people to fly. Given that the aviation industry expects to grow by 3,7% per year, savings from efficiency gains are outpaced by the growth in the number of passengers and flights. That means overall more greenhouse gases are emitted from more flights. Efficiency improvements are good - they just need to be used to shrink emissions, not grow them. Learn more in this three minute talk.
Electric planes in development today are a long way from becoming commercial jets. They can carry up to 10 passengers for about one hour. The problem isn’t the propulsion technology but the energy storage - batteries simply weigh too much to make large scale, long distance flying commercially viable. Duncan Walker, Senior Lecturer in Applied Aerodynamics at Loughborough University, has concluded that the large passenger aircraft most people use are not going to be fully electrically powered any time soon. Electric flying may become viable for the smallest aircraft, flying short distances in the next decade. But electric flight will not cut greenhouse gases from large scale, long haul commercial flying, which accounts for the vast majority of greenhouse gases from the aviation industry. Learn more in this three minute talk.
Synthetic fuels made from electricity (such as hydrogen) are technically feasible, but there are almost no facilities to produce them yet and hydrogen weighs a lot more than kerosene to store in a plane. Converting electricity to fuel is also an energy intensive process. E-fuels could in theory be produced by surplus renewable energy and serve as storage technology in times of high wind or solar energy production. The problem is we are a long way from even producing enough renewables for transport on the ground or for manufacturing, agricultural production or heating. If all current planes were to fly with e-fuels, they would consume more than the existing renewable electricity in the world, leaving nothing for other sectors. Worse still is that the non-CO2 climate effects of flying remain – and these effects are at least two times the CO2 emissions. What’s more, hydrogen aircraft fuel will simply be very expensive compared to conventional aircraft using kerosene for the foreseeable future. Find out more in this three minute talk.
Alternative fuels are chemically equivalent to kerosene but produced from non-fossil fuel sources. There are two categories: biofuel and synthetic fuel. Biofuels cause more harm than good, as they intensify competition for scarce land and water resources around the world. For context, the wheat required to meet today’s aviation needs from biofuel is almost as much as humanity’s entire food calorie requirement (and remember the aviation industry plans to quadruple existing air traffic by 2050!). Synthetic fuel can be ‘scaled up’ without requiring as much land, but is very energy intensive. It's therefore a massive waste of our limited low carbon energy sources and in any case, it will be significantly more expensive than kerosene. Learn more in this four minute talk.
International aviation isn't included in the Paris Agreement to cut greenhouse gases. Instead, in 2016 the aviation industry created the "Carbon Offsetting and Reduction Scheme for International Aviation” (CORSIA). The idea is that airlines will have to buy credits when they emit CO2 and those credits will go towards reducing CO2 elsewhere. Essentially: ‘I don't want to reduce my CO2 emissions, so I'll pay somebody else who promises to reduce theirs…’ However, CORSIA has numerous weaknesses: from 2020 it’s voluntary and only becomes compulsory after 2027; it isn’t legally binding and there are no enforcement mechanisms to ‘police’ the scheme; it only applies to CO2 and ignores non-CO2 emissions, despite their large climate impact; it only applies to emissions in excess of 2019 levels, so the majority of CO2 emissions will not be offset at all. What’s more, the offsetting schemes used so far are very ineffective and the offset credits are far too cheap. For example, they will cost much less than $10 per tonne of CO2. As a comparison, the cost of capturing CO2 from industry is currently closer to $1,000 per tonne and is projected to reduce (best case) to $100 per tonne over the next few decades. This doesn't even include the costs of then storing the carbon, after it’s captured. Learn more in this four minute talk.