Dreaming of electric planes and planting trees will not save our planet

By Professor Julian Allwood  – The writer is professor of engineering and the environment at Cambridge University

FEBRUARY 7 2020 (FT – Opinion, climate change)

The UK aviation industry this week promised to bring its net carbon emissions down to zero by 2050 while growing by 70 per cent, and Prime Minister Boris Johnson boldly predicted that “viable electric planes” would be available in just a few years.

But past experience with innovation in aviation suggests that such ambitious targets are unrealistic and distracting. The only way the UK can get to net zero emission aviation by 2050 is by having a substantial period of no aviation at all. Let’s stop placing impossible hopes on breakthrough technologies, and try to hit emissions targets with today’s technologies. Our recent report “Absolute Zero” draws on work at six British universities to explain how.

Wellington Airport’s expansion plans at odds with city’s zero emissions plan, environmental group says [RNZ, 05/02/21]

There are three ways to deliver net-zero aviation: invent new electric aircraft, change the fuels of existing aircraft or take the emissions out of the atmosphere.

Electric planes already fly. Solar Impulse 2, powered by solar cells flew one person round the world in 2016, but slow progress in photovoltaics mean this is unlikely to scale up. Demonstrations of short battery-powered flights with a few passengers will soon begin. However, the technology is in its infancy and aerospace is, rightly, a highly regulated industry. Commercial long-haul electric flights will not be operating at any significant scale by 2050.

Alternative fuels, such as hydrogen or synthetic kerosene, only deliver zero emissions flight if their production is powered by renewable electricity. Right now, green sources supply about 15 per cent of the world’s primary energy consumption. Over the next 30 years, while road vehicles, heating and industry are being electrified, there is unlikely to be spare clean power to make aviation fuel.

Finally, there are currently no meaningful negative emissions technologies. It requires more energy to recapture carbon dioxide from the atmosphere than was generated when it was released. Using renewable electricity to power carbon capture rather than to displace fossil fuels does not create a net reduction. And tree planting only goes so far: we must increase the total area of forest in perpetuity to produce a one-off reduction in atmospheric carbon dioxide.

So the commitment to net zero aviation by 2050 is really a commitment to zero aviation. Rather than hope new technology will magically rescue us, we should stop planning to increase fossil-fuel flights and commit to halving them within 10 years with an eye toward phasing them out entirely by 2050.

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