Scientific report questions net-zero...

Global co-ordination would be required to achieve goals, warns Royal Society science academy

There is no single, clear, sustainable alternative to jet fuel able to support flying on a scale equivalent to present day use, scientists have warned.

Producing sustainable aviation fuel to supply ‘net zero’ ambitions would require enormous quantities of agricultural land or renewable electricity to keep flying at today’s levels.

A briefing by the UK's the Royal Society science academy estimates that meeting existing aviation demand entirely with energy crops for the UK alone would require around half of UK agricultural land. Meanwhile, producing sufficient green hydrogen fuel would require 2.4 to 3.4 times the UK’s 2020 renewable – wind and solar – electricity generation.

While alternative aviation fuels will likely have an increased cost, persisting with traditional kerosene jet fuel is likely to become increasingly expensive as decarbonisation in other sectors accelerates, the report notes.

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It explores challenges to the availability of new resources, as well as likely costs, life-cycle impacts, infrastructure requirements and outstanding research questions across four fuel types – green hydrogen, biofuels (energy crops and waste), ammonia and synthetic fuels.

“While each fuel type has advantages and drawbacks, the findings underscore the challenges of decarbonising aviation, especially when resources are likely to be in global demand for a range of ‘net-zero’ objectives,” the Royal Society said.

The report also identifies “significant research requirements” in scaling up net zero fuels, from storage and handling, to environmental impacts including CO2 and non-CO2 emissions.

Global co-ordination would be required, particularly for navigating the transition period between current and future generation aircraft.

Professor Graham Hutchings, professor of chemistry at Cardiff University in Wales and chair of the report working group, said: “Research and innovation are vital tools for the delivery of net zero, but we need to be very clear about the strengths, limitations and challenges that must be addressed and overcome if we are to scale up the required new technologies in a few short decades.

“This briefing tries to pull together those realities, to allow policymakers to understand the future resource implications of today’s policy and R&D decisions, and to support international dialogue on this global technology transition.”

Professor Marcelle McManus, director of the Institute for Sustainability at the University of Bath and a working group member, added: “How fossil fuel alternatives are produced is critical, as this is how we measure their sustainability across the entire cycle of their use.

“We need consistency, and we need to apply this globally, because adopting any of these new technologies will create demands and pressures for land, renewable energy or other products that may have knock on environmental or economic effects.”