David Strahan, an author whom you should definitely read on a regular basis, has a longish, excellent post on his site delving into the nooks and crannies of the problems higher oil prices and the growing pressure to omit less CO2 present to airlines.

I can’t hope to do his post, How do you solve a problem like jet fuel?, justice, but let me give you just a taste:

First, the airline industry is rightly seen as the cuckoo in the nest of carbon reduction. Britain is now legally bound to cut CO2 emissions 60% to 65MtC by 2050, but under the government’s “best case” projection UK aviation alone will emit 15.7MtC in that year, almost a quarter of the economy’s entire carbon ration. According to the Tyndall Centre for Climate Change, if the additional “radiative forcing” impacts of aviation are taken into account, that figure could rise to over 100%. Either forecast is of course entirely unsustainable.

Second, aviation is uniquely exposed to peak oil. Whereas ground transport could in theory be completely electrified and run on renewable power, for jet engines there is no alternative to energy dense liquid fuels. And while soaring crude prices are already hammering airline finances at $110 per barrel, analysts Goldman Sachs now forecast potential spikes of $150-$200, a risk Sir Richard acknowledged during his biofuel launch: “In about four or five years’ time there’s going to be more demand for fuel than there is fuel on this planet. So fuel prices will go through the roof, and we’ve all got to come up with alternatives”.

If airlines are to have any chance of staying aloft in post-peak, carbon-constrained world, they must quickly find an alternative fuel with low emissions, but one which also matches the stiff technical standards of jet kerosene. Because planes have to lift their fuel into the sky, and carry every gallon for the entire journey, it has to be energy dense. Because they fly at altitude, it needs to remain fluid at minus 50C. Because they fly long distances, chemically identical supplies must be available all over the world. And because they have long lives, the new fuel must be compatible with the existing fleet. What’s needed, in other words, is an exact replica of fossil jet kerosene – a so-called ‘drop-in’ replacement – which also emits substantially less carbon. “Meeting all these conflicting demands is a very tall order” says Dr Mike Farmery, Global Fuel Technical and Quality Manager at Shell Aviation. “There are lots of exciting ideas, but it will be hard to achieve quickly”.

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In the context of global aviation, the numbers are even more daunting. To produce the world’s current jet fuel from BTL would require – assuming the average European crop yields suggested by Mr Blades of 10 tonnes of biomass per hectare - nearly 1.2 million square kilometres. That’s well over three times the size of Germany, and makes no allowance for the predicted rapid growth in aviation. On the same assumptions, replacing all current transport fuel requires more than 10m km2 – bigger than China – demolishing any claim that second generation biofuels would not compete with food production.

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The biggest shortage may be not so much space as time. At the Virgin launch, Sir Richard suggested that algae might produce enough fuel for the entire airline industry, and that such technological breakthroughs represented the only chance of mitigating peak oil, which he said could arrive within six years. But when asked if fuels like jatropha or algae could be ready by then, he did not sound so confident: “we have to try our best to make them available as fast as we possibly can”.

One of the things I’m grateful for in this life is that I’m not the one tasked with finding a way to keep commercial airlines flying anywhere near the same number of seats in five or ten years as they do today.

Barring some sort of techno-econo miracle, I can’t see how the airlines avoid a significant reduction in their passenger volume in the coming years. Flying is getting more expensive and far less pleasant, thanks to more crowded planes and passengers feeling like they’ve been nickeled and dimed to death, which will only push people to using alternatives, like making more use of trains and teleconferencing.

One of the biggest changes will simply be people not making trips. Very few people in the US can afford the time to travel from NY to LA via train, and teleconferencing isn’t much good as a substitute for attending a relative’s wedding, for example.