Green Days

There are few practical alternatives to jet fuel – for decades the practical application of hydrogen powered aircraft has been decades away; can you imagine the size of the batteries needed for an electric powered aircraft; and apart from perhaps high flying surveillance UAVs; solar power is totally impractical for aircraft.

So for now that just leaves biofuels, fuels manufactured from biological materials, with their promise that they will be ‘carbon neutral’, that is the equivalent carbon they release into the atmosphere when burnt in an engine is offset by the carbon absorbed by new plant growth in biofuel production. The promise is alluring, not just for the environmental benefits but potentially cost benefits too, once the price of oil picks up again when economic growth returns.

An Air New Zealand trial flight last December offered a quick peek at an alternative fuel future. The flight was only short, about two hours, and only one of the 747-400’s four engines was powered by a 50:50 blend of conventional jet fuel and a biofuel made from the oil of jatropha plant nuts, but it was a significant achievement pointing the way to aviation’s future.

Most significantly, Air New Zealand reported that the trial revealed no surprises, and the engine performed just as if it were powered by conventional fuel, despite tests that involved rapidly closing and opening the thrust lever to check for surges or flame-outs, and inflight engine shutdowns and re-starts.

The Air New Zealand flight followed a Virgin Atlantic 747‑400 trial earlier in 2008 (which had a 80-20 jet fuel/biofuel mix) and preceded a January 2009 trial by Continental Airlines of an algae-jatropha and jet fuel 50:50 mix in a 737-800. At the time Virgin Atlantic’s trial was dismissed by many, in Britain at least, as a stunt, but a new international standard for biofuel could be agreed upon this year, and commercially available biofuels for aviation seem likely to be available within three years. Further, biofuels offer the promise of useful improvements over jet fuel, including a lower specific gravity, higher calorific value and lower freezing temperature.

Still, biofuels won’t be an immediate silver bullet. The world airline industry burns something like 320 billion litres of jet fuel a year, so it will be many, many years before enough biofuel refining infrastructure is in place to provide a significant proportion of that amount.

And then there is the biggest criticism levelled at biofuels, that they compete for land that would otherwise be used to grow food, thus potentially pushing up food prices. But Air New Zealand says it chose jatropha for its trial as that hardy shrub can be grown on land unsuited for food crops. And the biofuel that offers the most promise for aviation is based on algae – which can be grown using waste or ocean water and has a yield per hectare 30 times that of other biofuel crops – even if its availability in commercial quantities is still some years off.

For now though the Air New Zealand trial represents an exciting glimpse of a greener aviation future, and is a good news story in an otherwise bleak aviation environment.

NANCY-BIRD From the perspective of 93 years on, it is hard to imagine the world as Nancy-Bird Walton was born into it. Powered flight was barely a decade old, as was women’s suffrage in Australia. So it’s certainly fair to describe Nancy-Bird as a true pioneer, learning to fly with Charles Kingsford-Smith as her early instructor, and becoming the youngest woman pilot to hold a commercial pilot’s licence in the British Empire.

Most of us of younger years will never know the obstacles Nancy faced and overcame to become a young woman pilot in the 1930s, but her passing in February (see p21) gives pause for reflection on the barriers she helped break down.

Aviation has always been a male dominated industry, but today it is at least no longer remarkable to hear a female voice announce over an airliner’s pa “this is your captain speaking”, while in December a RAAF C‑17 flew for the first time with an all-female crew. We can all be thankful to Nancy and other female aviation pioneers for showing what can be achieved with determination and perseverance, and in providing an inspiring example for all.