Even if the Solar Impulse completes a successful circumnavigation, though – it would fly day and night – there is not much chance of a solar-power aviation industry emerging any time soon, if ever.
There seems no way for solar to power the loads required of civil aviation or to achieve the heights or speed required.
But the aviation industry is looking at alternatives to jet fuel that are practical and sustainable, and have a smaller carbon footprint, particularly in light of emission trading schemes that seem likely to be a feature of the world economies in coming years.
Air travel is estimated to contribute just two per cent of greenhouse gas emissions, but the industry’s high growth rate has raised concerns about future emissions. The European Union recently included aviation in the third phase of its emissions trading scheme.
The International Air Transport Association, which represents more than 230 airlines, or almost all the commercial airlines in the world, has set a target of using 10 per cent alternative fuels by 2017.
Although several options to reduce emissions are available, including synthetics known as Fischer-Tropsch fuels and first-generation biofuels, the industry is favouring so-called second and third-generation biofuels because they have the required high energy content, do not freeze at cold temperatures produce fewer carbon emissions and do not compete with food crops.
During the past 12 months, there have been at least four flights by leading airlines that have tested biofuels.
Virgin Atlantic flew a Boeing 747-400 with one engine operating on a 20 per cent mix of babassu oil – derived from the nut of a native Brazilian tree – and coconut oil. Air New Zealand flew a similar plane in December with one engine operating on a 50 per cent mix of biofuel from jatropha.
Continental Airlines flew a Boeing 737-800 in January with one engine using a 50 per cent mix of algae and jatropha, while Japan Airlines in January also flew a Boeing 747-300 with a 50 per cent biofuel mix containing jatropha, camelina (an energy crop grown in rotation with wheat and other cereal crops) and algae.
IATA and the airlines are still digesting the results, but the initial response is promising.
Honeywell, which provided the process technology to convert the second-generation, renewable feedstocks to green jet fuel, says the demonstration flights will have a tremendous influence on how the aviation community thinks about biofuels.
Honeywell subsidiary UOP’s renewable energy and chemicals unit general manager Jennifer Holmgren says the tests demonstrate that its technology produces “on-spec” green jet fuel from sustainable feedstocks.
She says commercial-scale production and usage of these biofuels in the aviation industry could be a reality in a few years, and having a substantial effect on aviation jet fuel supply within three to five years.
However, according to those providing the potential feedstocks, market accessibility and economic benefits still need to be addressed, as it is not yet clear that there is enough raw material to supply the entire aviation industry.
Read more at The Australian.