Solar Impulse
Bertrand Piccard, latest scion of the family of balloonists and inventors, is going to fly an aircraft called the Solar Impulse around the world. Solar Impulse is, as the name suggests, a solar-powered, heavier-than-air vehicle.
For climatic and mineralogical reasons, we need to use less oil; indeed, it would appear that we need to use as little as possible. For many applications, that’s not such a big problem. From the point of view of charging your mobile phone or watching your television, it doesn’t matter how your electricity is generated. Trains are frequently electric and advances are being made in storage, efficiency and regeneration that also apply to cars.
The particular problem aircraft face is energy density. Avgas offers a balance of energy per unit mass and energy per unit volume (that is to say lots of energy in a compact form that’s not excessively heavy). Hydrogen has lots of energy, but you need a big volume of it; aluminium has lots of energy, but you need a big mass of it. Avgas is in the goldilocks zone. It doesn’t seem that solar power is going to replace jet fuel in the near future; Solar Impulse carries one person, has a wingspan slightly larger than the A380 and requires materials with densities about one-twentieth that of traditional aerospace materials.
However, even small differences count. If solar power could be used, for instance, to provide hotel electric power – for cooking, cabin lighting and so on – that would reduce the amount of fuel needed to be carried. The A380 has a wing area of 845 square metres. More importantly, I would say, is that Solar Impulse will push for lighter aerospace construction materials, which all helps to save fuel.
xD.
