alt.energy.renewable

-> True, but this isn't very useful for travelling across rugged or
-> politically hostile terrain, water or similar.

Flying in an airliner over politically hostile terrain isn't such a
great idea, either. Remember what happened to that Korean jet that went
into Soviet airspace back in the 1980s. Mind you, I was once in a Cuban
plane that over-flew the United States, which was forbidden at the
time. What the pilot told the controllers on the ground, I don't know,
but he managed to get us to Toronto nearly two hours ahead of schedule
by not going all the way up around the north of Maine. But we probably
wouldn't have been shot down if the Yanks had found out. Probably...

Trains are great for travelling between cities that are not too far
apart, on tracks that carry a lot of traffic. But building and
maintaining the tracks is expensive, both financially and
environmentally. If they have to be very long, or don't get much use,
the costs can outweigh the benefits, compared to planes.

dow