Actually, in my day-dreams I have dreamed quite long that there would be some technology that would make it economical from fuel cost point of view to operate helicopter ambulances as freely as it can be done with car-ambulances. Specially in more remote areas like Saaremaa, where the local hospital may reside tens of kilometers from the potential patients.
In my day-dreams I thought that it boils down to having some concentrated energy source, may be some new kind of atomic energy unit or something like that, which would reside on the vehicle and power the engines.
In my night-dream, which ended about 10min before I reached writing this sentence here, I had a revelation: the technology actually already exists.
You see, Saaremaa and Hiiumaa are very windy places. In fact the Hiiumaa is so windy that they even plan huge sea wind parks there that are capable of powering the whole Estonia. Electrolysis is an old technology for decomposing water to hydrogen and oxygen and people actually do it at home, for fun, using plain, small, batteries. Hydrogen gas engines already exist and using huge, pressurized, gas tanks on an helicopter is not a problem, because if one is going to fall with the hely, one is probably going to get pretty hurt, if not die, anyway and unlike commercial planes, the helicopters fly quite low, which means that one can probably design gas tanks that withstand the fall from the height that the helicopters typically fly to a sharp edge of a cliff. (Here is a video, where people shoot a gas tank with firearms.)
And there it is: an helicopter ambulance system with low-enough maintenance cost that probably even a small hospital can afford running it. Buying the helicopters and windmills is a different story, but it does not matter so much, because it's a single-time investment, at least in the form of the wind mills and hydrogen production infrastructure.
What regards to the dream, then actually, I wasn't fully asleep. I fell asleep about 5.00AM, after a huge effort to get a software release candidate ready by the morning, which I did not, and woke about 6.30AM (feeling truly fresh and surprised that I have slept just abut one and a halve hours) and then thought about the scene that I saw in my dream, where I had that revelation. It turned out that in my dream I was trying to get to sleep while lying in bed in a flat that had a same structure, floor plan, than in reality the flat in Saaremaa had, where me and my parents lived when I was just a few years old. The location of the bed in my dream matched with that of the real location and the size of the rooms in my dream were about the same as I saw the real flat, when I was a little boy.
So, yes, I sure had a dream, this time. A bit like the Mendeleev supposedly had. :-D
Actually, there was more in that dream, but it's a bit private, so I won't write it down here. Quite weird though.