Thermoelectric devices are available now that run on propane, last 30 years without maintenance, have no moving parts, are very reliable, fairly small, and oh, so expensive.
I can not afford one, but it seems like an elegant solution to the problem of electric power in remote locations. Compared to fuel cell technology, though, they seem quite attractive.
Here's a link for more specific information. Global Thermoelectric - Home
My own solution is yet to be achieved, but I think I will build a permanent magnet DC alternator and run it using a bicycle. They are very efficient, produce power at low rpms, and won't wear out if the bearings are heavy duty, since otherwise there is no contact like with brushed generators. With modern niobium magnets they have reached the point of practical utility.
I have considered windmill, waterwheels, human power, solar panels, you name it. Of course, the easiest yet affordable solution is a gas powered generator, but I don't want to use more gas and have the noise.
Presently, I have two 60W solar panels atop my '58 Bubble, but they don't keep up with my power needs unless it is totally sunny and summertime with the sun up high. The array is not aimable yet, but the mounts I made can be upgraded for some additional angle adjustment. Even that won't give me the juice I want, and additional panels would have to be ground mounted since there's not much more roof on my little twinkie. I already have over $500 in the two 60-watters. By the way, I have not seen the official output claimed by the manufacturer, even at noon in June, so get more wattage than you think you'll need. Without direct sunlight, you get hardly any charge amps.
Hope this helps. Sorry for the long post, but I don't get out much.
Airstream bubble (I know, but it really is a '58, possibly the last one, SN493)
Chevrolet 4-door sedan
Dodge Power Wagon
1999 Volvo V70