A friend (thank you Bruce) sent me a link to one of these great gadgets which sent me off on a search of the possibilities, since many of us hike/hunt in mountain areas where there is often ample flowing water. Something like this would also be good for providing power to your Wilderness Hut.
What you have here is a Waterproofed DC dynamo powered by a prop (or turbine) basically with a transformer circuit which stabilises the output to 5 volts then charges a battery which can then be used to draw off power for a multitude of uses.
All these are small systems in the range 5 to around 20 watts which would be sufficient for most people’s modest backcountry purposes providing they have access to a good steady flow of fast moving water with a good ‘head’ (ie fall).
This one is the ‘Waterlily’ one of the best priced units I found.
Of course such an idea lends itself to DIY. The dynamos, props etc can be purchased very cheaply from eg Aliexpress. Have a look at some of the links at the bottom of this page for example. If you are handy and can master the waterproofing you might come up with something like this prototype, the Enomad Uno. Website here.
Here is one you can buy (from) E299) the Blue Freedom:
You can buy the Blue Freedom here.
And here is the Waterlily (US199 – Mar 2021)
You can buy the Waterlily here.
Tha Aliexpress model is a bit cheaper (about half price) but it is not (quite ) clear whether it works in water! That might be a problem.
What these devices have in common is a weight around 750 grams, an approx 5000 mAh battery and USB charging.
Your Wilderness Hut or semi-permanant camp might lend itself to one of these much cheaper (US$10) devices supplied (with head) by a length of poly pipe – also very cheap. These particular ones are small (8.8 x 5.8 x 3.9cm) and clearly lightweight. It appear they will put out 220 mA at a head of 5 metres which should not be hard to find. Considering that they will do that 24/7 (trickle charging) into a small sealed lead/acid battery (also cheap – 9000mAh will cost about $30 and last for maybe ten years) they might be better than more intermittent solar to keep your hut ‘s lights etc functioning nicely – or at least as a supplement, particularly if you are running water to the hut anyway. Obviously there are also bigger ones of the same type (turbines) if you have larger flows/heads etc.
If you are thinking of making up something on your own you might consider a cheap ($US16) generator like this (clearly you would have to waterproof it and add a propeller) and some circuitry. USB output circuits are only a couple of dollars at Aliexpress.
It could be run by a small Pelton wheel like this (around $40) if it was a permanent installation.
Good luck with your next adventure!