Butane is pointess
If you have to carry butane with you to make this huge thing work then you may as well just carry more batteries which are far more energy dense.
If you power it with found materials then this is potentially useful, but a hand crank charger might be faster and more effective.
Nothing at all new in this though... In the Seebeck effect has been used for years to provide power from heat.
In the 1950s, the Russians made a Seebeck effect collar which was fitted to kero lamps to provide power for radios.
In the 1970s, I remember some encyclopedia giving instructions on how to build a Seebeck device to power a single transistor radio.