Although cellophane is nearly impermeable to air and
liquid water, it is permeable to water vapor, aka humidity.
Because of that, it should be usable as a key component of
a dehumidifier (or perhaps an atmospheric water
generator), using the following simple setup:
First, fresh air passes
through a dust filter, then across the
top surface of our cellophane filter, then between the heat
sink fins of the hot side of our peltier effect heat pump,
then it's discharged out into the room.
Meanwhile, humidity moves through the cellophane film
into a pressure vessel, then goes between the fins of the
heat sink fins of the cold side of our peltier effect heat
pump, and then is removed from pressure vessel by way of
a pump which can handle both gas and liquid.
The discharge of the pump goes into a bottle, where liquid
will remain, but from which air can escape.
The efficiency of the device will depend in large part on
the surface area of the cellophane filter. To maximise this
area, without making the entire device huge, can be done
by shaping the cellophane into a spiral.
Some of you reading this may wonder what is the
advantage of this over using the peltier effect heat pump
by itself, and the answer is that it eliminates the need to
chill the nitrogen and oxygen in the air, and allows it to
only chill the water vapor. This is very important, since
even at 100% relative humidity, air only contains a few
percent water vapor.
You might also be thinking that the efficiency of the pump
must inevitably be low, but that will only be true when it's
starting up and removing air. When the system is in a
steady state, it will only be removing liquid water, which
shouldn't require much power.