Put so many together in a small space and you'll incur in more issues. This might be huge in the future, but for now just a cool concept.

10mA @1.5 volts is plenty for all sorts of things! Just two of those things and you've got 10mA @3V which is more than enough to power a Bluetooth Low Energy microcontroller and some occasionally-lit LEDs, displays, sensors, buttons, etc.

Simple, real-world example: Nest sells these remote temperature sensors that you can place around your home to use any given location (e.g. your living room) as the place where you want the thermostat temperature setting to apply. They take a 3V CR123A battery that needs to be replaced about every 3 years.

A CR123A battery only holds about ~2.4 watt-hours of power. That's 2500 milliwatt-hours or 250 hours of 10mW @3V. That means the Nest temperature sensor uses about 0.0095mA of current (@3V). In reality it uses a lot more than that; it just stays in a sleep state nearly all of the time and only powers up every few minutes when it needs to take a temperature reading and send it to the thermostat.

TL;DR: Just one or two of these energy harvesting devices could power a Nest temperature sensor forever (assuming they don't wear out or lose much efficiency over time).

There's zillions of low-power devices that today use batteries (that often corrode and need to replaced every few years even if they might not run out of power) that could be powered by these humidity power harvesting devices. It could change low-power engineering forever!

10 kWh per day from a washing machine sized cube is nothing to sneeze at. Whether the humidity to keep it powered consistently is achievable and the maintenance to keep it running is sensible and the cost of building up enough of this stuff to output that level of energy can be commercially viable - that's the big question.

Self recharging vibrator

If that was the case I'd be able to power a building by myself.

check out energous.com stock ticker WATT

The issue is the amount of energy produced (minuscule) and the requirement for very humid air. It's also likely that the device needs to be colder than ambient temperature if I've got my thermodynamics right, so removing heat might be necessary, obliterating any gains and turning it into a dehumidifier that produces a small amount of waste electricity.

It might be another option in the pile of 'energy harvesting' solutions, where you need microwatts to miliwatts to power devices like remote temperature sensors, to avoid fitting ten-year lithium batteries. It doesn't seem likely to go beyond that.

I'm going to assume you got auto corrected from seppuku to sudoku. Because that is hilarious.

There's always some humidity, so I guess in the end it depends entirely on how efficient they can make this technology. It's probably a bit too early to say.

That said, if you live in a tent in the Sahara you probably shouldn't postpone investing in solar panels over this.

It doesn't look like it dehumidifies the air, just takes advantage of the humidity's electrical charge.

we could use this in Japan during summer

Yes, just like using wind turbines slows down the wind