The requirement is that
"anyone skill at the art can follow your instruction
to replicate the work and that will work to perform
the functions you made in your claim"

That's it, but the functions does not need to be *useful*.
Plus, the way you describe it must be *unique* and not be
*done before*, but it does NOT need to be a way most
effective to achieve the function.

For example, you probably will get a patent for
taking water, turn it into hydrodrine, then
combine with CO2, then through a complex, expensive
operation, turn into gasoline to drive a car.
That is the most useless patent, but you can still
claim it.