Air bending. Air bending could be done using some form of pump to push air. However, it takes a stretch to compare Aang's graceful movements to the mechanisms we have in place. And yes, such "air-bending" would be uni-directional in movement, with little or no control over its movement.

The power of hydrokinetics or "Waterbending" as they call it in Avatar is an extremely rare ability for a human to posses (unlike in Avatar where over half of the Northern Water Tribe can Waterbend). Few people have said they can manipulate water and even fewer have proved it.

WATCH 01:32

The Loop (TV)

"Fire is the element of power."— Iroh to Zuko.[1]

FirebendingGeneral informationSourceSun^[2]

Learned fromDragons^[3]

Alternate stylesCombustionbending Lightning generation[4] and redirection[1]

Firebending, one of the four elemental bending arts, is the pyrokinetic ability to control fire. It is unique among the bending arts, as it is the only one in which the performer can generate the element. The first human firebenders lived in a city atop a lion turtle during the era of Raava and the art later spread to the Sun Warriors,^[3] the Fire Nation, and the United Republic of Nations.^[5][6] The Earth Kingdom also has a small firebending minority.^[7][8]