Air lift pumps
An air lift pump consists of a vertical pipe immersed in a liquid, an
air compressor, and a conduit to introduce the compressed air
into the bottom of vertical pipe. As air flows
from the conduit into the vertical pipe, a vertical flow of
bubbles and liquid is created in the pipe. The bouyancy of the
bubbles lifts the
liquid and ejects it from the upper end of the pipe above the surface
of the liquid.
An air lift pump can lift a liquid to a height above the surface of the
liquid equal to about 2/3 of the depth at which the air is injected
into the bottom of the vertical pipe
Air lift pumps may have a number of applications in solar water
heating. 12 volt DC air pumps are common and cheap, and may be
powered directly by solar electric panels.
Here are three old patents for air lift devices.