The Aqueous Accumulator is used as a pump to get water into pipe systems, the most efficient way to utilise one would be to place a source block of water on 2-4 sides of the machine, it doesn't need power to function.

For early in the game, placing a fluiduct on top of the machine and leading into a steam dynamo, then all that is needed is coal or charcoal for a quick power source. Hooking up a tree harvesting farm to a furnace to make charcoal and leading that to a steam dynamo is a cheap way to produce slow but plentiful power.

Or use the infinite water leading into a glacial precipitator, to make ice and snow. Or into an igneous extruder along with lava from a pump or a lava fabricator or likewise, in order to make easy obsidian.

The aqueous accumulator does not work with other liquids, only water.