Building habitable structures on water is an interesting concept that has been explored in various ways, from floating homes to entire cities built on water. While there are many engineering and environmental challenges to consider when building on water, there are also many potential benefits, such as the ability to utilize the vast space of the oceans and reduce the pressure on land-based resources. In my opinion, a potential way to power these structures is by the use of hydroelectric turbines located under the structures(buildings) themselves, though the engineering challenges of designing such systems would need to be carefully considered.
Currently yet to develop a graphical representation of how these structures would look like.