by Emil Morhardt
Seems like it’s getting to the point that no possible source of power should go unharvested. This paper envisions the water tanks at the top of apartment complexes in Taiwan as mini-pumped storage projects: by installing miniature turbines in the water supply pipes feeding the building from these tanks, electricity can be generated whenever the occupants use any water. The pipes are 4–6 inches in diameter, and a single turbine can generate about 3 Watts under the expected water flows. The experimental turbine blades were printed on a 3-D printer until the engineers got the result they wanted; a set of three airfoil blades that didn’t alter the flow rate of the water. (I’m not quite sure how this could be…if the blades extract energy it seems to me that the only place it could have come from is by diminishing the flow rate. Perhaps someone could explain this in a comment.) In any event, extracting this amount of energy apparently didn’t interfere with the functioning of the water supply system. The authors figure that they could get enough electricity out of a building’s water supply lines to run a few light fixtures. They didn’t explore it much, but the drains are another obvious source of potential energy. This all seems good.
Chang, C.-Y., Huang, S.-R., Ma, Y.-H., Hsu, Y.-S., Liu, Y.-H., 2014. The Feasibility of Applying Micro-hydroelectric Power Technology in Building Water Supply Pipes. Scientific-Journal.com. http://www.scientific-journal.com/articles/environmental/3/11.pdf