Engineering360: "Composite materials may boost hydropower turbine output"

"... Composite blades require higher hydraulic heads due to their higher degree of blade bending. ..."

This doesn't make much sense as presented. Why would less stiff matetial require greater stress to perform as well as a more stiff material? A material that bends more would usually havre more restrictive limits and not a hugher minimum required.

It's not about providing stress to the material, it's just that the blades bend more under the same force-- and they bend into a less efficient profile for transferring the energy. But my immediate thought is why not design them to bend INTO the preferred profile? That is, make them as a modified, non-ideal profile when not loaded, and then, when forced by the water, they will deform into the correct profile.