If wind turbines stood 20 or 40 meters taller than they typically do today, they would produce more energy and possibly make wind energy economically viable in areas where it currently is not. An Iowa engineer says the solution to provide the necessary growth spurt is to switch from steel to concrete. Sri Sritharan of Iowa State University is developing a wind-turbine tower constructed of modular concrete blocks that can be assembled to any height and any width. He believes it would address one of the major factors now limiting the height of wind-turbine towers: the overhead clearance between highways and their overpasses.