▁wind s ▁and ▁heavy ▁cloud ing ) ▁or ▁un stable ▁( ris ing ▁air ▁because ▁of ▁ground ▁he ating — by ▁the ▁sun ). ▁Here ▁again ▁the ▁ 1 / 7 ▁power ▁law ▁applies ▁or ▁is ▁at ▁least ▁a ▁good ▁approximation ▁of ▁the ▁wind ▁profile . ▁Indiana ▁had ▁been ▁r ated ▁as ▁having ▁a ▁wind ▁capacity ▁of ▁ 3 0 , 0 0 0 ▁M W , ▁but ▁by ▁raising ▁the ▁expected ▁tur bine ▁height ▁from ▁ 5 0 ▁m ▁to ▁ 7 0 ▁m , ▁the ▁wind ▁capacity ▁estimate ▁was ▁raised ▁to ▁ 4 0 , 0 0 0 ▁M W , ▁and ▁could ▁be ▁double ▁that ▁at ▁ 1 0 0 ▁m . ▁ ▁For ▁H A WT s , ▁tower ▁height s ▁approximately ▁two ▁to ▁three ▁times ▁the ▁bla de ▁length ▁have ▁been ▁found ▁to ▁balance ▁material ▁costs ▁of ▁the ▁tower ▁against ▁better ▁util isation ▁of ▁the ▁more ▁expensive ▁active ▁components . ▁ ▁Road ▁size ▁restrictions ▁makes ▁transport ation ▁of ▁to wers ▁with ▁a ▁diameter ▁of ▁more ▁than ▁ 4 . 3 ▁m ▁difficult . ▁Swedish ▁anal ys es ▁show ▁that ▁it ▁is ▁important ▁to ▁have ▁the ▁bottom ▁wing ▁tip ▁at ▁least ▁ 3 0 ▁m ▁above ▁the ▁tree ▁to ps , ▁but ▁a ▁t aller ▁tower ▁requires ▁a ▁larger ▁tower ▁diameter . ▁A ▁ 3 ▁M W ▁tur bine ▁may ▁increase ▁output ▁from ▁ 5 , 0 0 0 ▁M Wh ▁to ▁ 7 , 7 0 0 ▁M Wh ▁per ▁year ▁by ▁going ▁from ▁ 8 0 ▁to