The 160-ft-high blade of a wind turbine broke off in Tuscola, Mich., in June. Bryan Garner, a spokesman for NextEra Energy Resources, which owns the 120-MW, 75-turbine Tuscola Bay Wind Energy Center, termed the break an isolated incident connected to equipment inside the turbine. The break is one of four NextEra Energy wind turbine failures in the U.S. in recent weeks.