Producers of wind power at mercy of weather

San Francisco

POWER producers who invested billions in turbines are finding that making money off the wind can be as unpredictable as the energy source itself.

NextEra Energy Inc, NRG Yield Inc and Duke Energy Corp all said a lack of sufficiently windy days cut into second- quarter sales. And neither power generators nor forecasters seem to know exactly why.

"There was a definite trend with several utilities talking about weak wind resources," said Shahriar Pourreza, a New York-based analyst for Guggenheim Partners. "This isn't something that has been major in the past so definitely a phenomena worth following to see if it's sustainable or an anomaly." Wind, once a marginal resource for power suppliers, has begun to matter. Installations surged sevenfold in the US last year, making it the largest market for the technology worldwide after China, according to Bloomberg New Energy Finance. Spurred by tax incentives and state clean ener…