Sempra Energy's (SRE) merchant generation unit said Thursday it bought a 22-megawatt wind farm under development in Hawaii from a unit of Royal Dutch Shell PLC (RDSB, RDSB.LN).

The wind farm, called Auwahi Wind Energy project, is planned for construction on the island of Maui and will include a battery storage system where up to 28 megawatt-hours of electricity could be stored for later use. Sempra said it could begin construction on the project in 2011 and start commercial operations in 2012.

Sempra has applied to the U.S. Department of Energy for stimulus funds to help pay for an expansion of the battery storage component to more than double its storage capacity.

Shell WindEnergy Inc. sold the Hawaii project to focus on its renewable energy projects on the U.S. mainland and in Canada, Dick Williams, the unit's president, said in a statement. The company has eight U.S. wind farms with combined generating capacity of almost 900 megawatts, he said.

Maui aims to use renewable sources for 95% of the power the island uses as part of Hawaii's renewable energy initiative.

In addition to the Maui wind project, Sempra Generation recently announced that it took a 50% stake in a 200-megawatt wind farm in Indiana being developed by BP PLC's (BP) wind energy unit. Sempra is also working to complete a 100-megawatt wind farm in Baja California, Mexico by 2012, and plans to start construction soon on a 48-megawatt solar farm near Las Vegas.

Shares of Sempra were recently trading up 9 cents, or 0.2%, at $52.77.

-By Cassandra Sweet, Dow Jones Newswires; 415-439-6468; cassandra.sweet@dowjones.com