The company said it would pay "traditional" rates for the power, which is expected to provide 15 percent of its electric needs in Texas, The Dallas Morning News reported Thursday.

In effect, Wal-Mart will be purchasing renewable energy credits, as it is impossible to separate the electricity from the wind farm from other electricity once it joins the established power grid.

The kilowatts the retailer is purchasing is equal to the amount of power used each year in about 18,000 homes, the newspaper said.

Duke Energy is constructing a wind farm in Notrees, Texas, which is expected to begin producing power in April, the Morning News said.