BP Wind Energy and Sempra US Gas & Power yesterday announced they have moved a second giant US wind into full commercial operation, just four days after announcing that they had brought the largest single-build wind farm in US history online.

The partners confirmed the $250m, 141MW Mehoopany Wind Farm in Pennsylvania is now commercially operational, following hot on the heels of the 470MW Flat Ridge 2 Wind Farm in Kansas, which began exporting power to the grid last week.

The projects, which combined boast over half a gigawatt of capacity, were developed by a 50:50 joint venture between BP and Sempra and will now be operated by a wholly-owned affiliate of BP Wind Energy.

Located on a 9,000-acre site 20 miles north west of Scranton, the Mehoopany Wind Farm will sell its power to the Old Dominion Electric Cooperative and Southern Maryland Electric Cooperative Inc under a long-term power purchase agreement.

A similar arrangement is in place for the $800m Flat Ridge 2 Wind Farm, which will see the site’s entire power output sold to Associated Electric Cooperative Inc, Southwestern Electric Power Company, and Arkansas Electric Cooperative Corporation.

“The state of Kansas has created a predictable, stable environment in which companies can invest and do business,” said John Graham, president and chief executive of BP Wind Energy in a statement released last week.

“The Flat Ridge 2 Wind Farm is a testament to the success of this strategy and is helping the state to be a net exporter of energy. This pro-growth strategy is the kind of approach wind energy needs from state legislators and BP looks forward to further expanding its wind energy footprint in Kansas if and when the business opportunity becomes available.”

He also yesterday offered similar praise to the Pennsylvanian authorities, insisting the company appreciated “the ongoing support that we have received at both the state and local level and look forward to a long-term partnership in the community”.

The commercial operation of the two wind farms represents a further boost to a US wind energy industry that received a major fillip at the turn of the year with the extension of crucial tax credits for wind energy developers as part of the “fiscal cliff” deal agreed by Congress.