American Electric Power’s $2bn plan to add 1.48GW of wind capacity in four central US states achieved a key milestone with approval by Oklahoma for a subsidiary there to acquire 45.5% of that amount for its customers in 2021.

Public Service Company of Oklahoma (PSO) won approval to spend $908m to acquire from Invenergy 675MW of capacity from three wind farms under development in the state’s north-central and northwestern regions upon their completion.