Puerto Rican power utility PREPA (also known as AEE) is engaged in the production, transmission, distribution and sale of electric power. It is the sole provider of electricity for 1.5mn customers, serving the 3.8mn Puerto Rican population. AEE generates some 70% of the electricity itself and purchases the remaining 30% from two co-generators, EcoEléctrica and AES Puerto Rico. It operates six fuel oil-fired power plants (Costa Sur, Aguirre, San Juan, Palo Seco, Cambalache and Mayaguez) and two combined cycle plants (San Juan and Aguirre), as well as transmitting and distributing electricity generated by the two private producers. Founded in 1941, the company operates as a public corporation of the Puerto Rican government.