 Chilean copper mines Escondida and Spence, controlled by BHP, will jointly pay 840 million for an early end to a contract signed in 2008 with a coal-fired thermoelectric plant in the north of the country. BHP, like other mining companies in Chile, has been migrating its energy contracts to renewable sources to reduce its carbon footprint. In a letter to the local securities regulator on Friday night, power company AES Gener - a unit of AES Corp - said that the end of the agreement signed with its Angamos plant was modified to August 2021. 