(Adds details on investment plans and projects, further comments from interview, paragraphs 4-13)
By David Alire Garcia
MEXICO CITY, Aug 10 (Reuters) - A new partnership between U.S.-based power company AES Corp and Mexico's Grupo Bal launched on Monday will invest up to $2.5 billion over the next five years mostly in Mexico's newly opened power sector, a top AES executive said in an interview.
The 50/50 joint venture with Grupo Bal aims to direct about three-quarters of the five-year investment plan to electricity generation from both conventional and renewable sources, including wind and solar power.
"In terms of scale, the idea is to grow our portfolio in the next five years at least by 2 gigawatts with estimated investment of between $2 billion and $2.5 billion," said Juan Ignacio Rubiolo, head of AES's Mexican unit.
AES, which has operations in 18 countries, will operate the power plants that the partnership builds. All new projects will require the agreement of Grupo Bal, owner of the world's largest silver producer Fresnillo Plc and base metals miner Penoles. Gurpo Bal also owns a pension fund and retail assets in Mexico.
AES operates three existing power plants in Mexico with total generation of about 1,055 megawatts. These include a plant that has supplied Penoles with electricity for several years.
In February, Grupo Bal announced the creation of oil exploration and production subsidiary Petrobal.
The unit aims to take advantage of Mexico's historic energy sector opening finalized last year. The reform allows private companies to produce oil for the first time in decades and completely opens the power sector to private investment.
Grupo Bal is owned by billionaire Alberto Bailleres, one of Mexico's richest men.
The remainder of the joint venture's five-year investment is likely to be spent on projects focused on liquefied natural gas, water desalination and energy storage, an area where AES is already a global leader, said Rubiolo.
AES Chief Executive Andres Gluski first announced the joint venture in a second-quarter earnings call with analysts on Monday, noting that over the next decade Mexico will need 25 gigawatts of new or replacement generation.
However, he gave no details on the scope of the plans.
Rubiolo said the AES-Grupo Bal tie-up will pay close attention to upcoming auctions by CENACE, Mexico's new independent grid operator, in which bidding terms on new power generation projects are expected in October.
"We will play an active role in the auctions," he said, adding that "this alliance in particular is designed to be aggressive and a heavyweight in this market." (Reporting by David Alire Garcia; Editing by David Gregorio)