The pledge is set to be made as part of a trilateral summit of North American leaders in Ottawa, said the person, who spoke on the condition of anonymity prior to the official release. Canada already gets more than half its power from clean sources.
The commitment will apply to any electricity generated without producing carbon dioxide emissions. That includes nuclear power as well as renewable sources such as wind, solar and hydroelectric. It does not include natural gas, which burns cleaner than coal but still produces carbon dioxide emissions that contribute to climate change.
Over the past year, the U.S. derived about a third of its power from carbon-free sources, with nuclear providing 19.9 percent, according to April data from the Energy Information Administration.
The target represents a stronger pledge for both President Barack Obama and Mexican President Enrique Pena Nieto. The Obama administration had previously said it was aiming for the U.S. to get a fifth of its electricity from renewable sources by 2030, as part of a commitment made with Brazil last year. Mexico said last year it was aiming to get 35 percent of its electricity from wind, solar and other renewable sources by 2024, up from 3 percent a year ago.