Redford was on hand Saturday for the premiere of "In Harmony" at the Sundance London film festival and told the crowd the movie was a tribute to the prince's dedication to preserving the environment.
"This important film showcases his diligence, passion and achievement, which include his efforts to amplify the work of social innovators on the front lines of change the world over," said Redford, the founder of the Sundance festival and a devoted environmentalist himself.
The film focuses largely on the establishment of wind farms in Europe as a clean source of electricity. In the film, Charles says support for alternative energy is a gesture to future generations.
"I don't want my grandchildren, or yours, to come along and say, 'Why didn't you do something? You knew what the problem was,'" he said.
The Telegraph said the premiere of "In Harmony" came not long after Charles' father, the duke of Edinburgh, had said publicly government promotion of wind generation is impractical and the concept of wind farms is "absolutely useless."