TfL also argued that a private scheme could save money in the long term.
It also said the move would help meet the Mayor of London’s goal of zero carbon emissions by 2030.
TfL’s Lilly Matson said: “We are discovering new ways to make our network and the energy we use greener.
“Opening up new opportunities in the energy market and creating green jobs along the way, it’s the start of a long-term journey towards decarbonising London’s iconic transport system.”