Santiago’s metro system is to be powered mostly by solar and wind energy.
Chilean President Michelle Bachelet said the station and trains which are used by more than 2.5 million passengers will run on 60% green energy.
Metro de Santiago has signed a 15-year contract to use clean energy produced by two renewable sites which will be completed by 2018.
The project, claimed to be the first of its kind in the world, is expected to reduce around 130,000 tonnes of carbon emissions per year.
That will help towards meeting its UN target of cutting emissions by 30% by 2030.
Ms Bachelet added: “We are supporting the efforts our country does to consolidate a power mix which has low prices so our companies can be more competitive and reduce bills for households, doesn’t harm the environment, health and quality of life of the people.”