Renewable energy will need to make up the majority of global electricity generation by 2050—as much as 90%, according to the International Energy Agency—for the world to achieve net-zero emissions by then.

Renewable energy’s share stood at 29% in 2020, which suggests that it would have to triple by 2050—no easy feat since, as the IEA notes, the total amount of electricity generated will have to jump by more than two-and-a-half times to achieve global decarbonization ambitions.

Most of the electricity that is generated from renewable energy will have to come from variable sources because of constraints on the availability of dispatchable renewable generators (such as hydropower, geothermal, and biofuel plants). In 2020, sources of variable renewable energy (VRE) accounted for 9% of global generation. According to the IEA’s net-zero roadmap, however, they will need to represent close to 70% by 2050.