system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 - How is Costa Rica able to switch to 100% renewable energy and what energy sources in particular are they using?
gpt
They are not 100% renewable, not even close. Most energy is used for transportation, which still uses fossil fuels. Much of the rest is farm machinery, also powered by fossil fuels.  

100% of their electrical generation comes from renewables.  

They don't have a very high demand. They have a mild climate and no heavy manufacturing to speak of. As a hilly and wet country they are able to make a great amount through hydroelectric power (over 80% of their production) and as a small and volcanically active country, geothermal power is able to make up a sizeable amount as well (15%).  

Consider a country like France. They do not have significant hydroelectric or geothermal potential. They do have plenty of heavy manufacturing. They are the world's 8th largest electricity producer and world's largest exporter. Only 10% or so of production comes from fossil fuels. They are able to do this because about 80% of their generation is nuclear power.