Fossil fuels -- coal, natural gas, and oil -- provide the large majority of our power in the United States and around the world. In this episode of TILclimate (Today I Learned: Climate), John Reilly of the MIT Sloan School of Management joins host Laur Hesse Fisher to demystify fossil fuels: what are the different kinds of fossil fuels, and how do they compare to each other? What is “fracking” and how did impact energy use and CO2 emissions in the United States? What kinds of decisions do we need to make to transition to clean energy, while providing electricity to a growing number of people?John Reilly is a senior lecturer at the MIT Sloan School of Management and Co-Director of the MIT Joint Program on the Science and Policy of Global Change. An economist, he researches economic models that connect human activity with natural systems like the ocean, atmosphere, and vegetation.Season two of TILclimate focuses on our global energy system, its relationship to climate change, and what our options are for keeping the lights on while creating a clean energy future. We’re partnering with the MIT Energy Initiative, which will air longer interviews with each guest to take a deeper dive into these topics. For more episodes of TILclimate, visit: tilclimate.mit.eduTo listen to the MIT Energy Initiative podcast, visit: energy.mit.edu/podcastFor in-depth analyses on energy technologies, check out the MIT Energy’s “Future of” report series: energy.mit.edu/research-type/future-of/For the full break-down of where U.S. gets its energy: https://www.eia.gov/energyexplained/us-energy-facts/CreditsLaur Hesse Fisher, Host and ProducerDavid Lishansky, Editor and ProducerRachel Fritts, Graduate Student WriterOlivia Burek, Student Production AssistantMusic by Blue Dot SessionsArtwork by Aaron KrolProduced by the MIT Environmental Solutions Initiative at the Massachusetts Institute of Technology