Renewable Energy - What Will It Take to Replace Fossil Fuels?

Global energy demand is expected to grow by at least 15% by 2050. By 2050, we'll need somewhere between 183 and 203,000 TWh of thermal energy. The four commonly recognized renewable energy sources are hydroelectric, wind, solar, and geothermal power. Hydroelectric power only works in places with waterways conducive to building that kind of power generation.