To maintain a technological civilization, humanity requires energy. We cannot, however, continue to obtain the majority of that energy by burning fossil fuels. There are carbon-neutral and sustainable substitutes available, including biofuels, hydrogen, wind, solar, new technology nuclear, and engineered geothermal. More exotic energy sources like nuclear fusion may be on the horizon, but the urgent need to replace fossil fuels as quickly as possible suggests that we have to use what we currently have available. Displacing fossil fuels with new energy sources will be disruptive and challenging, but it must be done. Government policies and leadership are necessary, because it has become obvious over the last few decades that the fossil fuel replacement will not be achieved by the “free market.” Fossil fuels should be replaced first in the electric power sector to completely decarbonize the electric grid. This should be followed by the decarbonization of the transportation sector. Many nations have pledged to become carbon neutral by the middle of the twenty-first century, but the sooner this can be achieved, the better.