The two primary motivations for energy policy in the United States are promoting energy security and combating climate change. Because the electricity sector accounts for roughly 40 percent of national carbon dioxide (CO2) emissions, renewable sources of electricity could be particularly important for
addressing this latter concern about climate change. However, renewables are typically more expensive than fossil-fueled electricity sources such as coal, which supplies nearly 50 percent of our electricity today; as a result, renewables are not economic absent policy intervention. Moreover, most renewable
sources of electricity, such as wind and solar, must be exploited in the sometimes-remote locations where they are found, and they are not dispatchable