This article predicts future global energy demand under a business-as-usual scenario. According to the MIT projections, conventional technology supported by fossil fuels will continue to dominate under a business-as-usual scenario. In fact, in the absence of climate policies that would impact energy prices, fossil fuels will supply nearly 80% of global primary energy demand in 2100. Alternative energy technologies will expand rapidly. Non-fossil fuel use will grow from 13% to 20% by 2100, with renewable electricity production expanding nearly tenfold and nuclear energy increasing by a factor of 8.5. However, those sources currently provide such a small share of the world's energy that even rapid growth is not enough to significantly displace fossil fuels. In spite of the growth in renewables, the projections indicate that coal will remain among the least expensive fuel sources. Non-fossil fuel alternatives, such as renewable energy and nuclear energy, will be between 40% and 80% more expensive than coal.