Without energy, the economy can neither function nor grow. However, for at least the next half-century, the U.S. will not have an inexhaustible supply of inexpensive, clean energy. Dependence on energy imports, vulnerability to energy supply disruption, and issues of proliferation of nuclear material are cause for special concern. This paper addresses the geopolitical realities of and connections between energy and security, especially how the energy security issues that we face in the future differ from those we faced in the past.