Hydrogen is the lightest and simplest of all elements. It can be manufactured from water by electricity derived from clean energy sources. When burned in air, hydrogen reverts back to pure water. Because of this simple, clean energy cycle, hydrogen has been called the “Ultimate Fuel”. It is possible to formulate a “Hydrogen Energy Economy” that is completely free of carbonaceous fossil fuels and associated contributions to climate change. These lectures will cover the long and fascinating history of hydrogen energy, including the instructor’s own roles in that history, e.g., hydrogen storage in metal hydrides. We shall also discuss the principal economic and infrastructure challenges that must be overcome before hydrogen energy can fully displace conventional fuels derived from coal, petroleum and natural gas.