Abstract
Ocean currents in tidal flows and at the western boundaries of the ocean basins, as well as currents in rivers, can have as much potential for power production as the wind. With increased interest in sources of renewable energy, realizing this potential has undergone a renaissance in recent years. This chapter provides an introduction to ocean current energy conversion by emphasizing the contrasts between winds and currents and discussing some of the unique challenges associated with this untapped renewable energy source.