A high density capacitor system, comprising: a housing having a cavity; a plurality of capacitors forming at least one capacitor bank disposed in the cavity, the capacitors each having an outer surface, the at least one capacitor bank having spacings between the outer surfaces of the capacitors; a native cooling fluid disposed in the cavity; a heat exchanger coupled to the housing; and a pump fluidly coupled to the heat exchanger and configured to circulate the native cooling fluid from the cavity, through the heat exchanger, through the spacings and along the outer surface of each of the capacitors to cool the capacitors using forced convection; wherein the heat exchanger is configured to communicate a secondary fluid through the heat exchanger and draw heat from the native cooling fluid flowing through the heat exchanger; the heat exchanger has a plenum having a plurality of openings configured to dispense the native cooling fluid from the heat exchanger proximate the at least one capacitor bank; the heat exchanger has a first passageway configured to communicate the native cooling fluid from the pump to the openings of the plenum, a second passageway configured to communicate the secondary fluid, and a thermally conductive member separating the first passageway from the second passageway; the first passageway is planar and the second passageway is planar; the thermally conductive member separating the first passageway and the second passageway from each other is planar; and the first passageway is formed by a first plate, the second passageway is formed by a second plate, and each plate has a plurality of fins (82, 62) configured to create even planar flow of fluid through the respective passageway. a housing having a cavity; a plurality of capacitors forming at least one capacitor bank disposed in the cavity, the capacitors each having an outer surface, the at least one capacitor bank having spacings between the outer surfaces of the capacitors; a native cooling fluid disposed in the cavity; a heat exchanger coupled to the housing; and a pump fluidly coupled to the heat exchanger and configured to circulate the native cooling fluid from the cavity, through the heat exchanger, through the spacings and along the outer surface of each of the capacitors to cool the capacitors using forced convection; wherein the heat exchanger is configured to communicate a secondary fluid through the heat exchanger and draw heat from the native cooling fluid flowing through the heat exchanger; the heat exchanger has a plenum having a plurality of openings configured to dispense the native cooling fluid from the heat exchanger proximate the at least one capacitor bank; the heat exchanger has a first passageway configured to communicate the native cooling fluid from the pump to the openings of the plenum, a second passageway configured to communicate the secondary fluid, and a thermally conductive member separating the first passageway from the second passageway; the first passageway is planar and the second passageway is planar; the thermally conductive member separating the first passageway and the second passageway from each other is planar; and the first passageway is formed by a first plate, the second passageway is formed by a second plate, and each plate has a plurality of fins (82, 62) configured to create even planar flow of fluid through the respective passageway.