In this study, we delineate the combined consequences of finite channel aspect ratios, wall slip effects and steric interactions on the energy transfer mechanisms in narrow fluidic confinements By considering the details of ionic interactions within the electrical double layer, we demonstrate that considerations of finite aspect ratios and steric effects may result in dramatic alterations in the predictions of effective viscosity as well as the energy transfer efficiency, particularly for high magnitudes of the surface charge density, as compared with the predictions based on parallel plate channel considerations. We also illustrate the possibilities of obtaining very high energy transfer efficiencies by employing channels of aspect ratios close to unity, with a judicious exploitation of steric interactions and wall slippage effects in highly confined geometries