A closed-loop system for harnessing subterranean heat energy from a selected subterranean zone having a quantity of subterranean material to a surface location, the system comprising: a well bore comprising a substantially vertical well bore section extending from the surface location to the selected subterranean zone and at least one angled well bore section extending from the substantially vertical section into at least a portion of the selected subterranean zone; a substantially vertical transfer section having an outer casing located within the substantially vertical well bore section; a first passive heat transfer device extending away from the substantially vertical transfer section within the at least one angled well bore section, the first passive heat transfer device having an outer casing and an inner tubing, wherein the outer casing is connected to the substantially vertical transfer outer casing and having a proximately located sealed end, and at least a portion of the outer casing having a rifled configuration, and wherein the inner tubing is configured within the outer casing in a concentric arrangement defining a first fluid path in an annulus space between the outer casing and the inner tubing, the first passive heat transfer device having a second fluid path within the inner tubing, and the inner tubing having an open end proximate the sealed end of the outer casing such that the first and second fluid paths are in fluid communication, wherein the outer casing of the first passive heat transfer device further defines an exterior surface and an interior surface, wherein the rifled configuration comprises rifling on the exterior surface and the interior surface of the outer casing, and wherein the inner tubing of the first passive heat transfer device further defines an exterior surface and an interior surface, wherein inner tubing comprises rifling on the exterior surface of the inner tubing; a working fluid located within the first and second fluid paths; and an output apparatus for receiving a heated working fluid from the selected subterranean zone, characterized in that the inner tubing further comprises rifling on the interior surface of the inner tubing. a well bore comprising a substantially vertical well bore section extending from the surface location to the selected subterranean zone and at least one angled well bore section extending from the substantially vertical section into at least a portion of the selected subterranean zone; a substantially vertical transfer section having an outer casing located within the substantially vertical well bore section; a first passive heat transfer device extending away from the substantially vertical transfer section within the at least one angled well bore section, the first passive heat transfer device having an outer casing and an inner tubing, wherein the outer casing is connected to the substantially vertical transfer outer casing and having a proximately located sealed end, and at least a portion of the outer casing having a rifled configuration, and wherein the inner tubing is configured within the outer casing in a concentric arrangement defining a first fluid path in an annulus space between the outer casing and the inner tubing, the first passive heat transfer device having a second fluid path within the inner tubing, and the inner tubing having an open end proximate the sealed end of the outer casing such that the first and second fluid paths are in fluid communication, wherein the outer casing of the first passive heat transfer device further defines an exterior surface and an interior surface, wherein the rifled configuration comprises rifling on the exterior surface and the interior surface of the outer casing, and wherein the inner tubing of the first passive heat transfer device further defines an exterior surface and an interior surface, wherein inner tubing comprises rifling on the exterior surface of the inner tubing; a working fluid located within the first and second fluid paths; and an output apparatus for receiving a heated working fluid from the selected subterranean zone, characterized in that the inner tubing further comprises rifling on the interior surface of the inner tubing.