A structure and method for changing or controlling the thermal emissivity of the surface of an object in situ, and thus, changing or controlling the radiative heat transfer between the object and its environment in situ, is disclosed. Changing or controlling the degree of blackbody behavior of the object is accomplished by changing or controlling certain physical characteristics of a cavity structure on the surface of the object. The cavity structure, defining a plurality of cavities, may be formed by selectively removing material(s) from the surface, selectively adding a material(s) to the surface, or adding an engineered article(s) to the surface to form a new radiative surface. The physical characteristics of the cavity structure that are changed or controlled include cavity area aspect ratio, cavity longitudinal axis orientation, and combinations thereof. Controlling the cavity area aspect ratio may be by controlling the size of the cavity surface area, the size of the cavity aperture area, or a combination thereof. The cavity structure may contain a gas, liquid, or solid that further enhances radiative heat transfer control and/or improves other properties of the object while in service.

A receiving layer of a radiant energy concentrator has a set of collecting members arranged on a same level. In one embodiment upper edges of the members form a hexagonal honeycomb structure in a plane, and in another embodiment the members form an orthogonal matrix of square shaped elements. In the hexagonal honeycomb structure the collecting members are made in the form of funnels with reflective internal surfaces, and in the orthogonal matrix the collecting members are optical lenses or made in the form of paraboloidal-hyperboloidal concentrators. Layers having reflectors are provided under the receiving layer. Light beams from peripheral collecting members are transmitted by reflectors disposed under the receiving layer to a center of a central member. Successive layers further concentrate receiving light beams in a similar manner.

A method for powering a vehicle comprises, in one embodiment, receiving infrared radiation emitted as heat from a roadway surface, and converting energy of the infrared radiation to a form of energy that is useful for providing power to the vehicle. In another embodiment, a method for powering a vehicle comprises: insulating a first region of a road's surface with a material that transmits visible light but blocks infrared radiation, while leaving a second region of the surface uninsulated; conducting heat from portions of the road beneath the first region, to the second region; receiving infrared radiation emitted as heat from the second region; and converting energy of the infrared radiation to a form of energy that is useful for providing power to the vehicle.