An oil shale formation may be treated using an in situ thermal process. Hydrocarbons, H₂, and/or other formation fluids may be produced from the formation. Heat may be applied to the formation from one or more heat sources to raise a temperature of a portion of the formation to a desired temperature. Some of the heat sources may be conductors placed within conduits. The conductors may be resistively heated so that the conductors radiantly heat the conduits. The generated heat may transfer to the formation.