An anonymous reader quotes a report from Phys.Org: Rice University scientists are designing arrays of aligned single-wall carbon nanotubes to channel mid-infrared radiation (aka heat) and greatly raise the efficiency of solar energy systems. Their invention is a hyperbolic thermal emitter that can absorb intense heat that would otherwise be spewed into the atmosphere, squeeze it into a narrow bandwidth and emit it as light that can be turned into electricity. The aligned nanotube films are conduits that absorb waste heat and turn it into narrow-bandwidth photons. Because electrons in nanotubes can only travel in one direction, the aligned films are metallic in that direction while insulating in the perpendicular direction, an effect called hyperbolic dispersion. Thermal photons can strike the film from any direction, but can only leave via one. Adding the emitters to standard solar cells could boost their efficiency from the current peak of about 22%. “By squeezing all the wasted thermal energy into a small spectral region, we can turn it into electricity very efficiently,” he said. “The theoretical prediction is that we can get 80% efficiency.” The study has been published in the journal ACS Photonics.