 WC is a major component of a TCN-based cermet, which is widely used as a cutting tool. After use, this material is often discarded. However, it can be reused as a solar absorption film if treated properly. Our calculations show that WC has a low energy plasma excitation of 0.6 EV, making it a suitable candidate for a solar absorber. Additionally, its figure of merit for photothermal conversion is higher than those of other materials in the TCN-based cermet. Furthermore, the imaginary part of the dielectric function is small near the zero point of the real part, indicating a clear plasma edge. Thus, WC is a promising material for solar absorbers. This article was authored by Shota Haikawa, Toshiharu Chono, Kosek Watanabe, and others.