Fig. shows the radius, wall thickness, and tankage fraction for bulk xenon storage over a pressure range of 20 bar to 125 bar. The optimal storage pressure is P opt = 77.6 bar, which provides a minimal tankage fraction of m v (P opt )/(n Xe w Xe ) = 0.08. Notably, P opt > P c to exploit the large slope of ρ Xe (P ) in Fig. , where a small change in pressure results in a large change in xenon density. See the x in Fig. that marks (P opt , ρ Xe (P opt )).