; and (2) to improve the energy efficiency of critical facilities by decreasing the size and cost of generators. (c) Use of funds In carrying out subsection (b), the Secretary shall ensure that the funds made available under subsection (d) shall be used for, with respect to critical facilities— (1) provision of on-site back-up power with renewable and low-carbon liquid fuels; and (2) installation, at the transmission and distribution level, of interoperable technologies, advanced power flow control, dynamic line rating, topology optimization, and communications systems. (d) Authorization of appropriations There is authorized to be appropriated to the Secretary $100,000,000 to carry out this section, to remain available until expended.