Economic Assessment of a Liquid-Nitrogen- Cooled Cable

This paper outlines the design of a rigid underground line for transmitting electrical energy with tubular aluminum conductors cooled internally by liquid nitrogen and supported on suitable dielectric spacers in high-voltage vacuum insulation. The installed cost of a specific line with terminations and refrigerators has been estimated and found to be easily competitive with oil- paper insulated pipe-type cables of ratings in excess of 1000 MVA and in the voltage classes 138, 230, and 345 kV. It is shown that the nitrogen-cooled cable has great operating flexibility in so far that it may be adapted to long-term load growth, emergency over- loads, and repetitive load fluctuations of daily, weekly, and seasonal cycles. The first commercial installation, it is argued, may come into service before 1975.