News from industry

A solid-state conversion terminal is the heart of a new “coal by wire” power project that moves energy 734 km (456 mi) between Center, N. Dak., and Duluth, Minn. The ac power generated by the Square Butte Electric Cooperative, near the lignite fields of Center, is converted to direct current and sent via dc transmission line for use by the Minnesota Power and Light Company of Duluth. The dc transmission line is rated at ±250 kV, 1000 amperes. At Duluth, the dc energy is reconverted into ac power for use by the utility´s customers. The system was built by the General Electric Company. By contrast, one proposed ac tie line between the two sites would have required more than twice the right-of-way cable miles as compared with that for the dc line as well as much wider right-of-ways to accommodate the greater number of conductors and wires needed for ac transmission.