Supplying demand efficiently: Utilities step up direct-current transmission; more alternative energy systems come on line

Power utilities and manufacturers of energy equipment reached out last year for cheaper and more efficient ways to transmit existing power, even as they pressed their search for fuel substitutes for oil. New efforts began to reap the benefits inherent in dc transmission (more capacity on existing lines) and superconducting cables (less loss of power during transmission). And new protective devices became available: zinc oxide surge arresters to control the damaging effects of lightning on transmission equipment, optical boiler-flame scanners to prevent boiler explosions, and tagging compounds used in conjunction with an ionization chamber to detect hot spots in generators.