A DIRTY war is raging across the globe. Enemy air strikes target our vast networks of power lines, transmission towers and substations. The grid was engineered to withstand the most ferocious lightning strikes, but struggles to resist these unrelenting assaults. For almost a century the network has been shaped by an arsenal of weaponry developed to counter this formidable foe: bird droppings.
The first major assault occurred in California in 1923, along transmission lines strung for 390 kilometres between the Big Creek hydroelectric plant and the power-thirsty city of Los Angeles. Southern California Edison was one of the first companies to upgrade its lines from 150 to 220 kilovolts. As soon as it did so, the network suffered a spate of blackouts. The problem was caused by “flashovers” – bolts of artificial lightning formed as electricity arcs from live power lines to earthed metal supports – tripping circuit breakers and frying parts of the network.
There had always been one or two unexplained flashovers a month, but between June and August 1923, 31 occurred. This rate of disruption nearly forced the company to abandon high-voltage transmission and could have stymied its adoption worldwide, says Etienne Benson at the University of Pennsylvania, who has studied the crisis of ’23.
What was going on? Strange and desperate theories abounded. Then, by chance, a worker on the Big Creek line noticed an eagle squirt out a long string of liquid excrement as it took off from a transmission tower. When Harold Michener – an engineer who was also an amateur ornithologist – heard about this, he suspected that he had found the culprit. Bird faeces …