ON MARCH 13th 1989 a surge of energy from the sun, from a “coronal mass ejection”, had a startling impact on Canada. Within 92 seconds, the resulting geomagnetic storm took down Quebec’s electricity grid for nine hours. It could have been worse. On July 23rd 2012 particles from a much larger solar ejection blew across the orbital path of Earth, missing it by days. Had it hit America, the resulting geomagnetic storm would have destroyed perhaps a quarter of high-voltage transformers, according to Storm Analysis Consultants in Duluth, Minnesota.
America runs on roughly 2,500 large transformers, most with unique designs. But only 500 or so can be built per year around the world. It typically takes a year or more to receive an ordered transformer, and that is when cranes work and lorries and locomotives can be fuelled up. Some transformers exceed 400 tonnes.
Kit that protects transformers from EMP also saves them from geomagnetic storms, though the reverse is not true. … The expense of installing surge-blockers and other EMP-proofing kit on America’s big transformers is debated. The EMP Commission’s report in 2008 reckoned $3.95bn or less would do it. Others advance higher figures. But a complete collapse of the grid could probably be prevented by protecting several hundred critical transformers for perhaps $1m each.