Auroral Electricity

When a major auroral display spreads across Alaska's skies, intense electric currents flow in the ionosphere about 110 km (70 miles) above the earth's surface. Sometimes a current as large as a half-million amperes flows, usually east-west, across Alaska and Canada.

If we could just get some of this auroral juice into our power lines it would seem like we might have a good thing going. The truth is that it does get into our power lines. Unfortunately, the end effect is more likely to increase rather than decrease our power bills.

The electrical currents in the ionosphere induce additional currents in the conducting surface of the earth and in any nearby conductors such as power lines and pipelines. Long conductors, particularly those running north-south, pick up the greatest current. Hence appreciable current flows in the Alyeska pipeline. Recent measurements of current in the power line running from the mine-mouth coal generating plant at Healy northward to Fairbanks have been made by the Geophysical Institute's Drs. Syun Akasofu and Bob Merritt. They find that the aurora can induce an extra 6 amperes of current in the line in addition to the 100 amperes normally carried.

This additional surging current can cause outages by tripping protective circuit breakers in the power line. If a larger power grid were to be built, such as one that might connect Anchorage and Fairbanks, special design would be required to avoid aurorally associated problems, since the longer the power line the greater the induced current within it.