This week NASA Science News described a new NASA project called Solar Shield, designed to protect the U.S. electric grid from solar storms—large eruptions on the the sun (coronal mass ejections or "CME") that shoot charged particles towards the earth and cause the earth's magnetic field to vibrate. These changing magnetic fields, in addition to causing brilliant auroras, induce currents in the earth and power transmission lines. The induced currents can be strong enough to melt transformers connected to power transmission lines. The number of transmission lines has increased by an order of magnitude, from about 10,000 miles in 1950 to just under 160,000 miles in 2000. Demand for electricity has increased by approximately a factor of 10 in the same time.
On March 13, 1989, near the peak of sunspot cycle 22, a geomagnetic storm knocked out power across the entire province of Quebec for more than 9 hours and damaged transformers in Quebec, New Jersey and Great Britain. This storm was much weaker than the Carrington Event in 1859, which was strong enough to shock telegraphic operators and set some of their offices on fire. If a similar event happened today, the impact on the economy and our standard of living would be much worse due to our dependence on overloaded electrical grids. USA Today, in the article Electromagnetic pulse impact far and wide, begins its description of the risk from a massive solar storm or an electromagnetic pulse generated by a nuclear explosion this way: "The sky erupts. Cities darken, food spoils and homes fall silent. Civilization collapses." A 2009 North American Electric Reliability Corp (NERC) and US Department of Energy report concluded modern power systems have a "significantly enhance[d] vulnerability and exposure to the effects of a severe geomagnetic storm."
NASA's "Solar Shield" won't stop the charged particles or stabilize the magnetic field but it will provide utility operators in locations most susceptible to induced currents warning of a solar storm in sufficient time for them to disconnect transformers from the grid until the danger passes. This will, of course, result in massive blackouts while the storm is in progress, but it is much better to suffer a blackout that should be less than a day than to melt a large number of heavy-duty transformers that could take months, if not a year, to replace. What would happen if electrical power was rationed in the U.S. in the same way it is in countries like Iraq today?
The Solar Shield project will be able to to deliver transformer level predictions, minimizing the extent of the blackout. Solar Shield project leader Antti Pulkkinen, a Catholic University of America research associate working at NASA's Goddard Space Flight Center, said, "We believe we can zero in on specific transformers and predict which of them are going to be hit hardest by a space weather event." He explains, "Solar Shield springs into action when we see a coronal mass ejection (CME) billowing away from the sun. Images from SOHO and NASA's twin STEREO spacecraft show us the cloud from as many as three points of view, allowing us to make a 3D model of the CME, and predict when it will arrive. We quickly feed the data into CCMC computers. Our models predict fields and currents in Earth's upper atmosphere and propagate these currents down to the ground."
Pulkkinen cautioned that the Solar Shield is experimental and has never been field-tested during a severe geomagnetic storm. He said, "We'd like more power companies to join our research effort. The more data we can collect from the field, the faster we can test and improve Solar Shield."
The next solar maximum is expected around 2013. See the Space Weather Prediction Center for information on current space weather conditions.
