After last week’s post on a Carrington storm – a solar event able to do large-scale damage to anything electrical, especially power grids. I fielded a few questions which deserved a post. And I had some new ones of my own…
Does the whole Earth get hit?
The issue isn’t the Coronal Mass Ejection that goes with the flare, but the magnetic storm the CME provokes when it hits us. This affects the whole Earth in one hit, because the Sun-side of Earth’s magnetic field is pushed. The shadow side is pulled and zings back. Here’s an animation:
How powerful are these geomagnetic storms?
It depends on the CME, which – don’t forget – is super-hot plasma. The biggest can mass up to 100,000,000 tonnes, moving at up to 1000 km/second. These can really bang into our magnetic field. The current the geomagnetic storm induces in conductive material on Earth will vary as a result of the speed of the field movement, and of the scale of the conductive material. This acts like an aerial, so the more conductive material, the higher the voltages and current induced in it. That’s why the power grid is vulnerable, because transmission lines act as aerials and transformers have copper windings.
Can the excess voltages be calculated?
The voltage generated in a conductor is a product of the rate of change of magnetic flux and the direction of the field lines relative to the conductive material. In a closed loop like a transformer, for instance, this voltage can be calculated by Faraday’s Law of Induction, via James Clerk Maxwell, which states that the negative of the rate of change is equal to the line integral of the electric field. This is a bit of math that quantifies results when direction and intensity are both changing.
Will a geomagnetic storm burn out all power grids?
It depends on the loading of the grid and on the intensity of the storm, which will differ from place to place because the rate of change and flux direction keep changing. A heavily loaded power grid is more vulnerable because it’s operating closer to its designed tolerances. Needless to say, in this age of engineering to cost, some grids are fully loaded in normal operation. That’s why even the modest geomagnetic storms of in the last few decades have sometimes generated localised blackouts – some grids were vulnerable when others weren’t. With a big enough geomagnetic storm, all power grids would be blown out.
What about domestic appliances – computers, hand-helds and so forth?
It depends on the intensity of the storm. Anything plugged into the mains would suffer a voltage spike. Your stove or kettle wouldn’t notice it. Your computer might lock up. A re-boot might fix it, if the power stayed on. Or gear might be physically damaged. Newer devices are more vulnerable than old, partly because the older stuff was over-engineered. Anything with looped wire in it, like an electric motor – which includes DVD drives – might be at risk. Just about everything relies on low-voltage CPU’s these days, including cars, and it’s possible a really big geomagnetic storm would damage some of these. The effects probably wouldn’t be consistent across all gear because there are so many variables in electrical hardware, including whether it’s operating or not when the storm hits.
So some stuff, like the old Morrie Thou every Kiwi wishes they never got rid of, would still work and we’d otherwise mostly be OK?
Don’t forget, there won’t be any mains power, possibly not for months. No water pumps. No sewerage pumps. No heat. No light. No cooking. No battery charging. Hospitals out of action just when needed. Shall I go on?
Please don’t. Will the storm induce current in anything else?
Gas and oil pipelines. Older plumbing. They’re metal too.
Sounds scary. Is there anything we can do?
NASA has satellites on solar weather watch. They’re also implementing Solar Shield, an early-warning project. Whether anybody pays attention to warnings, or even hears them, is another matter. Even if the warning’s broadcast, who listens to dumb science stuff when the rugby news is about to start? But if you hear a warning, turn everything off, keep things unplugged, get your emergency kit stocked with food and water, buy a can opener, dig a long drop, and so on.
Is there a plus side?
We’d get amazing aurora displays towards the equator. Would that compensate for the damage? Uh…no.
Copyright © Matthew Wright 2014