The takedown of the Puerto Rican power grid by Hurricane Irma will, we hope, provide a teaching moment.  The United States power grid is vulnerable, and the consequences of a widespread failure, especially if lengthy, will be a disaster of monumental proportions.  This should not be a new realization.  Serious analysts such as the Foundation for Resilient Societies and the EMP Commission have been warning us for a long time.  The warnings have been ignored or even actively opposed by the electric power industry.

America's electric grid can be brought down by sabotage or by natural forces, such as the hurricane in Puerto Rico.  Hurricanes have limited geographic scope, but solar storms can affect the entire country.  As was shown by the Puerto Rican experience, without electricity, credit and debit cards don't work.  Cash becomes king.  Without electricity, communications become dubious.

Among natural threats to the electric grid, solar storms are perhaps the most serious.  A solar storm causes the Earth's magnetic field to move and induce large direct currents in long conductors, such as power lines and communications cables.  The 1859 Carrington Event was so powerful that some telegraph operators were electrocuted by voltages induced in the wires.  Fortunately, in 1859, the power grid did not exist.  A smaller March 1989 solar storm crashed the Quebec power grid and destroyed a large power transformer at the Salem nuclear generating station in New Jersey.  If the 1989 solar storm had been as severe as the Carrington Event, much of the North American grid could have gone down for months or years.

Since a solar storm is associated with the mass ejection of charged particles from the Sun, it is possible to have a warning and possibly prevent damage to the grid by turning off the grid until the storm is over.  Obviously, a deliberate blackout would be inconvenient, but not as inconvenient as a blackout lasting for years.  But electric utilities are unlikely to proactively turn off the grid, because their insurance companies have policy exclusions for "intentional acts."

Deliberate physical attack and sabotage of the grid are also major threats.  But perhaps the biggest danger would be an electromagnetic pulse (EMP) created by detonation of a nuclear device above the atmosphere.  The North Koreans have already threatened an EMP attack.

A small nuclear weapon detonated 200 miles above Kansas would create no direct damage – only a bright flash in the sky.  But gamma rays released from the explosion would interact with atoms in the upper atmosphere, knocking electrons loose.  These electrons would move in a spiral path as they interact with the Earth's magnetic field.  Strong electric and magnetic fields would strike the entire United States as a kind of electromagnetic shockwave.  There would also be slower variations in the Earth's magnetic field, much like the effect of a solar storm.

An EMP attack has the potential to damage computers and other semiconductor-dependent devices.  Stalled automobiles could fill the roads and block emergency vehicles.  Control system for power plants and refineries could fail.  Above all, there could be widespread destruction of the all-important high-voltage grid transformers.  Critical infrastructure can be hardened against EMP, as, indeed, our military systems are and have been for decades.

If there is a large-scale blackout lasting for weeks or longer, the immediate problem is food; water; and, in cold areas, sufficient heat to sustain life.  Without power, the normal food pipeline would be disabled.

To bolster societal resilience, everyone could be required to have a 30-day supply of food and water, or local areas could have warehouses and distribution schemes to fill the void.  Certainly, there is no shortage of food.  At any time, there are enough corn and soybeans stored in the Midwest to feed the entire country for five years.  The problem is distribution, as well as preparing the grain as an edible meal.  As an example, the Las Vegas, Nevada metropolitan area has about 2 million people.  If each person consumes two pounds of corn and soybeans per day, then 4 million pounds, or 2,000 tons, a day is required.  A train with 100 cars could transport enough food to Las Vegas for five days' consumption.  But will their diesel engines be disabled by the EMP?  Can the railroad operate if much of its electronic infrastructure is damaged?  Can sufficient diesel fuel be found to operate the trains?

The grid's high-voltage transformers would take years to replace and must be protected against damage.  These devices can be as big as a house and are mainly manufactured in Asia.  Lead time is months or years and would be longer if large numbers of orders were placed.  The manufacture of these transformers is an example of a critical industry that should be preserved and protected within the U.S.  Protecting the thousands of  transformers with automatic devices might cost $50 billion, or possibly much less, but this cost is nothing against the $50-billion-per-day cost of a national blackout.  Other capital equipment, such as generators and turbines, must also be protected, but these devices are probably less vulnerable to damage than the transformers.

In times of crisis, there must be a plan to produce and distribute enough diesel fuel to keep the railroads and heavy trucking industry operating.  The railroad engines and truck tractors must be hardened against an EMP.  The idea that it is enough to have 24 or 48 hours' worth of fuel for emergency generators simply postpones the disaster for 24 or 48 hours.  There has to be a plan to keep essential services going until the grid can be bought back up.  Without communications, nothing can be coordinated, so basic means of communication, such as the cell phone network, must be protected.

The problem in Puerto Rico of truck drivers being unavailable because they were busy taking care of their families is instructive.  Organizations equipped for emergencies, such as the military, fire departments, and police, are too small in numbers and not necessarily located where they are needed to hold things together in a widespread blackout.  A volunteer corps of people ready to deal with emergencies is necessary.  Such a corps would also be invaluable for emergencies such as earthquakes and hurricanes.

Everything comes down to having a plan to deal with what might happen.  There is no such plan today.  In the case of a national blackout, help will not come from outside the affected area, because the entire country is affected.

The threat by North Koreans to detonate a nuclear device over the Pacific Ocean could be a ploy to test an EMP device.  A variation of nuclear weapons is devices, probably with low explosive yield, designed to have a high gamma ray output to create a powerful EMP.  Given such devices, along with delivery systems, the North Koreans could institute a devastating attack on the United States.  They must be denied this technology.  Nuclear weapons often have a shell or "tamper" made of a heavy metal to contain the explosion for a few more nanoseconds before the bomb blows itself apart and aborts the increasing chain reaction.  The tamper increases explosive yield but also absorbs gamma rays.

It would be incredibly foolish to allow the North Koreans to continue on the path of developing the means to destroy the American economy and perhaps kill a large part of the population.  The North Koreans are clearly working on these technologies that permit a weak state to launch a devastating attack against a strong state, and further, they are obviously prepared to sell the technology to states that are even more dangerous, such as Iran.  The Russians and Chinese are obviously delighted to have a proxy that can attack or threaten the U.S. while said Russians and Chinese protest their innocence.  We can have a small war now or something much worse later.

Norman Rogers writes often on environmental and political topics.  He has a website.