The 5 Volcanic Ashfall Effects on the Power Grid

We fear powerful volcanic eruptions with the flowing lava and balls of fire. But, the destructive volcanic ashfall effects on the power grid go unnoticed.

I’ve already discussed the impact of a powerful coronal mass ejection hitting Earth. The destruction would be unworldly.

I want to now go over the impact of a powerful volcanic eruption. More specifically, the impact of the ash falls from a supervolcano eruption on the U.S. power grid.

I’m going to focus on the supervolcano in Yellowstone National Park.

What’s considered a powerful volcanic eruption?

We haven’t experienced a large volcanic eruption in our modern history. One of the most recent large eruptions was Mount Saint Helens in Washington State in 1980.

I use the word “large” loosely though. To show you what I mean, let’s go over some eruption data. I’m comparing the Mount Saint Helens’ 1980 eruption to past historic eruptions.

This data puts the Mount Saint Helens’ eruption into perspective.

Volcano nameEruption time periodVolume of erupted magma
Toba74,000 years ago671.8 cubic miles
Yellowstone Huckleberry Ridge2.1 million years ago587.8 cubic miles
Yellowstone Lava Creek640,000 years ago239.9 cubic miles
Long Valley Caldera760,000 years ago139.1 cubic miles
Yellowstone Mesa Falls1.3 million years ago67.2 cubic miles
Mount St. Helens30 years ago (1980)0.06 cubic miles

Scary thing is, in our own backyard is a supervolcano in Yellowstone. Very few supervolcanos exist on Earth. And if they erupt, they’d make the Mount Saint Helens’ eruption look like a small burp.

Below is a schematic of the Yellowstone hotspot. It shows the magma building up under the caldera. You can see the pressure building up underground.

yellowstone hotspot upper mantle magma
Photo Credit: Kbh3rd

We all know volcanic eruptions are dangerous. But what specifically makes them dangerous is:

  • Lava flows and domes
  • Volcanic gases
  • Large mudflows
  • Volcanic earthquakes
  • Tephra release

Clearly, volcanoes are dangerous in many ways. But my main concern is the tephra fall out.

Tephra is all the material ejected from a volcano. This includes small fragments of rocks and ash.

Ash are particles that are less than 2 millimeters in diameter.

Now, to make matters worse, supervolcanos create powerful winds from their eruption force. Winds that can race across a continent.

Thus, ash can travel thousands of miles because of this wind and its small particle size.

This is my biggest concern, as ashfall affects the largest area and most people.

What are the volcanic ashfall effects on the U.S. power grid?

I know most people will think of lava that’ll melt equipment. But, lava won’t have a long enough reach. It won’t destroy electrical equipment that’s far away from the supervolcano.

So, lava would only destroy electrical equipment that’s around the supervolcano. But, the effects of ash on the power grid will be much greater.

I’m going to go over the 5 most important factors of ash from an eruption we need to consider:

#1 Amount of ash released from an eruption

The more ash that’s released in an eruption, the greater problems we’ll face. It’s like the more water that floods an area, the greater the damage will be.

This also ties into the duration of the ashfall. The median duration of an eruption is 7 weeks. But, we don’t know how a supervolcano would behave.

The eruption may last several weeks or stretch out to even years.

Now, to better visualize the ashfall, let’s take a look at past Yellowstone eruptions. In an earlier table, I showed you the amount of ashfall from monstrous eruptions. All in recent history.

Now, I want you to look at the ashfall from Mount Saint Helens in the below graphic, as a comparison in yellow. Look how small the ash fall area looks in comparison to the mega eruptions. Even though the media labeled the eruption as a major natural disaster.

Don’t get me wrong now. The eruption was deadly, and the economic impact was near 1 billion dollars.

But this would be peanuts compared to the impact of Yellowstone’s supervolcano eruption.

yellowstone volcano ash beds
Photo Credit: USGS

#2 Ash content

What is the ash made from? Ash differs from volcano to volcano.

The damage from ash depends on the following factors:

  • Ash chemistry: the level of soluble salt content and electrical properties for conductivity. Volcanic ash can hold moisture very easily. And saltwater is a great conductor of electricity. So, the electrical conductivity of ash improves with greater salt content.
  • Wet or dry ash: volcanic eruptions can eject water vapor. So a wet eruption produces moist ash. Moist ash sticks to things. Also when wet, the salt content in ash dissolves. This makes ash more electrically conductive.
  • Size of ash particles: particle size distribution and shape. For example, spherical or angular-shaped ash particles. When the surface area of an ash particle is greater, it’ll conduct electricity better when wet. Because this creates a better path for electricity to flow.
  • Compaction level of ash: the more compact ash is, the better it’ll conduct when wet. Because ash particles will be closer together allowing electricity to better flow.

#3 Weather conditions in the time of an eruption

If it’s dry weather, the number of problems we’ll face will be less. The ash will less likely stick to insulators. Plus, it won’t be conductive.

A fine line exists though. Too much rain and the ash will wash off, which is what we want. But just enough rain will make the ash stick and become electrically conductive.

All in all, a light drizzle or high humidity will make life more difficult for humans in an eruption.

#4 Strength of an eruption

The volume and duration of ashfall depend on a volcano’s eruption energy. The greater the eruption energy, the greater the ejected height of the ash into the sky.

This means ash can travel farther and cause greater problems.

#5 Human preparation for an eruption

Today in America, we’re not prepared for a supervolcano. And frankly, we don’t know what to expect. It has never happened before in modern times.

Also, because it has never happened, it’s out of sight out of mind. I believe it’ll be worse than any major earthquake or hurricane we’ve ever experienced.

With that out of the way, let’s now go over the impact of ash on our power grid.

#1 System outages from insulator flashovers

What is an insulator? electric hardware that serves two purposes.

  • Mechanically support energized lines or electrical parts. Electrical conductors are heavy. Insulators help hold up conductors mounted to poles and towers you see as you drive on roads.
  • Electrically isolate energized lines or electrical parts. As the name implies, insulators prevent the flow of electric current. They’re specially shaped using the right material to prevent electric current flow. So, overhead conductors connected to transmission towers use insulators. This way electric current can’t flow from the cables through the tower to the ground.

Now, what is an insulator flashover? It’s when you have a disruptive electrical discharge over an insulator’s surface.

Let’s go over an example of how this happens: the surface of an insulator becomes wet. This then allows pollutants in the air to create a conducting path on the insulator. The electric conducting path improves too, as pollutants stick to the insulator.

This is when you have leakage current. Where a small amount of electric current flows across an insulator’s surface.

Then if you have enough electric current flow, a “flashover” will happen. The electric current will flash across the insulator surface.

In the image below, 3 millimeters of wet volcanic ash cover a high voltage insulator. You can see the flashover.

electrical insulator flashover from volcanic ash
Electrical insulator flashover from volcanic ash (Photo Credit: Grantw13)

This is something we don’t want to happen. Again, we install insulators to prevent electric current flow through them.

So you can see the problem here with volcanic ash. A lot of ash can buildup over an insulator if it’s damp outside. The ash will then create a great conducting path.

The below table is data that shows the most humid states in America. On the plus side, the states around Yellowstone’s hot spot are not too humid. These states include Montana, Idaho, and Wyoming.

But, if the eruption produces wet ash, then even the driest states will be heavily affected. Only excessive rain can wash off the ash.

That said, who knows how our atmosphere will change from a supervolcano eruption. The ash can travel as high as 30,000 miles into the sky. That’s more than 4 times as high as a flying commercial jet.

StateAverage total yearly precipitation Rank among 50 states
Nebraska23.6 inches38
South Dakota20.1 inches41
Idaho18.9 inches42
North Dakota17.8 inches43
Colorado15.9 inches44
Montana15.3 inches45
Wyoming12.9 inches48
Utah12.2 inches49

Important Note: dry ash is not electrically conductive enough to cause insulator flashovers. Also, dry ash will only fall and stay on horizontal services.

But if the weather is slightly wet, wet ash will stick to everything that’s exposed. So, the season when a volcanic eruption happens is important. Especially since a volcano may only release dry ash. 

Above ground electric lines

In the U.S. we have thousands of miles of overhead electric lines. We use these lines for:

  • Generation
  • Transmission
  • Distribution

The overhead lines are all exposed to ashfalls. This includes electric lines in:

  • Your neighborhood
  • City centers near buildings
  • Running across highways
  • Hidden on mountains

Each transmission tower you see as you drive on the highway has its own set of insulators. So we’re dealing with countless insulators.

But, the voltage rating of these electric lines is important as well. We’ll use the 1980 Mount Saint Helens’ eruption as an example. From this eruption, nearby 110-kilovolt to 500-kilovolt transmission networks faired well.

These insulators withstood the ash build-up on them. They tolerated 6 to 9 millimeters of ash fall before flashovers occurred.

Lower voltage electric lines, from 33-kilovolts down to 480-volts, saw more damage. This is because the surface area of these lower-voltage insulators is smaller.

So, the risk of flashover increases on smaller insulators.

This is why the Mount Saint Helens’ eruption led to hours of outages for people living around the volcano. But compared to a supervolcano, the Mount Saint Helens eruption was tiny as I pointed out earlier.

Outdoor power transformers

Flashovers also happen across the insulation (bushing) of power transformers. This can burn or crack a bushing

Not only that, but ash can damage internal parts like the transformer’s windings. This would be a costly replacement that could take months.

Also, ash can cause a lot of damage to pole-mounted transformers. The ash enters into the transformer boxes.

Then the ash builds up around the terminals. Again, causing leakage current. This then can cause cables to burn out.

Even more, is the damage to large transformers at generation plants. The failure of these transformers has a domino effect.

Let’s use a transformer at a hydropower plant as an example. This transformer steps up the voltage to send power across transmission lines to you and me.

Now, imagine this transformer fails. As a result, everything powered by this hydroelectric plant will lose power.

I assumed other sources of power will have their own issues. Thus, they can’t come to the rescue to divert power to a given area.

Longterm effects from flashovers

Flashovers aren’t only short-term problems. Leakage current across high-voltage insulators causes long-term problems too.

You may not see a problem right away. But the flashovers may cause burning and etching on an insulator’s surface.

This then compromises how well an insulator will work in the future.

#2 Electrical line breakage due to ash loading

Electrical overhead lines in many U.S. states will encounter some level of ash loading.

The weight from a lot of ash build-up can cause problems. Especially when wet as the weight of the ash increases. Think of all the potential ash buildup on the steel towers and wooden polls you see outside.

Even more, ash can fall on overhanging vegetation. This added weight can break branches onto power lines.

I see a lot of areas with many trees right next to power lines. Not only will this damage power lines, but it can start fires. A problem we don’t need after a supervolcano eruption.

#3 Abrasion and corrosion of outdoor electrical equipment

Volcanic ash can speed up the wear on metal parts through erosion. We wouldn’t see the damage on day 1 though.

Like the leakage current we discussed, the damage will come in future months.

Volcanic ash is corrosive when wet. Not a good combo with electrical equipment that’s almost all metal.

Even more, equipment with moving parts will face problems. Volcanic ash can be hard and angular.

It’ll clog up mechanical parts. If it doesn’t cause failure, it’ll for sure jam mechanical parts.

Imagine the large wind turbines you see in the distance as you drive on highways. These are huge fans spinning in the air. In other words, they have moving parts.

Substation power transformers

Large substation transformers use many fans to stay cool. Without fans, they’d overheat. Especially if they’re operating at near full capacity in blistering heat.

Also, ash will impact equipment with air-intakes. The ash will block airflow.

Here in California, a lot of electrical equipment relies on air cooling systems. It’s necessary because of the blistering heat.

That’s why I specify most outdoor electric equipment with AC units. Also, all buildings here have HVAC.

That said, heavy ashfalls will bury HVAC equipment and overload them. Also, cut off their airflow.

#4 Change in substation surface rock sensitivity

A lot of ash build-up on the surface of a substation will reduce the ground resistance of the substation. Again, when ash is wet it becomes electrically conductive.

This ash build-up is a problem because it affects step and touch potential.

Step potential: the difference in surface voltage between 2 points. So, we’re analyzing a human step under rated fault conditions.

In other words, the voltage between the feet of a person next to an energized, grounded object.

Touch potential: the difference between earthing grid voltage and surface voltage. So, the voltage between an energized object and the feet of a person touching that object.

Now, what does this all mean? The substation surface will decrease in resistivity. As a result, more electric current can pass through a human body. This applies to both step and touch potential cases.

So, the chance for electrocution for substation operators increases. This is a serious danger if the equipment is still energized after an eruption.

#5 Disruption of power generation facilities

Excess ash can damage any equipment that breathes. We learned this already. Ash will block air intakes reducing air intake quality and quantity.

Several examples of equipment that would see damage include:

  • Turbines
  • HVAC
  • Substation equipment
  • Generators

Let’s focus on power plant generators. For almost all electric generation, we use generators. And generators have moving parts. Think of your regular home diesel generator.

Plus, generators need proper airflow to operate.

Now, newly designed equipment comes with safe keeps to prevent damage. But, the safe keeps are for extreme normal operating conditions. Not for when a supervolcano erupts.

Go drop a new piece of equipment in a desert with constant sand storms. The equipment will more than likely quickly fail. The conditions from a supervolcano I imagine to be much worse than a sandstorm.

For example, in the U.S. there are roughly 2,400 hydropower plants. Each has its own unique construction. While many are old and outdated.

The main problem is the high amounts of ash that would enter into a dam. This ash-filled water would run through all the hydroelectric equipment. This can then damage many parts of a facility, including:

  • Runner blades
  • Wear rings
  • Seals
  • Wicket gates

The damage would be great if hydroelectric plants continue to operate as ash falls from the sky.

What would be the worst-case end outcome of the Yellowstone supervolcano eruption?

Disruption of the power grid for years on end. Imagine if the Yellowstone supervolcano continued erupting. Ash would continue to fall endlessly on us.

More specifically though, I see the biggest damage with:

  • Power transformers
  • Distribution and transmission lines
  • HVAC equipment
  • Generation equipment

In short, large parts of the power grid would shut down. Whether by choice or due to equipment failure. Regardless, millions of people would be without power.

It could take years to fix and replace the widespread damage of equipment.

What can we do to limit the damage to power grids from the Yellowstone supervolcano eruption?

I’m going to go over 5 protective measures to limit the damage from a supervolcano eruption. The key is to limit the damage. We can’t prevent damage.

#1 Protective coatings to prevent erosion and pitting

Applying a protective coating to exposed electrical parts. For a turbine, for example, we’d apply this protective coating to the following parts:

  • Runner blades
  • Wear rings
  • Band seals
  • Cheek plates

We can do this on other exposed electrical parts and equipment too. This would reduce the level of corrosion from wet volcanic ash.

#2 Hydroelectrical plant bypass channels

Adding a specially designed floodgate system. Think of a water bypass. The goal is to divert the ash-filled water flow from the generation components.

The ash filed water would instead flow into a river and not pass through the turbine channel. This requires dam operators to closely monitor an eruption.

Many hydropower plants already have this bypass built-in. But also, many don’t.

#3 Planned power system shutdowns

This is the most effective method to prevent damage.

Operators will put equipment offline. Then also maybe seal and cover them.

I find this especially important for large equipment. For example, large power transformers.

Large power transformers can overheat or experience flashovers from a buildup of ash. This is one component of the power grid we don’t want to damage.

They’re costly to replace, and they have a very long purchase lead time.

That said, this is not a decision to take lightly either. Shutting down a critical power transformer to avoid $50,000 plus in damages may not always be wise. Because the shutdown can cost millions of dollars for customers who depend on the power.

In short, after an eruption, grid operators need to make quick decisions. Then operators also need to quickly tell their customers if they’re cutting power.

#4 Cleaning electrical equipment fast

We need to clean ash from electrical equipment fast. This is even more important if the ash is wet.

If not cleaned, the ash will stick like glue to surfaces. It’ll then become very difficult to clean. This will lead to flashovers and more damage.

Keep in mind, a supervolcano eruption would cover insulators everywhere with ash. So, cleaning tens of thousands of insulators fast would not be easy. Frankly, it’d be a logistical nightmare.

Normally, insulators are quickly cleaned using helicopters that blast water. But, in a time where ash fills the sky, helicopters can’t even fly.

Even more, there will need to be countless controlled outages during ash cleaning. And because of this, we’ll need to rely on diesel-powered generators.

As we learned with supervolcano eruptions, generators will need to be well protected. Otherwise, they’d breathe in ash.

#5 Upgrading power system equipment

I see a lot of improved equipment designs. Equipment that’ll prevent problems that come with small particles like ash.

But, a lot of power grid equipment is old and very badly maintained.

Thus, we need to more quickly modernize our aging power grid with better equipment.

Also, the equipment needs to be better maintained. A lot of times, I find large emergency generators that plant operators haven’t used much, fail. All because they weren’t properly maintained.

It’s one thing to dismiss the maintenance schedule for your home fridge. But, doing the same for very expensive equipment is insane. You should never leave $300,000 equipment untouched for years outside.

So for old equipment, one problem is the cost of replacement. Another is just laziness over proper maintenance and documentation.

In the end, we can avoid a lot of heartaches by providing better care for equipment. I find facility operators scrambling for an emergency generator fix in good times. All because of poor care.

I can’t imagine what would happen when a supervolcano erupts.


The impact of a powerful volcanic eruption I rarely hear discussed. The fear is real, and so is the resulting destruction.

To make matters worse, there’s a lot of unknowns with supervolcanos. We have limited knowledge of them, even though we have one snoring in our backyard.

I also hear talk about certain substation components going unharmed from an eruption. Such as disconnect switches, circuit breakers, bus bars, capacitors, and metering transformers.

Truth is, we don’t have enough data on supervolcano eruptions to make this call.

Plus, we don’t know the atmospheric conditions that’ll come with a monstrous eruption. This alone is a huge factor in the damage we could see as ash and moisture are a dangerous combo as we learned.

In short, the damage from supervolcanoes on our power grid is not talked about enough. The least we could do is have a national plan of action in place, with set standards enforced.

We don’t need to spend a lot of money either. Because truth is, we can’t spend endless money we don’t have on “what if” scenarios. Too many other unaddressed problems already exist today.

In the end, an eruption may come a week from now, or maybe 500,000 years from now. Who knows?!

But, it doesn’t hurt if we prepare ourselves to some reasonable level. As a result, we may even have a better power grid because of it.

Do you think we’re prepared for a supervolcano eruption? What do you think would be the impact of  Yellowstone’s supervolcano erupting? What are your thoughts on volcanic ashfall effects on the power grid?

Featured Image Photo Credit: NASA (image cropped)


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