Day 37: who’s got the power?

Here’s a technical question raised by the lectures in our introductory class at Reykjavík University: given Iceland’s natural resources, would it be correct to say that Icelanders have access to virtually unlimited power?

Here’s a lawyerly answer:  well, it depends.

Iceland sits atop a rift in the surface of the Earth where two continental plates are slowly pulling apart.  Each year, on average, North America slides about half an inch to the west, and Europe about half an inch to the east.

Icelandic rift zones.  Image credit: Hutton Commentaries.
Icelandic rift zones.  Image credit: Hutton Commentaries.

That’s not a lot of distance, but consider the masses involved: even if you only look at Iceland, you’re talking about the movement of thousands of miles of rock and ice, and of rivers and farms and cities and people.  The energy involved in the drift is phenomenal: on a human scale, it would be fair to call it virtually unlimited.

As it happens, though, the energy involved in continental drift is also distributed over huge areas and a timetable that runs into the millions of years.  Harnessing it is, for the most part, beyond the present grasp of human technology.  But not completely.

Where the continents are pulling apart, the Earth’s crust tends to be thinner, and magma finds its way to the surface more easily.  The longest rift zone runs down the middle of the Atlantic, but on occasion the eruptions there breach the surface of the sea.  Iceland itself is the result of such eruptions.

Undersea volcano reaches the surface.  Image credit: Getty images.
Undersea volcanic eruption reaches the surface.  Image credit: Getty Images.

What’s more, Iceland sits atop a mantle plume, where geophysical properties of the Earth itself channel magma toward the surface in vastly greater quantities than elsewhere.  Between the rift and the plume, Iceland has more volcanoes, packed into a smaller area, than almost any other place in the world.  Being a safe and peaceful country, Iceland may well be the only spot on earth with more volcanoes in its landscape than prisoners in its jails.

Major Icelandic volcano systems.
Major Icelandic volcano systems.  Image credits: as shown, and volcanocafe.com.

Could Icelanders harness their volcanoes to produce electricity?  Here’s another lawyerly answer:  well, yes and no.

Just one volcanic eruption can yield phenomenal bursts of energy: the 1883 eruption of Krakatoa, a volcano in Indonesia, included an explosive event roughly equivalent to detonation of a 200 megaton bomb – more than 10,000 times the force of the weapon that obliterated Hiroshima.

Nineteenth-century lithograph depicting the Krakatoa eruption.  Image credit: Wikimedia.
Nineteenth-century lithograph depicting the Krakatoa eruption.  Image credit: Wikimedia.

Converting that much energy into useful form would be a fantastic feat of engineering … but building a power plant that can stand up to such an explosion is still a bit beyond our ability.*

What’s more, volcanic eruptions tend to be unpredictable, at least until right before they occur.  The duration and power of an eruptive event is difficult to predict as well.  The Krafla fires, a fissure eruption in eastern Iceland, lasted for nine years between 1975 and 1984.  The Holuhraun eruption, a similar event not far away, lasted only six months between 2014-2015 … but it was far more energetic, pouring out more lava than any event in Iceland in the last 200+ years.

Krafla and Holuhraun eruptions: which is which?

You don’t know exactly where or when an eruption will occur, how long it will last, or how powerful it will be.  So harnessing an actual eruption is out, at least for now.

But the fact that you can’t harness a volcano as it erupts doesn’t mean you can’t harness it at all.  Not all of the magma makes it to the surface; some of it remains trapped underground.  These magma chambers are reasonably close to the surface: they’re a few kilometers down, easily within reach of existing well-drilling technology. Magma can retain its heat there for a long, long time, meaning there’s energy available relatively close to the surface, if you know where to look.  Because magma tends to flow through cracks and fracture zones already present, the magma chamber also can be periodically replenished.  The net effect is that a volcano can simmer as a potential source of energy for a long, long time.

Overlook near Nesjavellir power station, on the northern flank of Hengill.
Overlook near Nesjavellir power station, on the northern flank of Hengill.

How long?  Well, the two largest geothermal power plants in Iceland, the Hellisheiði and Nesjavellir stations, both extract power from Hengill – a volcano whose last known eruption was about 2,000 years ago.  These plants produce hundreds of megawatts of electrical and thermal energy essential to the Icelandic economy and standard of living.

The power provided by the Earth isn’t unlimited, because not all of the energy is accessible using current technology: but the store of magma is in no danger of running out and there’s no reason to think the volcanoes that built Iceland are going to suddenly fall silent.  So looked at on a timetable that matters to humankind: yes, Icelanders have access to virtually unlimited power.

Just one more technical question remains:  is it possible for humans to screw this up?  And one more lawyerly answer:  it’s always possible for humans to screw something up.

More on that next time.

* The eruption also ejected about six cubic miles of rock and ash from the depths of the volcano.  Even if your power plant survived an event like Krakatoa, you’d need a lot of shovels to dig it out of the rubble.

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