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Monday, October 18, 2021

Q&A with an energy expert

Back in 2009, UC Davis scientists made an unexpected discovery in the rocky hills of Iceland. The team, which included geology professor Robert Zierenberg, spent months drilling for volcano-heated water when the drill hit magma just two kilometers beneath the surface. Though the find was an accident, studying the molten rock could lead to progress in the field of geothermal energy.

The Aggie: What were you expecting to find at the drill site?

Zierenberg: We knew there was magma at great depths underneath that site, but our intent was not to drill into magma. We wanted to drill near it. We wanted to drill into high temperatures, but not drill into molten rock. But our ability to see underneath the surface is pretty limited. We happened to drill into a little pocket that we didn’t intend to hit. That, unfortunately kept us from drilling deeper. But it did lead to a new, exciting scientific discovery.

What was the scene like on the rig when they hit magma?

Well, they were having lots of drilling trouble. They couldn’t drill through. They kept getting stuck whenever they got to this level. And it wasn’t until a third attempt to get through that they actually figured out what was going on.

Normally, when you’re drilling, you’re pumping water down the hole and little rock chips come back so you can figure out what you’re drilling into. But they would not get any material back whenever they got into this magma. So the last time they tried to drill through it and they finally got some material back to the surface, they could identify it as molten rock.

Is it common that geothermal energy comes straight from magma?

Well, we always drill in places that have excess heat, and often they’re young, volcanic areas. But this is only the second time anyone has ever drilled into magma. In both cases it was unintentional. It’s unusual to hit magma at these shallow levels.

How did you become interested in geology in Iceland?

I’ve spent most of my career looking at hydrothermal systems, but mostly on the sea floor. Hydrothermal vents on the sea floor that are commonly called “black smokers” make deposits of metals, like copper and zinc, that we mine. They have exotic life forms around them.

But what we’ve never been able to do on the sea floor is know what’s controlling the chemical reactions that make those deposits form. That’s going on very deep on the sea floor – deeper than were able to drill with any technology we have. There is a scientific drilling ship, but it’s never been able to get to those kinds of depths. So we went to Iceland as a place where we could study this process by drilling on land.

Is geothermal energy used anywhere in the U.S.?

The biggest geothermal field in the world, in terms of installed electric capacity, is about 150 kilometers just west of us – the geysers. There’s a huge geothermal field in California. It’s one of the oldest and one of the largest in terms of capacity. Even though it’s a huge field – because we use so much energy – it’s a small percentage of our energy. It’s a large geothermal field that’s been productive, oh, since at least the 60s.

Do you think geothermal energy will gain popularity at all now that we’re looking at sustainable energy alternatives?

We don’t buy energy based on popularity; we buy it based on its availability and its cost. If you take out some of the subsidies for coal and oil, then geothermal energy would actually be competitive right now. It’s a matter of how you tax things and who pays the environmental costs of things. We will see a rise in geothermal, but it depends a lot on government policies.

Right now, in Iceland for example, more than 90 percent of the houses are heated by geothermal energy – which is why we were drilling there. They have a very robust geothermal energy economy there. They produce energy that’s either hydroelectric or geothermal.

I didn’t know UC Davis sent people to Iceland. How many times have you been there for research?

Probably four or five now, I think. I spent nine months actually living in Iceland when I was on sabbatical as part of a Fulbright Scholarship, and so I got to work closely with the geothermal industry in Iceland. Actually, I hope to run a summer-abroad course in Iceland this year.

Studying what?

Looking at the relationship between geology and history and culture in Iceland. Looking at how geology influences culture. If you go to the study abroad website, you’ll see that there’s a program that two of my colleagues and I are trying to run this summer. Iceland’s a wonderful place. We want to get more students over there.

MADELINE McCURRY-SCHMIDT can be reached at science@theaggie.org.

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