Methane Hydrates: Fire and Ice
Gas hydrate deposits are found in both permafrost and deep-water regions. (Figure modified from Ruppel (2011))
After the Fukushima nuclear accident, Japan shut down most of its nuclear power plants. Now, researchers are drilling deep into the ocean in search of a new source of energy called methane hydrates. U.S. Geological Survey researcher Carolyn Ruppel tells host Bruce Gellerman that tapping the methane stored in ice could help Japan fill its nuclear energy gap, and is a huge potential source of energy for the world.
GELLERMAN: And now experimental drilling, designed to commercialize what is known as methane hydrate, is picking up speed. Promising a new source of energy, not just for Japan, but the world. Carolyn Ruppel, of the U.S. Geological Survey at Woods Hole Massachusetts, studies methane hydrate, which some call fiery ice.
RUPPEL: One reason we call it fiery ice, or fire in the ice, is that you can actually light this little chunk of icy material on fire and it will sustain the flame. If you see them in their concentrated form, they look like little chunks of ice. And, sometimes, if you put them in your hand, they will fizz because they are releasing the methane. They are not stable at normal pressures and temperatures, so it’s releasing its methane.
GELLERMAN: These crystals of ice contain and lock in a lot of methane.
RUPPEL: Right. One way to think about it is if you have one cubic meter of methane hydrate, if you were to break that down at sort of our atmospheric pressure and temperature conditions, you would get about 164 cubic meters of methane, essentially a very concentrated form of methane.
GELLERMAN: So, methane, natural gas?
RUPPEL: It’s natural gas, but it’s natural gas that is trapped within this form that concentrates it.
GELLERMAN: And there’s a lot of this methane hydrates in the world.
RUPPEL: Right. And there’s still, even today, after many decades of study, there’s still a lot of controversy about how much there is, but it’s still very substantial.
GELLERMAN: I heard that maybe a thousand years worth of natural gas, methane, at current consumption worldwide.
RUPPEL: Some people say a hundred and some people say a thousand.
GELLERMAN: Well, how could we mine this - could we mine them?
RUPPEL: What you’d probably want to do is stimulate the formation to release the gas. So, ways to do that might be to depressurize the formation. It’s under pressure, and take the pressure off. The other method that has been actually attempted is to heat the formation up, and that way, you could produce the methane.
GELLERMAN: What are they using in Japan in these experimental wells that they hope to turn into commercial wells?
RUPPEL: What they’re doing now is they’re starting to drill the series of wells that will be necessary to get to the point of doing a long-term production test. And what a long-term production test would mean is proving that the amount of methane hydrate down there and the rate at which you could produce methane from it this would make this a viable resources.
GELLERMAN: The United States has projects on the north slope of Alaska to find out if we have these methane hydrates and find out if we can exploit them - we know we have them there, right?
RUPPEL: We know we have them and the more critical question is how and if we can exploit them. Ultimately the questions that we’re all looking at would be what are the best ways to exploit them and is it economically feasible to get to the point that gas hydrates become part of the total natural gas supply for the U.S.
GELLERMAN: I understand that one of the richest places on the planet is in the Gulf of Mexico.
RUPPEL: In terms of gas hydrate concentrations from what we’ve found so far, there are some very high saturation deposits within the Gulf of Mexico.
GELLERMAN: We should say that methane, natural gas, is a very potent greenhouse gas.
RUPPEL: It is a very potent greenhouse gas. It’s estimated to be 15-20 times more potent than CO2 in the atmosphere, but the concentration of CO2 is obviously much, much higher than methane.
GELLERMAN: If I were a drilling company in the Gulf of Mexico and I was drilling down through these methane hydrate layers…
RUPPEL: Uh huh.
GELLERMAN: And causing them to disrupt, could that cause a problem?
RUPPEL: Well, we don’t have any published evidence that there has been any kind of failure or problem related to drilling through gas hydrates. But certainly, there needs to be a lot more work done on these hazards.
GELLERMAN: Do you think a mistake in drilling could trigger climate problems?
RUPPEL: No. You know, when we’re drilling, it’s a discrete borehole that’s being made in the ground, so that’s unlikely to create a methane release so large that this would have an impact.
The other thing to remember is that, particularly with deepwater drilling, that methane when it’s released goes into this huge pool of the ocean where the ocean is very under-saturated. So mostly, it dissolves in the ocean. That may not be so good for the ocean, but it’s not usually a freight train to get that gas directly out into the atmosphere.
GELLERMAN: So, you think that we can manage the risks?
RUPPEL: I don’t think there really are large risks to worry about with the production.
GELLERMAN: I was surprised to hear you say that because I’ve been reading about this and they talk about geo-hazards from methane hydrates.
RUPPEL: Mm hmm. Right.
GELLERMAN: Let me go through a couple of them. One would be climate change - 55 million years ago - they say that there was a large scale disruption of the methane in the ocean and it caused basically mass extinction of marine life.
RUPPEL: Yes. That’s one explanation for a period for this mass extinction event and also there was a large warming event. But I think it’s important to make a distinction here between so-called geo-hazards which are hazards like climate change or submarine slope failure, which is another hazard that has sometimes been attributed to gas hydrates. It’s important to make a distinction between those kinds of hazards and the kinds of hazards that might be attributed to drilling or producing in these deposits.
GELLERMAN: What you just talked about are basically landslides in the ocean.
RUPPEL: Which occur in the oceans, sometimes, yes.
GELLERMAN: Because of the disruption of methane hydrates?
RUPPEL: Well, I think it’s very unlikely that gas hydrates themselves trigger the landslides, but they may precondition these slopes for failure if there’s an outside triggering event.
GELLERMAN: So, an earthquake, if you have an earthquake…
RUPPEL: Yes, yes.
GELLERMAN: It would disrupt the methane hydrates?
RUPPEL: Or the associated free gas, yes. And potentially, destabilize the slope, right.
GELLERMAN: Causing a tidal wave?
RUPPEL: That has also been postulated, but the problem is again, after a slide has already occurred, we have very little proof of what caused the slide.
GELLERMAN: So, Japan has a very ambitious program, right now, relative to the United States. How big is it compared to what we’re doing?
RUPPEL: Well, the total spending in the U.S., since about 1999, has probably been about 130 million dollars. In Japan, the project they’ve undertaken now, the investment is about one billion dollars, and that’s from sort of doing what we call the geotechnical wells through the production tests.
GELLERMAN: But Japan has the compelling forces of urgent necessity - they’re…
RUPPEL: Absolutely. Absolutely.
GELLERMAN: So if you were an optimistic person, I’m guessing you are, when do you think we could start mining this if it was economically feasible?
RUPPEL: Well, Japan may be there in a decade, easily. Let’s talk about the U.S. We’re probably talking 15 years before we’d start being able to add that to the natural gas stream. There is one important thing to note, which is that natural gas has the same problem in many places, which is it has to be near a way to move the natural gas.
So here’s a situation where the natural gas may be sitting in deep water environments very far from the coast, or in Alaska. And you have the same problem again. Natural gas in that sense is natural gas.
GELLERMAN: Well, Dr. Ruppel, thank you so very much for coming in.
RUPPEL: It’s my pleasure.
GELLERMAN: Carolyn Ruppel is a research geophysicist with the gas hydrates project at the U.S. Geological Survey at Woods Hole Massachusetts.
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