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USGS Gas Hydrates Lab

7 minutes

(Describer) Titles: USGS – science for a changing world.

(Describer) Gas hydrates are crystalline solids consisting of gas molecules surrounded by an ice-like cage of water molecules. They are stable at the temperatures and pressures that occur in ocean-floor sediments at water depths greater than about 500 meters and beneath Arctic permafrost. These minerals represent a significant future potential energy source, with worldwide estimates of the amount of carbon in methane stored in gas hydrates at about twice the amount of carbon held in all fossil fuels on Earth.

(Describer) USGS scientists are studying gas hydrates in the USGS Gas Hydrates Lab in Menlo Park, California.

(female) We make several different hydrates. Some are with hydrocarbons,

(Describer) Laura Stern:

methane being the most abundant. We also make carbon dioxide hydrate, ethane hydrate, propane...

(Describer) She pulls a hose from a thick bucket.

a number of different structures.

(Describer) She carries it to other containers, which she opens.

Liquid nitrogen is very cold. It's about 100 degrees colder than the temperature at which these hydrate samples would dissociate, when they would decompose to ice plus gas

(Describer) She pours the liquid onto packages in the containers, and opens a package.

on the tabletop. In here we have a little piece of methane hydrate.

(Describer) Wearing gloves, she gets tweezers.

It's enclosed in a soft, metal jacket. So the samples we make, they're polycrystalline.

(Describer) She peels off the jacket.

They look like snow-- looks like compacted snow.

(Describer) She sets the tweezers aside.

But honestly, it does contain gas inside.

(Describer) With a blade, she cuts some of the white material onto a mat.

Take a little piece off here. As it warms up, you'll begin to see it pop.

(Describer) Tiny pieces pop.

It's reverting to ice plus gas. Then as the ice would melt as it continues to warm, it'll end up being water plus gas. This'll form anywhere you have water and gas at moderately low temperatures or high pressure.

[crackling]

(Describer) In another room…

My name is Steve Kirby. I'm a geophysicist here with the U.S. Geological Survey in Menlo Park. I work with Laura Stern, who's also a geophysicist in this lab that is devoted towards the investigation of planetary ices and gas hydrates. Gas hydrates in nature occur in very remote places. They're very complex with the sediment interactions and the conditions that they form under. Samples that are brought up are under some sort of alteration or decomposition. We've educated ourselves by experiment in learning how to make them in a form that's suitable for doing material property testing. We start in the lab's main portion making ordinary ice, used as a reactant for the hydrates. That ice is ground, sieved, and packed into pressure vessels.

(Describer) Cylinders.

We put that package into this freezer. We load them onto these two ports. We evacuate all the pore space between the ice grains. Then we have these reservoirs

(Describer) ...like a stock pot.

that have pre-chilled gas in them we then put into that pore space to react with the ice to make hydrate. We make the pure end-member hydrates then add complexities in the known fashion so that the properties that we measure we understand the individual effects of those complexities,

(Describer) She opens a cryogenic x-ray diffractometer.

unlike looking at just the samples retrieved from nature, which are so difficult to analyze. This is a structure II gas hydrate.

(Describer) She cuts some onto a fine grate.

It's predominantly methane-- has a little ethane in it. We're gonna demonstrate how much gas is actually in this. If you bring a cubic meter of methane hydrate from the ocean floor and put it on the tabletop, it would release 163 times its volume of gas at standard conditions. So it really is a very efficient way of storing gas. I'm gonna demonstrate that by lighting this sample on fire.

(Describer) She holds a match flame around the small pile of fuzzy white blocks, and it catches fire. As it burns steadily, the edges get rounded.

[crackling]

So it's decomposing to ice plus gas. The gas is flaming and the ice will soon melt to water.

(Describer) Parts of it bubble.

You can see it's not just a pile of snow.

(Kirby) They contain abundant amounts of natural gas. This natural gas is thought to be a significant potential resource for our energy needs later in this century.

(Describer) Stern goes back to a container.

This is a gas hydrate from the Cascadia margin. This is a natural hydrate. It's brought up from the ocean floor.

(Describer) It’s grey with white chunks.

You can see the marine muds and these nice nodules of predominantly methane hydrate. This laboratory is unique in that we have low temperature capabilities to make the samples. We make different ice samples or gas hydrates or ammonia hydrates, both planetary ices and gas hydrates. We also have unusual capabilities in looking at those samples with the cryogenic capabilities on our X-ray diffractometer as well as, in another laboratory, a cryogenic setup for scanning electron microscopy, where we can look at the grain textures and pore structures of samples

(Describer) Many have flat sides.

and how they interact with the sediments, how they look in nature compared to those made in the laboratory. Lastly, we give insight from our laboratory experience as to the governing physical processes that govern their stability in nature and how they respond to deformation-- changes in pressure and so on. So this is an unusual lab. There are only a handful of them worldwide. We are very fortunate to be here at the Geological Survey and to have the opportunity of working on them.

(Describer) The hydrate created in the lab is shown burning again, melting slowly.

[crackling]

(Describer) Funding to purchase and make this educational program accessible was provided by the U.S. Department of Education. Contact the Department of Education by telephone at 1-800-USA-LEARN, or online at www.ed.gov.

Funding to purchase and make this educational production accessible was provided by the U.S. Department of Education:

PH: 1-800-USA-LEARN (V) or WEB: www.ed.gov.

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Gas hydrates are a significant potential energy source occurring in ocean-floor sediments at water depths greater than 500 meters. The USGS (US Geological Survey) operates a gas hydrates laboratory on its Menlo Park campus. USGS geophysicists Laura Stern and Steve Kirby detail how they study and create gas hydrates in their super-cooled lab.

Media Details

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