WEBVTT
Kind: captions
Language: en

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Laura Stern: We make a number of different
hydrates in the laboratory.

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Some are with hydrocarbons.

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Methane being the most abundant.

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We also make carbon dioxide hydrate, ethane
hydrate, propane.

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A number of different structures.

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Laura Stern: So liquid nitrogen is very cold.

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It’s about a hundred degrees colder than
the temperature at which these hydrate samples

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would dissociate.

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When they would decompose to ice plus gas
on the table top.

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In here we have a little piece of methane
hydrate . It’s enclosed in a soft metal

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jacket . So, the samples we make, they’re
poly-crystalline.

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They look like snow.

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It looks like compacted snow.

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But, honestly it does contain gas inside.

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Laura Stern: Take a little piece off here
and, as it warms up, you’ll begin to see

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it pop, it’s reverting to ice plus gas,
and then as the ice would melt , as it continues

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to warm, it will end up being water plus gas.

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So, this will form anywhere you have water
and gas at moderately low temperatures or

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high pressure.

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Steve Kirby: My name is Steve Kirby.

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I am a geophysicist here with the U.S. Geological
Survey in Menlo Park.

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I work with Laura Stern who is also a geophysicist
in this lab that is devoted towards the investigation

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of planetary ices and gas hydrates.

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Laura Stern: Gas hydrates in nature occur
in very remote places and they are very complex,

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with the sediment interactions and the conditions
that they form under.

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And samples that are brought up are under
some sort of alteration or decomposition.

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Steve Kirby: We’ve educated ourselves by
experiment in learning how to make them in

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a form that’s suitable for doing material
property tests.

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Laura Stern: We start in the main portion
of the lab making ordinary water ice that

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we use as a reactant for the hydrates.

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We grind and sieve that ice and we pack them
into pressure vessels and we take that package

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and we put it into this freezer and we load
them onto these two ports and we evacuate

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all of the pore space between the ice grains
and then we have these reservoirs that have

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pre-chilled gas in them that we then put into
that pore space to react with that ice to

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make hydrate.

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So we start simple, we make the pure end member
hydrates and then we add complexities in the

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known fashion so that the properties that
we measure we understand individual effects

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of those complexities.

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Unlike just looking at the samples that are
retrieved from nature which are so difficult

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to analyze.

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Laura Stern: This is a sample of, this is
a structure two gas hydrate.

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It’s predominantly methane has a little
bit of ethane in it.

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We’re going to demonstrate how much gas
is actually in this.

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If you bring a cubic meter of methane hydrate
from the ocean floor up to the lab and put

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it on the table top it would release one hundred
and sixty three times its volume of gas at

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standard conditions.

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So, it really is a very efficient way of storing
gas.

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We’re going to demonstrate that by lighting
this sample on fire.

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So, it’s decomposing to ice plus gas the
gas is flaming and the ice will soon just

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melt to water.

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And you can see it’s not just a pile of
snow that I was showing you.

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Steve Kirby: They contain abundant amounts
of natural gas.

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This natural gas is thought to be a significant
potential resource for our energy needs later

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in this century.

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Laura Stern: This is a gas hydrate from the
Cascadia Margin so this is a natural hydrate

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brought up from the ocean floor.

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So, you can see the marine muds in here and
these nice nodules of predominantly methane

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hydrate.

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Laura Stern: So, this laboratory is unique
in that we have the low temperature capabilities

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to make the samples.

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So, we make different types of ice samples
or gas hydrates or ammonia hydrates both planetary

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ices and gas hydrates.

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And we also have unusual capabilities in how
we look at those samples afterwards with the

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cryogenic capabilities on our x-ray diffractometer
as well as, over in another laboratory, a

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cryogenic set up for scanning electron microscopy.

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Where you can actually look at the grain textures
and pore structures of samples and how they

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interact with the sediments and how they look
in nature compared to how we make them in

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the laboratory.

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Steve Kirby: Lastly, we give insight from
our laboratory experience as to the governing

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kind of physical processes that say govern
their stability in nature and how they respond

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to deformation, changes in pressure and so
on.

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So this is an unusual lab, like I say, there
are only a handful of them world wide and

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we are very fortunate to be here at the geological
survey and to have the opportunity of working

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on them.

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END