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Gas Hydrates: Our Energy (and Climate) Future?
Lecture Outline:
1)What are gas hydrates anyway?
2)Gas hydrates as an energy source – pros
and cons
3)Gas hydrates and climate change: adding
fuel to the flames?
Hydrates - What are they?
Gas Hydrates are solids formed
from hydrocarbon gas and liquid water
They resemble wet snow and can
exist at temperatures above the
freezing point of water
They belong to a form of
complexes known as clathrates
Clathrates - What are they?
Clathrates are substances having a lattice-like
structure or appearance in which molecules of
one substance are completely enclosed within
the crystal structure of another
Hydrates consist of host molecules (water)
forming a lattice structure acting like a cage, to
entrap guest molecules (gas)
 CH4 (most common), CO2, H2S form hydrates
98% in ocean
2% on land
white dot = gas samples recovered
black dot = hydrate inferred from seismic imaging
dotted lines = hydrate-containing permafrost
using seismic-reflection profiles
Bottom Simulating Reflection (BSRs)
Methane Hydrate stability diagram
-methane hydrates can occur at
water temperatures up to 30°C,
if the pressure is high enough
-stable over most of ocean floor!
a methane hydrate lattice
redrawn after Kvenvolden (1993)
“The Burning
Methane hydrate
supporting its own
Methane Hydrates as an energy source
- 1 cubic meter of gas hydrate (90% site occupied) = 163 m3 of gas
-there is A LOT of it,
and it’s everywhere
natural gas
• USA has gas hydrate reserves of 112,000-676,000 trillion cubic
feet (tcf)
• USA has 2,200 tcf of natural gas reserves (EIA)
• USA uses 25-30 tcf/yr of natural gas
• India and Japan are leading the charge to hydrate recovery
An Energy Coup for Japan: ‘Flammable Ice’
Water depth: 1000m
subfloor depth: 300m
NYTimes, 3/12/13
Methane Hydrates as an energy source
-hydrate dissociation upon recovery; engineering challenge
-expense of long pipelines across continental slope, subject
to blockage with solid hydrate
-methane release into atmosphere problem for climate change
(20x more potent than CO2)
-fragile ecosystems surround
sediment surface hydrates
& seeps
ice worm that lives in hydrate
photo by Ian Mc Donald
1 cubic meter of gas hydrate (90% site occupied) = 163 m3 of gas + .87 m3
Undersea slides (slope failures) may be caused by methane hydrate dissociation;
implications for pipeline?
Large, expensive pilot programs
focus on drilling in frozen
permafrost areas
Ex: Mallik, Canada
New ocean sediment drilling technologies
invented for hydrate recovery and storage
an Ocean Drilling Program core locker
with lone hydrate core in pressurized chamber
dissociating methane hydrate at sediment/water interface
Westbrook et al., 2009
-lots of CH4 escaping from
melting gas hydrates
-powerful positive feedback
on global warming
-CH4 is a powerful greenhouse gas
-most likely oxidizes to CO2 before
it enters the atmosphere… but still!
-see Archer et al., 2007 for
detailed investigation of
methane hydrate dissociation
during global warming
Westbrook et al., 2009
An interesting twist:
- replace CH4 with CO2 in the hydrate lattice
- have your energy cake and eat it too?
Park et al., PNAS, 2006
Take-home point
Methane hydrates represent the largest fossil fuel reservoir,
but problems ranging from yet-to-be-developed
technologies and climate change feedbacks remain to be