Proposal
Serpentinization of olivine ---- A new energy source?
Kaitlynn Heflin (Chemistry)
Olivine hydration, also called serpentinization
is a geochemical process resulting in the synthesis
of molecular hydrogen. Hydrogen in the presence of carbon
dioxide is then capable of producing methane. This natural
production of hydrogen and methane occurs in a number
of geological environments. This natural production
of hydrogen may explain the origins of life on Earth
and on other planets because hydrogen is capable of
the sustenance of simple forms of life. The serpentinization
of olivine is also a potential source of hydrogen that
may be exploited as a new energy source if the rate
of formation is high enough. The purpose of my off-campus
research will be to study the rates at which serpentinization
yields hydrogen and methane at elevated temperatures
and pressures (similar to the environment in mid-ocean
ridges and forearc environments), to be conducted at
the U.S. Geological Survey space under the direction
of Bob Rosenbaum in Menlo Park, CA, using flexible-gold
cell technology. My research advisor's hypothesis is
that the rate of hydrogen production increases with
increasing temperatures and is independent of pressure
(assuming a high pressure, 100- 500 bar) for average
Earth olivines (Fo90). The second hypothesis is that
methane production due to serpentinization is inhibited
without a mineral catalyst such as chromite. The overall
importance of this research will be to further understand
the complex relationships of serpentinization reactions,
in order to advance our current knowledge on the origins
of life and to potentially find alternative fuel sources.
Summary
Kaitlynn Heflin
Experimental Geochemistry Lab Intern
Costal and Marine Geology Group
U.S. Geological Survey, Menlo Park, CA
Mentors: Bob Rosenbauer (USGS), Chris Oze (Bryn Mawr
College)
Geochemical Processes
This summer I participated in geochemical
research at the U.S. Geological Survey in Menlo Park,
California. I worked under Bob Rosenbauer, a Senior
Researcher at the U.S. Geological Survey, with Camille
Jones, a Geology major at Bryn Mawr College. We focused
on two topics of research that have a similar experimental
setup, and sampled for both throughout the summer. The
first topic of research is part of Bob's ongoing work
at the U.S.G.S., and was on carbon dioxide sequestration
by basalt and saltwater under 200 bars of pressure and
at 100 degrees Celsius. This is relevant to the storage
of carbon dioxide in deep brine formations in the sandstone
of used oil wells. The second part of the research was
about serpentinization and its production rates of hydrogen
and methane at 300 bars of pressure and 200 degrees
Celsius. This is part of Chris Oze's research, who is
a professor at Bryn Mawr College. Throughout the summer
we ran two experiments on serpentinization, and one
on carbon sequestration.
The experimental materials we used to
study hydrothermal water-rock interactions at increased
pressure and temperature conditions included a pressure
vessel full of pressure fluid, into which we placed
a flexible gold reaction cell. By increasing the pressure
of the pressure fluid, the gold reaction cell would
warp and the pressure inside it would change as well.
We then placed this pressure-controlled vessel into
a temperature-controlled autoclave, which allowed us
to raise the temperature of the experiment up to 100
and 200 degrees Celsius.
The two experiments involving olivine
included the following starting reagents: for experiment
1, olivine and synthetic seawater; for experiment 2,
olivine, synthetic seawater, sodium bicarbonate, and
chromite. The experiment about carbon dioxide included:
basalt, sodium chloride, and carbon dioxide.
Periodic sampling of the experiments
was then done to test for pH, refractive index, methane
and hydrogen content, cations, and carbon. At the end
of the experiment, we examined the samples using SEM,
and will use XRD to further characterize the solids.
EM was used at the beginning of the experiment to ensure
that initial reactants were indeed olivine.
The experiments did not go as predicted,
and so there is no conclusion as of yet. It will take
more data analysis and research to discover what may
have occurred in the reaction vessels.
This experience was useful in showing me the daily activities
of a geochemical research scientist. I got a good feel
for what a career in this field would be like, as far
as what they do, and how much time they spend on which
aspects of their job. I also learned how exciting lab
work can be.
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