Hitting the Natural-Gas Jackpot
Technology Review: Hitting the Natural-Gas Jackpot
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January 2002
Hitting the Natural-Gas Jackpot
There may be enough natural gas on earth to meet our energy
needs for thousands of years. The trick is to ferry it across
continents without blowing up.
By David Voss
Compared to oil, natural gas is so abundant it's staggering.
Proven petroleum reserves are good for another one trillion
barrels or so. At today's rate of consumption, they will last
about 40 years. Add in oil reserves thought to exist but still
undiscovered, and the timeline stretches out some 160 years.
Known reserves of natural gas, which is composed mainly of the
simple hydrocarbon methane, will last for about 50 years at
today's consumption rate. Estimates of likely but as yet
undiscovered gas resources extend that projection to about 200
years. But when the natural gas thought to lie buried deep
under the ocean in methane hydrates is added in, the potential
is mind-boggling. Hydrates, ice crystals that trap methane
molecules, form below a depth of 300 meters as a result of
methane-producing bacteria. Very little is known about how
much gas is bottled up in these crystals or how to get it out,
but best guesses are that the reserves could, even with
natural-gas consumption rates doubling over the next several
decades, last tens of thousands of years.
However you do the arithmetic, there's a lot of natural gas
out there. Adding to its attractiveness as the fuel of the
future is that methane is far cleaner burning than oil. But
there's a big problem: natural gas is volatile and expensive
to transport. One of the beauties of oil is that you can pour
it down pipes, load it onto tankers or barges and safely ship
it around the world. Natural gas, by contrast, is most often
shipped as a liquid, which must be maintained at a temperature
of -130 C or at tens of atmospheres of pressure. It can also
be transported as a gas in pipelines, but because the gas must
be kept compressed, that is an expensive proposition: one
estimate is that a pipeline to get gas out of Alaska and into
the Lower 48 would cost around $15 to $20 billion to build.
Throw in the fact that many large reserves are in remote
locations like Alaska's North Slope or Siberia, and the result
is that much of the world's natural gas is now commercially
worthless. "Of the [natural gas] that everyone agrees is
there, over half has absolutely no market [value]," says Mark
Agee, president of Syntroleum, a Tulsa, OK, energy firm. "None
whatsoever. It's in places like the northwest shelf of
Australia, Papua New Guinea, the west coast of Africa, the
North Slope of Alaska. Really remote places with no ready
market close by."
For a chemical engineer, the solution to this quandary, in
theory at least, is relatively simple. If you could chemically
transform this dangerous gas into a liquid hydrocarbon, like
synthetic oil or even gasoline, it could be transported easily
and cheaply at room temperature and normal pressure. These
synthetic fuels could flow right into existing oil pipelines
or be put aboard tanker ships bound for market. After further
refinement, they could even be distributed through the
existing network of service stations. As an added bargain,
since the starting material is virtually-zero-sulfur natural
gas, the resulting fuels would also be free of the sulfur and
aromatic pollutants that taint other petroleum products. You
would, in other words, have a readily available source of fuel
that is potentially far cheaper and cleaner than oil.
Some of the world's largest oil companies are now investing
billions of dollars to build refineries that use "gas-
to-liquid" technology to convert methane into ultraclean
diesel and gasoline fuels. Using high-pressure,
high-temperature refinery processes, these new plants, which
are being constructed in places such as Bintulu, Malaysia,
will turn natural gas into liquid products that are easily
shipped to market and quite likely cost-competitive with
petroleum products.
But some researchers believe they have a far better idea. The
processes used at the new plants are based on chemistry that
dates back to the early 1920s and are costly and inefficient.
A small group of chemists and chemical engineers is working to
discover catalysts-materials that speed up chemical reactions
but are not themselves consumed in the process-for directly
converting natural gas into liquid fuels at low temperatures
and pressures. If these catalysts work-and that is still a
giant if-they will make possible cheap, simple refinery
processes that could unleash the vast untapped reserves of
natural gas. Indeed, they would force experts to redo their
calculations of the world's energy supplies. Suddenly, the
untapped methane resources in Siberia and northern Canada
could be just as important to the world as the vast oil fields
of Saudi Arabia.
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