Page 27 - Synthetic Fuels Handbook

FUEL SOURCES 15

TABLE 1.4 Advantages and Disadvantages of Gas-to-Liquids (GTL) Technology
ADVANTAGES: • Allows owners of remote gas reserves a way to bring their gas to market.
• Tighter air quality standards will create high demand for low sulfur
diesel, like that produced by GTL.
• Diesel fuel is ultra-low sulfur free and has a higher cetane number than
diesel from crude oil.
• Allows stranded to be turned into useful/valuable products.
• Products are compatible with existing tankers, pipelines, and storage
facilities.
• Engines running on GTL fuels pollute less.
• Greater global use of GTL-made gasoline and diesel could slow down
oil demand.
DISADVANTAGES: • If gas or products need to be imported, does not reduce dependence on
foreign energy.
• Conversion plants are expensive to build.
• Many large gas reserves are found in politically unstable areas.
• Products will have to be transported from distant production centers—
adds to cost.

products derived from coal upgrading or by extraction or hydrogenation of organic mat-
ter in coke liquids, coal tars, tar sands, or bitumen deposits. More recently, the potential
for natural gas as a source of liquid fuels has been recognized and attention is now on the
development of natural gas as a source of liquid fuels.
Projected shortages of petroleum make it clear that, for the remainder of the twenty-first
century, alternative sources of liquid fuels are necessary. Such sources (e.g., natural gas) are
available but the exploitation technologies are in general not as mature as for petroleum.
The feasibility of the upgrading of natural gas to valuable chemicals, especially liquid fuels,
has been known for years. However, the high cost of the steam reforming and the partial
oxidation processes, used for the conversion of natural gas to syngas has hampered the
widespread exploitation of natural gas. Other sources include tar sand (also called oil sand
or bituminous sand) (Berkowitz and Speight, 1975; Speight, 1990) and coal (Speight, 1994)
that are also viable sources of liquid fuels.
The potential of natural gas, which typically has 85 to 95 percent methane, has been
recognized as a plentiful and clean alternative feedstock to crude oil. Currently, the rate
of discovery of proven natural gas reserves is increasing faster than the rate of natural gas
production. Many of the large natural gas deposits are located in areas where abundant
crude oil resources lie such as in the Middle East. However, huge reserves of natural gas
are also found in many other regions of the world, providing oil-deficient countries access
to a plentiful energy source. The gas is frequently located in remote areas far from centers
of consumption, and pipeline costs can account for as much as one-third of the total natural
gas cost. Thus tremendous strategic and economic incentives exist for gas conversion to
liquids; especially if this can be accomplished on site or at a point close to the wellhead
where shipping costs becomes a minor issue.
However, despite reduced prominence, coal technology continues to be a viable option
for the production of liquid fuels in the future. World petroleum production is expected
ultimately to level off and then decline and despite apparent surpluses of natural gas, pro-
duction is expected to suffer a similar decline. Coal gasification to syngas is utilized to
synthesize liquid fuels in much the same manner as natural gas steam reforming technol-
ogy. But the important aspect is to use the natural gas reserves when they are available and
to maximize the use of these reserves by conversion of natural gas to liquid fuels.