- Some remote natural gas can now be economically converted through a GTL
process into an ultra-clean fuel for diesel engines. At times this fuel can be
economically blended with conventional petroleum diesel fuels to: extend
California's diesel fuel supplies, and improve refinery capacity of cleaner
diesel fuels.
- An opportunity exists to use GTL fuels in California and reduce the
emissions from old diesel vehicles especially school buses. One plant in South
Africa (Mossgas) and Shell's Indonesia plant both produce GTL fuels suitable for
use in heavy-duty diesel applications.
- Discussions are underway to develop a GTL production facility in Alaska to
produce 40,000 barrels per day (23% of our current demand) with a goal to produce
300,000 bbl/d. However, with existing technology, oil pipeline capacity and North
Slope gas reserves over 1,000,000 bbl/d could be produced.
- Building such a facility would extend the Trans Alaska Pipeline's economic
life, which provides 50 percent of California's oil supply.
- Natural gas, is four times more expensive to transport than oil.
- Converting natural gas to a liquid through a Fischer-Tropsch technology
provides an opportunity to expand the use of the natural gas and lower the
transportation cost from remote sources of low-cost gas.
- Fischer-Tropsch is a gas-to-liquid (GTL) process that can produce a
high-quality diesel fuel from natural gas, coal and biomass resources. Shell
refers to the GTL process as a middle distillate synthesis (MDS). In all cases
the middle distillate produced from this process can be blended with today's
diesel fuel.
- GTL diesel has extremely low (0-5-ppm) sulfur, aromatics, and toxics. GTL
fuel can be blended with non-complying CARB diesel fuel to make a cleaner diesel
fuel complying with stringent diesel fuel standards.
- California's current nearest GTL supplier is the Shell-Malaysia, Bintulu MSD
plant. The plant, which began, operation in 1993, and was shutdown between
December 25, 1997, and restarted on May 20, 2000, can produce up to 2400
barrels/day which is 1.5% of California's diesel demand.
- From November 1993-December 1997 Shell's MSD plant sold over 1 million
gallons of middle distillate to four California refiners, which was blended into
roughly 4 million gallons of diesel fuel and sold to on-highway fuel consumers.
- Synthetic diesel fuel offers a new opportunity to use alternative fuels in
diesel engines without compromising fuel-efficiency, increasing capital outlay,
and impacting infrastructure or refueling cost.
- Further commercialization of this fuel improves the prospects of new engines
meeting proposed national 2007 heavy-duty diesel engine emission standards. In
the near-term, this fuel can play a role reducing existing diesel vehicles
exhaust and toxic emissions.
- Since the late-1990s nearly every major oil company including: ARCO,
Chevron, Conoco, Exxon, Phillips, Mobile, Statoil, and Texaco announced plans to
build pilot plants or commercial plants to produce synthetically derived diesel
fuel through the improved GTL process.
- Stringent diesel exhaust emission standards and fuel specifications are
compelling the petroleum industry to revisit the new, improved GTL process to
competitively produce aromatic and sulfur complying diesel fuel.
- Key to the commercial success of the GTL process lies in increased reactor
capacity proven in the mid-1990s. This new process uses a slurry-bed reactor that
has 100 times the capacity per reactor over some 1990 reactors and offers lowers
cost.
- Synthetic diesel fuel appears to be the most economical fuel product from
the GTL process, compared to producing gasoline. Preliminary testing of an
unmodified diesel engine, fueled with neat synthetic diesel fuel, shows the
following emission reductions compared to typical California diesel:[ 1 ]
![[Graph of emissions]](images/synthdiesel.gif)
- The GTL process needs low-cost natural gas, less than $1 per million BTUs,
to compete with traditional diesel fuel. Some remote natural gas sources, called
"stranded gas," that are not otherwise economically available may be ideally
suited to this process, like Alaska.
GTL fuels produced from pipeline supplied natural gas would not be competitive due to the higher value of pipeline supplied natural gas.
NOTES * * * * * * * * * *
1Southwest Research Institute, AIChe, Emissions Performance of Fischer-Tropsch Diesel Fuels, March 1997. Document Date: July 5, 2000