Future Transportation Systems - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 271

17.1.2.7 Natural Gas in Fuel Cells
CNG costs much less than gasoline or diesel fuel. The reason is not only its
optimal physical and chemical properties, but also the current taxation system.
Vehicles powered with compressed or liquefied natural gas emit 25% less CO 2
and 75% less pollutants than those using gasoline. Instead of natural gas, cars can
use biomethane produced in a renewable way. Using Liquefied Petroleum Gas is
usually less sustainable for the environment because it emits more pollutants in the
exhaust gas [ 26 ].
Retrofitting costs €2,000-3,000, i.e., US $2,860-4,290. Changing from gasoline
to CNG to fuel a car is cheaper only after driving 50,000-70,000 km (31,075-
43,505 mi) per year. New CNG vehicles have a more reasonable price. In the
future, the advantage of natural gas will certainly appear sooner for drivers
because of the increasing price of gasoline and diesel fuels.
17.1.2.8 Methanol in Fuel Cells
The reformation of methanol (CH 3 OH) seems to be the key to fuel cell technology.
Methanol is produced from natural gas with approximately 65% efficiency. It is a
liquid similar to gasoline and diesel fuel, and has a high energy density. Methanol
is available in the existing infrastructure.
The reaction takes place with air and water at temperatures of 800-900C
(1,472-1,652F). Natural gas is partially oxidized and converted in two catalytic
steps with H 2 OtoH 2 ,CO 2 , and CO. Carbonization and inhibition of the catalyst
must be avoided. The remaining residue of CO must be separated by gas selection,
because it inhibits the electrodes of the fuel cell [ 27 ].
The reformation of methanol is substantially more difficult than the conversion
of methane to hydrogen. The process could be substantially improved in the future
if catalytic technology were developed.
17.2 Future Trends in Aviation Technology
Civil air transportation will need approximately 24,000 new airplanes in the next
20 years. Freight transport is expected to increase 5.2%. About 3,440 new air-
planes and approximately 850 rebuilt airplane will be needed for air freight ser-
vice. The total cost of all the new airplanes will be approximately €145 thousand
million, i.e., US $210 thousand million in 20 years [ 28 ].
By 2030, passenger transportation will require approximately 1,700 Very Large
Aircraft each carrying more than 400 passengers. The investments will cost €399
thousand million, i.e., US $571 thousand million in 20 years.
There is a projected need for about 6,250 large airplanes carrying 250-400
passengers, i.e., 42% of the market and for about 17,000 small single aisle air-
planes, i.e., 39% of the market in the same time interval.