Future Transportation Systems - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 263

generated by the engine and from the exhaust gas system is harmful. The exhaust
gas after treatment system must also reduce noise by means of mufflers [ 8 ].
There are three basic methods to improve the efficiency of exhaust gas after
treatment systems:

• Improving particle diminution in the engine's rough emission;
• Combining the particle filter with the NO x reduction catalyst; and
• Developing highly durable filters which can be frequently heated and

regenerated.

This technology has been successfully developed over the last years, but still
requires further investment, especially in heavy-duty vehicles and ships. In ships,
the system can also recover heat, in order to use a part of the exhaust gas energy
for preliminary fuel heating. An exhaust gas recovering system consists of a
recuperator that may be a steam generator or a distribution heater fitted to the gas
turbine or the self ignition ship engine.

17.1.2 Far Future Phases of Development

Although hybrid technology is state of the art in the spark ignition passenger car
technology, the development will go more and more on in the self ignition and
heavy-duty technology. Self ignition hybrid in passenger car is state of the art.
In the far future, electric vehicle technology could be improved in a way that is
not yet imaginable. However, the rate of development is not sure. Recent expe-
riences have proven that new technology will develop slowly and not in a revo-
lutionary way. This includes the cost, safety, durability of the electric storage
battery, the supplying manufacturers with new raw materials, e.g., with lithium
and the recycling of all parts of the electric engine and the connected technology.

17.1.2.1 Hybrid Propulsion Systems

Hybrid technology means the common use of an internal combustion and usually an
electric engine for driving. Theoretically, many principles are possible for hybrids,
which can store and utilize the recuperated energy from braking, e.g., flywheel,
hydrostatic systems, compressed air, etc., but today the electric solution seems to be
the most viable way. Wide ranged applications for commercially usable vehicles
with hybrid technology are available only up to lower mid-size performance. The
main markets are Japan and the USA, but the European market is increasing [ 9 ].
There are new hybrid commercial vehicles in specific sectors of road trans-
portation, e.g., in mining technology. However, the development is going in the
direction of general using hybrid technology in road transport. In hybrid vehicles,
recent performance of the internal combustion engine attaches 250-1,397 kW
(335-1,873 HP), the cylinder volume reaches up to 7-16 l (0.25-0.56 ft 3 ), and the