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Fuel logistics/refuelling Fuel properties of alternative fuels Driveability Incentives and laws Leasing and financing Operation and Maintenance Technological potential Emission reduction potential

Alternative propulsion explained
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Otto Cycle - Internal Combustion Engine


Replacing of gasoline/petrol is possible either by liquid or gaseous fuels. Adapting the engine is necessary and the following impurities in the replacing fuel have to limited:
  • organic BTX (benzene, toluene and xylene (benzene components with one or two methyl groups attached)
  • inorganic impurities as NH3, HCN, H2S, COS and HCl, volatile metals, dust and soot

Ethanol
Some cars later than 1994 with adapting multipoint injection in the fuel hose should not experience driveability problems when run on E85 more... but generally a second controller has to be installed which alters the injection. Adaptation to direct Ethanol injection into the chamber has not been possible so far (if youhyear of it please tell us).
For older engines replacing the controller is a way to cope with the differing fuel characteristics (more...).

The fuel consumption in kg (mass) is not higher although more volume is needed due to a lower density of the biofuel. So the endurance is lower with a given tank volume.

Ethanol has the potential to reach higher efficiency with internal combustion engines in the future because of the higher octane rating. This requires adaptation of the operational regime of the engines as well as changes in the lay-out. Thus higher fuel costs may be compensated by a higher MPG (lower fuel consumption).


Natural Gas
Compresses or liquefied natural gas may be used with minor adaptations.
Since methane oxidation in the catalyst requires higher temperatures than gasoline/petrol the engine control needs adaptation.
Phased, sequenced, multipoint and indirect CNG injection system were developed.
The high research octane number (>130 RON)reduces engine knock. The engine may be designed with a higher compression ratio. Operated at maximum best torque with spark advance (MBT)this increases the thermal efficiency and reduces exhaust emissions, especially for turbocharged engine. (source)

Wood gas is a complicated fuel which may only be used after purification Wood Gas




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Diesel Cycle - Internal Combustion Engine

In diesel engines other liquid fuels may be used.

Biodiesel
Since the feedstock influences the fuel characteristics heavily, discrepancys in the finding are not unsual.
Biodiesel was long regarded as unproblematic before modern injection pumps came on the market.
Three things have to be observed:
  • Filters have to be changed some time after having switched to biodiesel
  • Timing of the injection may be used to further improve emission ()
  • Rubber materials have to be biodiesel certified and are for most modern vehicles
more...

Biodiesel used in unmodified compression ignition engines will reduce CO and possibly also HC-emission and is ideal for selective catalytic reduction (SCR) reducing NOx because of the low content of impurities.

In Europe, Peugeot and Citroën diesel cars are guaranteed to run on B30, as long as the biodiesel blends conform to quality norms.
A blend of 30% biodiesel provides sufficient lubricity of the injection system and requires no major modification of the engine or vehicle. B100 may be unsuitable for engines because of its lower stability, lower cetane and higher viscosity, causing more oxidation, deposits and fouling. B100 would require the adaptation of materials, particularly elastomers, in the engine and modifications in the injection system (which have been implemented with Deutz engines).

FAQ on biodiesel production and use download pdf
Oil should be checked regularily to avoid problems and avoid to frequent oil changes.
Wearcheck.de more in German

Straight vegetable oil
SVO/PPO has not enough lubricity- thus a preheated fuel is needed (also for the injection pump if it has no separate lubrification).
SVO may used in a two-tank systems where the engine starts on fossil diesel. Start up and shut down is done on diesel fuel (or biodiesel) more... Operation with cold engine and cold SVO may damage the injection pump and the engine.

When driving during switching to SVO high RPM should be avoided. Downhill engine braking or idling should be done with diesel.
Oil level should also be checked regarding rising level, base and acidity number.
The fuel filter should be changed regularly - especially in case of power loss.
The SVO quality should be certified by the producer or you are familiar with filtering and degasing yourself.

Elsbett/Wearcheck.de more in German

If converting an used vehicle to SVO a deeper check of the injection system and the fuel pump is necessary. Inline diesel pumps and rotary type pumps (Bosch EPVE,VP37 Axial Plunger Distributor Injection Pump, PSA XUD) may be used only (and not Bosch VP44). Injection Timing should be advanced around 3-4 degrees crank, but no more.
more...

Some experience has been made running Deutz engines with SVO/PPO for about 1500h, more info is to come (source).

Gas to Liquid fuels (Synfuel/Sunfuel..)
The Fischer Tropsch Synthesis allows to produce very clean fuels out of the whole plants. The fuel has better quality compared to diesel and may be used in existing diesel engines and even improve efficiency when adapting the engine control and ignition.

Using GTL diesel fuel with higher Cetane number in unmodified vehicles shows significant reductions of HC, CO, and PM emissions (HC and CO also in the cold phase), compared to a sulfur-free European diesel fuel. GTL allows higher exhaust gas recirculation (EGR)-ratios - which may be used to reduce NOx.


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Hybrid Electric Vehicles

Hybrid Electric Vehicles are produced in three concepts:
  • serial having no mechnical connection of the ICE to the wheels
  • parallel adding momentum from eletric motor and ICE
  • combined allowing to load the batteries while contributing to the propulsion
Serial concepts are better for stop&go operation only. Parallel hybrids require sophisticated control algorithms, but have better efficiencies at full load operation. With serial concepts it is not possible to hide very small electric traction power and energy storages between the shining hybrid label. So parallel hybrid concepts may be so calls mild ones beeing not more than improved start/stop concepts without the ability to drive electrically. Plug in hybrids try to improve those concepts allowing longer eletric only operation.
Very simple but ineffective concepts have four wheel drive with one axle ICE-driven and one electric driven.

HEV's explained more about HEV's from the ATTI...

film showing crossection of engine 320px

film showing scrossection of engine 640px

Prius technical info more...


Hybrid rail cars
download JR-east description

Hybrid bicycles
So called PEDELECs combine smaller electric motors with lightweight bicycle structures. It is not possible to drive at max. speed on batteries only.
The background ist the EU-directive limiting power (250W) and max. velocity (25km/h) for bicycle like two wheelers with power assist.

The power assist system comprises of:
  • energy storage
  • power controller
  • electric machine
  • transmission gear

The energy storage stores energy over a longer or shorter period of time. For longer periods it is mainly a Nickel metal hydride battery (NiMh) but Li-Ion battery is also a candidate. Ultracaps or Supercaps may be used in future to have higher electric currents when loading (regenerating) or accelerating without damagig the batteries but only store energy for short durations (-30s).

The power controller is a device comprising charger and power control. Regeneration is only used by a few producers.

The electric machine should be lightweight and robust - especially if mounted in the hub. Brushless synchronuous machines with rare earth magnets are the latest development combining high efficiency with small weight.

The transmission system now uses mainly transmission belts, in the beginning friction wheels and (plastic)gears were used (car whiper motor). The transmission system either acts on the rear wheel or the bottom brackets or the front wheel. It might be completely embedded in the hub.

The endurance of such PEDELECS is up to 60km with an weight of approx. 35kg.


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Battery Electric Vehicles

So called BEVs are well suited for indoor, tunnels, neighbourhood vehicles etc.
Because of the low endurance of the heavy battery packs (maninly NiMh or Lead Acid) a usage for private cars or for high daily milages is not possible. Latest developments like Li-Ion batteries and range extensions through fuel cells have reintroduced the concept and new application fields may be explored.

more about electric vehicles from the ATTI...
more about EVs from the ADFC




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Grid Connected Vehicles

There are basically two methods in operation. The catenary type and the ground level power supply. Both get their energy from the grid but may be decoupled partially by using capacitators or batteries but also internal combustion engine energy generators. The installation may be using lighting masts and for trolley busses have to use two catenaries (one for trams). The panthograph for trolley busses is using catenary switches similar to track switches. The panthograph is secured with a rope.



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Fuel Cells

Fuel Cells consist of a stack which converts hydrogen from an onboard hydrogen tank or fuel reformer and oxygen from the air to water generating electricity.
Research is undertaken to use methanol or diesel for the reformer. The reduction of sulphur whit synthetic fuels improves the chances for doing so. Methanol is exchanged by the less toxic ethanol.
A wide roll out of fuel cells requires a reduction of the precious metals used. The huge stack masses required to cope with fuel impurities also lead to a very bad driveability without storage- serial hybrids are best suited.


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Stationary Combustion Engines

Stationary combustion may be used in
  • gas turbines
  • Stirling engines
  • steam vessels

None of those have reached the market, only gas turbines were tested with trucks.


 


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