Driving Range and Its Cost

It is interesting to investigate the driving range as a function of the system effectiveness. In this respect we assume system effectiveness and a performance indicator of the powertrain given in terms of shaft torque energy for each kilometers of driving. We consider here a reasonable value for this indicator of 1 MJ/km and take three illustrative values for system effectiveness defined as

Figure 5.8 compares some performance indicators for hydrogen from ammonia solution, pure hydrogen, and more conventional fuels. To calculate the data shown in Fig. 5.8 we assumed that gasoline, CNG, and LPG vehicles run with 28% efficiency. For methanol we assumed a fuel cell system with 40% efficiency. For hydrogen a PEM fuel cell system has been considered, and an efficiency of 50%. For

H2 from NH3 case the power system is not specified; thus we only considered two efficiencies (35, 45, and 55%) that are specific for fuel cell systems and ICEs.

E 50

Ii 20

Fig. 5.8 Comparative performance analysis of several power systems for vehicles; fuel tank compactness (a) and specific driving cost (b).

The results in the above figure show that the driving range of gasoline vehicles is the largest, but the associated cost is the highest among all options considered here. The hydrogen tank is the least compact. However, the driving cost of hydrogen vehicle is at half with respect to all common fuels. Regarding the hydrogen from ammonia alternative, the fuel tank is reasonably compact, and the specific driving cost is the lowest. If the considered specific cost of ammonia would be 25% higher, i.e., CN $ 0.4/kg, still the cost of driving of "hydrogen from ammonia" vehicle with 35% efficiency is lower than that of hydrogen vehicle at 50%.

Table 5.3 Conversion of a H2ICE Ford Focus to NH3 fuel.

Parameter

Unit

H2

NH3

Storage tank volume

Liter

217

76

Storage pressure

Bar

345

10

Energy on board

MJ

710

1025

Cost of full tank

CN $

25

14

Driving range

km

298

430

Driving cost

CN $/100 km

8.4

3.2

Tank compactness

Liter/100 km

73

18

Several automakers have developed the prototypes of hydrogen-fueled vehicles in recent years. Here, for analysis purposes, we select a Ford Focus (2008) H2ICE prototype. In Table 5.3 we list the performance parameters of the actual prototype and some calculation results for the same prototype when converted to NH3 fuel. In calculation it has been assumed that the cost of ammonia is $0.30/kg and the powertrain performance is characterized by 1.19 MJ/km shaft power. This figure has been deduced from the published data by automaker (Ford Focus, 2008) and is based on stated 50% efficiency, 710 MJ stored in the full tank, and 298 km driving range. The efficiency of the ammonia engine has been taken the same as the hydrogen engine. In fact, ammonia can be decomposed on board at no additional cost (only using the heat rejected by the ICE) and the engine is fuelled with pure hydrogen.

As can be observed, the driving range of the NH3 vehicle is much higher and hence more economical as shown by a driving cost of $3.2/100 km as compared to $8.4/100 km of H2ICE. Moreover, the tank compactness of the ammonia car is about four times better.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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