Hydrogen Private Car LH

The second approach (i.e. using historical failure rate data) has been used to estimate the overall failure frequencies of the on-board storage tank in the private car. The reason is that according to experience of the past [2], a flammable release resulting from a road accident can be more significant than from normal operation. Therefore, the release frequency of the onboard hydrogen storage used in the study was extracted from the vehicle road accident data.

The road traffic accident rates for Germany can be calculated from the road accident data (Chapter 2) by using of Eq. 4-5. The results (Table 5-16) show that the overall road traffic accident rate for Germany (2003) is 3.31 x 10-6 accidents/vehicle-km. the results is comparable with a typical value given in reference (see 4.4.3.1).The annual distance for a given vehicle was calculated from Table 2-5 and Table 2-6. The results (Table 5-17) show that the annual distance travelled by a private car in Germany (2003) is 12,900 km/veh.yr.

The expected frequency of hydrogen release from the onboard storage in a private car can be calculated by using Eq. 4-6, and the private car data in Table 5-16 and Table 5-17. Assuming that the overall chance of hydrogen release from the storage is 0.02 (one accident in 50 results in a release), the calculated release frequency of the onboard hydrogen storage is about 7.1 x 10-4 per year (once in 1408 years). Assuming that 20% of the release may lead to a catastrophic failure (instantaneous release), the incident frequencies of the continuous and instantaneous scenarios are shown in Table 5-18.

Furthermore, by multiplying the above initial frequencies with the outcome probabilities resulting from the event tree analysis (Fig.4.5), the associated outcome frequencies are shown in Table 5-19. The table also shows that the fire outcomes may dominate the accidents from the onboard hydrogen storage, which accounted for about 62%. Only about 4% of the accidents may lead to an explosion and the rest (about 35%) has no effect on the population.

Table 5-16 Road traffic accident rate (accidents/106 veh.km) for Germany

Vehicle Type

1990

1995

2000

2001

2002

2003

Private cars (incl. Stationwagons)

3.53

3.05

3.00

2.90

2.77

2.76

Buses (incl. Trolleys)

0.01

0.01

0.01

0.01

0.01

0.01

Trucks

0.16

0.17

0.17

0.17

0.16

0.16

Tractor-trailers

0.01

0.01

0.01

0.01

0.01

0.01

Motor cycles (incl. Mofas, mopeds)

0.14

0.16

0.19

0.19

0.19

0.19

Micscellaneous

0.26

0.20

0.21

0.20

0.19

0.19

Total

4.12

3.58

3.54

3.48

3.33

3.31

Table 5-17 Annual distance each type of vehicles (x1000 km/veh.yr) for Germany

Total Distance

1990

1995

2000

2001

2002

2003

Private cars (incl. Stationwagons)

14.1

13.2

13.060

13.0

13.1

12.9

Buses (incl. Trolleys)

44.1

42.9

43.237

42.7

42.2

42.0

Trucks

23.8

23.8

23.230

22.8

22.1

22.2

Tractor-traillers

74.2

78.2

80.661

77.5

76.5

79.1

Motor cycles (incl. Mofas, mopeds)

7.0

6.6

6.072

6.1

5.4

5.4

Micscellaneous

2.7

3.7

3.855

3.8

3.9

4.0

Total

165.8

168.4

170.1

166.0

163.2

165.4

Table 5-18 Expected frequencies of the onboard LH2 storage in private car_

Release Type Frequency (/yr) Percentage Source

Instantaneous 1,4E-04 19,7% Estimated based on the

Continuous 5,7E-04 80,3% accident rate data

Overall 71E-04 100,0%

Table 5-19 Accident outcome frequencies of the onboard LH2 storage in private car

Release Type

Conditional Probability on Release

Outcome Probability

Outcome Frequency

(/yr)

Instantaneous

Early Explosion

0,0360

2,6E-05

Fireball

0,1440

1,0E-04

Pool fire

0,0064

4,5E-06

Late explosion

0,0000

2,0E-08

Flash fire

0,0001

8,2E-08

Continuous

Jet fire

0,4000

2,8E-04

Pool fire

0,0640

4,5E-05

Late explosion

0,0014

1,0E-06

Flash fire

0,0058

4,1E-06

No effect

0,3423

2,4E-04

Overall

1,0000

7,1E-04

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