The Anonymous Widower

Hydrogen And Electric Propulsion Compared

Stadler have given us an interesting way of comparing the range and other properties of hydrogen-powered and battery-electric trains, as their Flirt H2 and Akku trains have both set Guinness World Records for distance travelled.

The Hydrogen-Powered Flirt-H2

In Stadler’s FLIRT H2 Sets World Record For Hydrogen Powered Train, I write about how a Stadler Flirt-H2 had set a record of 2803 kilometres, without refilling.

This page on the Stadler web site gives details of the Flirt-H2.

• Hydrogen Range – 460 km.
• Operating Speed – 127 kph
• Refuelling Time – < 30 minutes
• Seats – 116

This graphic clipped from the Stadler web site shows the Flirt-H2.

Like Greater Anglia’s Class 755 train, it has a PowerPack in the middle, which contains a fuel cell and the hydrogen tank, instead of the Class 755 train’s diesel engines.

The Battery-Electric Akku

In Flirt Akku And Class 755 Train Compared, I compare a Flirt Akku and Greater Anglia’s Class 755 train, after the battery-electric Akku had set a record of 224 kilometres, with recharging.

This page on the Stadler web site gives details of the Flirt Akku.

• Battery Range – 150 km
• Operating Speed – 160 kph
• Chrging Time – 15 minutes
• Seats – 120-180

This graphic clipped from the Stadler web site shows the Flirt Akku.

At a quick glance, the trains seem to be fairly similar, with the exception of the PowerPack.

• Both have regenerative braking.
• Both have the battery and the power converter on the roof.
• I would expect that the Flirt-H2 could be fitted with a pantograph and a transformer.
• Both trains have two passenger carriages.

I also suspect, both trains can be lengthened by adding extra coaches.

These are my thoughts.

Thoughts On The PowerPack In A Flirt-H2

This picture shows the PowerPark car of a Class 755 train.

Note.

1. These PowerPacks have slots for up to four 480 Kw diesel engines.
2. PowerPacks on a Class 788/4 train with four diesel engines weighs 27.9 tonnes.
3. PowerPacks on a Class 788/3 train has two diesel engines.
4. In the UK, trains with PowerPacks have up to four passenger cars.
5. The PowerPack has a walkway from one end of the car to the other.

As customers, might like to replace their diesel PowerPacks, with something that was zero-carbon, I would expect, that the hydrogen PowerPack would have the following properties.

• Hydrogen and diesel PowerPacks would be interchangeable.
• The hydrogen PowerPack would come in two handy sizes of hydrogen fuel cell; 0ne and two MW.
• The weight of both hydrogen and diesel PowerPacks would be similar, as if power and weight were similar, then this could help certification.
• The Flirt-H2 for California, which would only have two passenger cars, would have the smaller hydrogen fuel cell.

I would expect that a conservative designer would use any spare space for hydrogen storage.

• Perhaps, there would be one tank either side of the walkway.
• The quoted range of 450 kilometres for the Flirt-H2 is just under 300 miles, so it would probably cover most regional round trips in Europe without refuelling.
• On many routes refuelling would only need to be done once-per-day.
• Refuelling can be some distance from operation.
• Large tanks would explain the thirty minutes refuelling time.

Obviously, large tanks have the collateral benefit of setting distance records.

The Kinetic Energy Of A Flirt-H2 Train

In My First Rides In A Class 755 Train, I calculated the kinetic energy of a Class 755/4 train.

I said this.

I will use my standard calculation.

The basic train weight is 114.3 tonnes.

If each of the 229 passengers weighs 90 kg with Baggage, bikes and buggies, this gives a passenger weight of 20.34 tonnes.

This gives a total weight of 134.64 tonnes.

Using Omni’s Kinetic Energy Calculator gives these figures for the Kinetic energy.

• 60 mph – 13.5 kWh
• 100 mph – 37.4 kWh
• 125 mph – 58.4 kWh

If we are talking about the Greater Anglia Class 755 train, which will be limited to 100 mph, this leads me to believe, that by replacing one diesel engine with a plug compatible battery of sufficient size, the following is possible.

• On all routes, regenerative braking will be available under both diesel and electric power.
• Some shorter routes could be run on battery power, with charging using existing electrification.
• Depot and other short movements could be performed under battery power.

The South Wales Metro has already ordered tri-mode Flirts, that look like Class 755 trains.

The calculation for a Flirt-H2 train is as follows.

Train Weight – 82.3 tonnes

Passenger Weight – 10.4 tonnes

Total Weight – 92.7 tonnes

This gives these kinetic energies

• 60 mph – 9.3 kWh
• 79 mph – 16.0 kWh
• 100 mph – 25.7 kWh

It looks like the 79 mph; Flirt-H2 would only need  a 16 KWh battery.

It seems when a battery is not for traction and only handles the regenerative braking, it can be surprisingly small.

Mathematical Advantages Of Hydrogen

I do wonder that on balance, there may be mathematical advantages to hydrogen; long range, less frequent refuelling and small batteries.

But as I indicated in Zillertalbahn Hydrogen Plan Dropped In Favour Of Battery Traction, the decision doesn’t always go hydrogen’s way!

Conclusion

I feel Stadler have the right approach of a modular concept that incorporates both hydrogen-powered and battery-electric trains.

I also think, if you have a route, you want to decarbonise, Stadler have the train for you.

April 9, 2024 - Posted by AnonW | Hydrogen | Battery-Electric Trains, Decarbonisation, Hydrogen-Powered Trains, Stadler, Stadler FLIRT Akku, Stadler Flirt H2, Zillertalbahn