Voyager Fuel Consumption

[starrymarkb]

Something I was wondering for comparison is how much fuel a Voyager would use to go from say Bristol to Edinburgh?

I'd put this in traction but here is the comparison.

An Airbus A319 in Easyjet config holds 156 passengers (a similar figure to a 4 car Voyager baring standees) and will use about 2 tonnes of fuel to make the trip.

I'm wondering how near the Voyager's consumption is to the bus given you have 4 19l engines chugging away for 6hours. Would a voyager burn through 2t?

 

[Erniescooper]

A Voyager has a range of 1350 miles and each car is fitted with a fuel tank of 1300 litres, so a Voyager would burn 4 litres for each mile travelled. According to the internet 1 litre of diesel weighs 0.832 Kg , i've no idea how many miles it is from Bristol to Edinburgh so I will leave the working out to you.

 

[matthewmacleod]

The RSSB has some information here:

http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/Research/T618_traction-energy-metrics_final.pdf

A simulation using optimised coasting gives a fuel consumption of 2904 litres for a 1000 km journey, giving an average consumption of 1.18 litres/100 seat-km. For “all out” running, the simulation gives 3413 litres for 1000 km which is equivalent to 1.39 litres/100 seat-km.

Bristol to Edinburgh is probably around 600km or so, or around 1740 litres of fuel. Assuming 850g/litre, that's 1.47 tons.

Interesting that the Voyagers seem to be the most fuel-hungry trains mentioned in that report!

 

[mbonwick]

Call it 400mi for the sake of a round figure.

400*4*.832 = 1331 Kg.

Round that out and you have a voyager burning around 1.3t - substantially less than the aircraft although our calculations don't take into account the difference in density between diesel and avtur, but that's fairly insignificant.

 

[DXMachina]

The maths is complicated by the fact that a major part of fuel consumption for the whole train - assuming all engines have comparable torque curves - is from fighting the wind resistance against the leading vehicle

Adding more carriages actually reduces fuel consumption per carriage (or improves performance for the same economy) as the wind resistance penalty is subsidised over more engines...

 

[asylumxl]

I also feel it's worth adding that modern engine emission regulations usually have an impact on economy. I may be mistaken but I believe the engines run with a slightly richer air to fuel mixture than normal to reduce particulates.

 

[Royston Vasey]

Call it 400mi for the sake of a round figure.

400*4*.832 = 1331 Kg.

Round that out and you have a voyager burning around 1.3t - substantially less than the aircraft although our calculations don't take into account the difference in density between diesel and avtur, but that's fairly insignificant.

I'm not so sure a ratio of 1.5 is all that significant (Im actually shocked its that close to run a train vs a plane!)

But there is a lot more to it, possible benefits of air may include:

- What is the comparative loading: on average, how many empty seats are on the train per mile across the whole route, or more accurately on average for all seats on ALL services on a given day on the route. Is the plane full every trip? First say that Virgin's current West Coast loadings average only 35%!
- How much more load carrying capacity does each have, passengers, luggage, cargo, mail alongside passengers.
- How many non passenger-carrying miles are required for positioning for trains which planes don't have
- Beyond the cost of fuel (ignoring environmental concerns briefly) is the economic benefit brought by each mode to its users, such as speed and the extra productivity for a business person.
- Jet A1 is cheaper than low sulphur diesel

Then on the other hand, likely benefits of the train:

- Electric trains would be much more efficient per MWh
- Trains can be lengthened to greatly increase their efficiency
- A diesel train could be run on renewables
- A train is more flexible in terms of capacity, in terms of doubling up and accommodation of standing passengers
- The relative environmental harm done by burning 1 tonne of A1 at 35,000 feet compared to 1 tonne of ULSD at 3.5 feet.

So many variables and aspects to consider. These are just ideas, not much real evidence, but show you can't oversimplify this calculation. I think the answer is not that either form is significantly better or worse in this example but I think the train has much more upside in terms of possible and technically achievable efficiency gains. Double your Voyager up and you're probably going to widen the gap rapidly.

 

[Yew]

How would a HST compare by the way? Lots of mention is made about the better acceleration of dmu's. But in the future could fuel consumption be more of an issue?

 

[Blindtraveler]

How would a HST compare by the way? Lots of mention is made about the better acceleration of dmu's. But in the future could fuel consumption be more of an issue?

it could well be if costs continue to rise. I know now that I neednt feel so guilty about flying having read the numbers. As regards the voyager speciéic issue if they could be converted to run on toilet smells there wouldnt be an issue.

 

[Metroland]

How would a HST compare by the way? Lots of mention is made about the better acceleration of dmu's. But in the future could fuel consumption be more of an issue?

Fuel consumption on an HST is better, nearly half a class 221. Voyagers are lard arses, and easily the worst performing trains on the network. Pendolinos, IC225s, and electric commuter trains are the best. Intercity trains perform far better than anything else, with CO2 commissions similar to coaches or better. The worst trains are lightly loaded regional trains in the North of Scotland.
--- old post above --- --- new post below ---

I'm not so sure a ratio of 1.5 is all that significant (Im actually shocked its that close to run a train vs a plane!)

But there is a lot more to it, possible benefits of air may include:

- What is the comparative loading: on average, how many empty seats are on the train per mile across the whole route, or more accurately on average for all seats on ALL services on a given day on the route. Is the plane full every trip? First say that Virgin's current West Coast loadings average only 35%!
- How much more load carrying capacity does each have, passengers, luggage, cargo, mail alongside passengers.
- How many non passenger-carrying miles are required for positioning for trains which planes don't have
- Beyond the cost of fuel (ignoring environmental concerns briefly) is the economic benefit brought by each mode to its users, such as speed and the extra productivity for a business person.
- Jet A1 is cheaper than low sulphur diesel

Then on the other hand, likely benefits of the train:

- Electric trains would be much more efficient per MWh
- Trains can be lengthened to greatly increase their efficiency
- A diesel train could be run on renewables
- A train is more flexible in terms of capacity, in terms of doubling up and accommodation of standing passengers
- The relative environmental harm done by burning 1 tonne of A1 at 35,000 feet compared to 1 tonne of ULSD at 3.5 feet.

So many variables and aspects to consider. These are just ideas, not much real evidence, but show you can't oversimplify this calculation. I think the answer is not that either form is significantly better or worse in this example but I think the train has much more upside in terms of possible and technically achievable efficiency gains. Double your Voyager up and you're probably going to widen the gap rapidly.

Something like a Pendolino is 27.2 g CO2 per passenger Km, A Voyager is 74.1g C02 per passenger km, a low cost airline like easyjet is 96g CO2 per pass km - all taking into account real world AVERAGE load factors. New cars in 2008 on average in 2008 were 140g Co2 per vehicle or 105g per pass km with average load of 1.5 worst of all local buses are 115.8 g CO2 per passenger km (all down to load factor)!

http://www.pteg.net/NR/rdonlyres/99...AEAPTEGCarbonFootprintingfinalversion2009.pdf

The devil is in the detail though. Clearly air doesn't include the effects of radiative forcing (multiply by 2.7 making the real low cost airline figure 259.2 according to the IPCC or multiply by 1.9 by more recent reports or 163.2g) and you are obviously going to put far more CO2 into the air on the average plane journey compared to that of a bus, especially as commercial aviation uses 75 billion gallons of jet fuel each year. Because of the convenience of cars, they tend to promote travel when walking, cycling or local trips may be more appropriate.

On page 3 is a pie chart prepared by the DFT showing overall transport emmisions UK

http://assets.dft.gov.uk/statistics/series/energy-and-environment/climatechangefactsheets.pdf

Rail is just 1.8% of transport emissions for 1.4 billion passengers, whereas domestic aviation is 1.6% for just 21 million passengers. There is a list on page 6 showing overall comparisons.

Fuel costs are a minor part of Rail operating costs at around 4%. Profit is 3% and staff costs are 17%.

http://www.atoc.org/2012fares/fares-facts

Network rail have the highest costs, but some of that is capital investment and over £1.2 billion a year in interest on loans.

 

[WatcherZero]

For the plane its a short hop, almost all the fuel is burned getting it up to height midway through the journey, it then almost immediately begins descending again, there isnt much cruising after reaching cruising height which would occur on a longer journey.

 

[TDK]

For the plane its a short hop, almost all the fuel is burned getting it up to height midway through the journey, it then almost immediately begins descending again, there isnt much cruising after reaching cruising height which would occur on a longer journey.

No difference for a stopping service or an express the law of physics determins this, the longer the journey without stopping the better the ratio of fuel consumption per passenger per km

 

[maniacmartin]

A Voyager has a range of 1350 miles and each car is fitted with a fuel tank of 1300 litres, so a Voyager would burn 4 litres for each mile travelled. According to the internet 1 litre of diesel weighs 0.832 Kg , i've no idea how many miles it is from Bristol to Edinburgh so I will leave the working out to you.

1 kg of diesel doesn't produce 1kg of carbon dioxide when burnt. 1kg of diesel makes 3.16 kg of CO2 - the extra mass comes from the oxygen that is also used in combustion

 

[Erniescooper]

1 kg of diesel doesn't produce 1kg of carbon dioxide when burnt. 1kg of diesel makes 3.16 kg of CO2 - the extra mass comes from the oxygen that is also used in combustion

I'm sorry to be pedantic but my post does'nt make any mention of CO2 as the original poster wanted to know the weight of fuel used for a particular journey.
The reason the Voyager is so thirsty is that the QSK19 uses the pressure time system of injection control which uses a common rail for control of fuel timing unlike more modern systems which uses individual electonic control of each injector for more accurate timing and delivery.
The one thing that amazes me about the decision to award First group the west coast is that they appear to be only bidder not to replace the Voyagers with the Baby Pendolino/Eurolight combination to avoid diesels running under wires and yet the Great Western franchise must have Bimode and has a franchise commitment to make most use of the new 25kv wiring, it just does'nt make any sense that the two franchises should be treated so differently.

 

[DynamicSpirit]

Then on the other hand, likely benefits of the train:

- Electric trains would be much more efficient per MWh
- Trains can be lengthened to greatly increase their efficiency
- A diesel train could be run on renewables
- A train is more flexible in terms of capacity, in terms of doubling up and accommodation of standing passengers
- The relative environmental harm done by burning 1 tonne of A1 at 35,000 feet compared to 1 tonne of ULSD at 3.5 feet.

Just to add one more to that, the train very likely gets you nearer to your intended destination than the plane, resulting in less fuel consumed getting to/from the stations compared to getting to/from the airports.
--- old post above --- --- new post below ---

- How many non passenger-carrying miles are required for positioning for trains which planes don't have

But planes presumably do consume a lot of fuel and travel considerable extra distances circling around airports waiting for landing slots, which looks to me like a rough equivalent (it's miles travelled that are useless from the point of view of taking passengers anywhere).

 

[Rhydgaled]

it could well be if costs continue to rise. I know now that I neednt feel so guilty about flying having read the numbers.

You probably should still feel guilty about flying, certainly if the train is not a class 22x. However, while you should generally feel guilty about driving when you could take a train, maybe a car against a Voyager is pretty equaly unsustainable.

The one thing that amazes me about the decision to award First group the west coast is that they appear to be only bidder not to replace the Voyagers with the Baby Pendolino/Eurolight combination to avoid diesels running under wires.

I think this is the ONLY reason why I'm not completely anti-Virgin on their complaints that First got the franchise.

 

[billio]

From the train's point of view, the comparison between a plane and a train is not so good when you compare an end to end journey.

But make the comparison with the plane stopping at some intermediate points similar to the ones the train stops at. This more than makes up for the fact that the train may not be 100% loaded for the full journey.

Also some trains have standing passengers so they load at more than 100%.