birchesgreen
Established Member
I suspect the extra weight of sliding fairings and supporting systems would negate the minimal aerodynamic benefit. Plus it would be something else to go wrong.
Not an assumption, the energy consumption required for high speed running on battery power would require vastly superior battery technology to what we have now.That's your assumption not mine, my worked case was using an IET and power consumption from a London to Newcastle run so significant time at 125mph or (200kph) which was within the working range of that estimate.
On a train aerodynamic benefits are generally only of any value above 90mph so extra weight and complexity would negate any gains whilst running in battery mode.I suspect the extra weight of sliding fairings and supporting systems would negate the minimal aerodynamic benefit. Plus it would be something else to go wrong.
Not an assumption, the energy consumption required for high speed running on battery power would require vastly superior battery technology to what we have now.
The electron rocket uses lithium ion batteries to power its turbopumps, that drains the entire battery flat in a handful of minutes.Not an assumption, the energy consumption required for high speed running on battery power would require vastly superior battery technology to what we have now.
Yes, but it won't produce that for very long before it runs out. It's not the power that's the issue but total energy contained.It doesn‘t. It’s a question of scale. A mate of mine has a Polestar 2 that chucks out 350kW. Multiply by 10 and you have more power than a Class 395 that can hit 225km/h with horses to spare.
Yes, but it won't produce that for very long before it runs out. It's not the power that's the issue but total energy contained.
Bigger batteries are easy - the more important question is where would you run at 200 km/h that isn't already wired - I suspect that would mostly be short stretches“we need to get a bigger battery”…
Precisely. It is the extra weight of batteries being unnecessarily carried around that is the problem.Why not?
So ‘carrying batteries for many miles under the wires’ isnt desirable, but having them lie around at a changeover station is?
Read back up the thread, I used IET energy usage specs (which represent a do not exceed value not a target) then looked at the mass of the engine and fuel and replaced it with a commercially available LFP battery pack.Not an assumption, the energy consumption required for high speed running on battery power would require vastly superior battery technology to what we have now.
On a train aerodynamic benefits are generally only of any value above 90mph so extra weight and complexity would negate any gains whilst running in battery mode.
Cars can go very long distances with battery power, intercity ones. To do so they need battery packs with masses of around 1/4 their unladen mass. In many cases with weight reduction and the removal of unnecessary components EVs are similar in weight to a ICE car of equivalent performance.Yes, but it won't produce that for very long before it runs out. It's not the power that's the issue but total energy contained.
Why on earth would you not use the OHLE, that is already in place, on the ECML?Read back up the thread, I used IET energy usage specs (which represent a do not exceed value not a target) then looked at the mass of the engine and fuel and replaced it with a commercially available LFP battery pack.
This gives us a range of 125 miles off the wire assuming the rate of energy usage on the East Coast mainline. That is a functionally useful amount of range which I then showed would allow an IET to run to Sheffield from where the current electrical ends at Kettering. Ergo such trains could cross very large gaps in electrification.
That's with a IET which is adequately aerodynamic but hardly designed with extreme attention to detail.
You make my earlier point for me with the 90mph comment. With diesel and electric it made less of a difference, with a battery train it makes a big difference to how useful it is:
I did just run some numbers:
At 100mph a Thameslink sized EMU with a flat front would use 47% more energy than a train with the aerodynamics of an ICE Evo. At 60mph it's 26% even at 40mph the difference is 14%.
Aero makes a big difference at most speeds and intercity train will go at.
Precisely. It is the extra weight of batteries being unnecessarily carried around that is the problem.
Why on earth would you not use the OHLE, that is already in place, on the ECML?
Sticking with LNER services, for them batteries would be useful for the north of Edinburgh/Stirling services, as well as the various off-wire extension (Harrogate, Hull, etc.). Those are either lower speed (as in Scotland) or relatively short distances (the other extensions) or both. The assumption of long distances on battery at 125 mph you make is certainly not reasonable.
There are certainly ways to improve rolling stock, but you make a lot of unstated assumptions, and cite numbers that appear to be made up (unless you work in rolling stock design? if so my apologies).
Who said anything about using battery trains on the electrified sections of the ECML? Go re read my posts:Why on earth would you not use the OHLE, that is already in place, on the ECML?
Sticking with LNER services, for them batteries would be useful for the north of Edinburgh/Stirling services, as well as the various off-wire extension (Harrogate, Hull, etc.). Those are either lower speed (as in Scotland) or relatively short distances (the other extensions) or both. The assumption of long distances on battery at 125 mph you make is certainly not reasonable.
There are certainly ways to improve rolling stock, but you make a lot of unstated assumptions, and cite numbers that appear to be made up (unless you work in rolling stock design? if so my apologies).
Not too dissimilar to Scotland's strategy then?Conclusion; I don't see why we don't have a national strategy for getting rid of diesel very rapidly using partial electrification and ambitiously designed BEMUs nicking as much tech out of EVs. Frankly everything should be accelerating at 1.3m/s/s whatever the top speed, larger high power motors are cheap commodities now there's no reason to not make every train gloriously overpowered.
Worth adding here that a couple of electric buses have caught fire recently. Luckily no one hurt, I think.BEVs catch fire much less often than ICE vehicles. It is perfectly possible to design a pack where battery faults are self limiting and cannot take the pack down.
Pack fires are not more vigorous than fuel fires and passengers could safely evacuate before the train combusted. While the pack is more difficult to extinguish I would imagine that firefighter action is never relied upon to save life as any vehicle would be on the way to fully burnt out before you could guarantee firefighters on the scene.
Dealing with the pack and keeping it cool are just new problems not insanely difficult ones. Most car recovery solutions involve putting the vehicle in an enclosure which sprays them to keep them cool before they are extracted to a salvage yard where they are kept away from other items until they can be dismantled.
The most recent story, about recall of 1,800 electric buses due to fire risk was relating to their HVAC systems provided by Hispacold, not the traction system/battery, despite what some hysterical tabloid coverage tried to imply...Worth adding here that a couple of electric buses have caught fire recently. Luckily no one hurt, I think.
this is definitely worth me bookmarking and requotinghttps://www.fleetnews.co.uk/news/tusker-fleet-data-reveals-the-truth-about-ev-fires
"A study by the Swedish Civil Contingencies Agency backs up Tusker’s findings. It concluded that EVs are 20 times less likely to catch fire than petrol and diesel cars."
There are practical limits to charging speeds that can be imposed by grid capacity and/or the charger and/or the vehicle, any can be the rate-determining step.The impressive range and charging times being displayed by the class 230 under tests which have exceed the expectations change the electrification debate.
86 miles on one charge and ultrafast charging speeds mean this technology should allow significant electric operation of secondary and branch routes without incurring the cost of full electrification.
I think the voltage drop in the Southern 3rd rail is quite a lot at the London end in peak periods is quite a lot. I am unsure at what low voltage the circuit breakers kick in in substations and trains.There are practical limits to charging speeds that can be imposed by grid capacity and/or the charger and/or the vehicle, any can be the rate-determining step.
Combine that with the dwell time at the station and you get limits on how much energy you can get, with weight/speed of service translating into the range. Today's ultra-rapid 350kW EV chargers are almost always limited by the vehicle capability, and frequently by the supply capacity from the grid. This means for a given dwell time, you might get less range than you'd expect from looking at specifications.
For recharging battery trains, this highlights a couple of issues that have location/route/service specific answers
- Appropriate grid connections (with/without a lineside battery to support train charging) to charge enough trains, quickly enough.
- Are the dwell times required for recharging at either end greater than other operational limits? i.e. might you need to build more platforms, buy more trains, increase journey times, add passing loops to accommodate extended dwells at recharging locations?
Many of these problems can be offset by installing top-up chargers along the route and then identifying somewhere with suitable capacity for a long deep charge. Also worth pointing out a train would not need to reach 100% every time.There are practical limits to charging speeds that can be imposed by grid capacity and/or the charger and/or the vehicle, any can be the rate-determining step.
Combine that with the dwell time at the station and you get limits on how much energy you can get, with weight/speed of service translating into the range. Today's ultra-rapid 350kW EV chargers are almost always limited by the vehicle capability, and frequently by the supply capacity from the grid. This means for a given dwell time, you might get less range than you'd expect from looking at specifications.
For recharging battery trains, this highlights a couple of issues that have location/route/service specific answers
- Appropriate grid connections (with/without a lineside battery to support train charging) to charge enough trains, quickly enough.
- Are the dwell times required for recharging at either end greater than other operational limits? i.e. might you need to build more platforms, buy more trains, increase journey times, add passing loops to accommodate extended dwells at recharging locations?
When electric vehicles do burn, the fires do seem to be more serious though.The most recent story, about recall of 1,800 electric buses due to fire risk was relating to their HVAC systems provided by Hispacold, not the traction system/battery, despite what some hysterical tabloid coverage tried to imply...
That is not to say that EV powertrains can't catch fire, but the latest evidence suggests that they are much less likely than traditional power trains (see link below):
https://www.fleetnews.co.uk/news/tusker-fleet-data-reveals-the-truth-about-ev-fires
"A study by the Swedish Civil Contingencies Agency backs up Tusker’s findings. It concluded that EVs are 20 times less likely to catch fire than petrol and diesel cars."
Sorry, I didn't see this until now.Who said anything about using battery trains on the electrified sections of the ECML? Go re read my posts:
I used the figures for energy usage for the IET/Class80x train to help with the scoping of power usage. The fact that those figures are for the ECML is irrelevant other than that as a fast line they are likely to result in conservative assumptions.
Your assertion that a battery powered train couldn't run at 125mph is based on what exactly?
My numbers come from the following sources:
Energy consumption of IET from Newcastle to London. This is a spec so actual train will be better. 4600 KWh for 268 miles
This shows that the Bimodal train is 10 tonnes heavier than the pure electric, it also carries 4.5 tonnes of fuel. Ergo we could fit 14.5 tonnes of battery pack without affecting overal weight. If we want to keep the same axle load we could add a lot more battery mass as the coaches with the diesels on are much heavier and we could fit batteries to every coach. Ergo 14.5 tonnes is a conservative estimate.
CATL launches CTP 3.0 battery “Qilin,” achieves the highest integration level in the world
On June 23, CATL launched Qilin, the third generation of its CTP (cell-to-pack) technology. With a record-breaking volume utilization efficiency of 72% and an energy density of up to 255 Wh/kg, it achieves the highest integration level worldwide so far, capable of delivering a range of over...www.catl.com
CATL Quilin LFP battery pack, has 160wh/kg. Obviously battery capacity goes up overtime so picking a tech already in cars is conservative.
I used an estimate of 150wh/kg for conservatism.
Put that all together our BEMU has a range of 268/4600*(14500*0.15)= 126 miles.
That is with conservative numbers. I then showed that the train could operate London to Sheffield and back without the train going below 10% state of charge, this assumes that we install a small piece of OHL to charge the train at stations, though we could get by without it except at the terminal.
To summarise BEMUs can make long journeys off the wires at mainline speeds. Dedicated BEMUs will probably do a lot better as train design and battery technology improves. Electrification plans should be built around these observations.
FYI I'm not a rolling stock engineer but I am a 20 year veteran of aerospace, nuclear and automotive. All the companies I've worked at are cross pollinated with people from rolling stock design. That experience is enough to be able to observe that rail vehicles and especially UK rail vehicles have a great deal of potential optimisation in the field of aerodynamics and integration.
The GWR class 230 charge ultra fast at up to 2000KW's. Yes they will ramp up and down from that charging speed and environmental conditions will vary it a bit but it's not going to exceed normal turnaround times at terminal stations.There are practical limits to charging speeds that can be imposed by grid capacity and/or the charger and/or the vehicle, any can be the rate-determining step.
Combine that with the dwell time at the station and you get limits on how much energy you can get, with weight/speed of service translating into the range. Today's ultra-rapid 350kW EV chargers are almost always limited by the vehicle capability, and frequently by the supply capacity from the grid. This means for a given dwell time, you might get less range than you'd expect from looking at specifications.
For recharging battery trains, this highlights a couple of issues that have location/route/service specific answers
- Appropriate grid connections (with/without a lineside battery to support train charging) to charge enough trains, quickly enough.
- Are the dwell times required for recharging at either end greater than other operational limits? i.e. might you need to build more platforms, buy more trains, increase journey times, add passing loops to accommodate extended dwells at recharging locations?
Many of these problems can be offset by...
Yes, I don't think anybody is saying they are unsolvable issues - I certainly wasn't - but they are issues that need to be considered beyond just measuring how many kWh are in the traction battery. Obviously it makes sense to start with a lightweight, slower train on a short branch line spur, rather than jumping in with both feet and trying - I don't know - the Chiltern Main Line.The GWR class 230 charge ultra fast at up to 2000KW's. Yes they...
This is true. Plane crashes are also more serious than car crashes, yet travelling by plane is much safer!When electric vehicles do burn, the fires do seem to be more serious though.
Agreed.Yes, I don't think anybody is saying they are unsolvable issues - I certainly wasn't - but they are issues that need to be considered beyond just measuring how many kWh are in the traction battery. Obviously it makes sense to start with a lightweight, slower train on a short branch line spur, rather than jumping in with both feet and trying - I don't know - the Chiltern Main Line.