Alternatives to conventional catenary electrification.

[eisenach]

If this is in the wrong section, please move it to the appropriate place.

With standard electrification in the UK running into so many problems, despite our european friends having managed to get it done over the years, I was wondering what new technologies might promise us as alternatives.
Battery operation over shorter distances may well become attractive; Teslar have just today announced their electric lorry, promising a reasonable range of up to 500 miles depending on state of battery charge, with a 30 minute "mega-charge" giving a range of 400 miles.
Other than that, are there any nascent technologies that could get electric power to a train other than by using a third rail or overhead wires and that might eventually be easier and cheaper to fit to the railway ?
As an aside, I've always thought the German overhead installations, especially over multiple tracks at large stations, a particularly simple and elegant way of stringing up the wires.

 

[Taunton]

What has been done on the GW electrification project is merely a triumph by the salesmen of a couple of extremely expensive yet inappropriate items, both the means to do the works and the actual installed product. All that was needed was some competent engineers at the purchasing stage to spot that.

 

[gordonthemoron]

is their enough raw material to make all these batteries that these electric vehicles will need?

 

[furnessvale]

As an aside, I've always thought the German overhead installations, especially over mutliple tracks at large stations, a particularly simple and elegant way of stringing up the wires.

If you are referring to headspans I think they are somewhat discredited in the UK.

 

[eisenach]

If you are referring to headspans I think they are somewhat discredited in the UK.

Probably: I mean the large lattice towers each side of the site, with wires strung across at right angles to the track, supporting the catenary wires. It seems to be the standard German way of doing things. Why is this method discredited in the UK ?

My OP was probably a bit rambling. What I'm really interested in is in learning what new technologies there might be on the horizon that could electrify the railway more easily and eventually, once mature, potentially cheaper than overhead wires.

 

[rebmcr]

I mean the large lattice towers each side of the site, with wires strung across at right angles to the track, supporting the catenary wires. It seems to be the standard German way of doing things. Why is this method discredited in the UK ?

They are already in use on the ECML for the last 30 years — the failure rate is far too high.

 

[reddragon]

is their enough raw material to make all these batteries that these electric vehicles will need?

Oil companies say no, well they would, wouldn't they!
\the reality is that there is enough resource to cover the worlds needs and unlike fossil fuels, batteries are very easy to recycle on that scale

 

[BestWestern]

I do wonder if it might be time to look into other methods a little more advanced than OHLE, or indeed even rather than bog standard electrification in general. I know it's "sort of" already being looked at, but I mean properly, with serious intent. When you look at the advancement of most technologies over past decades, the concept of continuing to string miles upon miles of heavy, cumbersome wiring in the sky looks positively ancient. And as we see on the GWML, the kit itself is actually getting bigger, heavier and more expensive, rather than lighter and smarter. The sheer volume of metalwork being installed on the Western is mind-boggling! We are looking at decades, maybe even a generation or two, before the majority of the UK network is wired, and I seriously wonder if alternative tech is going to creep up and render it obselete before it's even finished. Electric vehicles appear to be very close to cresting the hill of becoming a sensible, mainstream reality, and once that happens I feel there'll be a much greater push in other areas - like the railway - where the idea hasn't really been thought of as a serious prospect yet. Hybrid, for example, has yet to find a place on the railway, perhaps it's time to look at it rather more seriously as a starting point?

 

[axlecounter]

Hybrid is being looked at. Electric vehicles need a lot of wiring too.

 

[yorkie]

Probably: I mean the large lattice towers each side of the site, with wires strung across at right angles to the track, supporting the catenary wires. It seems to be the standard German way of doing things. Why is this method discredited in the UK ?

Because of the unacceptable frequency of incidents on the East Coast Main Line where this cheap and nasty method was deployed

 

[coppercapped]

I do wonder if it might be time to look into other methods a little more advanced than OHLE, or indeed even rather than bog standard electrification in general. I know it's "sort of" already being looked at, but I mean properly, with serious intent. When you look at the advancement of most technologies over past decades, the concept of continuing to string miles upon miles of heavy, cumbersome wiring in the sky looks positively ancient. And as we see on the GWML, the kit itself is actually getting bigger, heavier and more expensive, rather than lighter and smarter. The sheer volume of metalwork being installed on the Western is mind-boggling! We are looking at decades, maybe even a generation or two, before the majority of the UK network is wired, and I seriously wonder if alternative tech is going to creep up and render it obselete before it's even finished. Electric vehicles appear to be very close to cresting the hill of becoming a sensible, mainstream reality, and once that happens I feel there'll be a much greater push in other areas - like the railway - where the idea hasn't really been thought of as a serious prospect yet. Hybrid, for example, has yet to find a place on the railway, perhaps it's time to look at it rather more seriously as a starting point?

You are absolutely right - things will be changing. However, the difficulty in prediction (especially of the future!) is that what we can foresee is based on existing knowledge. It's very difficult to anticipate scientific and technological breakthroughs and the economic and social effects they bring in their train. (Sorree, pun intended!)

By 'hybrid' I take it you mean on-board batteries or fuel-cells which work together with diesel engines? The diesel's main advantage is the high specific energy (commonly called 'energy density' although that's not quite right!) of the fuel. Diesel fuel contains some 50 megajoules/kg (similar to liquified natural gas) compared to about 2 megajoules/kg for rechargeable lithium ion batteries. Battery technology is improving - but as the available physics were fixed 13.8 billion years ago at the time of the Big Bang batteries are unlikely to achieve the same specific energy as diesel fuel. So the battery is suitable for peak-lopping (or for running into and out of New Street!) but not yet the Lickey.

There are some interesting battery technologies on the horizon, see here and here, which are not based on lithium and are more appropriate for storing electricity for grid distribution - but for trains they still need the overhead or conductor rail.

Looking out over the next twenty years I think it would be helpful to try and see which parts of the railway would be most suitable for the introduction of hybrid technology and I would suggest that one way to do this is to look at services types. For example we could use the existing broad groups of:

• intercity with speeds of 200km/h and higher, non-stop
• inter-regional (150km/h to 200m/hr, infrequent stops)
• country and inter-urban services (up to 150km/h with frequent stops)
• suburban/metro (many stops, up to 150km/h).

For each of these groups the total power and the power-to-weight ratio are important parameters in the trains' performance.

I would suggest that in the foreseeable future the intercity group would continue to be pure electric on the grounds of the maximum installed power needed for high speeds and that the maximum diesel power that can be installed in an 80 tonne locomotive which meets the current and future emissions limits is about 3,500bhp - and that without any batteries on board. One of these at each end of an 8 or 9 coach train would push platform lengths to the limits. My few journeys to date in GWR's 'IETs' tell me that underfloor diesels - although quiet - do not give a journey experience commensurate with the cost of the ticket!

Similarly suburban and metro services operate within limited geographic areas - most of these are electrified already - and carrying diesel engines in such trains for the occasional branch line in these areas does not seem a good idea.

This leaves the inter-regional, inter-urban and countryside services where the speeds - and therefore the power needed - are not too high and would therefore be suitable candidates for hybrid drives of one form or another. Although several posters in these forums pour scorn on Vivarail, its attempts to produce a lightweight diesel and battery hybrid for branch and secondary line services deserve the support of everybody who want such lines to survive and prosper.

Not only must the technology be correct - the regulatory and legal frameworks in which the railway operates must support rather than hinder changes to the design and operation of rolling stock and infrastructure.

This may well be the more difficult part...

 

[coppercapped]

Because of the unacceptable frequency of incidents on the East Coast Main Line where this cheap and nasty method was deployed

More recent reports on the failures of the overhead on both the West Coast main line and now the East Coast show that most failures were due to lack of maintenance rather than design flaws or weaknesses.

There obviously have been failures in design, specifically where the stanchions are fixed in soft fenland soil where they have tilted or rotated.

The weakness of headspans is the interdependence of the alignments of the contact wires. This doesn't seem to be an insuperable problem as the German railways, as other have pointed out, use headspans as a matter of course; on the approaches to Munich HBf they stretch over a dozen tracks. I lived in Southern Germany for several years and have seen them covered in snow and ice for days at a time - yet still they work.

By all reports Railtrack, in its short life, did little or no maintenance on the overhead and Network Rail took ten years to realise the wires also needed repair from time to time.

 

[Taunton]

Because of the unacceptable frequency of incidents on the East Coast Main Line where this cheap and nasty method was deployed

So the Germans (and the Swiss, who also use this approach substantially) know nothing about reliable electrification methods?

Sounds a little unlikely to me.

 

[snowball]

Diesel fuel contains some 50 megajoules/kg (similar to liquified natural gas) compared to about 2 megajoules/kg for rechargeable lithium ion batteries.

Presumably that's ignoring the weight of the engine? You could argue that the weight of batteries is more analogous to the weight of the engine than to the fuel. As far as I know, there's no significant difference in weight between a charged battery and a discharged one.

 

[coppercapped]

Presumably that's ignoring the weight of the engine? You could argue that the weight of batteries is more analogous to the weight of the engine than to the fuel. As far as I know, there's no significant difference in weight between a charged battery and a discharged one.

It also ignores the mass of the fuel tank and the plumbing - that's why it's called specific energy.

 

[snowball]

It also ignores the mass of the fuel tank and the plumbing - that's why it's called specific energy.

So my point above is that you could argue that the specific energy of batteries is infinite!

 

[coppercapped]

So my point above is that you could argue that the specific energy of batteries is infinite!

No, you couldn't.

 

[edwin_m]

Because of the unacceptable frequency of incidents on the East Coast Main Line where this cheap and nasty method was deployed

I believe the Germans (and other countries) only use headspans in low-speed areas. Has anyone other than the UK installed them in large numbers on 125mph routes?

Presumably that's ignoring the weight of the engine? You could argue that the weight of batteries is more analogous to the weight of the engine than to the fuel. As far as I know, there's no significant difference in weight between a charged battery and a discharged one.

"Specific Energy" is a simplification that can be useful at times but like all such it has limitations. What it's really saying is that a battery train with the same range as a typical diesel train would end up much heavier because of all the batteries it had to carry. In fact so heavy that it would be impossible to build. This may improve with developments in battery technology particularly now car makers are pouring money into producing new types, but it has a long way to go to catch up with diesel.

 

[snowball]

So my point above is that you could argue that the specific energy of batteries is infinite!

No, you couldn't.

I don't see why not. Here's the analogy spelled out.

To measure the specific energy of diesel you start with an engine and everything needed to make it run (e.g. fuel tank) except the fuel. You fill it up (weighing the fuel tank before and after filling) and set it running. You then measure the mechanical energy you get out until the fuel is gone. You divide this energy by the weight of fuel you put in and that's your specific energy.

Now do the same with battery storage. You start with electric motors and everything you need to make it go (e.g. flat batteries) except the fuel (the electricity that the batteries will store). You then charge it up and weigh the batteries before and after charging. You perform the same calculation as before. The energy you have got out is finite, but the change in weight of the batteries is zero, as far as I know, so the specific energy in joules per kg is infinite.

I'm not being too serious about this. Edwin has explained my point in another way.

 

[coppercapped]

I believe the Germans (and other countries) only use headspans in low-speed areas. Has anyone other than the UK installed them in large numbers on 125mph routes?

I think it's truer to say that in Germany, Switzerland and Austria headspans are used on multitrack sections of route. For many reasons these are unlikely to be high speed, 100 miles/h or greater, routes - which tend to be twin track at best.

So I agree with your conclusion, but I think the path to the conclusion may be different!

But my point stands - headspans are used in areas with very severe climatic conditions spanning up to a dozen or so tracks. If there were any weaknesses in the design, materials or installation they would be shown up in such conditions - and in all the years I spent in southern Germany I can only remember a few occasions when the wires fell down.

(There was, however, a case some thirty years ago when cables on the Bahn's own 16.67Hz distribution system expanded in the summer heat so much that one part shorted out. The protection circuits then started to isolate bits of the railway to avoid overloading the remaining parts of the grid, which in turn caused other bits to trip out. After a short period of time the entire electric railway south of the Main river to the Alps closed down. It took hours to get it all powered up again...)

"Specific Energy" is a simplification that can be useful at times but like all such it has limitations. What it's really saying is that a battery train with the same range as a typical diesel train would end up much heavier because of all the batteries it had to carry. In fact so heavy that it would be impossible to build. This may improve with developments in battery technology particularly now car makers are pouring money into producing new types, but it has a long way to go to catch up with diesel.

Quite! Specific energy is a concept to be able to compare the energy available in different forms of storage, regardless of the type of reaction needed to release the stored energy when it is needed. The highest specific energy is stored in mass itself - as Einstein showed energy equals mass multiplied by a constant, the equation is E = mc^2 which I think everybody has heard of. The constant is the speed of light squared which is a huge number, so the energy released is enormous but it is only available through fission or fusion reactions.

Other reactions can be used to release other forms of stored energy and in order of magnitude of specific energy release these are, after nuclear reactions, chemical, electrochemical and electrical.

Note added: I was about to post this and then I thought I would look for a picture to demonstrate the spread of specific energies and I found this graph in Wikipedia which sums it up nicely. It plots energy per kg along the x-axis and energy per litre on the y-axis.
Note the position of the lithium-ion battery in the bottom left hand corner compared to diesel around the 50MJ/kg.

Batteries don't only need to get a bit better, they need to get 25 times better to really compete with diesel.

 

[Dr_Intoxicated]

Has anyone ever considered induction and cables buried beneath the tracks? I am not sure how much power you can transfer inductively.

 

[reddragon]

The technology already exists. The combined weight will be lower than Diesel + fuel system + fuel and it will not be batteries!

The prime mover will be the new super capacitors supported by batteries as they can load / unload power instantly. It will take a while to scale up the technology and make it mainstream, but we are talking a few years at most. One city in China has 14,000 buses that are pure electric with capacitors / batteries so its far from some distant pipe dream!

 

[eisenach]

Has anyone ever considered induction and cables buried beneath the tracks? I am not sure how much power you can transfer inductively.

Yes, induction was one of the technologies at the back of my mind. No idea whether it could work, though, which is why, in more general terms to catch things I of which I hadn't thought, I was asking!

 

[coppercapped]

The technology already exists. The combined weight will be lower than Diesel + fuel system + fuel and it will not be batteries!

The prime mover will be the new super capacitors supported by batteries as they can load / unload power instantly. It will take a while to scale up the technology and make it mainstream, but we are talking a few years at most. One city in China has 14,000 buses that are pure electric with capacitors / batteries so its far from some distant pipe dream!

The specific energy of current electrostatic super-capacitors ranges from 0.01 MJ/kg to 0.035 MJ/kg. As I wrote earlier the specific energy of diesel fuel is around 50 MJ/kg.

This means that to give an electrostatic supercapacitor powered train the same range as a diesel powered train of the same mass, supercapacitors have to improve their specific energy by some 1,500 to 5,000 times.

Not just a slight improvement, an improvement of 3 orders of magnitude...

MTU use supercapacitors for engine starting - which uses their ability to supply energy quickly. For some years to come that will be the limit of their capabilities.

 

[coppercapped]

Yes, induction was one of the technologies at the back of my mind. No idea whether it could work, though, which is why, in more general terms to catch things I of which I hadn't thought, I was asking!

Look up 'air cored transformers' and see why it is unlikely.

 

[Chris M]

As far as I know, there's no significant difference in weight between a charged battery and a discharged one.

The energy you have got out is finite, but the change in weight of the batteries is zero, as far as I know

There is a difference in weight between charged and flat batteries, but the difference in weight for the battery in a 2015 Tesla Model S is about the same as a single gain of sand, according to this video

 

[dgl]

Also what method is the most efficient from the point of generation to the point of use?

Batteries have charging losses and induction systems are not efficient at all and if you are having to distribute the power anyway then 25kV direct to the train seems to me to be the best way and will be for a long while to come.
Admittedly there are large costs associated with the installation of OHLE but as the electricity would have to get to the railway at some point then the costs aren't that bad. For short sections (such as a short branch line) and for structure/areas where OHLE cannot be fitted then batteries are ideal but not, I think, as the main power source for the train.

Also if charging of a battery powered train was done in short bursts rather than during a long section of OHLE runnung with a battery of the capacity required for a rail vehicle would be such that there would be huge spikes of power required from the national grid, something I can't see them liking all that much both National Grid and the batteries themselves.

*OHLE = OverHead Line Equipment

 

[najaB]

I am not sure how much power you can transfer inductively.

Certainly not thousands of amps with any reasonable level of efficiency.

 

[reddragon]

The specific energy of current electrostatic super-capacitors ranges from 0.01 MJ/kg to 0.035 MJ/kg. As I wrote earlier the specific energy of diesel fuel is around 50 MJ/kg.

This means that to give an electrostatic supercapacitor powered train the same range as a diesel powered train of the same mass, supercapacitors have to improve their specific energy by some 1,500 to 5,000 times.

Not just a slight improvement, an improvement of 3 orders of magnitude...

MTU use supercapacitors for engine starting - which uses their ability to supply energy quickly. For some years to come that will be the limit of their capabilities.

It is true that historically a capacitor had around 5% of the energy retention of a battery, but recently the latest super capacitors are achieving 1000 times that level, hence 50x that of a battery with a measured potential of 10,000x a capacitor or 500x a battery. OK so far being tested in smaller applications, but apparently easy to scale up. There are quite a few articles around about the latest developments

Batteries are doubling their storage per kg every 12 months at the moment with solid state batteries of many time the current KW/Kg in the lab.

It is only a matter of time before it happens with the scale of investment / research on EV and grid level batteries that's going on.

 

[coppercapped]

It is true that historically a capacitor had around 5% of the energy retention of a battery, but recently the latest super capacitors are achieving 1000 times that level, hence 50x that of a battery with a measured potential of 10,000x a capacitor or 500x a battery. OK so far being tested in smaller applications, but apparently easy to scale up. There are quite a few articles around about the latest developments

Ordinary electrolytic capacitors have not previously been mentioned in this thread so I don't understand their relevance. The current commercial state of the art is:

• Electrostatic tantalum capacitors have a specific energy of around 0.0002 megajoules/kg
• Electric double layer capacitors,(supercapacitors) have a specific energy of around 0.035 megajoules/kg
• Lithium ion batteries have specific energies of between 0.4 and 1 megajoules/kg depending on the chemistry
• Diesel fuel has a specific energy of around 50 megajoules/kg

Long way to go, huh?

Batteries are doubling their storage per kg every 12 months at the moment with solid state batteries of many time the current KW/Kg in the lab.

Do you have any examples of such developments?

It is only a matter of time before it happens with the scale of investment / research on EV and grid level batteries that's going on.

By the way, capital cost also plays an important rôle in the selection of a suitable drive technology so the price for these new storage technologies has to be competitive. In the meantime I'd go with pure electric for metros and fast trains and, possibly, hybrids (diesel and battery) for country, interurban and inter-regional services.
Waiting for a new technology to prove itself is not an option.