mandag 16. januar 2017

Hybrid Trains, Electro Diesels and Dual or Triple Mode Multiple Units

Through the days of 'blue n' yellow' BR railways, electro diesels and dual mode multiple units were a bit of a side show, but luckily Southern Region persevered and even raised the ugly duckiling class 73 to a swan like status on the Gatwick express services.

With the go ahead for the Thames link it was obvious that there would need to be dual 'voltage',  really dual mode trains with third rail shoes and pantographs. The same was true when the "Chunnel" (as it was first dubbed),  service had to meander into Waterloo on old 3rd rail lines at fraction of its 25kv overhead potential.

Technology Works But Is There Not the Pressure to Move Over?

There really has been no other pressure for dual mode and certainly not more complex systems since then, until the replacement for IC125 was chosen as a Japanese dual /triple mode with german technology which may offer later a battery hybrid mode varian. It has been tessted to proof of concept in the outgoing IC 125 ironically enough, with Hitachi's V/Train 2 Hyabusa tests.

There is quite a bias to the south of England regarding these trains so far. This is a rather insidious bias to the capital with nearly all other Metropoles having the potential application of multi mode tractive power.  You can also argue that London is the most electrified of cities and connurbations already, with only Glasgow and Liverpool being near the relative number of trains run on sparky stuff. What though is the future for more complicated trains away from the south east or on minor routes around there? What pull is there towards the technological shift? What are the economics?  Why bother?

Why bother indeed? Because there is currently no real punishment for diesel combustion under the rails other than fuel costs, which are far cheaper than running a fleet of upto 150 lorries to haul the same tonnage as a single 1000-2000 tonne train. As far as the author knows, this concept has only ever been aired in transport department and select comittee in the UK and regional parliaments.

However there is a wind of change. The mass change to diesel cars has lead to more low level, local emissions of nitrous oxide and the more dangerous 'particulates', which we used to call diesel-soot. With filters and diesel cats, these pollutants have become less oderously apparent, but due to the volume of diesel vehicles on urban roads, it has become an insidious source of pollution which threatens public health perhaps as much as lead in petrol. Trains have a part to play in this, because they transit slowly often through cities, accelerate blowing out those pollutants at high levels, and then sit on idle or the worst point for even the most 'green diesels', they have to switch off and be restarted at terminii.

Currently oil is at a pretty reasonable rate and most of the cost of fuels are in taxes and distribution. Trains are so much very more efficient than road vehicles because they roll at far lower friction over only slight gradients and usually incur far fewer stop-starts caused by conjestion, by the nature of signalling sections and operating them safely and efficiently. Where roads are really anarchic and unpredictable over time, some railway diagrams probably can be found to have originated in the 1950s. Trains in commuter areas really have not become that much faster, and frieght services have only become marginally faster on the slower, more arduous diesel routes.   

There is then off the main lines and premium passenger services, not any current incentive to experiment with dual mode electro diesels. These will in 25kv format cost significantly more to build than standard from either single type. However there is a flexibility in routes of course, and actual range the train can cope with before refuelling at a depot. Things will change a lot if and when a new 'clean air' act for Cities comes into force. 

Brexit has a small upside for the UK train fanatic and capital investor, because it may mean that UK trains no longer have to follow the consensus on every more quiet, efficient and expensive diesel power unit solutions. This means that if the UK decides to run dual mode or hybrid trains into cities to reduce particulates and noise pollution, then they can perhaps get the best system and compromise on emissions when running on diesel and get trains which are perhaps a little more economic than those of the continent.   

The Japanese Test On UK Steels

Hitachi certainly knew where they were  going, but in fact of course we owe the concept of battery hybrid to a far earlier form of covert travel-- the diesel electric submarine. This week even marks the 100th anniversary of the k13 sinking which was steam - battery powered.  Boats are a more extreme example of efficient load bearing when compared to rubber tyes on tarmac. Here  it has been efficient for a centtury to carry lead acid batteries and charge, while most submarines can use the diesels on full power to both charge and drive the 'ship'on the surface. Lead acid batteries are reasonably safe, a bit of hydrogen is released, but they are immensely heavy and it has taken years to get to the Litium ion batteries which are so much better a power to wieght that they render hybrid trains a real proposition within standard rolling stock.

The HST converted carried approximately 2 tonnes of batteries in the first trailer mark III of the set, with a VP185 2250hp new standard power  car infront. Hitachi swapped out the traction motors ( to be AC I beleive), with recurculative breaking capacity, which charges those Li Ion batteries of course. The engine can also charge the battery and can be kept at a higher power output than needed to provide tractive power such that batteries are charges, and the engine is kept in its most efficient range of rpm - power output, while also avoiding thermal cycling up and down between shorter stops.

THe unit also was built to run out of station on a dead engine, start engine underway and the take over power. The battery power available was an impressive 1MW,  about 1300hp, storage at 481  kwh.  This sped the train from a standing halt on battery only to about 50 mph when the engine could then be engaged.

As you see in this image though, the impressive acceleration in the video may be due as much to the fact that this is less than half a working IC 125 train 'set', and the GCR preserved line is hardly known for its gradients. Two tonnes of batteries is a negligible amount to carry slung under a single coach, so you could obviously imagine an 8 car set with two power cars and two battery trailers, pushing out 2MW or in excess of 2600 hp! Also as you can see, this is a prototype system which uses the entire mrk III trailer for electrical control systems and what looks like a large radiator to cool the batteries and high amp machinery. However, this is just at prototype level, and coaches already carry lead acid batteries so the whole system could probably be shrunken to fit under a specially designed coach with more being included in the locomotive power car specially designed for the purpose on outset.

A Realistic Technology for Today Already?

Practical battery hybrids are upon us in multiple units and light railways today, and probably very near to us if there is a green incentive,   would be locomotives which offer clean quiet hybrid mode,  or are operated with a battery trailer-driver for example. There is an obvious immediate advantage for commuter multiple units when they enter urban areas that they can switch off their power units and rely on their batteries to move without pollution. With some form of recharging pick up like a third rail shoe, an ETS supply connection or even a pantograph, then when at rest in a termini or siding, such trains could further avoid burning diesel. (In fact you could have a battery only train which recharges at planned points on a diagram (timetabled service) with either a dedicated special automated power connection, manual connection upon longer stops at the terminii or depot, or picking up power from over head or third rail to charge at rest or underway) 

On that point about burning diesel, and after the biodiesel fiasco of a few years back, why would we want to consider such a disgustingly ungreen thing in a new sparkling enviro-friendly type of train? Well currently battery power seems to be limited to operations of under 60 miles in that mode alone, and that is from the lighter dual mode which do not need to carry diesel power units and fuel tanks. Given a cold British winter affecting battery chemistry, and sliding doors on such services emptying the train of warm air every few minutes, it seems like a bit of a hiding to nothing.

There is though that nice benefit of making our cities safer, cleaner and quieter while using 20 miles worth of that battery capacity. Also when you combine recirculative (electric motor-dynamo mediated) braking then we start to see that we could have quite an efficient system for short, non electrified routes, or we could reach out our range beyond overhead or third rail routes to include nice little extra towns, airports or other places of interest where it is otherwise expensive to electrify. 

Diesel hybrids though have a little hidden surprise up their sleave in efficiency and also in performance from a hybrid train. The motor can be run at a far more constant high output in order to charge the batteries when actually on. A feature of mid sized (over 400 hp and 6L ) to large turbo diesels is that they are most efficeint when running around and above 80% of maximum power output. Also engineers can design even more efficiency into a diesel which has a constant rpm output or limited range of actual torque-rpm application.   Things like diesel "cats" and particulate filters work better too at higher rpms than being clogged up or not heated properly when idling a lot.

Yet another benefit is a little more technical, but very important. As any train driver will tell you, all trains actually have "gears" and electric or diesel electric are no exception. Electric traction motors eventually start to revolve so fast at the current amps-volts field being applied that they produce an electro magnetic feedback or resistance to further useful power and especially torque to be applied. Rather than grinding away in first gear, a locomotive lets the engine back down to lower revs or idle and resets the circuit to higher voltage such that the new rotational speed of the motors can be matched and more power applied. Most locos have three, or three and a half if you take the initial amp loads into account. Now some routes are terrible for this gear shift happening, both upwards and downwards, especially around the 40-50mph for older locos and some multiple units. For we syphon fans, this was kind of an achilles heel, which meant that while they excelled at both the grunting of the highland routes and the welsh valleys, also on 60 -80 mph services, on routes like the 'Fife circuit' or Inverness-Aberdeen, there are significant sections with just that nasty speed range, 40-50 , so performance was lack lustre unless a driver chose to break the speed limit. With batteries on board you can push through with a more rapid voltage transition (field diversion) maintaining speed and maybe accelerating until the engine streams back on to power the train through. WIth GPS and power management, this also means that stretches at this speed can be handled on battery power providing an optimum voltage output, while they are charged by an engine at higher RPM, or the engine is not used given a duration of battery use which is calculated. 

 In addition this peak performance output only means quite a small volume engine, based on a truck engine for example, can output the required power and be programmed for an optimal run up and down of RPM, which really helps reliability and extends service interval over an engine which is expected to deliver tractive power (torque strain) through a wide range of rpm. The diesel for a battery hybrid need only ever charge the batteries and thus be managed at a constant output over the duration of the amps replenishment to the batteries.  The other option is to use a larger, rail industry unit from the likes of MTU, tuned for 80% charging rpm and the using more than this up to 100% as boosting amps on the circuit under hard acceleration or on demanding gradients, 

We come back to that inherent benefit of rail over road when it comes to hauling larger weights. A hybrid battery vehicle as a coach or say a driving trailer attached in a 'pair' to a diesel or electric locomotive, need only weight 10% of the overall train weight to achieve this short but very desirable range. Taking up on that point of having a diesel or electric locomotive with a battery car attached (trialled by Hitachi in a converted IC 125 power car and leading coach btw) we get a very siginificant benefit in being able to traverse towns and cities with diesel off, or for an electric loco, outside electrified routes. That point applies too to non electrified rail heads and marshalling yards where shunting requires seperate locomotives currently. So there is a capital cost and train crew cost which can be reduced by allowing a single, main locomotive to conduct its own shunting. Also new rail heads near to AC or third rail routes would be far more economic and safe to connect to the network. 

We really don't need to be going that far or that fast to get several benefits from hybrid trains, but they are going to add a cost which is difficult to meet if there is not enough demand or pull from legilslation. The replacement of IC125 itself is a case in hand about the economics of actually having progress in this direction, with the class 800 series due to be largely electro diesel so far. In order to achieve standardisation on this large capital outlay, the government had to step in of course and help the industry achieve a critical mass or if you like economy of scale. 

On that point, what we need in future is the ability for investment to be optimised via economies of scale and standardisation, which is something that had become once again quite fragmented under privatisation and against intention. In the 1970s and 80s we saw a largely standard bodied 300+-400-500 series of electric multiple units in two forms (aluminium narrow bodied and steel Mrk III derived) , and then the successful (and aweful) class 150-158 series were based on this standard deriviative of the Mrk III BR Coach body and bogies. Over time an owner or the state can expect TOCs to come and go, and to vary what they want to lease or are required to lease to meet greening legislation, so a modular approach to any new leap forward into all that whacky but feasable dual mode, electro-diesel, hybrid and AC / DC charged battery units would be best suited by this same approach most likely. Here we enjoy economies of scale and common saftey compliance and commissioning at time of purchase, and then the ability to mix and match, repurposing train sets for different routes or requirements. 

Those self-same standardised multiple units built in the late 70s and 80s are now reaching the end of their life span, and for the diesels this may be accelerated by legislation or a decline in subsidies for the TOCs. So there is an opportunity, as we see with Class 800 IC125 replacement, for a collective consensus and common purchasing of cleaner trains which are potentially cheaper to operate in fact and open up new through routes which avoid the conjested terminal stations in our cities. In Scandinavia,  electric cars are all the rage, and the only hybrid to buy is a plug in one so that you can do the school run in blissful greenness while saving a good bob or six on all that warming engines up and standing in commuter traffic for those very many short journeys most people actually do most often. 

Personally I have never liked diesel multiple units because of their noise when compared to the gentle whine and clickety clack, plus the old shoogle as we called it of trains like the venerable class 303 electric multiple unit. DMUs also increased many journey times susbstantially over the previous type 3 and type 4 locomotive hauled services and offered often less capacity. I remember my first tour on a 150 series unit on a Crewe- Nottingham service at 6 am, trying to get some kip after an overnight stop over, and finding that torque convertor, moany engine set up most annoying, along with the strip lighting. The romance of compartment stock with subtle little dimpled lamp lights and sliding top windows may be consigned to the preserved branch line, but I would like to use quieter trains, the greener the better.