How energy efficient really is railway transportation?


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Description of the physical coherences of railway traction, superiority of electric against diesel traction, technical details, differences between electrical railway traction with trolley wire or accumulator battery to electric cars

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How energy efficient really is railway transportation?

  1. 1. How energy efficient really israilway transportation?Stefan FassbinderDeutsches KupferinstitutAm Bonneshof 5D-40474 DüsseldorfTel.: +49 211 4796-323Fax: +49 211
  2. 2. The German Copper Institute, DKI, isthe central information and advisoryservice dealing with all uses of copperand copper alloys.We offer our services to: Commercial companies We can be contacted by: The skilled trades  post Industry  phone R & D institutes  fax Universities  e-mail Artists and craftsmen  internet Students  online database, or Private individuals  personally
  3. 3. Does electricity boost mobility?Electric cars are• technically not feasible for long distances,• economically not viable for short distances.To charge up a laptop PC• costs 1 cent for electricity from the socket.• The battery costs 90 € and survives 1000 duty cycles.• This means: 10 times higher energy price while battery powered! With big units for vehicles the factor still is around 3.The »tank« of an electric car• costs 3000 €/l, converted to energy equivalent diesel• weighs 30 kg/l } fuel quantity (ηD = 30%, ηE = 90%)• and is over and done with after 1000 … 3000 fillings.
  4. 4. But still the trade presswanted it yet another time:»Market introduction of electric cars tostart in 2011«
  5. 5. Comparison: Citroën C-Zero Citroën C1 (electric) (petrol engine)Length 3480 mm 3430 mmWidth 1475 mm 1630 mm At least one thing isHeight 1792 mm 1470 mm certain:Empty mass 1195 kg 925 kgPayload 255 kg 265 kg  These vehicles areLuggage volume 166 l 139 l really comparable.Turning circle 9.0 m 9.5 m  This is a real electricDrive back front car in its own right!Gears (forward) 1 5  Only the payback –Power rating 49 kW 50 kW even without fuel taxTop speed 130 km/h 157 km/h – takes 469,000 km!Acceleration 15.9 s 13.7 sCruising range 150 km 760 km  This corresponds toCO2 emissions 100 g/km 107 g/km 3,000 chargingEnergy costs 2.20 €/100 km 6.90 €/100 km cycles – the end ofPurchase price 35,165 € 13,120 € the battery lifetime…
  6. 6. Electricity does boost mobility!If only there is a way to bring the power into the vehicleElectric motors• have their highest torque at standstill: No disengaging, no gearchange, no torque converter required,• provide a considerable short-term overload capability: Higher acceleration than the power rating would let you suppose,• do not have any no-load consumption during standstill, rolling or braking,• offer the opportunity to feed back energy during braking (motor = generator),• and their primary fuel is totally flexible (fossil, nuclear, hydro, wind – just mix as you like!).
  7. 7. So it is not a miracleif railway companies preferelectric traction! Characteristic data of 16.7 Hz railways Electricity system of DB AG in D-A-CH Installed EnergyType of power plant DB AG ÖBB SBB capacity productionVapour 42.2% 66.0% Employees 240242 42893 27822Hydro 11.0% 10.0% Passengers 1919Mio. 200Mio. 332Mio. Railway gridRotating convertor 34.3% 14.6% total 33862km 11000km 3011kmElectronic convertor 11.9% 9.4% electrified 19300km 8200km 3011km shareTotal 3.2GW 11.0TWh/a of lines 57% 75% 100%Sum of all electric vehicles 22.4GW (700%) of transport 85% 100% volume 56% of DB lines are … since the energy electrified. These 56% carry“consumption” of an electric 85% of all traffic.locomotive can be negative! However …
  8. 8. …what about the other 15%? e. g. the 612 series?• Engine power rating: 2*560 kW = 1120 kW• Smart and convenient: Tilting technique, air conditioning• Maximum permissible speed: 160 km/h• Fuel consumption: 1.7 l/km (for one, not 100 km!)
  9. 9. What about diesel locomotives?• On a series 232 diesel locomotive (6 axles, 120 t, 2,200 kW, max. 120 km/h) at a constant speed of 120 km/h a consumption of 3 l/km was measured.• (for good resons railway companies reference the fuel consumptions to one kilometre, not to 100 kilometres!)• There have not been any new diesel locomotives for decades.• There are old diesel locomotives with new engines.•BR 232 “Ludmila” is then >40%. The engine efficiency BR 220 “Taiga Drum”• But what„s the use of this if the engine is idling for >90% of its operating time?• And if a DB technician explains: “Diesel locomotives hamper the traffic when circulating on an electrified line!” …• …and if a railway trade journal reports the electrification of a line no longer than 22 km had already cut the circulation time by 5 minutes?„Elektrischer Betrieb bei der Deutschen Bahn im Jahre 2009“. „eb“ Elektrische Bahnen & Verkehrssysteme 1-2/2010, p.19
  10. 10. However, the 101 series electric loco(4 axles, 84 t, 220 km/h) provides amotor power rating of 6,600 kW!Note: It„s electricity that wakes trains up!
  11. 11. This explains it:800kW/t Inverse trends!600kW/t Power density of reciprocating combustion engines Power density →400kW/t Power density per size of respective electric motors200kW/t Power rating → 0kW/t 1kW 10kW 100kW 1000kW 10000kW 100000kW
  12. 12. The parameters responsible forthe energy demand are(at ≈200 km/h): of a car of a train factor (4…5 seats)(450 seats) 100Mass 1.5 t 450 t 300Coefficient of staticare a means of mass transportation! 0.3 Note: Trains friction ≈1 0.28…0.35Coefficient of rolling friction ≈2% <2‰! 0.1Resulting: some good reasons railwaykNNote: For Rolling friction force 0.3 companies give rolling 9 kN 30Power demand resulting from as per kW figures! friction coefficients this 15 mille 450 kW 30as a share of power rating 15% 7% 0.5Air friction force 1.5 kN 30 kN 20Power demand resulting from this 85 kW 1550 kW 18as a share of power rating 85% 23% 0.27Total power demand 100 kW 2000 kW 20as a share of power rating 100% 30%! 3.3
  13. 13. Now what are the other70% of power good for?Compared to a car, a train has:- A very great mass.- Significantly less static friction (steel on steel rather than rubber on asphalt).+ Significantly less rolling friction (steel on steel rather than rubber on asphalt).+ Significantly less air friction (since the train travels “in its own windshade”, so to say).
  14. 14. On rails even a »Unimog« universalminiature lorry can haul 1000 t!Though not at a particularly high speed
  15. 15. Worth noting:The top speedof a car is usually of a railway vehiclethe highest is usually thepossible highestspeed, limited by permissiblethe available speed.engine power.
  16. 16. With a great deal of good will 66kW 6,6MWwe will now requirement car anda train Power let a car with IC•55kW kW engine and (very tight) space for 66 P (car)  5,5MW P (IC train) •44kW 4 passengers travel at 4,4MW•33kW km/h, P (car) 200 3,3MW P (IC train)while a train with a drive power rating of 22kW 2,2MW• 6,600 kW offers plenty of space to•11kW passengers (including toilets, a 400 1,1MW bistro, …). At a travelling speed of 0,0MW 0kW v • 200 km/h50km/h requires: 150km/h 200km/h 0km/h this 100km/h
  17. 17. But a car accelerates faster?100%90% v/vmax 80%70% Well, initially process the Acceleration yes, but train has a lot of reserves! car and train (0 … 200 km/h)60%50%40% Car acceleration v/vmax30% IC train (10 carriages) v/vmax20%10% 0% 0km 1km 2km 3km 4km 5km s  6km 7km 8km
  18. 18. Quiz question 1:How far will an ICE2 expresstrain of the 402 series continue to rollunbraked in a flat area when suddenlythe power fails at a speed of 230 km/h?Answer 1:The test was not carried out all throughto the end. After 32 km the train was stillrolling at 120 km/h!
  19. 19. Quiz question 2:How fast will a railway carriagebecome when you let it roll down adecline of 5‰ (just 0.5%!)?Answer 2:Note: For some good reasons railwaycompanies give inclines and declinesAccording to technical documents by asper mille Bahn AGDeutsche figures! it will (finally) reacha speed of 44 m/s ≈ 160 km/h (after1 hour of rolling)!A street car would simply just stall and not roll at all!
  20. 20. Quiz question 3:Why is it that in a train repairhall which can be opened at both endsit is not allowed to leave both gatesopen at the same time?Answer 3:Because the wind might blow thelocomotoves out of the hall!
  21. 21. So let’s just accelerate a200km/hfully occupied street car v to 200 km/h, disengage150km/hand see what willhappen…100km/hMass: Train rolls kg 2000 Train rolls Train brakes Car rolling outRolling friction coefficient: Car rolling out 50km/h 2% Car rolling outFront surface area: 2 m²cx value: 0km/h 0.37 2km s Engine power: 1km 0km 105 kW 3km
  22. 22. Adapting the scale to the train:200km/h Rolling and braking: v  Express train (10 carriages) versus car150km/h100km/h Train rolls Train brakes Car rolling out 50km/h s  0km/h 0km 5km 10km 15km 20km 25km
  23. 23. Adapting the scale to the train:200km/h Rolling and braking: v  Express train (10 carriages) versus car150km/h100km/h Train rolls Train brakes Car rolling out 50km/h t  0km/h 0s 120s 240s 360s 480s 600s
  24. 24. Hauling force and power IC fast train with DBs 101300kN series locomotive and 6MW 9 carriages250kN 5MW Hauling force  Power 200kN 4MW150kN 3MW Required hauling force Required power100kN 2MW50kN 1MW Speed  0kN 0MW 0km/h 50km/h 100km/h 150km/h 200km/h
  25. 25. Hauling force – 80% left? IC fast train with DBs 101300kN series locomotive and 6MW 9 carriages250kN 5MW Hauling force  Power 200kN 4MW150kN 3MW Required hauling force Available hauling force100kN 2MW Required power50kN 1MW Speed  0kN 0MW 0km/h 50km/h 100km/h 150km/h 200km/h
  26. 26. Power – 70% left? IC fast train with DBs 101300kN series locomotive and Power limit 6MW 9 carriages250kN 5MW Static friction limit  Hauling force  Power 200kN 4MW150kN 3MW Required hauling force Available hauling force100kN 2MW Required power Available power50kN 1MW Speed  0kN 0MW 0km/h 50km/h 100km/h 150km/h 200km/h
  27. 27. Not while running uphill! IC fast train with DBs 101300kN series locomotive and 9 6MW carriages running up Power 250kN an 18.5‰ incline 5MW Hauling force  When it becomes steeper200kN than that the top speed 4MW cannot be held any more150kN 3MW100kN 2MW Required hauling force50kN Available hauling force 1MW Required power Available power 0kN 0MW 0km/h Speed  50km/h 100km/h 150km/h 200km/h
  28. 28. At 300 km/h, however …300kN 8MW ICE3 high speed railcar of DBs 403 series 7MW250kN … the demand does 6MW F 200kN increase rapidly  5MW150kN 4MW P  Required hauling force 3MW100kN Available hauling force Required power 2MW50kN Available power 1MW v  0kN 0MW 0km/h 100km/h 200km/h 300km/h
  29. 29. The ultimate train concept330km/h ICE3 high speed railcar 0,75m/s² a 300km/h of DBs 403 series270km/h 0,60m/s²240km/h210km/h 16 out of 32 axles driven 0,45m/s²180km/h v  by a 500 kW motor each150km/h provide optimal 0,30m/s²120km/h acceleration and 90km/h energy recovery 60km/h 0,15m/s² Speed 30km/h Acceleration s  0km/h 0,00m/s² 0km 5km 10km 15km 20km 25km
  30. 30. The ultimate train concept330km/h ICE3 high speed railcar 0,75m/s² a 300km/h of DBs 403 series270km/h 0,60m/s²240km/h210km/h 16 out of 32 axles driven 0,45m/s²180km/h v  by a 500 kW motor each150km/h provide optimal 0,30m/s²120km/h acceleration and 90km/h energy recovery 60km/h 0,15m/s² Speed 30km/h Acceleration t  0km/h 0,00m/s² 0s 60s 120s 180s 240s 300s 360s
  31. 31. Also you have to accelerate the train tothe desired travelling speed of 300 km/h(83.3 m/s) first in order to run that fastWith a 4% supplement for rotating masses and an efficiencyof 87%, measured at the pantograph, this makes about520 kWh for one single acceleration from 0 to 300 km/h.With the DB tariff of 9 c/kWh this costs approximately 47 €!It would be pretty sad to get nothing of this back at all.Counted with an efficiency of 87% again, you can retrieve75% during brakage – if all goes well. 2 m 450,000kg mWkin * v² * 83.3 1.56 *109 Nm 1.56GJ 434kWh 2 2 s
  32. 32. Bad outlook for the dieselElectric traction turns out to be far superior:• Power density and dynamic behaviour are outstanding.• 9% of all electricity consumed by locomotives in Germany has been used once before by another locomotive and fed back again into the supply system.• Usually this works only with water (or e. g. copper!) but never ever with coal, gas and oil.• The share will continue to grow, since by and large more and more old electric locos without feedback capability are being replaced with modern power electronic ones.• But we will still have to wait for a long time to see a diesel engine coming around that, when braking, sucks up fumes and converts them back into fresh air and fuel.
  33. 33. Electric power speeds us up!• For 2009, DB„s department for Energy Cost Management gives an average circulation of 347,620 km for each of their 145 locomotives of the 101 series.• The average consumption is ≈17 kWh/km (including electricity the locomotive has fed into the train for heating the carriages and for ancillary supplies).• This yields an electricity cost of half a million Euros per year.• The purchase price of the 101 series is around 3 million Euros.• So for the power consumption of a locomotive„s 30-year- long life you could buy in 5 complete locomotives!• 9% of energy fed back saves 1.2 million Euros per loco during 30 years!
  34. 34. Or let’s have a look atsuburban transportationThe regional train from Aachen to Dortmundtravels about 160 km far, calling 22 times.Its top speed is 140 km/h.If it went all through non-stop, it would consumeonly 800 kWh for overcoming the friction.But accelerating 22 times costs 1600 kWh!So this is 2/3 of the overall energy consumption!Hence, in theory about 3/4 out of 2/3, say half of theenergy, could be recovered, but unfortunately …
  35. 35. Or let’s have a look atsuburban transportation… according to DB Regio the real rate of recoveryis only 10% in this business unit!And now what to do? What’s the deficiency?
  36. 36. Hence DB’s plans for thecoming decades are:• Increase the share of inverter locos from 47% (2009) to 100%: 10% → 20%• Improve control infrastructure – no more odour of hot brakes: 20% → 50%• Replace all Loco-and-carriage trains with railcars: 50% → 60%• Railcars are lighter and hence use less energy• The dispersed drive expands the opportunities for energy recuperation
  37. 37. Not fragile … Stock of drive vehicles with DB AG40003500 Number  Drive vehicles with feedback capability3000 Tap changer regulated drive vehicles250020001500 Tap changer operated vehicles1000 have no longer been commissioned 500 already since 1985, but still… 0 2007 2009 2010 Year  2011
  38. 38. If you see a tap-changercontrolled locomotive todaythen it is most likely to be 36 years old.In case of the 110 series, forinstance, this vehicle must be between42 and 54 years old!And it still keeps on running …
  39. 39. Old tap-changer vehiclesstill on duty with DB AG Stock BR supplied 2007 2009 2010 2011 Age Locomotives 103 1972 to 1974 3 3 3 37a to 39aTap changer regulated drive vehicles DB Long 113 1962 to 1963 115 2 3 3 48a to 49a Distance 115 1962 to 1964 28 19 17 47a to 49a 110 1957 to 1969 109 88 64 42a to 54a 111 1975 to 1984 225 225 224 27a to 36a Locomotives Legacy to 1993 112 1992 from 1115 89 89 89 18a to 19a DB Regio 114 the GDR 1990 to 1992 40 39 38 19a to 21a 143 railways1990 1984 to 556 520 487 21a to 27a Railcars 420 1969 to 1994 189 167 163 17a to 42a 205 DB Regio 450 4 4 4 Locomotives 140 1957 to 1973 172 74 81 38a to 54a DB Schenker 151 1973 to 1975 648 163 140 133 36a to 38a Rail (freight) 155 1974 to 1984 219 195 185 27a to 37a Sums Locomotives 1877 1606 1395 1324 33a 36a 40a resp. Railcars / integr. trains 205 193 171 167 17a 30a 42a mean values Total 2082 1799 1566 1491 25a 33a 41a
  40. 40. Now what„s up withthe 44% of lineswithout a trolley wire?• There is a diesel railcar standing at the railway station. There are 2 engines mumbling under no-load conditions inside it – and are being cooled, while an oil heater fuelled with diesel fuel at the price of diesel fuel is heating the passenger cabin.• The railcar starts. The engines raise their voices a little bit.• Only above some 30 km/h … 60 km/h the full power can be transmitted to the rails: Now the engines hum a bit more vigorously – for about one minute. Then the top speed has been reached. About 30% of the engine rating suffice to sustain a constant speed of 160 km/h.• But very soon we are approaching the next station. The railcar is kept rolling for several minutes, the engines disengage, mumbling calmly.• Then the railcar brakes. The engines rev up – just to dissipate the heat from the hydraulic braking system via the engine radiators!Is this a concept for the future? – Or rather a makeshift solution?
  41. 41. But wasn‘t there something else?Oh, right: The 515 series!• Accumulator-operated railcars have been in use since 1907!• for 40 years, from 1955 to 1995, well over 220 motor vehicles of the 515 series have been in use:• Power rating 2*150 kW• Maximum speed 100 km/h• 10 t … 16 t of lead accumulators• Capacity 352 kWh … 602 kWh• Cruising range 300 km
  42. 42. Mental experiment:A modern re-issue• Today„s Li ion accumulators provide 4 times the energy density of the old lead acid batteries, so:• you can double the capacity while halving the mass.• Doubling the capacity doubles the cruising range to about 600 km.• halving the weight along with the use of modern inverter technique with generative brakage im- prove the performance (min. 140 km/h) and the comfort (e. g. air conditioning).
  43. 43. Comparing a hypothetical electricbattery railcar to a street car Tesla Electric Roadster railcarEnergy capacity 55 kWh 1100 kWhEnergy demand 200 Wh/km 2000 Wh/kmEnergy demand per seat 100 Wh/km 10 Wh/kmcruising range 350 km 600 kmBattery mass 0.45 t 9tas share of the vehicle 36% 12%Battery price 45.000 € 900.000 €as share of conv. vehicle 50% 25%
  44. 44. How much really is theelectricity from the battery?Battery price: 900.000 €Life time: 3000 cyclesEnergy capacity: 1100 kWhSo in effect the power from the battery costs:Electricity taken from trolley wire 90 €/MWhCharge cycle / conversion losses +10 €/MWhNight tariff rebate -10 €/MWhWear of the accumulator battery +270 €/MWhElectricity cost from the battery 360 €/MWh
  45. 45. Comparison to the existingseries 612 diesel railcar Diesel railcar Batt. railcarPrimary energy demand 20 kWh/km <6 kWh/kmSecondary energy demand 17 kWh/km 2 kWh/km (1.7 l/km)Net energy price 1.03 €/l 0.09 €/kWhEnergy price from the battery – – – 0.36 €/kWhNet energy cost 1.80 €/km 0.18 €/kmEnergy cost incl. battery – – – 0.72 €/kmAt 250,000 km/a 450,000 €/a 180,000 €/aDuring a 30 years„ life 13,500,000 € 5,400,000 €
  46. 46. Comparison to the existingseries 612 diesel railcarThe comparison is biased?It is, but towards which side?Note:• The battery railcar will need at least 2 new batteries during its 30-year service lifeBut:• Diesel driven trains require 3 times as much maintenance costs as electric trains doSo there is scope enough for 2 new batteries!
  47. 47. Alternative 1: Accumulatorrailcar with pantographLocal trains often leavethe city centres onelectrified lines and turnoff onto the secondaylines only a bit later on.Here the vehicles could• be charged up during ride• in part be driven as conventional electric railcars with pantograph (»pop-up hybrid«)• and thus require only a fraction of the (expensive) battery capacity.
  48. 48. Alternative 2:Hybrid diesel railcarsDo not confuse with the principle of the diesel-electric locomotive! Since this is an electric locomotive lugging aroundits own power plant.• With the hybrid railcar, however, the diesel engine has only some 10% of the electric power (e. g. a 66 kW car engine instead of 2*315 kW railway engines).• For the diesel engine is always running at the optimal point of operation (rated speed and power) instead of idling ≈90% of its time.• Also the generator rating is only 10% that of the electrical traction power.• The battery provides 90% or bears 110%, respectively, of the electrical traction power during acceleration and brakage, respectively.• Continuous heat generation. Combined heat and power generation replaces the oil heater.• Facilitates combination with alternative 1.
  49. 49. Hybrid diesel railcars – alsofor long-distance fast trains?Just take a trip from Berlin to Copenhagen!There they are using up the unfortunate series 605 now.• These railcars are equipped with diesel-electric drives, so these already avail of electric drive motors and inverters.• These trains arose on the platform of the 415 series 5- carriage electric railcar!• They had been withdrawn from service for several years.• They were offered abroad for sale, but nobody wanted them.• One of the reasons given for the latter two points are high fuel costs.So why not convert these trains first?
  50. 50. Series 605 – ICE without pantographJust consider:• Here the train does not run very fast and rarely stops.• Still the fuel consumption lies around 3 l/km!• This costs around 1800 € per single trip.• For this alone 7 full-charge or 45 low-cost ticket passengers will have to be sitting on the total of 195 seats.• Whereas the major share of the easement is electrified!• And for one hour the train is not travelling at all but is standing on a ship.So why not• remove 3 of the 4 diesel engines and generators,• replace them with accumulator batteries,• possibly add a pantograph and a transformer• but in any case reduce the fuel consumption by 1 l/km• and save about 600 € of fuel cost on one trip?
  51. 51. Summary and conclusions• Electric railway drives clearly outperform diesel engines.• At the same time electric railway drives are way more energy efficient than diesel traction is.• SBB operate 100% electrically – nothing left to do.• E. g. DSB are 27% electrified – need for action!• DB AG operate 85% electrically – this is fine so far.• For the remaining 15% a re-introduction of battery operated railcars based on modern lithium ion cells should be considered. 40 years of good experinece even with lead acid accumulators support this idea.• The economic viability of electric cars lies about 10 times further away from reality than that of the battery operated railway vehicle! The German Department of Technology and the EU Commission should urgently take this into consideration with their energy efficiency support programmes.