MTU Report 02/10 I 5

Chili chocolate is one. Grapefruit is another. Willthe onion rose be the next? Anywhere and every-where we are surrounded by hybrids. Be it merelya mixture of chili and chocolate or a cross be-tween and orange and shaddock or even betweenonion and rose. Even things seemingly very differ-ent at first sight are combined with one anotherto produce the proverbial whole greater than thesum of its parts. MTU diesel engines have had aperfect hybrid partner for nearly 40 years – thegas turbine. The two are joined together in propul-

sion systems for ships in order to utilize the ad-vantages of both systems at the same time. Onlong-distance trips or at low speeds the substan-tially more economical diesel engines operatealone, while the gas turbines are kept in reservefor the highest speeds. A highly successful modelfor large naval vessels in particular. It enables fuel-efficient cruising as well as ultrahigh top speeds.

Diesel engine meets electric motor. But nowthe diesel engine has found a new hybrid partner

– the electric motor. Actually they have knowneach other for many years. They have worked together for a long time in diesel-electric tractionsystems, in which electric motors are poweredby a diesel-driven generator. And now MTU is researching into uniting electric and diesel unitsin a hybrid system to get the best of both worlds.A diesel engine on its own is powerful and durable.The electric motor is quiet and produces no emis-sions. The two together will make new hybrid drivesystems possible that not only offer higher perfor -mance but also need less fuel and produce loweremissions. The principle is always very similar: > For normal traction, the diesel engine is usedon its own

> Whenever zero emissions or silent operationare required, the electric motor is used on itsown

> Both power units are used in combinationwhen maximum performance is needed imme-diately, such as when pulling away, acceler -ating or climbing.

As yet the rose and the ornamental onion are distinct flowers. But willthey ever be made into one? The diesel engine and the electric motorare one step ahead in that regard. They have already been combinedinto hybrid drive systems. MTU will soon be testing out prototypes inthe field.

Up to now the VT 642 railcar has been driven by a conventional MTU PowerPack. Now it is to be fitted with a hybrid system.

Cross-fertilization

Hybrid drive systems for ships and trains

Hy|bri|da: “A thing derivedfrom heterogeneous sourcesor composed of incongruous elements”

[From Latin hybrida, (h)ibrida]

It is the queen of flowers, the rose. But would it be possible to add to its attrib-utes by giving that queen a very special crown? For example, by crossing it withan ornamental onion? A plant that is resistant to all hardships? Then we mightcreate a flower that is the star of every show – the onion rose. It would not onlyoutshine every other flower, it would also last much longer. As yet there have beenno such cross-fertilization attempts in the botanical world. MTU is one step aheadin that regard. Diesel engines combined with gas turbines have proven them-selves as marine propulsion systems over many decades. And diesel engines arenow being joined together with electric motors to create new hybrid systems. As yet they are still delicate seedlings. But to find out if they can be grown intohardy plants, prototypes are soon to be tested out in research projects.

Techno

logy

MTU Report 02/10 I 7

Hybrid star of the rails. Significantly lowerfuel consumption and emissions than with con-ventional diesel-powered trains, virtually silentoperation at stations and substantially lower life-cycle costs – hybrid drive systems in trains are aworthwhile investment, especially for local serv-ices. Trains used for that type of duty have to fre-quently brake and accelerate again, and that isprecisely the pattern utilized by the MTU rail hybrid system that is to be trialed in a researchproject to be conducted jointly next year with theDB RegioNetz Verkehrs GmbH Westfranken. Everytime the train brakes, the energy is stored in abattery. And whenever it is required to power the electric motor, the battery gives that energyback – when pulling away, in stop-go conditions,when tackling uphill gradients or when accelerat-ing. Then the electric motor assists the diesel engine so that less fuel is required. When thetrain needs to run as quietly and as cleanly as possible, for example in residential areas or stations, the electric motor operates on its own.

For this project, one of MTU’s partners is work-ing to MTU specifications on the development ofa very special electrical machine, a crank-shaftstarter generator (CSG). It runs directly off thecrankshaft of the diesel engine and can function both as an electric motor and a genera-tor. A frequency converter controls the flow ofelectricity from the battery to the motor andback as required.

Predictive control. A strikingly beautiful fea-ture of the MTU rail hybrid system is its specialrail hybrid controller. It controls the use of thetwo power units with the aid of an electronicservice timetable. The timetable contains detailsof the precise speeds at which the train musttravel at various points along the route in orderto be on time. The MTU rail hybrid controller decides before the journey even begins when thediesel engine will be used alone, when the elec-tric motor will be brought in and when the trainwill run on electric power only. During the jour-ney, the controller continually checks whetherthe train is still on time or is behind or ahead of schedule. If the controller identifies that the

train is not keeping to the timetable, it checkswhether it would be helpful or possible to changethe traction mode – and does so without inputfrom the driver. “That predictive monitoring isunique in the rail sector,” reveals Ingo Lehmann,MTU project manager for the hybrid PowerPack.“The system is patented and enables us to mini-mize the fuel consumption as much as possibleas we only ever use the amount of power actual-ly required to keep to the timetable,” he adds.The rail hybrid controller also manages the entiretraction system peripherals: cooling systems,preheating equipment, auxiliary drive systems,auxiliary peripherals and the exhaust treatmentsystem. That is because the PowerPack containsan SCR system to reduce emissions and keepthem within the Stage 3B limits.

The first railcar with a prototype MTU hybridtraction system is due to start service in the middle of next year. In cooperation with a devel-opment team from Deutsche Bahn, a SiemensDesiro VT642 Class railcar operated by West-frankenbahn, a subsidiary of Deutsche Bahn, isbeing converted as part of a project sponsoredby the German Transport, Construction andUrban Development Ministry. Up to now the train has been driven by a conventional MTUPowerPack. Preliminary studies indicate that a15 to 25-percent fuel saving may be possible de-pending on route profile. “In this form and withthis type of performance, our hybrid system isunique in the rail sector,” points out RainerBreidenbach, Tognum COO with responsibility for the Engines business unit.

« In this form and with this type of performance, our hybrid system is unique in the rail sector.»Rainer Breidenbach, Tognum COO with responsibility for the Engines Division

Hybrid heat and power plant: a milestone in energysupply

Another hybrid: the HotModule already guarantees reliable and, aboveall, virtually zero-emission electricity generation on its own. But com-bined with a modular gas heat and power plant its flexibility is substan-tially increased. The two are linked together by a common heat pipe.While the fuel cell runs at constant output to cover the base-load de-mand, the gas CHP module is more variably controllable. The hybridcontroller constantly adjusts its output to the immediate energy demandand the amount of biogas fuel available.

MEMO

The fuel cell formsa hybrid with a gasCHP module.

Technology

The hybrid PowerPack forrail traction essentiallyconsists of a diesel engine,a crank-shaft starter generator, a frequencyconverter and a batteryfor storing the braking energy.

An odd couple? As un-usual, maybe, as thediesel engine and elec-tric motor might firstappear. But they aregrowing together andcreating hybrid systems.

6 I MTU Report 02/10

8 I MTU Report 02/10

Hybrid propulsion for ships. Winding one’sway out of the harbor using electric power, thendeploying the diesel engines to whizz at full speedacross the water in time to relish the romanticatmosphere and peacefulness of the bay late inthe evening. What sounds so tantalizing couldsoon become a real scenario for yachts. Togetherwith the British yacht manufacturer Sunseeker,development engineers at MTU are soon to testa hybrid propulsion system as part of a researchproject. As with hybrid rail traction, the crank-shaft starter generator (CSG) is coupled with thediesel engine. However, on the yacht this genera-tor is separated from the diesel engine by aclutch. With the clutch disengaged, the CSG cantake the ship from the harbor out into the opensea. At this, the electric motor showcases all itsadvantages: it is quiet, produces no emissionsand reaches its maximum speed immediately. At a maneuvering speed of six knots, batteries can provide the motor with energy for almostone hour. “That’s enough time to depart fromeven the world’s largest marinas” explainsDr. Gerhard Filip, applications engineer at MTU.If the captain then decides to go at full throttle,he will deploy the full power of his diesel en-gines. The coupling will engage and the combus-tion engines take over the ship’s propulsion.During this phase, the CSG, in its role as genera-tor, will recharge the batteries so that they will beavailable for their next task: to provide power forthe electric motor as a short-term back-up forthe diesel engines so that the yacht may acceler-ate even faster. When the boat is anchored in abay, the captain can revert to the batteries forhis on-board power supply and switch off the on-board power generator. This not only meansless noise but also prevents the emission of pol-lutants. Another advantage of the marine hybridsystem: in order to save fuel, the yacht captainmay shut down one diesel engine when cruisingat moderate speed and drive the second pro-peller using the electric motor (e-shaft mode).“One third of the time, yachts only move withone third of their rated power output. One dieselengine is enough to do the job, saving the fuelfor the second engine” adds Dr. Filip.

Amazing! The onion roseis fully grown and infull flower. But actuallyonly thanks to computergenerated imagery. MTUhybrid drive systems, onthe other hand, couldsoon be reality.

Comfort> Silent and low-vibration running> Silent onboard power supply

Environment> Maneuvering in harbors without producingemissions

> No emissions from onboard power supplyat night

> Lower emissions when accelerating

Advantages of the marine hybrid system

Performance> Significantly faster acceleration> Smoother transition from electric to dieselpower

Economy> Five percent less fuel consumption due to e-shaft mode (shutdown of one dieselengine); accordingly lower CO2 emissions

> Longer diesel-engine service life> Downsizing of diesel engines

MEMO

Final piece of the jigsaw. One of the keys to asuccessful hybrid drive system and, at the sametime, one of its greatest challenges is the bat-tery. Not only does it determine the range of theelectric motor, but also the weight, space re-quirements and cost of the entire drive system.Lithium-ion batteries currently represent the bestcompromise between size and performance andare thus the ideal energy stores for hybrid sys-tems. They are already widely used in entertain-ment and communication devices such as lap-tops and mobile phones, and they are also wellestablished in the automotive industry. But thebatteries for rail and marine power have to beconsiderably more potent and durable. As yetthere are no energy stores on the market thatcan meet those requirements. MTU is thereforetaking part in a publicly sponsored research project involving the development of lithium batteries tailored exactly to meet the require-ments of vehicles that have to deliver high powerlevels off-road.

And that will be another factor in ensuring theMTU hybrid seedling continues to grow strongly.So maybe we will look back in 40 years’ time and see that the diesel engine has had just assuccessful a relationship with the electric motoras it has so far with the gas turbine.

Lucie Dammann

To find out more, contact:Ingo Lehmanningo.lehmann@mtu-online.comTel. +49 7541 90-3467

Dr. Gerhard Filipgerhard.filip@mtu-online.comTel. +49 7541 90-4007

«Yachts with our hybrid system can maneuver powerfully, sail out of the world’s biggest harbors without creating any emissions and the owners can enjoythe silence of secluded coves thanks to their onboard electric power supply.»Dr. Gerhard Filip, MTU marine hybrid project manager

Technology

Luxury yachts made by British builder Sunseeker may be running on MTU hybridpower in the near future.