fuel cell or battery: electric cars are the future

Fuel Cell or Battery:Electric Cars are the FutureJ. Van Mierlo1*, and G. Maggetto2

1 Vrije Universiteit Brussel, Department of Electrical Engineering and Energy Technology (ETEC), Pleinlaan 2, BE-1050 Brussels, Belgium2 AVERE, European Association for Battery, Hybrid and Fuel Cell Electric Vehicles, Pleinlaan 2, BE-1050 Brussels, Belgium

Received December 19, 2006, accepted March 2, 2007

1 Introduction

The electric vehicle is an optimum solution for urban mo-bility as it emits no exhaust fumes. Particularly in cities andin adverse climatic conditions, traffic-generated emissions aredegrading air quality up to the point where the physicalhealth of the population is directly threatened. Several citieshave already had to apply repeatedly drastic traffic restric-tions. The electric vehicle is also ideally suited for integrationinto new traffic management concepts, such as automaticrent-a-car systems and goods distribution centres, or smallbuses for city-centre services.

For all these reasons, often with the support of the EUCommission and some member states, an increasing numberof cities and environmentally concerned companies haveintroduced electric vehicles into their fleets. Today, there is aclear necessity to generalize the support organized at a Eur-opean level in preparing for movement towards hydrogenelectric vehicles.

Energy storage remains a key point. The development ofalternative battery systems shows the possibility of making a

–[*] Corresponding author, [email protected]

AbstractBattery and hybrid vehicles are today’s sustainable mobilitysolutions, preparing a future shared with a hydrogen econ-omy. The summary report of the EU High Level Group forHydrogen and Fuel Cells, presented in June 2003, developsa vision on the contribution that hydrogen and fuel cellscould make to the realization of sustainable energy systemsin the future [1].

However, it seems necessary to emphasize that, as it is along-term vision (2000-2050), there is a need to take strongaction in the short- and medium-term in order to addresscurrent environmental and energy concerns.

As stated in the Commission’s November 2000 GreenPaper on security of supply [2], in 1998 energy consumptionin the transport sector was responsible for 28% of the emis-sions of CO2, the main greenhouse gas. According to the lat-est estimates, current CO2 emissions from transport areexpected to increase by around 50%.

It is both an ecological necessity and a technologicalchallenge to reduce the dependence on oil, from the currentlevel of 98%, by using alternative fuels and improving theenergy efficiency of the various methods of transport [3].It is planned that the hydrogen economy will only startaround 2020, at the earliest, and to be established around

2050. Fortunately, many of the electric drive technologiescommon with hydrogen drive systems are already in devel-opment today and implemented in battery or hybrid electricvehicles.

Two transport technologies are ready to play a significantrole in this context: the battery electric vehicle and the ther-mal hybrid electric vehicle. They are the missing link with afuture hydrogen transportation economy. It is an establishedfact that, from a well to wheel emission point of view, theresults are positive and in favour of battery electric vehicles[4]. Important and recent studies on the environmental bal-ance of battery electric vehicles show substantial emissionand primary energy benefits, and thus CO2 reduction, whencompared with conventional cars [4, 5].

The battery electric vehicles and thermal hybrid electricvehicles are considered as the bridge to the future hydrogentransport economy. In any case, the hydrogen and electricityvectors should be used in the most appropriate and effectiveway to ensure, for the various applications, the optimummix of the primary energy sources at a European level.

Keywords: Battery Electric Vehicle, Emissions, Energy Con-sumption, Fuel Cell Vehicle, Hybrid Vehicle

FUEL CELLS 07, 2007, No. 2, 165–173 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 165

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DOI: 10.1002/fuce.200600052

Mierlo et al.: Fuel Cell or Battery: Electric Cars are the Future

real technical and economic breakthrough in the short- or me-dium-term, consistent with important market developments.New battery types, such as high-temperature batteries,nickel-metal hydride batteries, and lithium-based batteriesare already on the market or will be available in the comingyears. Due to their extremely high energy density, they willoffer unprecedented vehicle ranges, of up to 250 km [6].However, a powerful publicised national and European sup-port is necessary, as well as an effective marketing approach.

The long-range or multi-mission electrically driven vehiclewill become a reality through the development of hybriddrive trains. Hybrid vehicles combine electric and other drivesystems, such as internal combustion engines, gas turbines,and fuel cells. The main advantage of this combination is thepermanent interaction between the highly efficient electric sys-tem and the thermal engine or fuel cell. Here, power batteries orother power boosters, such as super capacitors, play a key role.A number of reliable vehicles are coming on the market todaywith a large spectrum of hybridization ratios (from start andstop systems to a full hybrid power train).

Due to the inbuilt dual function, hybrid vehicles have alonger range than battery powered electric vehicles. They canoffer the option of running on electricity alone in urban envi-ronments, generating zero emissions at this time. Some ofthese vehicles can be plugged-in, effectively using conven-tional or renewable sources of energy.

Hybrid technology is now particularly favoured for heavy-duty vehicles, such as city-buses, and leads to a 20 to 30%reduction in both energy consumption and associated emis-sions.

2 Facts Related to the Mobility of People andGoods

2.1 Employment – Economy

The European transport industry is an important economysector, as stated by the following data (for the 15 EU memberstates): 14 million workers or employees (i.e., 10% of theactive population) with less than 6 million in transport ser-vices, 2 million in the equipment sector, and 6 million intransport connected activities. Fourteen percent (14%) offamilies’ revenue is devoted to transport. The modal distribu-tion of people mobility, expressed in passenger kilometres(p.km), is as follows: 79% by car, 8% by bus, 7% by air, 6% byrail, and less than 1% by tram or underground. The modaldistribution of goods transport, formulated in ton kilometres(t.km), shows a different picture: 43% by road, 41% by sea,9% by rail, 4% by inland waterways, and 3% by pipelines[7, 8].

2.2 Growth

European passenger transport is forecast to grow by 19%up to 2010, resulting from 16% for road transport and 90% forair transport. The growth in goods transport is 38%, resulting

from 50% for road transport and 34% for maritime transport.This growth means an increase, for cars, of 15% between 2000and 2010, and of 21% up to 2020 [7, 8].

The growth of the number of cars worldwide is more wor-rying. At the 2030 horizon, the number of road vehicles in theOECD countries (800 million vehicles) will be the same as inthe rest of the world, which means a doubling of today’sworldwide vehicle number. In addition, this corresponds to a65% growth in the OECD countries, resulting from a 2%annual growth [9, 10].

2.3 Energy

The energy efficiency of the different means of transporta-tion varies strongly as a result of the thermodynamic laws,type of technology, and power level.

The fact that the energy efficiency of a car in the city fallsbelow 15% doesn’t appear to worry anybody (but 80% of carsare driven in the cities!) notwithstanding the fact that thismeans that from a 50 litter fuel tank only 7.5 litres are usefuland the remaining 42.5 litres are transformed into heat andpollutants. Amongst today’s fuels, diesel is the most efficient,followed by gasoline and the gaseous fuels (natural gas andLPG).

Caution is required during the evaluation of the energy con-sumption of any means of transport. Indeed an empty vehicle iswasteful and there is a clear necessity to evaluate its efficiencywith regard to its function, i.e., moving people or goods.

Taking the following filling rate as a reference: 35% forcars (1.4 persons per vehicle), 40 to 70% for trains, 60% forintercity buses and national flights, the comparative resultslisted hereunder are obtained [11]:(i) For passenger transport:● the train uses 15 to 50% less primary energy than the car;● the intercity bus, lighter than the train, reaches about 70%

of the energy consumption of the latter and 42% of theconsumption of the car;

● the airplane is at 60% of the car but at 300% of the fasttrain (not valid for high speed trains); but for airplanestime plays an important economic role;

● in the city, the underground easily consumes 50% lessthan the car;

(ii) For goods transportation mass and volume have to beconsidered [11]:

● the boat used for inland transport can reach 200% of theconsumption of rail because of its diesel motorisation;

● rail transport reaches 40–50% of road transport consump-tion.

Whichever transportation case is considered, it is neces-sary to take the energy consumption of all transportationmeans used between origin and destination into account. Theduration of a trip has a non negligible importance for the eco-nomic evaluation.

The data given above are only indicative as they result from anumber of typical trips. They demonstrate the necessity to ana-lyse the trips per category, as well as the necessity to compare

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166 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim FUEL CELLS 07, 2007, No. 2, 165–173www.fuelcells.wiley-vch.de


the potential energy benefit of the different means of transporta-tion. The benefit of rail (tram, underground) is the result of thecombination of two important factors: the transport capacityand the use of electric energy, thanks to the efficiency of the elec-tric drive system (power electronics and electric motor).

Long distance transportation (more than 2,000 km) is con-sidered in a different way, since the choice of the transporta-tion means is a function of the object that has to be trans-ported. 90% of the export trade of the EU (referring to thevolume of goods) is performed by maritime transport, whichalso covers 41% of EU internal goods transportation.

The use of energy by today’s transport systems clearlydemonstrates low efficiency use.

2.4 Evolution of the EU Energy Supply

The energy dependence of the EU has evolved from 60%in 1973 down to 50% in 1999. This could reach 70% within 20to 30 years, corresponding to 90% for oil, 70% for natural gas,and 100% for coal. Again, this will be in increasing trend inthe extended EU [2].

Recently, oil companies revised their oil reserve, forecast-ing an end to cheap oil (or oil as an energy source?) towards2030–2040. This is confirmed by other independently pub-lished data. Referring to the IEA, Figure 1, the maximum oilproduction could be reached within 10 to 15 year, naturallyfollowed by a production decrease and demand exceedingthe available supply [12].

Consequently, a price increase is to be expected togetherwith geopolitical tensions. Even the exploitation of less acces-sible and/or lower quality reserves will not alleviate this situ-ation. The conditions prevailing for natural gas are the samebut with a somewhat longer delay (10–20 years).

2.5 Emissions

The environmental state of the earth is determined by thesuperposition of all local emissions, some are controllable(transport, electricity production, industry, etc.), whilst otherscannot be controlled (volcanoes, radiance of sun, etc.). Limit-ing the contribution of transport to pollution can only be per-formed through local and regional actions, whose success isstrongly dependent on the awareness of the people con-cerned.

The gradual introduction of the mandatory Europeanemission standards, EURO I, EURO II, EURO III, EURO IV,and EURO V will lead to the control of the CO, NOx, hydro-carbon, and particulate emissions. They will be reduced inthe EU and in the other OECD countries, despite the increasein the automotive fleet and distance covered. A significantincrease, of between 45% and 55%, is expected for the differ-ent pollutants in the rest of the world [12].

The emissions of the electricity-producing sector areclearly more and more under control, which is a very positivesituation for most of the public transport systems (trains,trams, underground, trolleybuses, and electric mini- and midibuses).

The case of CO2 emissions is totally separate, due to itsproportional connection with the performed p.km for peoplemobility and t.km for goods transport. The efficiency of theinternal combustion engine (ICE) can still increase somewhatover the next ten years (but with costly investment), but thethermodynamic limits are being reached and consequentlyasymptotic values are being approached. In any case, it isworth noting that the mean yearly emissions of a car is 4 to5 tons of CO2, corresponding to four to five time the mass ofa 1,000 kg vehicle.

Fig. 1 Oil demand and supply.

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FUEL CELLS 07, 2007, No. 2, 165–173 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 167www.fuelcells.wiley-vch.de


The automotive industry (ACEA) has committed itself toreducing CO2 emissions from 190 g km–1 in 1995 to120 g km–1 in 2012, in order to counterbalance the increase ofthe p.km [13].

An IFEU study for Belgium (that could also be valid as amean situation for the rest of the EU) forecasts an increase inCO2 emissions of 6 to 10% between 2000 and 2020. This corre-sponds to an annual increase of 0.3% to 0.55% and resultsfrom the combination of better vehicle performance and anincrease of the total number of kilometres driven [14].

The yearly increase in C02 emissions was 1.7%, between1990 and 2000, and is expected to be 0.86% between 2000 and2020. Alternatively, a total increase of 40% is predicted by anOECD analysis [10].

In the EU, 28% of emissions are transport related, while itis forecast that 90% of the total emissions increase will havethe same origin. Worldwide, the forecast increase is evenmore dramatic: not less than 110 to 120% [11].

3 Technical Evolution of Transport Means

Two important factors that will influence the technologyof future transport means are:(i) access to energy(ii) state of the environment

Two type of motorisation will drive the future for landand maritime transport:(i) thermal drives;(ii) electrical drives, associated with thermal drives, bat-

teries, fuel cells or with a combination of the latter.This partitioning of tasks is fundamental to the family of

hybrid solutions but is only feasible thanks to the support ofpower electronics, even in pure thermal solutions.

3.1 A Short Analysis of Propulsion Technology

3.1.1 Systems with ICE Motorisation

The energy chain is composed of a fuel tank (gasoline, die-sel or gas), an ICE (electronically controlled), a transmission(also electronically controlled), a differential, and the wheels.A coupling-decoupling system is needed to allow for stops,or sufficient torque while starting or changing gear.

3.1.2 Electric Systems

The energy chain is composed of a battery, a power elec-tronic converter, an electric motor (or wheel motors), a differ-ential, and the wheels. In this case, a fuel cell system thatcould replace the battery is a possible alternative solution forthe future. No coupling-decoupling system is needed andmaximum torque is developed at start-up.

Energy recovery, while braking, is a major feature of thissystem, if an energy storage system (battery or supercapaci-tor) is available. Furthermore, the presence of a battery neces-sitates the use of an on-board or off-board battery charger,also based on power electronics.

3.1.3 Hybrid Systems

The association of ICE’s and electric motors leads tohybrid systems, which fall under four basic structures:

The series hybrid only has an electric propulsion system(power electronic converter, electric motor(s), differential,wheels) electrically fed by one, two or three sources, con-nected in parallel (Figure 2 and Figure 3).

In the thermal series hybrid, one of the sources is com-posed of a fuel tank (diesel, gasoline, and gas), an ICE or gasturbine driving an alternator, and a power electronic convert-er (rectifier-charger). A battery and/or power unit (flywheelsystem or super capacitor) are connected in parallel to thissource and deliver power as required and can also recoverthe braking energy. If these units are not present then thestructure is the commonly named “diesel-electric”.

In the case where a fuel cell is used instead of an ICE or gasturbine system, the following are present: the fuel cell system(hydrogen tank or reformer), connected in parallel to a bat-tery and/or power unit (flywheel system or super capacitor).This power unit delivers power at due times and can alsorecover the braking energy. Energy recovery while braking isa major feature of these systems only when a battery, supercapacitor or flywheel, or a combination of these elements isimplemented.

The parallel hybrid system combines electric traction andICE traction (see Figure 4). The “fuel tank-ICE” system com-bines its mechanical output energy with the mechanicalenergy provided by the battery-power electronic converter-electric motor system. Both are mechanically coupled at thelevel of the transmission to drive the wheels. No fuel cellalternative solution has been considered for this structure forobvious technical reasons. The “start-stop” and the “mildhybrid” systems are possible exceptions. Energy recoverywhile braking is also a major feature of these systems.

Fig. 2 Series hybrid drive train.

Fig. 3 Series hybrid with peak power unit.

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Combining the series hybrid structure with the parallelstructure leads to the so-called “combined” or “series-parallel”structure (see Figure 5). The parallel energy pathway is com-posed of a tank, an ICE, a transmission, a power electronicconverter, and an electric motor. The series energy pathwayis composed of a tank, an ICE, a transmission, an electric gen-erator, a power electronic charger, a battery, a power elec-tronic converter, and an electric motor. Naturally, the differ-ential is common to both pathways.

There is evidently a continuum of possible solutions, thevalue of which have to be assessed from an energy efficiency,environmental, and economic point of view, as well as fromthe technological feasibility and user’s perspective. Simula-tion software has been developed at the “Vrije UniversiteitBrussel” for the evaluation of these drive trains, in the frame-work of a PhD thesis, which can be consulted at the followingweb address: http://etec.vub.ac.be/VSP/.

3.2 Evolution and Main Technological Characteristics

Numerous electrical subsystems are introduced into carsand other road vehicles for the comfort of the user. In this sit-uation, electricity is the energy driver and many elegant solu-tions are achieved. The features related to safety (for instanceABS), as well as the drive by wire solutions introduced inhigh class cars, are worth mentioning.

3.2.1 Internal Combustion Engines (ICE’s)

Considerable research is still performed to improve theirintrinsic thermodynamic features (though asymptotic regionsare now being reached) and their electronic control. A break-through is expected from SiC technology in relation to thenecessity to position the electronic components in high tem-perature areas.

EUCAR is still forecasting a dominant position for thistype of motorisation in the next 15 years, with a share of 30 to40% for diesel and 50 to 65% for gasoline vehicles. Hybridsand other alternative solutions could reach a share of 15%after 2010, increasing up to 25% after 2020 [4]. However,everybody understands that these shares will be stronglyinfluenced by access to oil, which in fact comes from fossilsources and is a powerful carrier of hydrogen atoms. The pos-sibility to decouple energy use from “geo-carbons” is underserious consideration, relating to the introduction of bio fuels,carbon atoms from biomass, and organic waste materials,which all lead to even more powerful carriers of hydrogenatoms.

3.2.2 Battery Electric-, Hybrid Electric-, Fuel Cell DriveSystems

Soft hybrid solutions, integrating the electric starter-generator and allowing the recuperation of braking energy,seem to be an important step towards future hybridisation.

The association of the electric motor and thermal engine ina parallel structure allows the use of the engine at its best effi-ciency, avoiding for instance, the bad impact of a transitoryworking period. However, success in only warranted if theelectric motor and its associated power electronics are de-signed properly. The introduction of alternative vehiclesbecomes possible without a dramatic multiplication of theground-fuelling infrastructure.

A discussion is arising, in the road transport sector, con-cerning hybrid technology and the use of only one source offuelling for all types of energy. In other words, how shouldthe on-board electricity used be generated? Obviously, thiscan only be achieved from loaded fuel or through a connec-tion with the mains. Evidently, the answer to this question iscomplex.

The electric vehicle is able to produce the highest energyeconomy, 40 to 50%, compared to an equivalent thermal vehi-cle. Nevertheless, this is only true if good system integrationhas been realised and this integration has to consider differ-ent working situations. Indeed, in city use, the electric vehicleoften works at low load and undergoes frequent braking. Thereal working pattern of the vehicle has to be taken intoconsideration when optimizing system efficiency, whichinfluences motor and power electronic design.

The same approach is valid for the design of the batterycharger for which two charging situations can occur: normalcharging conditions and end of charge. The time-sharebetween these two working conditions surely has an impor-tant impact on the resulting efficiency and the charger elec-tronics will have to be designed accordingly. No good electricvehicle could be developed without considering these work-ing conditions. Many examples of poor design have been puton the road in the past.

Thermal hybrid electric vehicles may lead to 30 to 40% energyeconomy, compared to an equivalent thermal vehicle. However,this is dependent on the grade of hybridisation, the same inte-

Fig. 4 Parallel drive train with torque addition.

Fig. 5 Combined hybrid drive train.

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gration considerations as for the electric vehicle, and the mostefficient use of electric energy delivered by the mains.

Diesel-electric motorisation, when used for urban buses,offers very good flexibility for the drive system, mainly instarting and acceleration conditions. However, the multiplica-tion of the efficiency of the different components of the drivetrain leads to a supplementary energy consumption of 10 to20%, compared to an equivalent thermal vehicle. In this case,this loss of energy is very difficult to compensate for, evenwith good drive train integration.

Finally, it is observed that the intelligent use of a chargingperiod from the mains cannot lead to substantial energyeconomy and CO2 emission reduction without creating thenecessity of implementing a large and costly new infrastruc-ture. This statement is not yet well understood (or isobviously rejected for profit considerations) by car manu-facturers or energy stakeholders.

Fuel cell electric vehicles are considered carefully from theviewpoint of energy economy because of the use of hydrogen.Hydrogen is a clean energy vector in the same way electricityis, but it has to be produced, as electricity has to be produced,from different primary energy sources. This is the realchallenge.

Another challenge is the clear duality existing in manycases between hydrogen and electricity. The PEMFC (ProtonExchange Membrane Fuel Cell) is clearly the best choice forroad transport. Comparing two equivalent vehicles, thermaland fuel cell, today’s optimal efficiencies can be listed for thedrive train efficiency evaluated for the same driving cycle [5]:● 42% for a fuel cell using compressed hydrogen,● 32% for a fuel cell fed by hydrogen produced by an on-

board methanol reformer,● 25% for an equivalent diesel driven vehicle,● 20% for an equivalent gasoline driven

vehicle.Important energy economy can effec-

tively be realised in the tank to wheel(T-t-W) pathway but the production effi-ciency of hydrogen or methanol, whichhas not been considered sufficiently.Well to wheel (W-t-W) analyses are ofutmost importance here [15].

Many pathways are being consideredto produce hydrogen [11]:● Water electrolysis starting from elec-

tricity produced from hydraulic (Nor-way, Canada), nuclear (France), solaror wind energy. A 50 to 80% effi-ciency is obtainable by an industrialelectrolysis production unit.

● For the case of a 32% efficient nuclearpower plant delivering electricity to a90% efficient distribution system, a95% efficient power electronic energycontroller, and a 50% efficient electro-lysis unit, the end efficiency for the

production of hydrogen is 13.7 to 21.9% of the primarynuclear energy.

● Hydrogen could be an innate result of electricity produc-tion in the case where a fusion power plant could be im-plemented.

● Solar energy accumulates 15% from the solar panels,hopefully 95% for the associated power electronics, and50 to 80% for electrolysis and resulting in 7.1 to 11.4% ofthe free available solar energy.

It is clear that the global energy efficiency of the abovelisted hydrogen pathways, as well as the associated CO2

emissions remains an open question. Complementary to theefficiencies already given, the following data values can alsobe considered separately or grouped [11]:● production of electrical energy in power plants: 35 to 60%,● industrial electrolysis: 50 to 80%,● hydrogen compression on-board the vehicle: about 75%,● off-board methane reforming: about 75% for the reform-

ing process and 75% for compression and distribution,● methanol reforming on-board the vehicle: 75%,● hydrogen compression and distribution after methanol re-

forming: 65 to 80%.An analysis of all these efficiencies is summarised in

Figure 6.In 2003 the EU hydrogen high level expert group produced

a report forecasting the different stages for the implementa-tion of the hydrogen energy vector [16]:● up to 2020: technological research and demonstration

fleets and infrastructure,● in the period 2020 – 2030: implementation of a large

demonstration fleet and infrastructure, together with thestart of real economical use,

● after 2030: market development.

Fig. 6 Well-to-wheel efficiencies: hydrogen vs. electricity.

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Evidently, this roadmap is matched to the duration ofaccess to cheap oil and indicates the steps necessary to reacha situation for a viable and sustainable hydrogen economy.It is a long-term viewpoint. However, it neglects the shortand medium-term situation, with the increasing geopoliticaltension around oil. Moreover, it neglects possible competitionbetween different energy vectors: hydrogen, electricity, biofuels, synthetic fuels, etc., and the corresponding transporta-tion technology.

There is an absolute necessity to consider today’s techno-logies and their evolution in the short-, medium-, and long-term,together with the emergence of long-term hydrogen technology.This is the best way to define continuity for our national indus-tries. As an example, let us consider the “Road Map for Environ-mentally Friendly Vehicles with Electric Propulsion Systems”,given in Figure 7 [17]. All systems are taken into consideration.The ICE serves as a reference.

Battery and hybrid electric vehicles offer clear short- and me-dium-term solutions, with a large number of common compo-nents. These common components must be defined and are ofthe utmost importance for our industry. An exhaustive list willbe the result of studies and of national and EU research pro-grammes. The following can already be pointed out:● batteries,● super capacitors,● power electronic converters,● electric motors,● voltage levels, 36/42V, high voltage(s) for drive systems,● components for auxiliaries,● etc.

Finally yet importantly, it is evident that a large number ofthese components will be common with the “hydrogen” solu-tions because of the absolute necessity to develop compo-nents for the largest possible market.

4 Conclusions

4.1 Battery and Hybrid Vehicles are Today’s SustainableMobility Solutions, Preparing a Future Shared with a HydrogenEconomy

The summary report of the High Level Group for Hydro-gen and Fuel Cells presented in June 2003 developed a visionon the contribution that hydrogen and fuel cells could maketo the realization of sustainable energy systems in the future.

However, it seems necessary to emphasize that, as it is along-term vision, there is a need to take strong action in theshort- and medium-term, in order to address current environ-mental and energy concern.

4.2 Energy and Environmental Challenges for Transportation

As stated in the Commission’s November 2000 GreenPaper on security of supply, in 1998 energy consumption inthe transport sector was responsible for 28% of CO2emissions,the main greenhouse gas. According to the latest estimates,CO2 emissions from transport can be expected to increase byaround 50% to reach 1113 billion tons by 2010, compared withthe 739 million tons recorded in 1990, 84% of which were at-tributed to road transport [18].

Fig. 7 Road map for environmentally friendly vehicles with electric propulsion systems.

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It is both an ecological necessity and a technological chal-lenge to reduce the dependence on oil from the current levelof 98%, by using alternative fuels and improving the energyefficiency of transport. It is planned that the hydrogen econ-omy will begin around 2020, at the earliest, and will be estab-lished by around 2050. Fortunately, much of the commonelectric drives technology preparing for a future shared witha hydrogen economy are already in development today.

Two transport technologies are currently ready to play asignificant role in this context: the battery electric vehicle andthe thermal hybrid electric vehicle. They are the missing linkto a possible hydrogen transportation economy.

The technology developed for the battery electric vehicleis, without any doubt, a basic technology for mainly fuel cellvehicles.

4.3 Battery Electric Vehicles, an Available Sustainable Solutionfor Urban Mobility

It is an established fact that from a well-to-wheel emissionpoint of view, research is in favour of the battery electric vehi-cle. Important and recent studies on the environmental bal-ance of battery electric vehicles showed substantial emissionand primary energy benefits and thus CO2 reduction, whencompared to conventional cars [19].

The electric vehicle is an optimum solution for urban mo-bility, as it emits no exhaust fumes.

In cities and in adverse climatic conditions, in particular,traffic-generated emissions degrade air quality, up to thepoint where the physical health of the population is directlythreatened. Several cities have already had to apply repeat-edly drastic traffic restrictions.

The electric vehicle is also ideally suited for integrationinto new traffic management concepts, such as automaticrent-a-car systems and goods distribution centres, or smallbuses for city-centre services. These measures emphasize thesynergies between different transport methods and contri-bute to the relief of traffic congestion. Again, the electric vehi-cle, through its respect for the environment, allows access tohistoric city centres and contributes to the reduction of airand noise pollution.

An increasing number of cities and environmentally con-cerned companies have introduced electric vehicles into theirfleets for all of the above reasons, often with the support ofthe EU Commission and some member states.

4.4 Batteries, the Challenge

Energy storage remains a key point. The development ofalternative battery systems shows the possibility of making areal technical and economic breakthrough in the short- or me-dium-term, consistent with important market development.New battery types, such as high-temperature batteries,nickel-metal hydride batteries, and lithium-based batteriesare already on the market or will be available in the comingyears. Due to their extremely high energy density, they offer

unprecedented vehicle ranges, even up to 250 km. However,a powerful public national and European support is neces-sary, as well as an effective marketing approach.

4.5 Thermal Hybrid Electric Vehicles Combining Long-Rangeand Energy Efficiency

The long-range or multi-mission electrically driven vehiclewill become a reality through the development of hybriddrive trains. Hybrid vehicles combine electric and other drivesystems, such as internal combustion engines, gas turbines orfuel cells.

The main advantage of this combination is the permanentinteraction between the highly efficient electric system andthe thermal engine. This leads to efficient energy manage-ment, as well as the recovery of the kinetic energy while brak-ing. Here too, the batteries or other power boosters, such assuper capacitors or flywheels, play a key role. A number ofreliable vehicles are coming on the market today with a largespectrum of hybridisation ratios (from start and stop systemsto a full hybrid power train).

Due to the inbuilt dual function, hybrid vehicles have alonger range than battery electric vehicles. They can offer theoption of running on electricity alone in urban environmentsand so are locally zero emission. Some of these vehicles canbe plugged-in using conventional or renewable sources ofenergy in an effective way.

The hybrid technology is now particularly favoured forheavy-duty vehicles such as city-buses and leads to a 20 to30% reduction in both energy consumption and associatedemissions.

For private cars, the deployment of hybrid drive trains is alogical way to reduce fuel consumption and CO2 emissions.

Battery and hybrid electric vehicles are able to ensure asustainable mobility solution, preparing a future shared withthe hydrogen economy.

At the present phase of their development, electric andhybrid vehicles still need support from public authorities, so thatthe market can reach a size allowing its natural development.

4.6 Components Development

R&D development efforts are also needed for higherefficiency and lower cost electric drive systems (batteries, powerelectronics, etc.). These components will also be needed for fuelcell vehicles in the long-term, though there will also be the needfor specific components (compressors, pumps, connectors, pres-sure valves, membranes, tanks, reformers, etc.).

List of Symbols

ABS Antilock brake systemACEA Association of European Automobile Manufac-

turersAVERE European Association for Battery, Hybrid and Fuel

Cell Electric Vehicles

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CO Carbon monoxideCO2 Carbon dioxideEU European UnionEUCAR The European Council for Automotive R&DEV Electric VehicleHEV Hybrid Electric VehicleICE Internal Combustion EngineIFEU Institut für Energie- und Umweltforschung Heidel-

berg GmbHKm KilometresLPG Liquefied Petrol GasNOx Nitrogen OxidesOECD Organisation for Economic Co-operation and

DevelopmentPEMFC Proton Exchange Membrane Fuel Cellp.km Passenger kilometresSiC Silicon Carbidet.km Ton kilometresT-t-W Tank to wheelV VoltW-t-W Well to Wheel

References

[1] Hydrogen Energy and Fuel Cells A Vision For Our Future,Summary Report, High Level Group For Hydrogen AndFuel Cells, European Commission, 2003, p. 35.

[2] Green Paper – Towards a European strategy for the securityof energy supply COM(2000), European Commission,2000, 769.

[3] G. Maggetto, J. Van Mierlo, Ann. Chim. Sci. Mat. 2001,26 (4), 9.

[4] R. Edwards, J.-C. Griesemann, J.-F. Larivé, V. Mahieu,Well-To-Wheels Analysis Of Future Automotive Fuels AndPowertrains In The European Context, EUCAR, CON-CAWE and JRC, 2004, 60.

[5] N. Brinkman, M. Wang, T. Weber, T. Darlington, Well-to-Wheels Analysis of Advanced Fuel/Vehicle Systems –A North American Study of Energy Use, Greenhouse GasEmissions, and Criteria Pollutant Emissions, ArgonneNational Laboratory and General Motors, 2005, p. 176.

[6] P. Van den Bossche, F. Vergels, J. Van Mierlo, J. Math-eys, W. van Autenboer, Journal of Power Sources 2006,162, 913.

[7] European union in figures: energy & transport; pocket book,European Commission, 2004, p. 197.

[8] White Paper: European transport policy for 2010: time to de-cide, European Commission, 2001, p. 370.

[9] Environmentally Sustainable Transport EST Synthesis Re-port of the OECD projects, OECD, 2000, p. 50.

[10] Motor Vehicle Pollution: Reduction Strategies Beyond 2010Paris, OECD, France, 2000.

[11] Hydrogen as an energy carrier, report of the Royal BelgianAcademy Council of Applied Science, BACAS, 2006, 40.

[12] J. Pershing in Proceedings of an IPCC Expert Meeting,(Eds. L. Bernstein and J. Pan), IPCC, WGIII, RIVM,International Energy Agency, 2000.

[13] P. Kågeson, The drive for less fuel. Will the motor industrybe able to honor its commitment to the European Union,T&E (European Federation for Transport and Environ-ment), Stockholm, Schweden, 2000, p. 44.

[14] J. Borken et al, Energy consumption and pollutant emissionsfrom Road Transport in Belgium 1980 to 2020 – IFEU/FEBIAC Report, 2000, p. 10.

[15] R. Choudhury, R. Wurster, Well-to-Wheel Analysis ofEnergy Use and Greenhouse Gas Emissions of AdvancedFuel/Vehicle Systems – A European Study GM, LBST, bp,ExxonMobil, Shell, TotalFinaElf, 2002, p. 135.

[16] Hydrogen Energy and Fuel Cells A vision of our futureDirectorate-General for Research, Directorate-General forEnergy and Transport EUR 20719 EN, European Commis-sion, 2003, p. 35.

[17] European Association of Batter-, Hybrid and Fuel Cell Elec-tric Vehicles, AVERE Position Paper, 2003, p. 3.

[18] Green Paper – Towards a European strategy for the securityof energy supply, European Commission, 2000, p. 769.

[19] J. Van Mierlo, G. Maggetto, P. Van den Bossche, S. Meyer,W. Hecq, J. M. Timmermans, L. Govaerts, J. Verlaak,Transportation Research Part D: Transport and Environment2004, 9 (5), 387.

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