1. Topic

2. Introduction

Hydrogen is sometimes called the “”fuel of the future” and hydrogen certainly has a number of inherent attractive features when considered as a fuel for road vehicles.

Hydrogen is by far the most abundant element (90% on number of atoms basis) in the universe and in the Earth’s crust it is one of the most abundant elements. On Earth, hydrogen is almost exclusively found in chemical compounds, whereas free molecular hydrogen is virtually not seen in nature. A consequence of the latter is that hydrogen is not a source of energy, but rather a convenient tool for handling energy. In many respects an illustrating parallel may be drawn to electricity, which is also not a source of energy, but instead an appropriate intermediate in energy transport and conversion.

Hydrogen is known in the liquid and in the gaseous states. The solid state, metallic hydrogen, is only possible at extreme conditions, as it is believed to exist in the interior of stars and larger planets. The most frequently found state for elemental hydrogen is the gaseous state because this is the stable one at normal temperatures and pressures. The critical temperature and pressure of hydrogen is about 33 K and 13 bar.

Binary, chemical compounds of hydrogen are known for many elements. In particular hydrogen reacts vividly with oxygen to form water. The reaction is strongly exothermic and results in a release of approx. 240 or 286 kJ/mole, the difference being the heat of evaporation for water. The standard Gibbs function of formation for (liquid) water is about 237 kJ/mole.

3. Discussion

The production of industrial hydrogen is currently based mainly on fossil fuels, but to some extent also electricity is used. If considered as an alternative fuel, hydrogen should not be produced from fossils, since that would not lead to decreased emission of greenhouse gas. However, as mentioned, hydrogen can be (and in fact it is) produced from electricity by electrochemical splitting of water. The energy efficiency of the electrolysis process is relatively high, just around 90 %, and therefore this production method seems viable, although capital costs for sufficient electrolysation capacity may constitute a serious drawback of the technology.

If considered as fuel, hydrogen is a very versatile one. A special reason for the technological interest in hydrogen is that hydrogen goes very well with fuel cells. Most fuel cells are basically powered by hydrogen, even though the primary fuel is not always pure hydrogen. Using hydrogen in a fuel cell leads to an optimised energy efficiency (for the conversion of chemical to mechanical energy) compared with use of hydrogen in an internal combustion engine. Conversion efficiencies approaching 70 % may be available (depending strongly, though, on operation mode and conditions) and this is at least 2 times better than the conversion efficiency observed for internal combustion engines. However, hydrogen may also well be used as fuel in internal combustion engines. Such engines have been demonstrated for instance by many car manufacturers and represent quite well known technology.

Use of hydrogen as fuel in the transport sector would require significant changes in infrastructure. Distribution of hydrogen and local fuelling of cars could not be done the same way gasoline is handled today. Therefore the infrastructural problems must be given careful consideration, both concerning economy and safety, in relation to a possible utilisation of hydrogen as an energy carrier.

Fuel Cell Electric Vehicles & Fuel Cell Hybrid Electric Vehicles (FCEV & FCHEV)

Fuel Cells are addressed as "zero emission" technology. This is, however, just one of the reasons why fuel cells are attractive. The second one is that Fuel cell systems produce electrical energy at high efficiency. Whether or not the efficiency is higher than that of internal combustion engines such as piston engines and gas turbines depends on factors like:

· Primary fuel source

· Type of operation (variable load versus constant load)

· Power level

At present, the energy source for transportation is oil. Fuel cells prefer hydrogen, which can be made of virtually any fossil fuel source, from biomass, and from electricity derived from e.g. wind and solar energy. These will very like be the energy sources of the future. Thus, fuel cells help to reduce the dependence of oil, and enable the transition to a sustainable energy system.

Fuel cells are modular and can be shaped in various designs. This allows designers to develop new products or to completely redesign existing products. Several types of fuel cells exist. They are generally (but not always) given names that refer to the electrolyte:

· AFC: Alkaline Fuel Cell

· PAFC: Phosphoric Acid Fuel Cell

· MCFC: Molten Carbonate Fuel Cell, with a special version being the internal reforming MCFC (IRMFCF) that will also accept natural gas for fuel.

· SOFC: Solid Oxide Fuel Cell

· PEMFC: Proton Exchange Membrane Fuel Cell (or Polymer Electrolyte Fuel Cell)

· DMFC: Direct Methanol Fuel Cell (here is exception to the name giving rule)

4. Recommendation / Conclusion

· stationary PAFC system, the progress in fuel cell development is most visible in the area of vehicles. The driving force here on the one hand is the Californian legislation with respect to zero emission vehicles. The fact that the Californian legislation is an important factor is clearly demonstrated by listing the companies that have shown to make significant progress: GM, DC, Ford, Toyota, Mazda, Nissan and Honda. These companies have significant market shares in California. The companies with low sales in the US, typically the EU-companies, have much less significant fuel cell development activities.

· Several experimental vehicles, including buses, have been built in the past ten years. To a large extent, the PEMFC is the technology used here. Currently, small fleets of “prototype” buses (Ballard, Daimler Chrysler Citaro, IVECO Altrobus, Man, Scania, Toyota) and cars have been built. These vehicles will mostly use hydrogen as a fuel. Commercialisation is foreseen to start in 2010. For buses, this may be somewhat earlier.

5. Examples / Further Reading

H2 and Fuel Cells vehicles in Amsterdam

The aim of the project is to demonstrate the feasibility of an innovative, high energy efficient, clean urban public transport system. This demonstration will encompass the operation of 27 purpose designed fuel cell powered, low-noise buses in 9 European cities. Therefore regional appropriate hydrogen (H2) production and refuelling infrastructures will be established. This public transport system will contribute to the reduction of overall CO2 emissions. In addition the elimination of local NOx, SO2 and particulate emissions will improve health and living conditions in urban areas. The outcome of the project will also be an improved public acceptance of the H2 fuel cell transport system, a more secure energy supply for the EU and the realistic application of renewable energy sources. It will strengthen the competitiveness of EU industry, create new jobs and greatly contribute to the Kyoto commitments of the Member States.

Specific template examples:

• Hythane – blending hydrogen with CNG for city buses in Malmö
• H2 and Fuel Cell vehicles in Stockholm and Reykjavik

6. Additional Documents / Web Links

The following projects, completed or “on going” in the framework of the 5th FP, deal with Fuel Cell related Projects:

The following projects, completed or “on going” in the framework of the 5th FP, deal with Fuel Cell related Projects:

· PROFUEL, On-board gasoline processor for fuel cell vehicle application

· BIO-H2, Production of clean hydrogen for fuel cells by reformation of bioethanol

· FUERO, Fuel cell systems and components general research for vehicle applications

· CPS2FCS, Critical Paths to Fuel Cells

· IM-SOFC-GT, Integrated modelling study of fuel cell/gas turbine hybrids

· AMFC, Advanced Methanol fuel cells for vehicle propulsion

· DREAMCAR, Direct methanol fuel cell system for car applications

· PMFP, Plasma & membrane supported catalytic gasoline fuel processor using hydrogen selectic membranes

· ECTOS, Ecological City Transport System: Demonstration, Evaluation and Research Project of Hydrogen fuel cell bus transportation system of the future

· Development of enhanced electrocatalysts for mobile fuel cell systems

· CUTE, Clean Urban Transport for Europe

· ELEDRIVE , Thematic network on fuel cells and their applications for electric & hybrid vehicles

· FRESCO, European Development Of A Fuel-Cell, Reduced-Emission Scooter

· APOLLON, Advanced Pem Fuel Cells

· FEBUSS, Fuel Cell Energy Systems Standardised for Large Transport, BUSses and Stationary Applications

· ACCEPT, Ammonia Craking for Clean Electric Power Technology

· MINIREF, Miniaturised Gasoline Fuel Processor for Fuel Cell Vehicle Applications

· SOFCNET, Thematic network on solid oxide fuel cell technology

· BIOFEAT, Biodiesel fuel processor for a fuel cell auxiliary power unit for a vehicle

· DIRECT, Diesel reforming by catalytic technologies

· FUEVA, European fuel cell vehicles technologies validation phase II

· FCSHIP, Fuel cell technology in ships

· POWERSIM, Powertrain and vehicle simulation

Last Updated

25th January 2005