Research is thriving on every front of fuel cell technology. This diversification is opening the door to many possible applications for non-polluting energy, ranging from vehicles to power stations, and including portable applications.
Discovered in 1839, the principle of the fuel cell is extremely simple. Two electrodes connected externally by an electric circuit and separated by an electrolyte are supplied, in the presence of a catalyst, in one case with hydrogen – which acts as a fuel – and in the other with atmospheric oxygen. The hydrogen atom at the anode breaks down to form a proton or H+ ion, with a positive charge, and an electron. The ion migrates through the electrolyte to the cathode where it combines with the oxygen to form water (also emitting heat), while the electron runs through the electrical circuit, producing a current. However, its applications vary a great deal depending on the type of hydrogen fed to the anode (they can be chemical elements containing hydrogen) and the nature of the electrolytes.
The fuel cell is ‘a very old innovation’. The very simple basic principle behind it was discovered and demonstrated, in 1839, by the British physicist William Grove (see diagram). For more than a century, however, the priority given to the development of thermal machines and electrical batteries overshadowed this invention. The fuel cell concept received little attention outside certain laboratory developments which were not taken any further.
Helping hand from Space Space research was the first to bestow favour on a contemporary use for fuel cells. In the 1960s, NASA chose to turn to this kind of generator to power the rockets of the Gemini and Apollo programmes. Development of the very specific fuel cells used in space has continued since then.
Beginning in the 1970s and 80s, this space application led to a growing interest in fuel cells, especially in the United States and Japan, primarily in the automotive sector and for various so-called ‘stationary’ applications. Such research paved the way for a wide diversification of the technological options. In addition to the traditional early fuel cells which required pure hydrogen (obtained by electrolysis), fuel cells were developed which used hydrogen produced by reforming hydrocarbons (petrol, natural gas, ethanol), as well as methanol obtained from biomass and carbon dioxide. This broadening of possible fuels undeniably made the process less ‘clean’ as it reintroduced carbon emissions into the equation, albeit on an altogether different scale to the pollution caused by the internal combustion engine. On the other hand, this recombining process rendered fuel cells a much more interesting prospect by enabling hydrogen production processes which were widely available and industrially perfected.
A large family There has also been diversification as regards the types of electrolyte through which the H+ or O- ions pass, depending on the type of fuel cell. There are potassium alkaline cells (mainly developed in the space sector), phosphoric acid cells (the most ‘mature’ technology at present, but limited in its applications), and polymer membrane, molten carbonate and solid oxide cells. Each category has specific properties in terms of fuel supply, operating temperatures and the resulting applications.
The most promising progress – on which European programmes have concentrated (see box) – concerns the family of polymer membranes (so-called PEMFCs). This type of fuel cell can be supplied with pure or reformed hydrogen and offers operating temperatures ranging from 80°C to 100°C. In particular, these are used to power the main automobile prototypes, which should soon become commercially available, and low-power stationary applications, especially in the residential sector.
Fuel cell technology. Upper section: fuel and fuel cell types.
A second category of methanol-fuelled polymer membrane fuel cells (DMFCs*) are most interesting for low-power portable applications such as mobile telephones, computing, etc. Nevertheless, their development has come up against a number of technological obstacles.
The molten carbonate (MCFCs*) and solid oxide (SOFCs*) fuel cells are able to operate at much higher temperatures and are competitors for the development of high-power units permitting heat and electricity co-generation, as well as for maritime applications. They offer higher performance and can be supplied with a range of fuels – methane, methanol, biogas, and gaseous carbon.
Europe has allocated increasingly substantial investments in fuel cell technology over the past decade. At Union level, many R&D and demonstration projects were devoted to this technology under the Fourth Framework Programme (FP4, 1994-1998), with ...
The energy ‘internet’
With nine European partners headed by the German heating manufacturer Vaillant GmbH, the Virtual FC Power Plant demonstration initiative aims to test the feasibility of micro fuel cell power plants. These must be able to supply electricity, heat and ...
Boosting European research
Europe has allocated increasingly substantial investments in fuel cell technology over the past decade. At Union level, many R&D and demonstration projects were devoted to this technology under the Fourth Framework Programme (FP4, 1994-1998), with financial aid totalling €54 million.
This drive continued under FP5 (1998-2002) under which some €150 million was allocated to support around 70 projects devoted to fuel cells and hydrogen. Most of these fuel cell projects were targeted specifically at polymer membrane electrolyte technology, currently the most promising in commercial terms. The challenge is to develop membrane fuel cells (PEMFCs and DMFCs) which can operate at higher temperatures (between 80 and 180°C) than the fuel cells developed to date, thereby boosting performance and reducing cost.
Leading European motor manufacturers (Fiat, Peugeot-Citroën, Renault, Volvo and Volkswagen) are working together on the Fuero project.
To optimise the work of these many and often precisely targeted projects, European programmes are giving special support to groups and networks seeking to integrate the various approaches and their results. These new synergies should culminate in developments with commercial applications. For example, the Fuero project, a consortium of Europe’s leading motor manufacturers (Fiat, Peugeot-Citroën, Renault, Volvo and Volkswagen), is trying to evaluate and draw on the research of a cluster of nine projects working on fuel cells, to carry out tests, clarify performance specifications, and develop modelling tools. Similarly, since 2003 the 50 or so research bodies and industrial users working within the SOFC network have been coordinating research and applications in the field of solid oxide fuel cells.
These SOFCs are of growing importance for stationary applications at a high temperature due to their very high output – as much as 70%. They are at the heart of the Real SOFC integrated project, allocated European support of €9 million following the first call for proposals on fuel cells under the Sixth Framework Programme (2003-2006). Three other integrated projects – Hytran, Furim and Manpower – are also working on polymer fuel cells (PEMFCs), with total funding of almost €15 million.
The energy ‘internet’
With nine European partners headed by the German heating manufacturer Vaillant GmbH, the Virtual FC Power Plant demonstration initiative aims to test the feasibility of micro fuel cell power plants. These must be able to supply electricity, heat and air-conditioning to a network of residential buildings, SMEs and public buildings. The EU is contributing €3.1 million to the total cost of €8.5 million. ‘By May 2004, we already had 29 micro power plants operational in Germany, the Netherlands, Spain and Portugal,’ stresses Alexander Dauensteiner, project coordinator. ‘They have produced a total of 160 MWh electricity and more than 300 MWh of heat.’
Virtual FC Power Plant project: press presentation of the micro fuel cell power plant in a residential building in Remscheid (DE).
This experience is particularly interesting as it prefigures a kind of energy internet. These decentralised installations, fitted with a system of common management, meet their own needs but can also inter-exchange power at times of peak energy demand and even deliver their surplus supply to public networks.
Fuel cells
Contact