Summary

Realising a sustainable hydrogen economy requires breakthroughs in the production and storage of hydrogen. Focussing on research areas that have been singled out as areas that might see such breakthroughs, the network aims to devise a tandem cell which can photoelectrochemically convert solar energy to energy in hydrogen with an efficiency greater than 10%, and to find the best possible complex-metal hydride hydrogen storage system for on-board storage in automobiles.

The importance of research for the hydrogen economy

The importance of research aimed at enabling the introduction of hydrogen as a clean fuel can hardly be overstated, and the introduction of the hydrogen economy is a stated policy goal of the EU [1, 2]. First, fossile fuels reserves are limited. Present estimates are that, at the current usage rate, oil will run out in 40 years, natural gas in 60 years, and coal in 200 years [3]. Second, scientific evidence is accumulating that the emission of CO2 that accompanies fossile fuel use is leading to global warming.

Current methods for production

The current commercial process for producing hydrogen is steam reforming of natural gas. Hydrogen can also be produced from coal using gasification technology. Both methods have as disadvantages that they result in CO2 emission (even if CO2 could be sequestered, the safety of sequestration techniques is presently under discussion), that the availability of natural gas and coal is limited, and a disadvantage of natural gas is that most of it is present in non-EU, sometimes unstable countries, with consequences for energy security [6]. Other methods of producing hydrogen use nuclear energy, electricity from solar cells or from wind energy, biomass (which cannot be grown in sufficient quantities to fulfill world energy needs), and photobiological and photoelectrochemical processes [6]. Photoelectrochemical hydrogen production is mentioned in both a recent energy technology analysis of the International Energy Agency (IEA) [6] and in a recent report of the National Research Council and the National Academy of Engineering of the US (NRC/NAE report) [5] as an important research area where the kind of technological and conceptual breakthroughs required for the hydrogen economy are possible, and the network will focus its research on production of hydrogen exclusively on this production technique.

Experiments & theory

There is not enough space to list all the methods that will be used in the research programme; we will therefore only mention the more important ones in this Section. In the theoretical research, we will use, for instance, density functional theory (DFT), a new QM-MM (Quantum Mechanics-Molecular Mechanics) approach, the time-dependent wave packet (TDWP) method, and quantum transition state theory (QTST).

State of the art research

Hydrogen can be produced efficiently and cheaply using a tandem cell [16, 17]. This device (see Figure below) connects a photoelectrochemical cell to a Grätzel solar cell. The Grätzel cell converts energy in red light to electricity, providing the small extra bias to drive oxygen production over the metaloxide electrode which absorbs blue light in the photoelectrochemical cell. Hydrogen Solar, which aims to bring the tandem cell to the market, reports an efficiency of 8% for a tandem cell based on a WO3 photoanode in the photoelectrochemical cell [18].

Objectives

The network's two research goals can be summarised as follows. The first goal is to devise a tandem cell which can convert solar energy to chemical energy with an efficiency of 10% or more, using a new nanostructured metaloxide material, and based on an atomic scale understanding of the mechanism of photooxidation of water on metaloxide surfaces, this step being the crucial step.

Multidisciplinarity & overcoming fragmentation

The team of principal investigators (PIs) contains experts with a broad knowledge of hydrogen production (EPFL) and storage (FRI), see also their two recent review papers in Nature [7, 16]. The researchers come from different disciplines (physics, applied physics, chemistry, chemical engineering). The team contains experts in nanoscience (for instance, EPFL, CHA, SHL, FRI) and surface science (for instance, LEI, OXF, UI, DTU).

Relevance to the specific objectives of the Marie Curie action

Integrating disciplines

The academic partners have their roots in fundamental physics (UI, DTU), applied physics (FRI, CHA) and chemistry and chemical engineering (LEI, EPFL, OXF, WAR), showing the highly interdisciplinary character of the network. The expertise of the partners is summarized in Table 2.1, which shows that the contributions to the training programme are highly complementary. Synergy comes from the fact that both research goals (w.r.t. production and storage of hydrogen) have to be achieved to realise the hydrogen economy, and from the unified nanoscience/surface science approach that will be taken in research on production and storage. Also, some of the partner groups (LEI, DTU, CHA) will perform research on both topics in the framework of this proposal. The groups have extensive experience with international collaboration, and there is already intense collaboration between many of the partners. Four of the groups (LEI, DTU, OXF, UI) are currently part of one and the same Research Training Network (Predicting Catalysis) that will end on 1 July 2006, and there are many links between these groups and the other participants, and among the other participants.