If it is not yet a source of energy used properly, hydrogen are a vital means of storage. However, the main challenge now is to produce a “green”. The Ecole Polytechnique Federal de Lausanne (EPFL) was launched recently in the development of a cell PHOTOELECTROCHEMICAL (PEC in English) can split water into hydrogen and oxygen to the same surface electrodes. Unlike existing systems, which are to involve a solar cell with an electrolyzer, the PEC have as their main shortcoming low efficiency. However, the EPFL hopes to reach yields of around 4.5% in 2009 and 7% in 2011.
The project is coordinated by the Center for Energy EPFL and driven by the Laboratory of Photonics and Interfaces led by Professor Michael Grätzel, inventor of the solar cells of the same name based on the photosynthesis of plants convert solar energy into electricity. These works are a continuation of those made in the late 90s in collaboration with professors Jan Augustynski in Geneva and Gion Calzaferri in Bern and had allowed the construction of a “tandem cell” PHOTOELECTROCHEMICAL whose results were promising. This cell linked a semiconductor with a dye cell, which could increase the electrical supply for the reaction of dissociation of water.
The new project, entitled PECHouse will try to improve this by developing materials more stable. Indeed, the main obstacle to the development of such cells is to find materials that resist corrosion while retaining an affordable price. With a budget of about 3.1 million, PECHouse is supported by the Federal Office of Energy and can benefit from the expertise and skills of EMPA, the federal laboratory dedicated to materials.
WHY PEC RESEARCH ?
Hydrogen, H2, has the potential to meet the requirements of a sustainable and carbon-neutral fuel in the future, if it can be produced from our sun, the world’s most abundant energy source, and stored and transported safely.
At present, there is still a large gap between our present global energy consumption (around 13 terawatts, TW), our use of solar energy to supply the world’s energy demand (less than 2 %), and the enormous untapped potential of the sun (120’000 TW).
The development of photoelectrochemical cells (PEC) is promoted by increasing public awareness that the Earth’s oil reserves could run out during this century. Public concern has been heightened as well by the environmental pollution and the climatic consequences of the greenhouse effect caused by fossil fuel combustion.
Photoelectrochemical cells (PEC) have been shown to directly split water into H2 and O2 (photoelectrolysis of water) thereby providing a basis for the renewable, clean production of hydrogen from sunlight. They rely on a photoactive material (a semiconductor) capable of harvesting and converting solar energy into stored chemical fuel, i.e. hydrogen.
The challenge arises from being the semiconductors robust in water splitting not responsive to a wide portion of the solar radiation spectrum, yielding relatively low efficiencies of conversion solar-to-hydrogen.
Closing this gap will lead to the development of cheap and efficient systems for hydrogen production directly from sunlight and therefore directly address, not only the conversion, but also the storage issues.
PECHouse is the photoelectrochemistry centre of competence at the Swiss Federal Institute of Technology (EPFL) which carry out R&D on semiconductor oxide-based PEC.
The innovative concept of the photo electrochemical PEC tandem cell for water splitting originates in 1994 as a result of the collaboration of the leading competences in Switzerland:
. Prof Jan Augustynski – University of Geneva (today at University of Warsaw)
. Prof Gion Calzaferri – University of Bern (retired)
. Prof Michael Graetzel – EPFL Lausanne
The basic elaboration of this promising idea was enabled due to the substantial support of Swiss Federal Office of Energy (SFOE), which still funds the on-going of the research and the running networking activities in this area resulting in the initiation of so called PECNet. Based on the international leading Swiss know-how on PEC water splitting technology the Swiss Federal Office of Energy SFOE has a continuing interest that the research activities in this promising field of sustainable hydrogen production will go on. This is stated in the “Konzept der Energieforschung des Bundes 2008 bis 2011″. Therefore the SFOE has generated and supports the following vision of a photoelectrochemistry centre of competence called PECHouse.
The PECHouse is a collaborative effort combining state of the art PEC research and development resources, leadership, and management with defined goals for the stepwise development of an efficient hydrogen production system. The ultimate vision for the PECHouse is to investigate and develop comprehensive PEC based, small scale (1-100kW), market-ready devices for distributed solar production, storage, and use of H2. By 2011 the PECHouse will be an established and internationally recognized research centre leading the research and development of materials and devices for efficient photoelectrochemical hydrogen production.