Producing hydrogen from water and sun
CESA installation– “Reflected light” by Miguel Hidalgo, Courtesy of the PSA
The project produces clean energy in the form of hydrogen exclusively from water and the sun without emitting any pollutants or greenhouse gases.
The efficiency of converting the solar energy is as high as 70 percent and appears to be the answer to the difficult problem of producing economically efficient hydrogen from renewable energy sources. It is the largest solar reactor in the world and has therefore attracted a lot of attention from researchers and investors. The project was awarded a 2005 International Global 100 Eco-Tech prize in Japan and the Descartes Prize for 2006 for scientific research.
At the heart of the program is the HydroSol Group, coordinated by Athanassios Konstantopoulos, Director of the Chemical Process Engineering Research Institute in Thessaloniki, Greece. The other members of the consortium are the German Aerospace Centre (DLR), Stobbe Technical Ceramics from Denmark, Johnson Matthey Fuel Cells from the UK and the Spanish Research Center for Energy and Environmental Technologies, Ciemat.
What is truly pioneering about this project is the reactor which is situated at the point where the rays are concentrated. It has no moving parts and is made from a ceramic material with high capacity for solar heat absorption. Its coating nanomaterials, with very high water-splitting activity and regenerability, are a key development in the system. At high enough temperatures (800-1,200 degrees Celsius) these coating materials strip water of its oxygen, leaving hydrogen gas to bubble away. The oxidized materials must then be recycled, driving off their collected oxygen as gas, in a separate reaction step at 1,000-1,200 degrees C.
The hydrogen produced can be channeled into a fuel cell to produce energy or to a combustion point. It can also be stored, solving the problem of storing and transporting solar energy. Secondly, the reactor can be used to recycle carbon dioxide. Thirdly, it can be used to desalinate water. This could be an integrated solution for islands around the world.
The system will take in half a litre of water every minute and should produce around 3 kilograms of hydrogen an hour – equivalent to a thermal output of 100kW. The next step is upscaling to 1 megawatt and bringing the costs down. ‘This will be competitive within a decade,’ Konstantopoulos claims.
Results from this landmark research project promise the potential for long-term production of renewable based hydrogen, particularly for regions of the world that lack indigenous resources, but are endowed with ample solar energy.