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Power generation from solar energy based on PEM fuel cell

Final Activity Report Summary - SOLARPEMFC (Power generation from solar energy based on PEM fuel cell)

Renewable energy sources are very promising solutions for global warming and solar energy is considered to be the ‘cleanest’ and inexhaustible source of energy. Efforts have been made by many workers to transform solar energy into power. The power generation from solar energy is primarily based on two main technologies, namely photovoltaic and solar thermal. The photovoltaic systems are widely employed for solar power generation. They depend directly upon the intercepting area of solar radiation from the solar panel. The solar power generation based on thermal absorption requires high operating temperature, greater than 400° C, that uses concentrated solar system to process solar heat at about 400° C and have low conversion efficiency. A new approach for solar power generation is required, so that it can boost its efficiency to increase its scope and promote the use of renewable source of energy.

Fuel cells are considered to be the solution of the 21st century energy crisis as they are highly efficient energy conversion systems which also are environmentally friendly. The scope of high efficient fuel cells can also be extended to generate solar power based on chemical methods. The proton exchange membrane (PEM) fuel cell fits best to solar energy utilisation because of the fact that it can operate at relatively low temperatures, smaller than 100° C, and has the capability of quick power generation. The novel proposed method of SOLARPEM solar power generation was based on PEM fuel cell technology that reduced the processing temperature requirement to less than 100° C and could have high energy conversion efficiency. The project was multidisciplinary, involving expertise in two fields, namely chemical engineering of hydrogen fuel cells and solar thermal engineering of heat collection to transform the concept of thermo-electrochemical systems operating on solar thermal energy into reality towards a new approach of solar power generation.

The main emphasis of the present work was to design the prototype of PEM fuel cell for SOLARPEM, as well as to test the prototype and optimise its operation for new solar power generation system. The existing PEM fuel cells worked on the coupling of hydrogen (H2) and oxygen (O2) to generate power and needed to change in order to work on the coupling of chemical reactions, namely 2-propanol, acetone and H2, in the PEM fuel cell for solar power generation.

For the development of PEM fuel cell for solar power applications, different types of catalytic electrodes were fabricated. These catalytic electrodes were made using the catalysts platinum (Pt) and ruthenium (Ru) in different proportions from the various precursors. Different techniques were used for making catalysts, such as the impregnation technique, the printing technique and the formic acid method (FAM) technique. In the impregnation technique, the catalysts were reduced under the atmosphere of mixture of H2 and nitrogen (N2). In the printing method, direct Pt and Ru on carbon vulcan XC-72, after making catalytic ink, was used. The catalysts were made in different loadings from 2.5 % to 25.0 % on the carbon cloths and papers. The catalytic electrodes in the PEM fuel cells were tested with different proportions of the liquid oxidant 2-propanol, acetone and water, ranging from 1 times 1times 98 to 12 times 12 times 76 in a different temperature range from room temperature 15° C to 80° C. The best result of PEM fuel cell so far was obtained at a temperature of 60° C. The power density (PD) that obtained from PEM fuel cells for SOLARPEM as follows:

1. PD equal to 259 µW/cm2 in 2001, by AIST, Japan
2. PD equal to 374 µW/cm2 in 2007, by UOB, UK
3. PD equal to 870 µW/cm2 in 2008, by UOB, UK and
4. PD equal to 2.11 mW/cm2 in 2009, by UOB, UK.

The results for power density were encouraging but not sufficient to generate appreciable solar power from SOLARPEM. Therefore, the work was planned to continue in order to maximise the power generation to reach the target of 10mW/cm2. The latter was the main future research objective.