hydrogen production from water using solar cells powered nafion ...

Interdigitated flow field is a different approach to flow field design. In other flow
field designs, reactant and products are transported in bulk phase in the channels via
pressure differences. Interdigitated flow field has a two parallel channel with dead ends.
The reactant flows through the input channel network and also diffuses into the membrane
to pass to the output channel network. The interdigitated flow field forces the reactants into
the active layer of the electrode thus high power densities can be achieved (Wang and Liu
2004). Large pressure loss occurs for the reactant which limits the using area of this pattern
with small stacks (Li and Sabir 2005).
Combining the observations from nature with interdigitated flow had led to some
modification on this flow type. A similar pattern like the tissues of plant or in animal lungs
was applied to the interdigitated flow field (Boff et al. 2006). Applying such a pattern of
channels of different width and depth has a great advantage to distribute gases uniformly.
The inventors have also realized that by forming sufficiently fine channels on the face of
the flow field gas diffusion layers are becoming unnecessary for electrolyzers.
In addition to the flow patterns mentioned above, a gas diffusion layer without any
flow channel or catalyst coated metal mesh (which is usually the case for PEM
electrolyzers because of the reduced catalyst life due to the carbon deposition from carbon
based layers) can be used for the distribution of reactants and collection of the products.
Various gas distribution methods have been shown to influence stack performances
in fuel cells and electrolyzers like various catalyst loadings and different membranes. As
the catalyst usage and membrane costs are reduced drastically, the cost of bipolar plates
becomes a significant portion (up to 30%) of electrolyzer and fuel cell stacks (Li and Sabir
2004, Larminie and Dicks 2003).
2.2.1.5. Solar Powered PEM Electrolyzer Applications
PEM electrolyzer driven by the power of photovoltaic array is one of the promising
hydrogen production methods just like wind turbines connected to the hydrogen generation
systems. Photovoltaic (PV) cells turn the sunlight into electricity directly. Briefly, when the
sunlight shines onto the semiconductor materials, the electrons in atoms of the
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