*1.6.5. PEMFC*

"PEMFC" uses a solid polymeric membrane as the electrolyte and platinum catalyst contained in porous carbon electrodes. Polymer electrolyte membrane fuel cells[2,4& 12]operate at moderately low temperature range of 80°C to 100°C. The low operating temperature range enables them to quick start (short warm-up time) and results in better durability (lesser wear on system components).

PEMFC utilizes the platinum catalyst on its membrane. Platinum catalyst[7]is very expensive even in small quantity and also very sensitive to carbon monoxide poisoning, making application of reactor that will reduce its concentration in hydrogen fuel gas-derived fossil fuel necessary. This adds to the overall cost. In recent times, researchers are exploring platinum/ ruthenium catalysts that are more resistant to CO, as better substitutes.

Another significant challenge to suitability of fuel cells for vehicles is low hydrogen storage capacity. Hydrogen is a very light gas with low energy density and will require a very large storage tank to store it onboard to power the fuel cell vehicles over a considerable distance, typically 300–400 miles like the gasoline-powered vehicles before refueling. Higher-density liquid fuels such as methanol, ethanol, natural gas, liquefied petroleum gas, and gasoline cannot be used directly unless they are processed into hydrogen through an onboard reformer unit. This increases costs and maintenance requirements.

**Figure 8.** Showing components of polymer electrolyte fuel cell (www.daviddarlin.info)
