ABSTRACT
Fuel cells utilizing hydrogen as fuels represent an important form of tomorrow’s energy because hydrogen is an efficient fuel and it is environmentally clean. Auto industry, which relies on oil-fueled cars, is perhaps the biggest driving force behind the massive investment in fuel cell development (Zhong et al. 2008). Harmful emissions of CO2, CO, SO2, NO x , and volatile organic compounds into the atmosphere cause serious environmental damage, increase respiratory problems in humans, and produce “greenhouse gas” that contributes to global warming. With these problems, fuel cell technology is inevitably seen as a viable alternative. Energy sources of the future will have to be cleaner and more efficient than current sources—fuel cells fulfill these requirements. “Hydrogen Economy” offers an energy system based upon hydrogen for energy generation, storage, distribution, and utilization. There are three main areas of challenges for the realization of hydrogen energy: hydrogen production, hydrogen storage, and hydrogen utilization. Fuel cells based on hydrogen fuel represent one of the most effective ways of hydrogen utilization. Proton exchange membrane fuel cell (PEMFC) (Figure 7.1) has become attractive because of high conversion efficiency, low pollution, lightweight, high power density, and a wide range of applications from power sources in automobiles and space shuttles to power grids for buildings and factories. Fuel cells are essentially electrochemical cells and operate by the same basic mechanism as regular batteries. Hydrogen fuel cells convert flows of hydrogen and oxygen into water and produce electricity. At the anode, hydrogen is forced through a catalyst where it is ionized. At the cathode, oxygen reacts with the products from the anode (the protons and electrons) to produce water. The close circuit of the two electrodes produces electricity and heat, and water as the only product.
