Fuels and Fuel Processing

Abstract

H2 is an ideal fuel for fuel cells (FCs) because of its high reactivity and zeroemission characteristics. Unfortunately, H2 is not easily available, and neither its production nor distribution infrastructure are widely spread. Therefore, development of technologies for production of H2 onboard and onsite from other sources such as natural gas, methanol, and gasoline is necessary. In the next section, different feedstocks that are suitable for H2 production for fuel cell application are presented. Subsequent sections focus on reforming of hydrocarbons that are processed by a series of steps that include fuel desulfurization, reforming, water-gas shift reaction and carbon monoxide (CO) removal [1,2,3,4]. Figure 5.1 illustrates what is known as the fuel processing train with some options for the essential steps. This general fuel processing train is usually used for PEM fuel cells running on fossil fuels such as natural gas. The processing steps that the feedstock are subjected to depend on the type of the fuel and the fuel cell. For example, if methanol is the fuel for PAFC, the CO removal step might not be necessary. The last two steps, water-gas shift reaction and CO removal, are not necessary in the case of MCFC. If feedstocks heavier than methane are used as a feed to the SOFC, an additional process step known as prereforming might be used. Such variations are described in more detail in Section 5.3.