ABSTRACT
One of the major concerns in using fossil fuels for hydrogen production is the emission of GHGs such as carbon dioxide (CO2). As shown in Figure 17.1, the atmospheric concentration of CO2 historically fl uctuated naturally on the timescales of ice ages. Concerns, however, stem from the recent dramatic increase in the CO2 concentration, which coincides with global industrial development. The atmospheric concentration of CO2 rose from 280 ppm in 1800 to 370 ppm in 2000. This rise is mainly due to the high use of fossil fuels (Fankhauser et al., 2001; IPCC, 2005; Caldeira, 2006). The increase in the atmospheric CO2 concentration has been most severe over the last few decades, and, unless actions are taken, the atmospheric CO2 concentration could reach 580 ppm, a threshold value thought to trigger severe climate change, within a mere 50 years (Stix, 2006; IPCC, 2007).
