As the later chapter on automotive fuel cell applications (Chapter 10) will demonstrate, the driving force behind the past two decades of fuel cell research and development was the striving for clean cars. Stationary and portable applications were seen as byproducts, which would follow automotive fuel cell commercialization once this — by then very cheap — power source became available. In retrospect, it is now easy to see that the development would necessarily occur in a different order. With automotive cost targets at $50 per kW of electric power for the whole power system, stationary targets at approximately $1000/kW, and portable targets hard to predict but certainly well beyond this figure, why would stationary and portable developers wait until the actual cost had reached the rock-bottom $50/kW figure? Commercialization of those applications would start when they became commercially viable, which is roughly at this moment in time, at least for portable units.