HYDROGEN ENERGY: THE GOOD, THE BAD, AND THE ENVIRONMENTALLY ACCEFTABLE

Abstract

Hydrogen is in many respects the ultimate fuel: it is the most abundant element in the universe; as a molecular species it possesses the highest gravimetric energy density of any chemical substance; it can be burned cleanly to produce only water as a reaction product; and its simple and rapid electrode kinetics open the possibility of high efficiency fce! cell-drivon power trains. On the otl1t.r hand, as a gaseous substance under standard conditions, it is inconvenient to use as an on-board fuel without severe compromises with respect to distance between refueling stops; rapid rates of effusion and wide combustibility range limits give rise to safety concerns; and finally, under terrestrial conditions, Hz is seldom found in Nature-it must be. derived from other compounds, often at considerable expense. The various aspects of hydrogen energy combine to paint a picture that is compelling but also technologically challenging