Transportation is now the biggest single source of U.S. greenhouse gas emissions, having recently passed electricity generation. Worse, zero-carbon transportation technology is only in its early stages — especially for air travel and shipping, which accounts for large and growing share of emissions.
Steampunk fans and climate hawks alike want to know: what about airships? After investigating the subject for a time, I've come to a tentative conclusion that airships could indeed play an important role in a zero-carbon transportation infrastructure — but probably not in the form of romantic luxury travel. Big and weird cargo shipping might just be where the airship does best.
Airships are, of course, aircraft which use a large envelope of lighter-than-air gas, typically hydrogen or helium, to provide most or all of their lift. There are three basic types: non-rigid (a blimp), or semi-rigid (with a partial supporting structure), or rigid (with a complete supporting structure). There is also the hybrid airship, which is slightly heavier than air and uses traditional wings or rotors to provide lift and control.
Airships have several important advantages. First is that with the envelope (that is, the ballon-like structure where the gas goes) providing lift, there is no need to expend fuel to maintain flight. Second is low-speed maneuverability, meaning they don't require as much infrastructure as airplanes — no runway for instance, or only a short one in the case of hybrids. Third is high potential lifting power — the largest new designs could theoretically carry 500 tons or more, in the same league as the largest cargo planes. Fourth is very high cargo volume — a heavy lift airship would have to be very large, and so would be able to accommodate a correspondingly huge cargo bay.