By 2030, the plane arriving at your gate could resemble this: a fuel-efficient, environmentally friendly behemoth with theater seating and a radica, stingray-shaped design. Clive Irving reveals the emerging wild green yonder

Imagine, if you will, the moment of boarding this airplane. As you enter, just about the only familiar feature would be the seats. But the rows are not 6, 8, or 10 seats abreast. There are 20 or more seats in each row, divided by many aisles. This is a wide cabin—a very wide cabin. Moreover, there are no windows at the ends of each row. In shape and proportions, the cabin is more like a theater, though without a raked floor. There are windows elsewhere: They provide a view of the sky ahead, along a promenade aisle that follows the front contours of the airplane's wings. The cabin is, in fact, subsumed inside huge arrowhead-shaped wings. This airplane has no fuselage; it's all wing. In theory, you could be flying in such a novel, unfamiliar kind of airplane in little more than 20 years.

That such a radical idea is even being considered is a mark of the challenge facing aircraft designers across the world. They are caught between the convergence of two seemingly irreconcilable forces: a predicted worldwide growth of airline passengers from 704 million in 2005 to 1.95 billion in 2025, and increasingly powerful—and concerted—environmental lobbies wanting to slow or, in extreme cases, halt that growth. Add to this the impact of soaring oil prices and everything is bearing down on one target: the airplane itself—how much fuel it burns, and the impact of its emissions on the sky and the climate.

The form of the machines that move us has, until now, been astonishingly consistent. It was settled, in each case, very early in their development: two of them, trains and cars, were devised in the nineteenth century, and the airplane early in the twentieth century. In principle, the sleekest high-speed train, like the French TGV, remains a string of "carriages," recognizably the descendants of the Victorian trains that were themselves adaptations of the stagecoach, with bench seats and windows on each side. The car followed the same idea with a change only of scale and propulsion. The commercial airliner began looking like a box built from wood and canvas, with seats and windows, and then, in its more refined form, became a metal tube with wings. The tube adapted very well to changes in size and in the distances flown. It just got wider and longer.

Only now have aircraft makers come to seriously ask whether the tube with wings can survive the enforcers who want to clean up the skies. Though we take the right to air travel for granted, most people in the world have yet to fly. Flying at will wherever and whenever we wish is beginning to look like one of those privileges that cannot be exercised without measuring its cost to the planet and to the lives of the millions to whom the silver streak high in the sky remains an unreachable luxury. In this atmosphere, the urgency and severity of the demand to green the flying machine seems, to those engaged in the airplane and airline industries, similar to the stress of a war. Wars are great technology accelerators. And so it was that I wondered, if that is the case, where is the new intensity of effort going to take us? Who are the pacemakers? And what will it demand of us, the airline passengers, in adaptability? What I found was that, for the designers and engineers involved, 2020—which is when the plane of the future may be flying—is not the distant future. It's tomorrow. Shaping the future will require multi-billion-dollar gambles on ideas barely out of the experimental stage. The outcome will take us into a new age of air travel that will make today's experience seem very quaint indeed—as different as listening to an iPod is from cranking up a gramophone.