Excitement hung low over the Yintai Consolidated Conference Center like a skateboarder's trousers early this month, as journalists and other scroungers gathered in anticipation of the latest gobsmacking science announcement from Doctor Fo Jing of the Nongda Energy Efficiency Rooms. Doctor Fo, a leading light in the field of unexpected sources of energy, is highly respected by several scientists, all of whom wear glasses.

"Good morning," said Doctor Fo as he mounted the dais - indicating both that he was aware of the audience's presence and that noon had not yet arrived. "Today I am very pleased to announce that we have tapped a source of energy hitherto languishing unused all over the city of Beijing. Bus stops!"

After the astounded gasps of the journalists, plumbers and other industry professionals in the room had subsided, Doctor Fo explained what he meant. The untapped energy apparently lies not in the bus stops themselves, but in the Beijingers waiting at them. Doctor Fo directed everyone's attention to a diagram on an electronically-projected factboard, laser-pointing out the relevant parts of the diagram with a laser-pointer.

At the approach of the bus they want to catch, the Beijing bus-waiter will surge towards it at a speed inversely proportional to the velocity of the bus in eagerness to board it. This, of course, brings them to a position well in advance of the actual bus stop. As traffic opens up, the bus continues on to its destination - the bus stop. This forces the bus-waiters to surge back, usually shouting, in the opposite direction to where the bus will actually open its doors.

Previously, this was merely wasted energy. However, with a new scheme whereby purchase of an yikatong travelcard will be accompanied by a subcutaneous implant resembling a miniature version of those things they use to generate power from waves, that kinetic energy can be used for vital civic projects such as heating, street lighting and having massive searchlights sweep across the sky from the roofs of nightclubs.