Pneumatic waste collection

Pneumatic waste collection — also called automated vacuum collection — moves rubbish through buried pipes instead of trucks. Residents drop bags into street-level or in-building inlets; on a schedule, a powerful fan at a central terminal creates suction and the waste is pulled through underground tubes at tens of kilometres an hour to sealed containers, ready to be hauled away in bulk.

Pioneered in Sweden in 1961, the technology suits dense new districts where daily truck rounds are noisy, polluting and hungry for street space. Running a separate pipe or timed cycle for each fraction lets the system keep recyclables apart. South Korea's built-from-scratch Songdo International Business District wired vacuum waste pipes into the city from 2003, and Bergen's Bossnett is a large retrofit threading tubes under an existing Norwegian city, serving over 10,000 properties and counting.

The honest catch is money and permanence. Laying pipe is hugely expensive, so it really only pencils out when built into a district from the start or during major redevelopment; once the network is in the ground it is hard to reroute or expand. The fans draw constant power, inlets jam, and mis-sorted waste contaminates whole batches — and Songdo, the global showcase, has fallen well short of its population targets.