A large proportion of the cost, disruption, pollution and exposure to natural disasters in a city would be eliminated if there were no infrastructure.

Imagine no sewage or gas pipes, electricity poles or even sidewalks from which people leap into the face of approaching traffic.

We have seen a beginning of independence with houses no longer requiring telephone wires because mobile phones are used. However, a city where buildings are fully independent seems like a pipedream.

Until now, that is. The smart materials and robotics approach to smart cities could prove more powerful than the initial IT and sensor-centric approach to cracking the problem.

For instance, Passivedom sells a residence that grabs its own water from the atmosphere and treats its own sewage, its electric power being from its own solar panels.

Separately, Microsoft co-founder Bill Gates unveiled a futuristic toilet in November 2018 that does not need water or sewers and uses chemicals to turn human waste into fertilizer. His foundation has committed $200-million and expects to spend the same amount again before the toilets are viable for widespread distribution.

“The current toilet simply sends the waste away in the water, whereas these toilets don’t have the sewer,” Gates said. “They take both the liquids and solids and do chemical work on it, including burning it in most cases.”

During a speech he held up a jar of human faeces to illustrate the importance of improving sanitation. “It’s a good reminder that in there could be 200-trillion rotavirus cells, 20-billion Shigella bacteria, and 100 000 parasitic worm eggs,” he said.

Gates expects the market for the toilets to be over $6-billion by 2030.

There is big money in smart cities based on smart materials. For instance, solar roads that self-device and charge vehicles at speed are being installed in China in 2022. They cost millions of dollars per kilometre so this will become another multi-billion dollar zero-emission business with good payback.

The IDTechEx report, “Smart City Opportunities: Infrastructure, Systems, Materials 2019-2029”, covers independence of food, power and water for cities and even the buildings within them.

It also details ways a city can produce hundreds of megawatts itself – for example from new solar windows and cladding on a high-rise building that gives affordable, secure, clean, electric cooking, HVAC, lighting and services not hostage to utility price rises.

Since most cities are on a large river or the sea, this could be boosted with plug-and-play wave, tidal and tethered-drone wind power with minimal intermittency and therefore minimal energy storage.

Combinations will be tuned to demand profile through the day, which is far more efficient than energy storage and requires few or no batteries.

As an example, the Facebook-funded smart city by Toronto will not have sidewalks because only gentle robot shuttles and people will pass. Transport is pure electric with energy independence thanks to solar bodywork and wind turbines that erect when vehicles are stationary.