The six vans run on biomethane gas generated from sewage treatment works.

BBC: 'Poo-powered' vans up and running in Sheffield

Flexibility is necessary to ensure that various types of networks get built (sewage lines, sidewalks, gas and power lines, and even communications systems).

FORBES: Adam Thierer, Infrastructure Socialist

FuelCell Energy touts the ability of its fuel cells to directly process a hydrocarbon, such as natural gas or waste gas from a sewage treatment facility.

FORBES: Beltway Bet: FuelCell Energy

Utility networks, such as for electricity, gas, water, and sewage, work the same way.

FORBES: The Weird Economics of Utility Networks

Water and sewage networks would be adapted to deal with flooding while old metal gas pipes would be replaced.

BBC: Generic water works

Microturbines can run on natural gas as well as other fuels, including kerosene and the methane given off by landfills and sewage-treatment plants.

FORBES: The Revolution That Wasn't--Yet