The vertical farm is more than just a produce factory. It's also a plan to rewire a city's infrastructure to mimic natural-resource cycles. Nowhere is that more evident than in the tower's basement, where sewage provides the farm's most crucial resources: energy and water. The surrounding city's sewage system would be redirected to the farm, where half of it would enter a "SlurryCarb" machine, developed by EnerTech, a green-energy start-up in Atlanta. The device heats and pressurizes the sludge , breaking it down into its base components—carbon and water. The machine extracts the water , and the solid, coal-like slurry burns to power steam turbines  that generate electricity. The rest of the sewage is treated with bacteria-killing chemicals and turned into topsoil through a heating and drying process developed by N-Viro, an Ohio-based biosolids-recycling company. Water extracted from both processes is filtered  through natural "bioremediators," such as zebra mussels, cattails and sawgrass, that clean it until it's suitable for agriculture, or further refine it for drinking. Any farming waste is composted to make fertilizer and methane gas, which can be burned for energy.