I think we could with solar panels, LEDs, hydroponics and sewage reclamation. It wouldn't take so much land if all this was in tall buildings or multiple levels

I think we could with solar panels, LEDs, hydroponics and sewage reclamation. It wouldn't take so much land if all this was in tall buildings or multiple levels underground. Any methane involved could be put into biofuels for vehicles or lighting/temperature control of the hydroponics.