It would be extremely hard to create a city that is fully sustainable, but that does not mean that it is not possible. Here are some ways that I would try to achieve this.
1. Energy and Fuel. My city would prioritize renewable energy, and would try to achieve close to 80% of our energy sources from renewable energy.. We would achieve this not through city building, but through subsidizing renewable energy groups who would want to build plants in strategic locations so as not to interfere with natural landscapes, but still able to generate enough energy to power the city. I would institute a system of tax cuts to homes that used energy saving appliances, as well as subsidizing companies research into more energy efficient practices. I would also cut taxes to those who own either a hybrid, electric, or fuel cell car, prioritizing in that order. In summary, a series of tax cuts and subsidies would push my city in the right direction to relying on renewable energy.
2. Economy. All of these projects take money, so I would need to boost my city’s income in a green way. There  are several things that I would do. First, I would institute a ‘Cap and Trade’ program for all companies that emit carbon. A full explanation can be found here: https://www.cfr.org/interactives/crisis … ate-change (Chapter 4, Policy Section).This would generate income for the city, giving it another source of money. I would also privatise the water and electric networks, but require the companies that pay to operate it charge fair prices, use as many renewable sources as possible, install water and electricity monitoring systems, and comply with city zoning and construction laws.
3. Policy and Transportation. I would start a recycling and compost iniative to try to reduce the city’s waste. I would also create various protected spaces to preserve the environment around the city. I would start funding various initiatives to create a green skyline, and I would start the construction of a hyperloop transportation system around the city. I would make public transportation free, and would promote walking and biking.

I believe prioritizing the use of renewable energy resources is an excellent solution to the issue of the greenhouse effect. Unlike fossil fuels, renewable energy resources do not run out. Water, wind, and solar power are all examples of renewable resources that many people use to power their homes. Using these resources is better for the environment because not as many greenhouse gasses would be let out into the atmosphere.

SOURCES:
http://homeguides.sfgate.com/definition … 79625.html