fastcoexist.com about a tiny piece of land between Croatia and Serbia — a disputed territory that doesn’t clearly belong to either country — where a group of libertarians is hoping to build a micronation dubbed the Free Republic of Liberland — a country they self-proclaimed into existence in 2015.

A new design shows how the city-state might look. To save space (the whole country is only three square miles) but allow the city to grow, neighborhoods are stacked in layers.

“I envisioned an intimate-scale city,” says Raya Ani, director of RAW-NYC, the architecture firm that created the winning design in response to a competition hosted by Liberland. Rather than build massive skyscrapers to house the 400,000 people who hope to live in the new city, each layer includes smaller, densely arranged buildings that allow sunlight to reach the street.

The underside of each layer platform is covered with algae – a genetically engineered version that doesn’t require sunlight to grow, and that can be converted into power. “The horizontal surface layer seemed to be the perfect home to grow algae that could power the city,” she says.

The design includes solar power, and a waste-to-energy system that converts any organic waste to biogas for cooking. Other trash is incinerated to create electricity.

The buildings would be covered with green walls and roofs to reduce rainwater runoff, and to keep temperatures cooler in heat waves. Along the edges of the city, since the area is a flood plain, parks are designed for occasional floods.

Liberland’s design team also included non-designers, such as economists, to think about other aspects of how the city would function. They propose that Liberland would have three economic hubs – sustainability, media, and technology – and promote entrepreneurship through a national crowdfunding site.

The first widespread introduction of catalytic converters was in the United States automobile market. To comply with the U.S. Environmental Protection Agency's stricter regulation of exhaust emissions, most gasoline-powered vehicles starting with the 1975 model year must be equipped with catalytic converters.[1][2][3][4] These "two-way" converters combined oxygen with carbon monoxide (CO) and unburned hydrocarbons(HC) to produce carbon dioxide (CO2) and water (H2O). In 1981, two-way catalytic converters were rendered obsolete by "three-way" converters that also reduce oxides of nitrogen (NOx);[1] however, two-way converters are still used for lean-burn engines. This is because three-way-converters require either rich or stoichiometric combustion to successfully reduce NOx.

Although catalytic converters are most commonly applied to exhaust systems in automobiles, they are also used on electrical generators, forklifts, mining equipment, trucks, buses, locomotives and motorcycles. They are also used on some wood stoves to control emissions.[5] This is usually in response to government regulation, either through direct environmental regulation or through health and safety regulations.

Model 1: 

A city that is completely powered by renewable energy resources.

It has an underground city incase of calamities,etc.

There are several resources in case of a famine or a disaster.

The street lights are solar powered 

Model 2: street with lights that detect the amount of pollution and helps the traffic, house with solar panels, a well where water gets collected by the rain, that water goes underground to the crops(green) and windmills

Model 3: the sugarcane ways etc are harvested and processed with yeast and producing alcohol. These productions can be used for sanitizers etc 

Model 4: catalytic converters are used to convert nitrogen dioxide into separate nitrogen and oxygen atoms, decreasing the pollution in air.