Envision all you want - - but this is where the rubber meets the road. From CityLab:
"Here's the catch: “It's one of the dirtiest industrial processes out there,” says Courland. There are two reasons for this. First, when limestone is processed into cement, it emits the greenhouse gas CO2. Second, cement-producing furnaces typically burn fossil fuels, often coal, to achieve the blistering temperature of 2500 degrees Fahrenheit. On a global scale, the resulting emissions boggle the mind. Concrete produces 5 percent of global CO2 emissions—as much as the entire country of Russia."