The Solar Chimney Power Plant consists of three main parts: a collector, turbines, and a tall chimney. Hot air rises in the chimney due to differences in air density, powering turbines to generate electricity. A prototype in Manzanares, Spain had a collector 1km in diameter and a 200m chimney. A proposed plant in Mildura, Australia would have a 1000m chimney and 200MW capacity, powering 200,000 homes using only solar energy without fuel. While large scale, pollution-free, and reliable, solar chimneys have very high capital costs compared to other power sources.