Reykjavik, Iceland [TIME] Xianyang, China, was once a great place to live — during the Qin dynasty, anyway, more than 2,000 years ago. Since then, it has gone pretty much downhill. Today Xianyang is one of the most polluted cities in a very polluted country, partly as a result of the air-fouling coal that’s burned to generate much of its power. The air in Reykjavik, by contrast, is crystal clear, because nothing is burned there. Iceland’s capital gets 100% of its heat and 40% of its electricity from geothermal power. (The rest comes from hydropower.) …Geothermal pumps will even be used to heat and cool some of the venues at the 2008 Olympic Games in Beijing.