China's heavy investment in clean energy is only the newest chapter in that country's commitment to finding and developing energy sources. That includes fossil fuels, by the way, including coal, which today supplies 70% of China's energy. As its population has exploded, so, too, has China's search for power, as you'll see in this energyTHEN from 1963.

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[ANNOUNCER] China has natural resources. More than 250 billion tons of coal reserves. It has somewhere around 5 billion tons of iron. It has three-quarters of a billion tons of oil. Despite the coal and the oil, however, power is miserably lacking in China. But China's greatest resource is people. And more people. And more people.

[ASSURAS] And, with more than a billion people needing energy, most of it from coal, it's caused a lot of pollution. According to the World Bank, China is home to 16 of the world's 20 most polluted cities.