In the latest episode broadcast Sunday night he shows that scientists in the late 19th century were predicting that industrial pollution could lead to the melting of the polar ice caps and the rise of the oceans.  A mathematician from the same time period dazzled Parisians at a world's fair with a device that used solar power to freeze ice.  (It looks like a sting ray of a science fiction movie.)

In a subsequent section Tyson hails the work of a German entrepreneur who figured out in 1913 how to use solar power in Egypt to water crops in the desert.  Alas, World War I interrupted the project and the price of coal dropped.

In the 1930s another entrepreneur saw his plans for solar power collapse when the price of oil dropped with the discovery of new fields. 

You can watch the full episode online here. 

You can watch all other episodes here.