4. Photovoltaics (Schönau's revolutionists)
Some bacteria have been able to convert sunlight directly into – biochemically bound –usable energy for more than two billion years. Mankind took until the mid-1950s to convert sunlight into electrical power, another form of usable energy.
From a niche product to a mass market
The first solar panels were very expensive and not very efficient. It is not surprising that, to start with, photovoltaics were almost exclusively used for satellites. After nuclear accidents, such as Harrisburg and Chernobyl, it was often initiatives or anti-nuclear activists campaigning for solar energy, even though it was completely unprofitable at the time. So did Schänau’s solar power revolutionists.