Energy is a resource that humanity has always needed, and before the Industrial Revolution, most energy came from human or animal labor. Oxen and horses plowed the fields, men built tools, women were textile experts, and horses even served as transport and war mounts as well. All of this changed, and gender norms for some types of labor vanished, when new energy forms arrived and modified society on a great scale. Now, anyone can drive a car, run a factory, and produce goods. In the 1800s, steam power was dominant, and fossil fuels such as coal and oil became standard power sources. One may think back on John D. Rockefeller’s enormous Standard Oil Company, for example. Then electricity arrived, pioneered by Nikola Tesla and Thomas Edison, and the 20th century introduced nuclear power and the first “clean energy” sources such as wind farms and solar panels. Now, in the 21st century, fossil fuels still persist but clean energy such as solar energy systems and residential solar energy are making for strong competition.