Watt's That Junior

Here's the answer to our $50 question:

A hundred years ago, 30 percent of the people in Pasadena, California used this to heat their water. What was it?

2. The sun.

Sorry...the correct answer is #2!
Solar energy is not a new idea! People in California -- and other sunny parts of the United States -- heated water with the heat of the sun in the 1890's.

Your opponent can choose a new question.