According to the chart on page 5, what is true of solar energy? It is a far less common source of electricity generation than wind. It is more commonly used than petroleum to generate electricity. In the United States, the flow of electrical power is vital to everyday existence. In fact, while there are many forms of power, when people say, "The power is out they usually mean just one thing: they do not have electricity Electricity is a secondary energy source, which means that it is created from the conversion of another source of energy. In most cases fossil fuels, such as coal, petroleum, and natural gas, generate electricity. In 2014 about 1.5 trillion kilowatt hours of electricity came from coal. It was the primary source for generating electrical power in the United States. It is less reliable than geothermal sources for generating electricity. It is likely to replace natural gas as a primary source of electricity