Solar energy: Solar One, Barstow, California, which consists of a circular arrangement of 1,818 mirrors, each measuring 23x23 feet (7x7 metres). These mirrors focus the sunlight onto a hugh central receiver, which sits atop a 300 foot (91 metre) tower. The mirrors are computer controlled to track the path of the sun. Water is pumped through the receiver and heated to a temperature of 960 degrees fahrenheit. The resultant steam runs a turbine, producing 10 megawatts of power for eight hours a day.