Solar Energy

The annual solar radiation that reaches the Earth's surface measures about 3.3E+24 joules, more than six thousand times the total world's energy consumption of 459 quadrillion Btu, or 4.8E+20 joules, in 2006. The table below lists available solar energy for eight exemplary regions in the world. The solar energy from any one of these regions is larger than the world's total energy consumption. Solar energy from just one percent land in the United States can meet the whole nation's energy needs. The Sun has been used to light the Olympic flame, for instance. Solar panels are unique for operating satellites. Furthermore, photovoltaic energy and solar heat are often used for generating electric power. The heat is also used for heating water.

Find Solar Power by Yourself

The map on the upper-left corner provides a tool for you to estimate solar energy for any location in the world. You can either roam to a location, type in a location name, or type in an address, and then use the zooming and drawing buttons to draw an area on the map. The total solar radiation available for power generation in that area will be shown. By multiplying a conversion factor, typically between 0.1 and 0.3, you can figure out how much solar power you may get through using a solar power device. If you type in your home address, zoom in on your backyard, draw an area in the backyard, and provide a conversion factor value (e.g. 0.2), you can estimate how many kilowatt hours of electricity can be generated from a region within your own backyard.

Solar Energy Storage

Solar energy can be efficiently stored as heat for applications at night and during cloudy periods. Liquid-fluoride-salt heat transfer fluids are proposed to raise the efficiencies of both the heat-to-electricity conversion and the solar energy storage. The salt melts at 221 °C and can be heated to over 700 °C by absorbing concentrated solar energy. The salt’s working temperature in a heat exchanger for generating electricity may be set to a temperature between 400 °C and 700 °C. This technique has been put to practical use. A cylinder tank with a radius of 10 meters and a height of 10 meters has a storage volume of about 3000 m³. By storing the molten salt at a temperature of 700 °C, the tank can provide more than 1000 giga joules of energy (for a temperature drop from 700 °C to 400 °C) available for generating electricity.