Solar energy

Solar energy is energy that is present in sunlight. It has been used for thousands of years in many different ways by people all over the world. As well as its traditional human uses in heating, cooking, and drying, it is used today to make electricity where other power supplies are absent, such as in remote places and in space. It is becoming cheaper to make electricity from solar energy and in many situations it is now competitive with energy from coal or oil. It can also be used for heating, drying and cooking.
Solar energy is used today in a number of ways:
- As heat for making hot water, heating buildings, and cooking
- To generate electricity with solar cells or heat engines
- To take the salt away from seawater.
Energy from the Sun
After passing through the Earth's atmosphere, most of the Sun's energy is in the form of visible light and infrared light radiation. Plants convert the energy in sunlight into chemical energy (sugars and starches) through the process of photosynthesis. Humans regularly use this store of energy in various way, as when they burn wood or fossil fuels, or when simply eating plants, fish and animals.
Solar radiation reaches the Earth's upper atmosphere with the power of 1366 watts per square meter (W/m2). [1] Since the Earth is round, the surface nearer its poles is angled away from the sun and receives much less solar energy than the surface nearer the equator.
The first diagram shows how solar energy varies at different latitudes because of this tilting away from the sun.
The second diagram shows how much of the Sun's energy is left after clouds and dust in the air have blocked some of it. [2]
At present, solar cell panels convert, at best, about 15% of sunlight hitting them into electricity. [3]
The dark disks in the third diagram on the right are imaginary examples of the amount of land that, if covered with 8% efficient solar panels, would produce slightly more energy in the form of electricity than the world needed in 2003. [4]
Types of technologies
Many technologies have been developed to make use of solar radiation. Some of these technologies make direct use of the solar energy (e.g to provide light, heat, etc.), while others produce electricity.
Solar cooking
Solar cooking uses the sun as the source of energy instead of standard cooking fuels such as charcoal, coal or gas. Solar cookers are an inexpensive and environmentally sound alternative to traditional ovens. By using the Sun as their source of energy, solar cookers allow people to allocate more of their resources towards food and other necessities by reducing the need to purchase conventional fuels. They are becoming widely used in areas of the developing world where deforestation is an issue, financial resources to purchase fuel are limited, and where open flames would pose a serious risk to people and the environment.
Other pages
References
- ↑ {{cite web | title=Solar Spectra: Standard Air Mass Zero | date=17 October [[172006-10-17 | work=NREL Renewable Resource Data Center | url=http://rredc.nrel.gov/solar/spectra/am0/ASTM2000.html | accessdate=2006-10-17 }}
- ↑ The average global irradiance calculated from satellite data collected from 1991 to 1993. For example, in North America the average insolation at ground level over an entire year (including nights and periods of cloudy weather) lies between 125 and 375 W/m² (3 to 9 kWh/m²/day).NREL: Dynamic Maps, GIS Data, and Analysis Tools - Solar Maps
- ↑ A solar panel in the contiguous United States on average delivers 19 to 56 W/m² or 0.45 - 1.35 (kW·h/m²)/day.us_pv_annual_may2004.jpg. National Renewable Energy Laboratory, US. Retrieved on 4 September 2006.
- ↑ International Energy Agency - Homepage
Other websites
- Solar Energy Industries Association is the national trade association for the US solar energy industry and has information on current commercial technologies and market developments.
- Direct solar U.S. Department of Energy: Energy Efficiency and Renewable Energy - Thermal water splitting
- U.S. Department of Energy: Energy Efficiency and Renewable Energy Solar History Timeline
- National Renewable Energy Laboratory: Concentrating Solar Power (CSP)
- Solar energy in the News
- ESTIF - European Solar Thermal Industry organization (statistics, market situation)
- Solar perspectives in Italy - Information on the Italian Solar Market
- Prometheus Institute for sustainable development
- Online article by scientist Jonathan G. Dorn, July 22-2008 The solar thermal power industry experienced a surge in 2007, with 100 megawatts of new capacity worldwide.
- Earth for Energy, make your own solar panels