The Earth is a closed system but for two things: energy enters as solar radiation and leaves as heat. Most types of energy that we use are non-renewable (coal, oil), and some are renewable (wind, water), but solar energy is the only type that harnesses the power of something coming from outside our world. Thus, its use does not change anything already in place. (As two counter-examples, think about coal, the mining of which fundamentally changes the composition of the earth, or hydropower dams, which change the flow of water on the earth.)
The need for renewable sources of energy is a strong one, as is the need for sources that do not pollute or generally have harmful effects on the earth and atmosphere, such as carbon dioxide emissions. Also, the dependence on non-renewable sources means that we need to be careful that known sources of energy are not depleted. Of the many types of solar energy, the most well-known one is photovoltaics (PV). The benefits of PV include:
· low life-cycle cost
· zero emissions
· can be used off-grid (for example, in small villages)
· low maintenance/operation effort
· small loads in urban environments
Other types of solar energy include
· Passive Solar
· Concentrating Solar
· Solar Hot Water and Space Heating and Cooling
For information on these types of solar energy, see The US Department of Energy's Energy Efficiency and Renewable Energy page. This page is an excellent, comprehensive summary of different types of solar energy, as well as some relevant issues. In particular, see the page on PV and the Environment.
The following links contain useful information on solar power and other sources of renewable energy.
National Renewable Energy Laboratory - The US Dept. of Energy laboratory for research and development of renewable energy.
California Energy Commisions's site on renewable energy - Information on buying a system, installation, and other practicalities.
The Race - An article (written in 2000) on the manufacture of cost-competitive PV cells.
International Solar Electric Technology - There are two PDF files linked from this page that provide information on PV. The first, from NREL, is called "2002 NREL Research Review - Solar Electricity, courtesy of National Renewable Energy Laboratory (2002)." This is a short article on R&D of NREL. the second file is the Federal Technology alert on photovoltaics. This lengthy article contains some information on uses of PV in the country, benefits, costs and cost analysis. It is organized well enough that it is easy to search for the desired information.
Solar Cells Turn 30 - This article is on the first solar cell to reach 30% efficiency. The article is from 1988 but has interesting information on the production of solar cells. (This page is only available with a JSTOR subscription.)
Solar Energy summary - This is a powerpoint file used for a presentation on solar energy. It mostly contains lists on benefits of PV, types of PV systems, etc. All information is from other sources listed on this page.
Views of the Solar System - This page has some incredible pictures of the sun and eclipses. Really incredible.
page created in May 2003 by Lindsay Brin, for the Environmental Studies class Human Nature, Technology and the Environment
sun image on top of page from http://www.geocities.com/CapeCanaveral/Lab/2683/sunimage.htm