Solar energy A Renewable Source of Energy

Solar Energy: a summary Solar energy is the direct radiant energy from the sun and a number of indirect forms of energy produced by the direct input. Solar and wind power currently provide only about 1% of the world’s commercial energy. There are two main main types of solar heating: passive solar heating systems and active solar heating systems Passive solar heating systems absorb and store heat from the sun directly within the structure. Ex: Adobe interior walls and special types of windows Active solar heating systems use collectors to absorb the solar energy and use a fan or a pump to distribute the heat throughout the structure.

Solar Energy: a summary Cont. There are a few options to cool a house naturally. Examples include using superinsulation, blocking the sun with trees or awnings, using windows and fans to keep air flowing, or suspending reflective foil in an attic to block heat from radiating through to the rest of the house. Solar thermal systems collect and transform radiant energy from the sun into high-temperature thermal energy or converted into electricity. A central reciever system, or power tower, used large computer-controlled mirrors to track the sun and focus sunlight on a central heat collection tower. A solar thermal plant, or distributed reciever system, collects sunlight and focuses it on oil-filled pipes that run through the middle of of curved solar collectors. A nonimaging optical solar concentrator intensifies the incoming solar energy by 80,000 times. Solar cookers cook food by concentrating sunlight on it.

Solar Energy: a summary Cont. Solar energy can be converted to electrical energy directly through Photovoltaic cells, or more commonly called solar cells. It contains an a semiconductor sheet that the sunlight energizes and causes the electrons to flow and creates a electrical current. The DC (direct current) is created by the electrons and can be stored in batteries and used directly or it can be converted to conventional alternating- current (AC) electricity by a separate inverter or inverter built into the cells.

Advantages of solar energy Saves money Reduces air pollution (99% less than coal) Land use less than coal Backup and storage devices available Energy is free Low to no CO2 emissions Reduces dependency on imported oil

Disadvantages of solar energy Making solar cells produces toxic chemicals Solar systems last only years Solar cells and solar thermal systems still too costly Some need access to sun 60% of the time Active solar systems needs maintenances and repair and they are unattractive Blocks sun from other structures that need it

Haley’s Reviews The Austin City council has started a project to build a 300 acre solar array that is going to generate enough electricity to power 5000 homes. This would be the largest in the US. This would be paid for through grants as well as tax credits, the grants would come from the recently enacted federal stimulus package. This project will be carried out in 3 phases and should be completed December Penn State researchers have found that carbon dioxide emissions could convert to CO2. A professor there, Craig A. Grimes and his team has used natural sunlight to test this and found that using visible light a higher yield of methane can be achieved. These researchers are currently working on converting their batch into a continuous flow-threw design.

Jessica’s Reviews I reviewed the article “Solar Power wins Enthusiasts but Not Money”, and learned that solar power energy can be converted from sunlight into electricity that can power crop fields or skyscrapers in L.A. Experts say that even in a quarter of a century the energy of Solar Power will only be about 2-3% of the energy used in the United States. Also, coal power plants are being built around the U.S at a rate of more than one per week. The plants contribute to the primary problem of global warming. I also reviewed the article “The Technology That Will Save Humanity”. I found out that using sunlight as a source of energy is one of the oldest ways used to create a power. Experts say that solar energy will be one of the major ways to help prevent and slow global warming.

Emily’s Reviews I reviewed the article titled “Solar-powered charging systems to help hurricane recovery efforts” which I found on Eurekalert.org.Eurekalert.org From this article I learned that the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the Florida Solar Energy Center (FSEC) provided solar electric charging stations to help residents of Kiln, Mississippi recover from Hurricane Katrina. They are providing them with charging stations which will keep vital communication equipment up and running. I reviewed tI reviewed the article titled “Solar electricity symposium” which I found on EurekAlert.orghI found on E From this article I learned that people in Israel are meeting at the Ninth Sede Boker Symposium to discuss solar-power generation projects from around the world and the ground breaking work they have been doing in Israel.

Kaitlyn’s Reviews This article lays out the plans for a 100% solar heated home. Economists normally say that it is only economically ideal to heat 70% of the time with solar energy and the rest with fossil fuels. However the author says that if you use passive solar heating as well, it is just as economical for the homeowner. The author also states that there are four basic passive solar systems that are effective in home heating: direct gain, water wall, Trombe wall, and sunspace. I think that this idea could be used in the future to cut down fuel cost. This article talks about major chains in the retail industry, such as Kohl’s, Macy’s and Whole Foods, installing solar panels on the roofs of there stores in order to cut back on energy uses and draw in green customers. According to this article, if Wal-mart’s test store does well they would possibly be the chain to use the most green energy. as s Macy’s and Whole Foods, installing solar panels on the roofs of there

Questions What type of heating system absorbs and stores heat from the sun directly within a structure? Solar and wind power only account for what percentage of the world’s commercial energy use? How much cleaner is solar power than coal (percentage based on air pollution)? In active solar heating, what is used to distribute the stored heat? How can solar energy be directly converted into electrical energy? What solar energy absorbing system uses mirrors to track the sun and focus sunlight on a central heat collection tower?

Answers Passive solar heating system 1% 99% cleaner Pumps or Fans Through the use of photovoltaic cells (or solar cells) A central reciever system