Walraven.Young.wiki.spring.2011

[] Solar Power  Mark Walraven and Brett Young   Spring 2011 Wiki Project The Problem

The world is running out of oil. It is impossible to make oil and when the supply runs out then new sources of energy must be found. With the emerging economies of China and India, the consumption of oil has been on a constant rise for the past three decades.

The world needs to find a viable source of renewable energy. We are slowly shifting from our dependence on oil: wind farms  are being constructed to harness the power of wind and people   are changing their cars to bio-diesel and running them with   vegetable oil. Although these new sources are being explored,  the demand for oil continues to rise. In this project we aim to  focus on solar power, just one of the many renewable sources   of energy that is available.

[]  The Solution

Solar power is a clean and efficient way of using the sun for energy. Solar power is used most commonly for photovoltaic cells, but technologies such as solar towers and solar water heaters use the power of the sun as well.

History of Solar Energy

Solar deities have been around since early religions were formed. People understood that the sun was a powerful part of their planet and worshipped the sun and the representing deity. Passive use of solar energy can be seen since the beginning of human life as well. Early man took a magnifying glass and focused the suns energy to create fire. This is the earliest known use of the sun to create energy. Other passive use of the sun can be seen during the time of the Ancient Romans. They took the sun into consideration when they built their bath houses. Large, south facing windows and open roofs where constructed in order to allow the heat from the sun to shine onto their baths. The North American Anasazi tribe had south-facing cliff dwellings to capture the heat of the sun during winter months.

[] The suns power has been harnessed and worshipped since the beginning of man. The transition into modern use of solar energy is just building on the technology of the past.

How it Works

Photovoltaics

The most common form of solar energy are photovoltaic cells. These cells use the photons in sunlight to create electricity. The cells use the photoelectric effect that was discovered in 1839 by French physicist Edmund Bequerel. This discovery showed that when sunlight hit certain materials an electric current is produced. The photovoltaic cells of solar panels take advantage of this discovery. The cells are constructed with a silicon semiconductor similar to those in electronics. [] The semiconductor is then coated with two elements, one that has an extra electron and one that needs an electron. The positive and negative sides give the silicon an electric field. The electric field created has the potential to create electricity, but it needs something to push the electrons across the field. This is where the sunlight comes in. Sunlight contains photons which carry energy in them. When these photons are absorbed by the cells, the electrons are able to move from their current position. This is known as photon excitation. This process allows the electrons to flow from the positive side of the semiconductor to the negative side. The positive charged hole that is created by the moving electron travels in the opposite direction and completes the circuit, thus creating electricity.

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Solar Water Heaters Solar water heaters are used in place of a conventional electric, oil or gas water heater. SWH’s use the natural heat emitted from the  sun to heat the water. This is done by setting up a collector box where  the heat from the sun is collected. Antifreeze is then used  to transfer the heat from the collection box to the water tank. Other models use a batch system where cold water is moved into  the collector box, heated up and then stored for use.

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Solar Power Towers

Solar power towers use the concentration of light to achieve greater amounts of energy in one location. Just like the famed heat ray of Archimedes, solar towers use mirrors to direct sunlight on one central location on the tower. The mirrors, also known as heliostats, are able to rotate and direct the sunlight throughout the day. The heat is absorbed by molten salts, a mixture of 60 percent sodium nitrate and 40 percent potassium nitrate. The heat is then used to create steam and run a traditional turbine generator.

[] Advantages and Disadvantages

Advantages
 * Can be used in large and small scale- from solar farms to watches
 * Easily constructed and installed at a consumer level- solar panels and solar water tanks can be mounted right at a person’s house
 * Completely silent- No loud, moving parts
 * Almost no maintenance- no moving parts mean no maintenance, only yearly cleaning
 * Long life span- solar panels generally last between 25-30 years

Disadvantages Many of the disadvantages are dwindling due to the increase in technology. The main thing holding solar panels back is the initial price but his will continue to decrease overtime as technology advances.
 * Solar panels are expensive to purchase- may take up to 8 years to be paid back in savings
 * Panels are useless when sun isn’t shining- during cloudy days or during the night the panels are not active
 * Location- City locations have very limited space to put solar panels, cloudy and overcast regions such as Seattle don’t get as much power from the sun

Conclusion

We only have a limited supply of fossil fuels available throughout the planet. The supply is only going to get smaller as time goes on. The dwindling supply of fossil fuels has continuously gone up in price and aren’t going to be getting any cheaper. Not only do fossil fuels present an economic issue they also emit greenhouse gasses which lead to global warming. Despite our best efforts to clean up emission standards they still emit thousands of tons of carbon dioxide and other greenhouse gasses. Solar power is among the cleanest forms of energy available. Other than manufacturing the panels, there is nothing being consumed other than the sun’s rays and nothing being released into the atmosphere. Solar Energy could be used to generate vast amounts of energy to power the world. Currently solar power is being used primarily to power our homes. However there are many new all electric cars available as well as in development. Potently we could use the solar energy to charge our new electric cars and fuel our need for a clean energy source for transportation needs. Despite the initial cost invest in solar panels they are very effective and economical. The more we invest in solar technology the more affordable it will become as new manufacturing techniques become available.

Sources

[|green econometrics — Information and analysis on the economics of solar and alternative energies] [|Types of Solar Power | Get Solar.com] [|Solar Power-Advantages and Disadvantages] [|How do Photovoltaics Work? - NASA Science] [|How Do PV Solar Panels Work - Solar] [|How Solar Cells Work] [|Energy Savers: Solar Water Heaters] [|What is a Solar Power Tower and How Do They Work?]