You walk outside in the middle of July and can instantly feel the effects of the big yellow ball in the sky that we call the sun. Light so bright that you may need sunglasses and mid-summer heat that reduces one to shorts and flip flops are just some of the more noticeable results of being in the presence of our closest star. What is less apparent is that sunlight sends more energy to earth in “one hour than the world uses in one year”. This is according to the National Renewable Energy Laboratory (NREL), which is part of the U.S. Department of Energy (DOE) and works on finding and improving renewable energy systems. At a time when “85% of the United States energy supply (is) coming from fossil fuels” (Sota), which are nonrenewable resources, it is imperative that we come up with alternative forms of energy before those fossil fuels run out.
Solar energy is one of the most readily available forms of alternative energy, not just because the sun isn’t going anywhere for billions of years, but because we already have technologies that can harness the sun’s energy. Solar energy can be used to heat water in homes. Electricity can be created using solar energy through a process known as Photovoltaics . It can also be used as both a heat source and a way to cool your home (NREL). This technology is not limited to homes and small businesses either. Industries have begun to use solar energy along with other forms of energy to reduce costs and improve efficiency. On an even larger level, there are technologies being developed to harness the sun’s energy to power entire cities (NREL). If we can begin to integrate more solar energy into our energy production, then we can reduce our reliance on fossil fuels, which will benefit our environment greatly and improve the sustainability of our lifestyle. Solar power is a readily available system and has the potential to become our country’s main source of energy.
Before we can talk about the benefits of solar energy, it is first important to understand how solar energy is collected. There are three basic methods that are used to collect solar energy; flat-plate collectors, focusing collectors, and passive collectors (Godwin). There is also a fourth method known as photovoltaics. Flat-plate conductors consist of a large plastic plate which covers a dark colored box made of either copper or aluminum and painted with a special coating that is better at collecting sunlight than black paint. It collects the sunlight, and then the box is insulated to retain heat. How flat-plates work is that the sunlight passes through the protective plastic cover where it is converted into heat energy by the absorber plate, which is usually surrounded by water. The heat is then transferred to the water causing a rise in temperature (Heating). This lends itself to the typical use of flat-panels, which is as a water heater because “flat plate collectors are sized approximately one-half- to one-square foot per gallon of one-day's hot water use” (Heating). These are typically used by large families that need a lot of hot water for showers and laundry. On a larger scale, businesses such as Laundromats, car washes, and restaurants employ this technology. Another application of flat-plates is that they can be used to heat buildings, especially ones that are in areas that are prone to power-outages or aren’t on a power grid. These systems have a huge benefit because normally, the hot water that is used by these families and businesses is heated by either electricity, which in America is created mainly through the burning of fossil fuels, or by natural gas, which itself is a fossil fuel. As for cost efficiency, a solar water heater has the potential to save between 50%-85% on the hot water part of the utility bill and will pay itself off within four to ten years according to Washington State’s Energy Program.
(flasolar.com)
Along with flat-panels, focusing collectors can be used to collect sunlight and convert it into energy. Focusing collectors are a bowl shaped object that use special mirrors called heliostats to focus the heat from the sunlight that can reach temperatures up to 4000 degrees Celsius (Oracle). This heat is then used to boil water to create steam. The steam is then forced through a generator that creates electricity. However, because of these high temperatures, the silicon that is used to create the plates can be damaged leading focusing collectors to be used infrequently and mostly in colder climates (LLC).
The third system of solar energy collection is called passive collecting. According to Passive Solar Design, a company that has been designing solar technologies for 16 years, passive collection is “the use of the sun’s energy for the heating and cooling of living spaces. In this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun.” These systems are considered to be the least complicated solar energy systems because there are very few parts to them. Because passive solar energy is such a simple system, it can be easily implemented. It uses a more scientifically based. They have methods such as Operable Windows, which are just windows that open which help with ventilation, or thermal mass, which are just materials such as stone or other forms of masonry that retain heat and can prevent sudden changes in temperature in the house which would reduce the need for electrically run temperature control systems. Passive systems also employ thermal chimneys which use the fact that hot air rises to control temperature and increase airflow. The cost of designing a building that incorporates passive collection is usually similar or barely greater than traditional costs and the masonry that is used is normally considered an aesthetic benefit (Passive). This system is the most environmentally sustainable of all the solar systems because it does not use anything that would not normally be used to build a structure, but it rather changes how the building is constructed.
As convenient as a simple system is, the big need is still electricity production and that is were photovoltaics, which is the science of transforming sunlight directly into electricity comes in. The main component in this process is the use of semiconductors which are otherwise known as photovoltaic solar cells. Many of these cells put together make up what is commonly known as solar panels. The most common semiconductor is silicon and what it does it that it converts the solar radiation from the sunlight into electricity by creating an electric field with the radiation. It does not take much sunlight for the solar panels to create electricity, so they can operate even on a cloudy day, but the brighter the light, the more energy that is produced. This system of photovoltaics is a significantly cleaner process than that of burning fossil fuels. In a ratio of grams of carbon dioxide per Kilowatt-hour, the process of creating solar cells produces only 9.1% as much CO2 as burning coal and 9.6% as much as burning oil. This is important because carbon dioxide is considered one of the leading contributors to global warming (Photovoltaic). What makes these systems even more environmentally friendly is that the materials they are made of are recyclable, allowing used cells to be converted into new ones. Photovoltaic cells also have a very short return on the energy it takes for production. It only takes one-and-a-half to three years for the cells to produce as much energy as it took to make them (Photovoltaic).
(renewablesmart.com)
Solar energy is only one of the forms of renewable energy, but it is by far the most abundant. It is also second only to wind energy in how little carbon dioxide it produces, making it the second cleanest form of energy available today. Scientists are researching more way to use sunlight and turn it into energy and they are also looking for ways to improve upon the efficiency of the current systems. It is important that we put more effort into installing solar energy systems to replace ones that use fossil fuels not only to reduce our dependence on dwindling stocks of nonrenewable sources of energy, but also to switch to a form of energy that puts out one tenth of the amount of carbon dioxide into the atmosphere. Who knows? Maybe that big yellow ball in the sky will power our entire planet.
Work Cited.
“Solar Energy Basics”, Renewable Energy Sources, NREL, 7 Oct 2009, http://www.nrel.gov/learning/re_solar.html 21 Feb 2011
“Renewable Energy” Sokol Sota, http://www.greenscreen.org/articles_sr/Energy/Renewable%20Energy/Renewable%20Energy%20-%20Sr.pdf
Feb 15 2011
“Methods of Collecting and Storing solar Energy”, Tim Godwin, 20 August 2009, http://www.articlealley.com/article_1043840_27.html , 22 Feb 2011
“Solar Water Heating” , Washington State University Energy Program, http://www.flasolar.com/active_dhw_flat_plate.htm , Feb 23, 2011
“An Introduction to Solar Energy”, LLC, 2010, http://www.leedintl.net/solar_energy , 24 Feb 2011
“Science of Photovoltaic Energy”, DuPont, 2011, DuPont 2011http://www2.dupont.com/Photovoltaics/en_US/science_of/ , 24 Feb 2011
http://passivesolar.sustainablesources.com/#guidelines
“Photovoltaic energy”, EPIA, 2007, http://www.epia.org/fileadmin/EPIA_docs/publications/epia/Epia_Techno_leaflet_FINAL_WEB.pdf , 24 Feb 2011
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