United States of America
Enviromental Issues Country Study
Website created by: Skye Henderson
Solar Power
Though solar energy is extremely powerful, it only makes up 1-2% of all renewable energy sources (see chart on "Energy Sources" page). Thankfully, techniques to produce solar energy are becoming more common and available. There are two ways for solar power to create energy. There is a smaller scale method that is more commonly used in houses or commercial buildings. The larger scale method is used for more power plant usage systems. The smaller scale method uses photovoltaic cells or PV cells to generate electricity. These PV cells are installed on the roof of a home or building. The semiconducting material that is used to create the PV cells uses sunlight to create free electrons (electrons that are not attached to an atom, molecule, or ion). These free electrons travel across the PV cell and create an electrical current. This method is very effective but it does not generate enough energy to power entire power plants or larger area. To produce more energy a different method is used. Using mirrors, sunlight is focused and used to boil water. The water turns into steam which is used to turn steam turbines and create energy. Roof mounted PV cells, are able to produce energy in most climates, even those without constant sunlight. Lager scale solar power plants, are better suited for sunnier environments such as the Southwest U.S..
To learn more: http://www.learner.org/courses/envsci/unit/text.php?unit=10&secNum=11
Geothermal Energy
Geothermal energy is another renewable energy source that, like solar power, only makes up 2% of all renewable energy. This energy source is extremely promising, and with the U.S. leading with the most geothermal energy produced, there are high hopes for this type of renewable energy. The earth's natural heat is used to create energy. Cool water is pumped into the ground using pipes. Using the heat from deep inside of the earth, the water is heated and turned into steam. The steam is extracted from the ground to turn a steam turbine which creates energy. In principle, geothermal energy is a simple concept, the most difficult aspect is where to drill. It is important to find "hot spots" in the earth to drill near to prevent drilling too far into the ground. Before drilling, scientists analyze charts, satellite imagery, and seismic studies to find underground reservoirs to drill near. The western half of the U.S. full of geysers that provide adequate amount of heat to create geothermal energy.
To learn more: http://www.learner.org/courses/envsci/unit/text.php?unit=10&secNum=9
Wind Power
Wind power is one of the oldest forms of renewable energy. Thought it was not as advanced, using a windmill to ground corn, is the same concept as the new technology that is becoming more and more common. Some of the largest wind turbines are tall as a 20 story building with each blade being 200 feet long. The largest wind turbines are able to power up 600 U.S. houses, according to National Geographic. How can wind alone power so much energy? When the wind blows, the blades begin to turn. The blades turn a shaft which connects to a generator that produces electricity. Despite how simple the concept is, wind power only generates 13% of all renewable energy. Many people have many arguments against the use of wind turbines, such as the noise the machines work, and how birds fly into them. Despite these arguments, the industry for wind power is booming. Natural Geographic states that the wind power industry had quadrupled between 2000 and 2006.
To learn more: http://www.learner.org/courses/envsci/unit/text.php?unit=10&secNum=10
Renewable Energy
What is renewable energy? Renewable energy is energy that is produced by renewable or self replenishing sources. Renewable energy is a great alternative to fossil fuels. When used, renewable energy produces little to no greenhouse gases or CO2 into the atmosphere. Learn more about the most common renewable sources that can power our world. *
Biomass
Biomass is materials from plants and animals. Using biomass to create energy is one of the oldest sources of energy. Simply burning wood and waste from crops are now mostly used in developing countries, but the idea of bioenergy is now being further developed and is predicted to become one of the largest sources of energy in the near future. Though fossil fuels are also derived from plant and animal materials, the EPA states that there are some huge differences between fossil fuels and bioenergy. First of all, biomass is truly renewable in a human life span while fossil fuels take thousands of years to form. Second, though some forms of bioenergy do release CO2 into the atmosphere, they remove the CO2 from the air to. This creates a closed carbon cycle. When plants are growing, they require CO2 to grow, meaning that they remove it from the air. In reality, the biomass, just releases the CO2 that it has taken in back into the atmosphere. Also, biomass releases a lot less CO2 and pollutants into the air than fossil fuels do. Now, there are also a lot more efficient ways to use the energy in the biomass. Now fuels to power transportation (cars, buses...) are being developed. Ethanol uses corn and other crops to create a fuel that can substitute gasoline and produces significantly less CO2 and other air pollutants emissions. Using cellulosic (woody) plants to make ethanol is extremely promising, for many of these cellulosic plants contain more energy than carbohydrates. Biodiesel is another fuel that is basically vegetable oil yet can power many heavy-duty vehicles. Biomass fuels are now also being used for creating electricity. By using the fuel to turn water into steam then using the steam to to turbines that produce energy is a good alternative to power plants using high levels of fossil fuels.
To learn more: http://www.learner.org/courses/envsci/unit/text.php?unit=10&secNum=7
Hydropower
The idea behind hydropower is extremely simple, water flows through pipes called penstocks to turn turbines that are connected to generators which produces electricity. For the water to flow through the pipes, it is necessary to dam rivers. This way it is possible to create reservoirs and hold water when new water is not needed. The dams also allow the water to be released at once to flow through the penstocks. These dams have caused a lot more trouble than most sources of renewable energy. These dams have killed entire ecosystems and displaced many aquatic animals from their homes. Additionally, the dams change the river's natural patterns which affects many animals migration patterns. The dams also change the levels of dissolved oxygen and other nutrients. Animals that have adapted to specific levels of nutrients and oxygen in the water are at risk of dying from lack of the necessary nutrients.
To learn more: http://www.learner.org/courses/envsci/unit/text.php?unit=10&secNum=8
Source: http://upload.wikimedia.org/wikipedia/commons /8/8b/GreenMountainWindFarm_Fluvanna_2004.jpg
*All useage percentages are from chart on "Energy Use" page
How can the U.S. help other countries with this new technology? Find out more here!
