Source: What's Up in the Environment?
National K -12 Subject:
Download and ShareThe United States primarily uses fossil fuels, like coal, oil, and natural gas, for its energy. You may think that we just use fossil fuels to run our cars, but many electric power plants burn coal, oil, or natural gas to generate electricity. Fossil fuels are considered non-renewable, meaning that Earth holds a limited supply of them and they cannot be replenished in a short period of time. Non-renewable energy sources come out of the ground as liquids (oil), gases (propane and natural gas), and solids (coal). They form from the buried remains of plants and animals that lived millions of years ago. Eventually it will be too expensive or environmentally damaging to tap these diminishing resources.
On the other hand, renewable energy sources are replenished by nature. Renewable sources include biomass (organic matter composed of plants and animals), water (hydropower), wind, geothermal energy (from heat in layers of rock below Earth's surface), and the Sun.
Solar technologies, for example, provide an alternate energy supply, reduce our dependence on fuels, and, unlike fossil fuels, do not add carbon dioxide to the atmosphere. Energy from the Sun can be converted to thermal (or heat) energy and used to heat water or spaces in homes, buildings, greenhouses, and swimming pools. It can also be changed into electricity using photovoltaic cells (also known as PV devices), which are cells made from silicon alloys. At the regional level, solar energy can be turned into electricity by solar power plants that collect heat in solar panels. Once inside the power plant, the collected heat is used to boil water and create steam, which then powers generators that create electricity.
Solar and environmental engineers, like those working at the National Renewable Energy Lab, are figuring out how to make renewable energy efficient and cost-effective. Currently, the machines used to manufacture solar cells cost tens of millions of dollars, and the materials used to make the cells are expensive. The solar-energy market has been plagued by the shortage of refined silicon, but scientists are researching alternate materials. In addition, in order to capture the most sunlight possible, solar installations generally take up a large amount of land, which makes them costly as they occupy valuable real estate.
The growth of the solar industry is creating many new jobs in the area of solar manufacturing and installation of solar technologies. Someday, systems that convert solar energy into electricity may replace the non-renewable energy sources we are so heavily dependent on today.
To learn more about energy consumption, check out Snapshot of US Energy Use QuickTime Video.
To find out how to use solar power in the kitchen, check out the Cooking Cookies with Solar Power QuickTime Video.
To learn more about the uses of solar energy, check out the Solar Car QuickTime Video.
To learn more about how technology is affecting the environment, check out the Global Warming: The Developing World QuickTime Video.
Chandler van Voorhis: Chandler speaking, what's up? As we become more gadget city USA we’re increasingly reliant upon the energy that comes through those electrical sockets of ours, and most of that energy is coal and natural gas.
Host 1: Coal, oil, and natural gas have to be burned in order to create energy. That burning create air pollution including carbon dioxide. People have been talking for years about making energy from clean sources, like the sun and the wind.
Radio Announcer: Welcome to GreenWave Radio, America’s number one show on the environment and business. Now here are your hosts, Carey and Chandler.
Host 2: Carey and Chandler are environmental journalists. They do their show every week on the radio and on the web. They’re crazy about energy, and they hang with the experts every day.
Chandle van Voorhis: Joining us today is Alden Hathaway.
Host 1: Alden Hathway is an electrical engineer, and he works for an organization that tries to get people to buy clean energy. He also recently built his dream house – a solar powered zero-energy home.
Alden: On average, I’m generating more energy I need from the solar energy, and that’s what makes this a zero-energy house.
Host 2: Alden’s house was built on the national mall for Earth Day 2000.
Alden: Between the Capitol and the President’s house.
Carey: Yeah, how'd that happen?
Host 2: He and his kids gave tours of the house to almost 26,000 people in just one week. Since then, the house was moved to Virginia and it’s not open to the public – but lucky for us, Alden’s 13-year-old son Tripp agreed to give What’s Up a private tour.
Tripp: Hi, I’m Tripp Hathaway and this is my home. First of all, this is a solar house. Panels that collect energy from the sun–that’s why they call them solar panels…that's solar comes from sun.
Host 1: It doesn’t matter if it’s cold out, but it can’t be dark or cloudy. This kind of solar energy system is called “photovoltaic,” which in English means it generates electricity from light.
Host 2: I think we all need a minute to see how it works.
Jean Posbic: This is the material that we use to make our solar cells. It’s silicon, pure silicon; it’s the second-most abundant element on earth.
Host 2: The little pieces of silicon are melted down at a temperature of nearly 1500 degrees centigrade – that’s 2700 degrees Fahrenheit. Then the silicon is sliced into super-thin wafers and coated with metals that conduct electricity. It’s one of these metals that gives them the blue color.
Jean Posbic: Interestingly, these solar cells regenerate the energy that it took to make them in less than a year.
Tripp: This is the inverter. The energy that goes through from the sun to the solar panels comes straight to the inverter. And energy that you are using would either go straight to where you are using it or it would be a stored to the batteries.
Host 1: The batteries are a back-up in for when it's dark or rainy.
Host 2: On sunny days, Tripp’s family sells the extra electricity to the power company. If the house produces more energy than the family uses, Tripp’s dad gets a check instead of a bill.
Host 1: Four words for that: energy efficiency and conservation. Tripp and Alden spent three years tracking the energy use in their old house, and figured out ways to cut it in half.
Tripp: This is basically what makes this house zero energy because it is so energy efficient. The pipes through here, they come in from under the ground, and they take the earth’s heat to heat the house and it is called geothermal heating, geo for earth, thermal for heat.
Host 2: The Hathaways also switched over to energy-efficient technologies like you might have at home –an Energy Star fridge, energy efficient computers, and compact fluorescent light bulbs.
Host 1: But did you know that if you leave the average desktop computer running all the time, it uses twice as much electricity as Tripp’s refrigerator does?
Host 2: How wasteful is that? Tripp told us that he’s really careful to conserve energy.
Tripp: Don't leave the TV running all day when you are not using it. Make sure your lights are turned off. Little things like that.
Host 1: You might think Tripp’s family is unique in generating their own electricity rather than buying it from the power company, but these solar panels in a park nearby generate electricity to power a community theater housed in this barn. And this is the solar array that powers GreenWave Radio’s web site and nearly 500 others.
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