more pictures to come . . .Sunday, March 28, 2010
Friday, June 26, 2009
Solar Energy
What's so great about the sun ?
It takes millions of years for the energy from the center of the sun to reach the sun's surface, and then just eight seconds for it to travel the 93 million miles to earth! The sun gives off more energy in one second than people have used since the beginning of time. Plants make food out of sunlight, and then animals eat plants, and then we eat animals (or maybe we just eat plants, if we?re vegetarians). The sun produces nearly all the heat on the planet, too--without it, the earth would be freezing cold--minus hundreds of degrees Fahrenheit, almost as cold as space. The sun also makes the wind blow and the ocean currents flow. Its heat makes clouds, rain, snow, and all the weather on our planet, too.
What does solar energy mean?
Solar energy just means energy (light or heat) that comes from the sun. There are as many different ways to use solar energy as you have ideas in your head. What gets you hot lying on the beach on a summer day? Solar energy. What gets your car hot when it's parked in the sun with the windows closed? Solar energy. What makes your solar calculator go? Solar energy. What makes the giant solar panels on satellites work? Solar energy. What makes plants grow? Rain and... solar energy. What makes the clouds that make the rain? You got it! Solar energy. What sets a blade of glass under a magnifying glass on fire? Yup, solar energy. And on and on.
What are different ways we can use solar energy?
There are endless ways to use solar energy. That's true, but, to make things easier to think about, all those ways can be divided into two basic categories. First, we can use the sun's energy to heat things--our houses, the water in our houses, the food in a solar cooker, and so on. This is called solar thermal energy. (Thermal means heat, so solar thermal energy just means heat energy from the sun.) The second basic way we can use solar energy is to turn light from the sun directly into electricity, using solar panels. This is usually called photovoltaics.
How do solar electric panels work?
Solar electric panels are made up of something called silicon, the same thing that makes up sand. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move around. (Electrons are teeny tiny specks--they?re way too small for us to see, even under a microscope.) The electrons flow through wires that were built into the solar panel. And We have electricity! We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity.]
What if I want my solar panel to make electricity at night, or on cloudy days?
When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.
Where are solar electric panels used?
solar panels are attached to batteries, so the signs stay lit at night. Little solar panels are used on solar calculators (the panel is usually in a little strip across the top). You might have seen solar panels on people's roofs or on poles in front of their houses. And how about in space? You know those flat, black "wings" that stick off satellites and space stations? Yeah, solar panels! Can you think of other places you've seen a solar panel, or that would be a smart place for one?
How many solar electric panels would I need to power my house or apartment?
That depends on how much electricity you use in your house, and how much sun shines where you live. You need a lot of panels to power a whole house, though. The first thing you'd have to do, before you "went solar," would be to cut down on your electricity use. Otherwise you'd need so many panels that you'd go broke buying them and you'd have no room to play outside, because everything would be covered in solar panels. The average size of a solar system that completely powers a house is 2,000 watts. That's not a lot of power--just enough to run 20 or 30 light bulbs. (Except that if you were going to run your house off solar panels, you wouldn't use the same old light bulbs you've been using, that mostly make heat and just a little bit of light. You'd use super-efficient, long lasting florescent light bulbs.) To make 2,000 watts of power you need solar panels that are about 24 feet long by 10 feet high. That's about as long as one and-a-half cars and a little higher than most of your ceilings. That's still a lot of panels. But once you get them up, they last for well over 20 years. And since they have no moving parts, they almost never break.
What is solar cooking?
One of the many cool things about solar ovens is that they don't need electricity, gas, or wood to work--they cook food using only sunlight! Basically, you put food in a box and trap the sun's heat by covering the box with glass or plastic. (Solar cooking is an example of using solar thermal energy.) And they're easy to make! You can make one with two cardboard boxes, one inside the other, covered with glass or plastic. You can put crumpled-up newspaper between the two boxes to help trap the sun's heat, paint the inside black, and put aluminum foil outside to help reflect more sun into the cooker. Even a simple solar cooker like this one can reach temperatures over 250 F. Solar cookers are great because they save money and energy, and produce no pollution. Solar cookers can also be used to make water safe to drink, make doctor's tools safe to use, and heat water for laundry.
What can I cook in a solar oven?
Anything you can cook in a normal oven--the limit is your imagination. Just remember to use a dark colored pot, and use potholders! Solar ovens get hot!
Are there solar energy power plants?
Yes, there are a few. They are usually in hot, dry places, like deserts in California. Many different countries are planning to build more soon(There are basically two different kinds of solar energy power plants. One kind makes electricity using lots and lots of solar electric panels. The other actually makes electricity using the sun's heat--solar thermal energy. Basically, solar thermal power plants use lots of mirrors to focus the sun's rays onto one central area. That heat is used to boil water, and then the steam produced from the boiling water is used to make electricity--just like in a coal or natural gas burning power plant.)
If solar energy is so cool, why isn't everybody using it?
Even though humans have been using the sun's energy for thousands of years, photovoltaic (solar electric) technology is still very new, and a lot of times adults don't like to try new things. Even if they are the type of adults who like new things, sometimes it's very hard to switch to a new system once you have another system working already. (We have all those giant coal burning plants built already--what would we do with them if we built solar plants instead?) Solar energy technology is also getting better every year, so a lot of people might not realize that it's become as cool as it has. Making electricity with solar energy is still more expensive than making it by burning coal, and adults definitely don't like expensive. [Actually, though, if you count how burning coal hurts the environment, and if you count that the government helps pay for electricity made in coal plants, solar energy might not really be more expensive. Some people think that if you counted everything fairly, solar energy would actually cost less than electricity made from burning coal.]
Future Solar Energy Use
It takes millions of years for the energy from the center of the sun to reach the sun's surface, and then just eight seconds for it to travel the 93 million miles to earth! The sun gives off more energy in one second than people have used since the beginning of time. Plants make food out of sunlight, and then animals eat plants, and then we eat animals (or maybe we just eat plants, if we?re vegetarians). The sun produces nearly all the heat on the planet, too--without it, the earth would be freezing cold--minus hundreds of degrees Fahrenheit, almost as cold as space. The sun also makes the wind blow and the ocean currents flow. Its heat makes clouds, rain, snow, and all the weather on our planet, too.
What does solar energy mean?
Solar energy just means energy (light or heat) that comes from the sun. There are as many different ways to use solar energy as you have ideas in your head. What gets you hot lying on the beach on a summer day? Solar energy. What gets your car hot when it's parked in the sun with the windows closed? Solar energy. What makes your solar calculator go? Solar energy. What makes the giant solar panels on satellites work? Solar energy. What makes plants grow? Rain and... solar energy. What makes the clouds that make the rain? You got it! Solar energy. What sets a blade of glass under a magnifying glass on fire? Yup, solar energy. And on and on.
What are different ways we can use solar energy?
There are endless ways to use solar energy. That's true, but, to make things easier to think about, all those ways can be divided into two basic categories. First, we can use the sun's energy to heat things--our houses, the water in our houses, the food in a solar cooker, and so on. This is called solar thermal energy. (Thermal means heat, so solar thermal energy just means heat energy from the sun.) The second basic way we can use solar energy is to turn light from the sun directly into electricity, using solar panels. This is usually called photovoltaics.
How do solar electric panels work?
Solar electric panels are made up of something called silicon, the same thing that makes up sand. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move around. (Electrons are teeny tiny specks--they?re way too small for us to see, even under a microscope.) The electrons flow through wires that were built into the solar panel. And We have electricity! We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity.]
What if I want my solar panel to make electricity at night, or on cloudy days?
When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.
Where are solar electric panels used?
solar panels are attached to batteries, so the signs stay lit at night. Little solar panels are used on solar calculators (the panel is usually in a little strip across the top). You might have seen solar panels on people's roofs or on poles in front of their houses. And how about in space? You know those flat, black "wings" that stick off satellites and space stations? Yeah, solar panels! Can you think of other places you've seen a solar panel, or that would be a smart place for one?
How many solar electric panels would I need to power my house or apartment?
That depends on how much electricity you use in your house, and how much sun shines where you live. You need a lot of panels to power a whole house, though. The first thing you'd have to do, before you "went solar," would be to cut down on your electricity use. Otherwise you'd need so many panels that you'd go broke buying them and you'd have no room to play outside, because everything would be covered in solar panels. The average size of a solar system that completely powers a house is 2,000 watts. That's not a lot of power--just enough to run 20 or 30 light bulbs. (Except that if you were going to run your house off solar panels, you wouldn't use the same old light bulbs you've been using, that mostly make heat and just a little bit of light. You'd use super-efficient, long lasting florescent light bulbs.) To make 2,000 watts of power you need solar panels that are about 24 feet long by 10 feet high. That's about as long as one and-a-half cars and a little higher than most of your ceilings. That's still a lot of panels. But once you get them up, they last for well over 20 years. And since they have no moving parts, they almost never break.
What is solar cooking?
One of the many cool things about solar ovens is that they don't need electricity, gas, or wood to work--they cook food using only sunlight! Basically, you put food in a box and trap the sun's heat by covering the box with glass or plastic. (Solar cooking is an example of using solar thermal energy.) And they're easy to make! You can make one with two cardboard boxes, one inside the other, covered with glass or plastic. You can put crumpled-up newspaper between the two boxes to help trap the sun's heat, paint the inside black, and put aluminum foil outside to help reflect more sun into the cooker. Even a simple solar cooker like this one can reach temperatures over 250 F. Solar cookers are great because they save money and energy, and produce no pollution. Solar cookers can also be used to make water safe to drink, make doctor's tools safe to use, and heat water for laundry.
What can I cook in a solar oven?
Anything you can cook in a normal oven--the limit is your imagination. Just remember to use a dark colored pot, and use potholders! Solar ovens get hot!
Are there solar energy power plants?
Yes, there are a few. They are usually in hot, dry places, like deserts in California. Many different countries are planning to build more soon(There are basically two different kinds of solar energy power plants. One kind makes electricity using lots and lots of solar electric panels. The other actually makes electricity using the sun's heat--solar thermal energy. Basically, solar thermal power plants use lots of mirrors to focus the sun's rays onto one central area. That heat is used to boil water, and then the steam produced from the boiling water is used to make electricity--just like in a coal or natural gas burning power plant.)
If solar energy is so cool, why isn't everybody using it?
Even though humans have been using the sun's energy for thousands of years, photovoltaic (solar electric) technology is still very new, and a lot of times adults don't like to try new things. Even if they are the type of adults who like new things, sometimes it's very hard to switch to a new system once you have another system working already. (We have all those giant coal burning plants built already--what would we do with them if we built solar plants instead?) Solar energy technology is also getting better every year, so a lot of people might not realize that it's become as cool as it has. Making electricity with solar energy is still more expensive than making it by burning coal, and adults definitely don't like expensive. [Actually, though, if you count how burning coal hurts the environment, and if you count that the government helps pay for electricity made in coal plants, solar energy might not really be more expensive. Some people think that if you counted everything fairly, solar energy would actually cost less than electricity made from burning coal.]
Future Solar Energy Use
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