Energy, Power, Alternative Energy.

What is energy and how is it measured?
Energy comes is many forms, chemical, thermal, kinetic (energy of motion), and several others. Amazingly, all forms of energy are the same in some mysterious fundamental sense understood only by physicists. Because they are all the same, they can all be measured with the same units, for example in British thermal units, BTUs. When you turn on your electric heater for one minute, a coal plant somewhere turns 900 BTUs of chemical coal energy into 900 BTUs of heat. Of, this 600 (or more) goes up the smokestack, and 300 turns into electrical energy. The electricity flows into your heater and turns back into 300 BTUs of heat.

So the good news is we only need one energy unit, say BTUs, and we can keep track of every kind of energy. The bad news is, there are at least 40 different energy units in use and it's very hard to keep track of them without a special calculator To simplify life, this book will use only two differnt units, one for individual energy use, and one for national energy use.

1 GGE = 1 gasoline gallon equivalent.
1 Quad = 1 quadrillion BTU.

But just for reference, several interpretations of these using different units will be given here. These will not appear again. First note that 1 GGE is the chemical energy in one gallon of gasoline, so putting 20 gallons in your tank means putting 20 GGEs of chemical energy into your car.

1 GGE = 114,100 BTU = 33.5 kWh
1 Quad = 293,000 GWh = 33.5 GWy

Since a large nuclear plant puts out about 1 GW, a Quad is the amount of power produced by abut 33.5 nuclear plants during a year. The US uses 100 Quads of primary energy per year, and the average person uses 8 GGE per day.

Primary vs Delivered Energy
When 9 units of coal energy make 3 units of electrical energy, the US Department of Energy records that 9 units of "primary energy" were used by the US. When 9 units of uranium energy are used to make 3 units of electrical energy, the DOE records that 3 units of "primary energy" were ued by the US.

The Conservation of Energy—a la Einstein
Physicists have an easy time with conservation. They know "energy is conserved." It's a law of nature, like gravity, and there's no getting around it. Trouble is the mean something different than the rest of us. They mean energy cannot just appear or get used up, it can only change forms or go somewhere else.

Because of this persistence physicists say it is "conserved;" it's a much older concept than the ecologist's idea of energy frugality. Energy can take the form of chemicals ready to burn, the motion of a speeding car, the heat to warm your home. But, while it changes form, its quantity never changes. When a car comes to a stop it seems to lose energy, but it's energy of motion just goes into the form of heat and hides in the brakes. Then it leaks out of the brakes into the air and warms the air, and finally it may leave for outer space, but its amount never changes.

The strangest form of energy is mass. Energy can turn into mass and mass into energy. Tthe most famous equation in physics is energy = mass times a big number, or as Einstein put it, E = M C². The big number is the speed of light (186,000 miles per second) squared, but the number to use depends how you measure mass and energy. One valid version of Einstein's formula is this:
Energy in kilowatt hours = 11,324,243,000 × mass in pounds So if a pound of anything were converted into electrical energy without any energy being wasted it would give us a little more energy that a large nuclear plant generates in a year. All the energy used by the US in 1 year has a mass of 2585 pounds.

But "conservation of energy" has more practical applications. There are simple formulas that tell how much energy is transferred if you push on you bicycle peddle so hard over such a distance, and how much energy you have going ten miles per hour, and how much energy it takes to heat water 20 degrees. Combined with the principle of energy conservation, amazingly complex things can be figured very simply. It's possible to tell how fast you will go if you push on the peddle without knowing what gear the bike is in or how it works. As long as it works well, the energy of peddle pushing will turn into the energy of motion and that determines a certain speed. When the brakes are applied, no matter what they are made of, or how they work, then same energy will turn into the same amount of heat.

When coal is burned to generate electricity, about 2/3 of its energy heats up the power plant and its surroundings while about 1/3 of the energy turns into electricity. If that electricity goes into your home and runs a TV, light bulb, or refrigerator, it will do some tricks such as lighting your room or cooling your beer, but in the end all energy turns into heat. So if enough coal is burned to make your house 9 degrees warmer, and 1/3 of the energy goes as electricity to your home and runs your appliances, how much will that heat your home. The answer is 3 degrees. It does not matter what the appliances do. That energy goes into your house and it cannot disappear—because it's conserved.

http://zfacts.com/p/727.html | 01/18/12 07:23 GMT
Modified: Sat, 21 Apr 2007 04:53:01 GMT