Get it? Thus, the rotating loop produces an oscillatory flux; if you plot its values, you will trace a sine wave. This creates an oscillating voltage in the wire, causing electrons to move and bang: you have alternating current. You just created a generator! This is called electrical induction.
Now you can strengthen this by replacing a single loop of wrapped wire with a coil containing many, many loops. Oh, and it also works the other way around: instead of rotating a coil in a stationary magnetic field, you can rotate magnets around a stationary coil. Only relative movement matters.
Spin it
As you can see, almost all methods of generating electricity come down to a magnet and a coil of wire. We just need a way to rotate one or the other. For this purpose we have several options. If you place huge blades on a rotor and expose it to the wind, the collision of air particles with the blades will create torque and rotate the shaft. It’s a wind turbine. You can also put turbines in a huge dam and operate the flowing water to turn them – that’s hydropower.
You can also boil water and operate the steam to drive turbines. In fact, this is what most power plants do, usually burning fossil fuels for heat. It could be coal, oil or natural gas, it’s the same technology. You can also tap into underground heat and operate it to generate steam – yes, that’s geothermal energy.
In fact, that’s how nuclear power works: you take a ponderous element like uranium and split it into smaller atoms, which creates energy to heat water and run steam turbines. Yes, the only difference between a coal-fired power plant and a nuclear power plant is how the water is boiled. You thought it was more complicated, right?
But once again there is a major exception – a manufacturing technology that does not operate electrical induction. Did you notice the omission? Ironically, these are solar panels. Photovoltaic cells are solid-state devices – they have no moving parts – and convert airy directly into electricity.
Straight from the source
How much juice can we get directly from the sun? Well, the intensity of solar radiation decreases as you move away from it, because a given amount of airy is scattered over a larger area. And when it reaches Earth, some of this airy is absorbed or scattered in the atmosphere. (That’s why the sky is blue.) But we’re at the perfect distance, one that prevents the oceans from boiling or freezing.
At the equator, the solar flux – the amount of energy hitting the earth – is about 1,000 watts per square meter. Of course, the Earth is curved, so its surface area decreases as you approach the poles. But in a good location, with a panel that has a conversion efficiency of 20 percent, you can get as much as 200 W/m2. This means that you only need a few panels to provide all the electricity your home needs.
So yes, most of the energy we operate comes from the sun. You can even think of fossil fuel deposits as batteries storing solar energy for future civilizations. However, thanks to senior technologies, we obtain this energy indirectly, after repeated transformations from one form to another – and inevitable losses along the way. Why not eliminate the middleman and go direct? No carbon dioxide emissions, no air pollution, no radioactive waste, no mining and transportation costs. And the sun will shine for 5 billion years.