Electricity is generated when magnetic fields intersect/interfere with each other.
The generators have two sets of magnets. One is fixed and the other can move around it. When they move against each other, magnetic fields cause electricity to be generated. You can use any way to move those magnets against each other, and it does not have to be rotating (though that is more efficient), sliding against each other will also create electricity.
Mechanically, it is simple to design a rotating turbine which can be driven by a number of mechanisms. This also provides an optimal way of magnetic fields interference with each other. So it is more efficient.
To my knowledge there are only 3 ways to produce electricity. Spinning a magnet around a coil ie a turbine . The photovoltaic effect ie solar panels. And chemical reactions ie bateries. Problem is with bateries they are one time use as the chemicals change after the reaction and to bring them back to its original state you have to use energy.
So that leaves the first two to continuously produce electricity.
You answered your own question.
Most electricity is generated by burning a fuel and generating heat. That heat is used to produce steam where the kinetic energy turns a turbine. That’s how you generate electricity from fuel. You can, technically, convert heat to electricity directly but the efficiency of that is so far beyond horrendous (it’s very hard to convert heat to anything really) that you’re wasting your time trying to do it on an industrial scale.
Other ways of generating power that don’t use fuels don’t use turbines, like solar. There are also Radioisotope Thermoelectric Generators (RTGs), which generate electricity from the heat from radioactive decay, but they’re very specialized and mainly used for space missions because they have no moving parts but very low output.
We don’t know of any way to generate electricity directly from a fuel otherwise, because the energy released from burning that fuel isn’t electricity.
Because we are very good at building turbines.
There are alternative methods, like photovoltaic like solar panels. We can use heat directly to make electricity. We can chemically make electricity. The problem is that these methods are all inefficient in some way or another. With a turbine, we understand the effect pretty well: Spin some magnets around a wire, and it will generate electricity via induction. Most methods end up being a turbine because it would be really difficult otherwise. Converting heat directly to electricity without a turbine is incredibly inefficient, less than 10% of the heat is being turned into electricity. Modern steam turbines can reach as high as 80% efficiency. With rates that high, it becomes difficult to suggest using anything else. Nuclear power plants, coal/gas plants, hydroelectric, wind, geothermal and wave turbines all follow this principle. There just different ways to spin those magnets.
I see none of the comments mentioning how it’s actually extremely convenient to generate electricity using electric motors. In layman’s terms, you can more or less directly pipe an electric generator’s output into a high voltage transformer and down the transmission line it goes to the receivers.
This is because due to the mechanics involved and the laws of induction, a motor will reliably generate natural sine wave in phase AC at the right frequency you need, which is exactly what we use for most transmission lines, so all you have to do is convert the voltage to a higher one.
By contrast, for solar power for example, you need an inverter to turn the DC current you receive from the panels into AC. This means expensive and complex electronics and filters for getting out the right frequency and phase to feed into a transformer for distribution. Not to mention how you need to be very careful with its design and even the best inverter will introduce *some* amount of harmonics and even deforming power into the network.
Generating AC with motors is so effective, in fact, that there’s a type of DC to AC converter that’s actually just 2 motors. One motor that’s powered by DC to spin an AC generator that then sends your converted AC power. The power lost in the kinetic rotation and motor magnetic field losses is compensated by the quality of the AC signal at the output and the ease of using it in the application. The only restriction for this is the size of the device, so naturally inverters usually beat it out.
We generate most electricity by having wires in a rotating magnetic field.
Turbines capture the energy of fluids (waters or gasses) and turns it into rotation. They can spin magnets, creating the rotating magnetic field that we use to make power.
So basically: One of the best ways we’ve found to make lots of electricity is spinning things, and turbines turn other energy (heat, gravity, wind) into spinning.
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