You know, thinking about this question a bit more, there’s two critical things I think @DougSpindler fails to grasp: A generator can run freely without any load and power isn’t what he thinks it is.
Think about this, I have a propane based whole home generator with automatic switchover. When it starts up, the engine is spinning the generator windings just fine even though they aren’t connected to an electrical load. At this point the generator is producing 120VAC@60Hz and putting out 0A. Suddenly, a solenoid throws an A/B switch and my entire house is connected as the load. Now, you can hear the engine connected to the generator briefly whine and slow down a bit. At this point it might be producing 110VAC@58Hz and putting out 30A. Within a second or so, the control loop inside the unit increases gas flow to the engine, to compensate for this newly added load. Now we’re back to 120VAC@60Hz. After a few minutes, say my Air Con kicks off, decreasing the load on the generator, so now the voltage jumps to 125VAC@61Hz until the control loop slows the engine.
Now, I know what you’re thinking, at the end there the “power” jumped up, right? Well, no. The voltage may have gone up five volts, however the current would have gone down an equivalent amount, keeping the total power draw the same.
So, while voltage may fluctuate as I add and shed loads to my generator, the overall wattage used will stay the same (since an appliance will use less current at a higher voltage and vice versa).
Keep in mind this is different for the typical power distribution network, as there are so many generators spread out over such a large area that as loads are added and shed it’s basically imperceptible to the home user.
@Timb, you are following me.
Second question.
What if the generators used permanent magnets and the speed of the generator was constant. IF the generator was connected to a load let's say 1,000 watts are being generated and consumed. When the switch is opened and current flow stops does that mean the generator has stopped producing 1,000 watts? I would not think so. The generator is still spinning at the same speed, the magnetic field is the same. So where does that 1,000 watts go?
It goes nowhere! The generator is no longer producing 1000W! It’s simply spinning unloaded. It’s producing xxxxV@60HZ with 0A output. Remember, power is V*I. If zero amps are flowing (no load) then zero watts are being produced.
Think about this: Say I take a wall adapter capable of 10W output (a USB charger perhaps) but instead of hooking my tablet to it (which can draw 10W) I plug in my phone (which can only draw 5W). Where does that extra 5W go? Nowhere!
Another thought experiment: You’re driving along in your car, the motor is at 3000RPM and you shift into neutral. Where does the “power” from the engine go? In this analogy power is mechanical force in the form of torque applied to the gearbox, which is applied to the drive shaft, which is applied to the wheels. Answer: Nowhere! Now the only difference is it takes less fuel flow to spin the crankshaft at the same RPM, since it has no load. So, as you engaged the clutch, you’d back off the throttle. In this scenario, *you’re* part of the control loop.
I think the critical flaw in your thinking is that generator is somehow “producing current” that must be “consumed” by a load. That is incorrect. A load *draws* current from a source. The current draw at a particular voltage is what makes up the power output of the generator. If the load is drawing no current, then the generator is sourcing zero watts and spinning freely.
Another experiment: Take a small motor (like the kind used in a toy) and connect it to a multimeter. Try to spin the shaft with your fingers. It should spin easily and you should see a voltage produced. (At this point the motor has a 10Mohm load.)
Now, connect a 1 ohm resistor across the terminals of the motor and try to spin the shaft. It should be a lot harder to spin. That’s because the current draw on the output is loading it down.
In the unloaded case, very little mechanical energy is required to spin the shaft.
In the loaded case, much more mechanical energy is required to spin the shaft.
Basically, it works like this: A source of heat (burning coal, natural gas or a fissile material) is used to boil water, which results in steam. The steam is run through narrow pipes to increase the pressure. This high pressure steam pushes a turbine that turns a generator. Heat is a source of energy. So, you can directly equate the amount of heat required to xxW of energy produced by the generator. If the generator is unloaded, very little heat and steam are required to turn the generator. (What is required are part of the losses from turning one form of energy into another; that is heat into mechanical energy into electrical energy.)
Is this making any sense?
Let's take your scenario but add a second generator. What happens if the second generator is 108 degrees out of phase with the other generator. I'm guessing here..... But I would assume there would be almost no current flowing to you home and all of the current would be flowing between the generators effectively resulting it a short and probably a fire (exothermic oxidative reaction) from over heating.
That scenario doesn’t reflect how generators in power distribution work. The generators at each plant would be locked in phase with the rest of the generators on the grid. I don’t know the technical details, but I imagine it involves monitoring the frequency of the grid and adjusting according.