ELI5- why do we need to find different ways to generate electricity if the main thing is turning the turbine? Can’t people turn it manually?

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ELI5- why do we need to find different ways to generate electricity if the main thing is turning the turbine? Can’t people turn it manually?

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Anonymous 0 Comments

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Anonymous 0 Comments

A person can manually crank at maybe 200 watts.

That’ll power a medium-sized PC.

So for every computer in the world would need to be a person on a treadmill.

And that doesn’t speak for factories, cars, lighting, heating…

Anonymous 0 Comments

Sure can. In fact you can buy emergency lights and radios with a hand crank on them. And in some parts of the developing world there are generators powered by peddling a bicycle. As long as the generator spins, you get power, it doesn’t really matter how you get it to spin.

The reason you can’t head down to your local power plant and offer to replace their need for fuel is because the amount of power you get out of a generator depends on its size and the bigger it is the harder it is to turn. Also the more power it generates the harder it is to turn. A human, and even a whole bunch of humans, simply can’t turn a big enough generator fast enough to generate the amount of power needed.

Also, even if a person could, you are just trading off the power source. People still need fuel, it is just in the form of food. It is massively less efficient to grow food, feed it to a person, to create the energy needed, to turn a generator, to create electricity. It is much more efficient to burn various kinds of fuel to generate heat to create steam to turn a generator. Less energy goes in for the amount that comes back out.

Instead we search for the most efficient, and these days least polluting, way of spinning the turbine to turn the generator. Some forms are very efficient for the power that goes in, such as hydro or wind. We harvest power that was there naturally to do the work (the water was going to flow and the wind blow regardless if we stuck anything in its path to let it turn). Alas both of them have limits in where you can put them and how much power you can get back out. So we continue to use other options like coal, natural gas, and nuclear. All of which create various levels of undesirable pollution.

Anonymous 0 Comments

No, that’d be too much effort for humans. We use far more electric power than we can generate using our bodies.

>In 2020, the average annual electricity consumption for a U.S. residential utility customer was 10,715 kilowatt–hours (kWh)

https://www.eia.gov/tools/faqs/faq.php?id=97

10,715 kWh ÷ 365.25 days/year = 29.3 kWh of electricity per household per day.

>Over an 8-hour work shift, an average, healthy, well-fed and motivated manual laborer may sustain an output of around 75 watts of power.

https://en.wikipedia.org/wiki/Human_power#Available_power

75 Watts * 8 hours = 600 Wh, or 0.6 kWh. That’s only 1/50^th of the electricity an average household uses in a day.

Anonymous 0 Comments

So we are bad at turning things to produce power. Some bike used to come with a little generator to power the headlight. When you clicked that light on you could really feel the difference it made, and that’s just a little 1/4 watt bulb.

Here’s a great example video. https://youtu.be/S4O5voOCqAQ

So if you are as strong as an Olympic cyclist you can manage to barely toast one slice of bread.

Anonymous 0 Comments

Turning a turbine does not generate electricity. A turbine is a device that harnesses the motion of a fluid (liquid or gas) and turns it into a rotational mechanical motion.

A water turbine uses the moment of water to rotate a shaft, a wind turbine use the moment of air, a gas turbine uses the exhaust gas from combustion, a steam turbine use steam.

The electricity is generated by a generator, the turbine is used to rotate the input shaft to the generator.

So humans can turn a generator but using a turbine is a bad way to do it, better is just directly push on coming like the pedals on a bike. The problem is the same as stated in other posts, the power of a human is quite low so it is impractical for most situations. It is used in some emergency radios and lights.

There is at least one relatively common nonemergency application, poser light in bicycles with a dynamo that one kind of generator. Today their dynamo-powered USB port to change phone when you ride a bike. That might not be a bad idea for long-distance bicycle trips, I talk about multiple-day backpacking trips. So generate electricity to power phones and other devices with similar power usage. It is not an economical way to generate electricity because the cost of the equipment will be more than ways grid power for phone charging will cost for a couple of decades. It is a way to change stuff when you are off the grin not to save money.

There is a way to generate electricity without a generator. The one way it can be done on the large scale at a reasonable cost is with solar panels. One other commonly used but not on that scale because of cost is non-rechagabe batteries.

There are some other ways like using a heat difference and a Peltier device. Devices exist for camping use with fire as a heat source. Some space probes and rovers use Radioisotope thermoelectric generators that use the radioactive decay for heat differential. This is an all cost and energy inefficient way to do but has niche use cases.

The bottom line is generators, not turbines generate electricity, turbines are just a good way to turn generators. Humans produce too little power to be relevant and there are other ways electricity is generated on the large scale in solar panels.

Anonymous 0 Comments

Easiest example: an iPhone 13 Pro Max battery contains ~16 Watt-hours. That’s enough energy to lift a 1000kg (one metric ton) block of concrete to a height of 5 meters (16.4 feet).

So you’ll have to do that every morning to charge your phone. And that’s just your phone!

Same amount of energy to use a microwave for 60 seconds.

Same amount of energy to use an electric stove burner for 30 seconds.

You’d die of exhaustion. 🙂

Anonymous 0 Comments

Some turbines rotors weight hundreds of millions of pounds. You aren’t spinning that with your (or a few thousand of your friends) hands.
Basically all the arguments about green energy are about how to spin that turbine.
And they do kinda turn it manually. They just use water or steam to do it.