How exactly does a turbine convert mechanical energy into electrical?

[AdrianGriff]

TL;DR Summary

What mechanisms and materials are used when a wind turbine converts the rotational mechanical energy to electrical energy within the generator? And is it possible to create a very small turbine for generating small amounts of DC power this way?

I understand that the turbine drives rotational motion of a low and high speed shaft which rotates within the generator, but how exactly, and with what components/materials does this create electrical energy? Is there a minimum required rotational speed or torque required to generate electricity? Does this minimum vary by size of turbine and generator? Does it vary by load? Is there a simple way to generate or convert this AC current into DC instead? Is it possible to make a very small version of this, potentially around 15mm in diameter of turbine blades?

 

[berkeman]

A couple questions for clarification...

Are you talking about wind turbines, or water turbines?

And are you familiar with how AC and DC motors work? If you are, then that is a good starting point. If not, you may want to read through the wikipedia introductory articles for background...

https://en.wikipedia.org/wiki/Electric_motor

https://en.wikipedia.org/wiki/Electric_generator

 

[anorlunda]

small amounts of DC power

You also need to clarify what you mean small amounts. A science fair demonstration that might make a single LED light glow is a very small amount of power. You could attach a homemade DC generator to a pinwheel and blow on it.

Some people think the power needed for appliances in an RV is a small amount of power, but it is several thousand times more power than a single LED.

 

[AdrianGriff]

A couple questions for clarification...

Are you talking about wind turbines, or water turbines?

And are you familiar with how AC and DC motors work? If you are, then that is a good starting point. If not, you may want to read through the wikipedia introductory articles for background...

https://en.wikipedia.org/wiki/Electric_motor

https://en.wikipedia.org/wiki/Electric_generator

I am referring to wind turbines with relatively lower speeds on a much smaller scale. And I am familiar with induction motors/generators and the like, but I am curious as to if there are any differences or more efficient methods for a generator in a wind turbine that can be used on small scales.

 

[AdrianGriff]

You also need to clarify what you mean small amounts. A science fair demonstration that might make a single LED light glow is a very small amount of power. You could attach a homemade DC generator to a pinwheel and blow on it.

Some people think the power needed for appliances in an RV is a small amount of power, but it is several thousand times more power than a single LED.

Well the "goal" is to attempt charging a 3.7V 350mAh battery with a turbine with a blade diameter of approx. 12mm. Obviously this is very small, so I'm curious if creating a teeny tiny generator would be viable.

 

[anorlunda]

Well the "goal" is to attempt charging a 3.7V 350mAh battery with a turbine with a blade diameter of approx. 12mm. Obviously this is very small, so I'm curious if creating a teeny tiny generator would be viable.

OK. That is possible if you have enough wind. However, it would be far easier and less expensive to do it with a solar panel. Below is a picture of solar panel phone chargers sold for campers.

And below is a picture of a wind powered phone charger.

 

[berkeman]

I am referring to wind turbines with relatively lower speeds

Well the "goal" is to attempt charging a 3.7V 350mAh battery with a turbine with a blade diameter of approx. 12mm.

With just one 12mm turbine? Or an array of turbines? Do you know the energy content of low-speed wind in that small of a swept area?

 

[anorlunda]

My experience with small marine wind turbines on boats is that they produce almost zero power until the wind increases to the range of 12-15 knots. Hence @berkeman 's question about wind speed where you are.

 

[cjl]

12mm? You won't make any kind of energy with a half inch turbine. The key with wind turbines is swept area, and you need a decent amount of it to make any kind of reasonable power. What's your application here - what are you trying to accomplish exactly? You could probably charge that battery at a reasonable rate (1hr charge time) with a turbine in the range of 10cm diameter or so, assuming a decent wind source (~10m/s), but that seems like it's probably not the ideal solution for a compact energy source given the unreliability of wind (especially down near ground level).