Making electricity out of thin air

Energy & Sustainability
Making electricity out of thin air

[Photo from Connors934 on Flickr]

For this final installment of our Make: Green series, we look at a promising technology for generating electricity: wind turbines. A wind turbine consists of a propeller, a generator, and either an inverter or storage system. The propeller is essentially two or more airfoils attached to a hub. When the wind blows across the surfaces of the blade, it creates areas of low and high pressure, and this difference causes a change in movement. As the turbine turns, a generator attached to the hub on the prop turns a coil in a magnetic field. Moving magnets cause electricity to move through the wires of the generator, which moves through the circuit towards the electronics that regulate either the battery storage system or the inverter for grid-tied systems.

OtherPower, the cutting edge of low technology, is a great resource for information on wind energy and turbine building. They’ve been building and testing wind-harnessing systems for years, and recently published a book HowmeBrew Wind Power, to help people learn how to generate their own wind power.

If you want to roll your own wind-powered electricity, definitely check out the great resources at The Workshop, which has all kinds of useful documentation of experiments and ideas. Their energy pages are especially good. I like this one on experimenting with the blades from box fans.

Hull, Massachusetts, is one of the leaders in municipal wind power in the United States. The town has a long history of generating power from the wind that blows across the nearby waters. Volunteers in the town operate the Hull Wind website, archiving and distributing information about wind power generation.


[Image from The Back Shed]

If you have some spare stepper motors in your junk/parts pile, you might want to check out some of the stepper motor based generators. The Back Shed has a neat project idea that uses steppers to convert the wind energy to electricity.

There is a lot of energy in the wind. Power is the cube of speed, so a 40kmh wind has eight times the power of a 20kmh wind. As an example: a perfectly efficient windmill may produce 200 watts of power in a 20kmh breeze, 800 watts in a 40kmh wind, and 6400 watts in a 80kmh storm gust.

But what sort of windmills are we talking about? First up a few simple rules about windmills. Windmills behave in a way very similar to your average car engine. They have a power and torque curve, with different speeds for maximum power or torque. For electrical power generation, ideally, you need to operate your windmill in its peak power output.

  1. More blades = less speed, less power, but more torque, perfect for pumping water.
  2. Less blades = more speed.
  3. Larger propeller diameter = less speed, but more power.

Shawn Frayne, author of one of the chapters in the Engineering the Future high school engineering text, developed a really clever way of generating electricity from the wind: the wind belt. Jason Striegel wrote about it here a few years ago. The video above points out some of the amazing possibilities.

You may also want to check out the other articles in our Make: Green series:

12 thoughts on “Making electricity out of thin air

  1. fascism says:

    There is nothing “green” about this technology. You still have to drill for the oil to make the plastics and strip mine the Earth for the copper and other raw materials. Not to mention how dangerous the batteries are.

    And, yes General Electric does control you. Through their manipulation of the presidential elections via the propaganda spread on NBC & MSNBC. General Electric is trying to get tax breaks and government grants from Obama and is set to make billions off cap-and-trade taxes and “free” health care. And I’ll bet you idiots protested Halliburton…

    Tell General Electric/NBC to cover ACORN voter fraud, and leave the technology stuff to those who understand it.

    1. zof says:

      man take a chill pill, yes you have to use something to make something, the question is, is the payout more then the cost. I suppose from your point of view, burning oil and gas for power is more feasible?

      When you shoot stuff out like that you don’t gain any sympathy to your views instead you alienate the people you are trying to convince so in essence you just wasted your time writing that, and so I am wasting my time replying to this flamebait. Either way just chill out, anyways I’m sure humanity will be killed by an asteroid way before it has a chance to kill itself with green house gases.

    2. Jack of Most Trades says:

      Whatsamattah, “fascism”, too many of your co-workers already posting at MSNBC’s “Newsvine”, so you came over here?

      “Tell General Electric/NBC to cover ACORN voter fraud, and leave the technology stuff to those who understand it.”

      There ought to be a corollary to Godwin’s Law about the name ACORN, but who would you suggest we rely on for our “technology stuff” (gawd, I love that techie jargon)? The American Petroleum Institute?

      I enjoyed these videos. These wind machines are popping up like weeds around here (6 are going in a mile from where I live)and I think they’re pretty exciting. Since Indiana ranks pretty close to the top of the list for “dirty” power production (almost 100% coal) I’m glad to see wind power being explored on such a large scale.

  2. swild says:

    Wind power is fantastic for small applications, such as providing supplemental energy to homes. But the cos vs. energy production is pretty steep. And large scale applications are largely impractical too, unless you have a constant wind source. A scotish energy compant made this statement in the following Reuters article:

    “Britain, which aims to install about 30 gigawatts (GW) of wind turbines by 2020, will need to build almost as much backup power generation for calm weather periods, an executive from Scottish Power said on Wednesday.”

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  4. Andrea says:

    With some research I was able to find a step-by-step process of how to create electricity from air.
    It is really interesting and I hope you all visit this site!
    Good luck everyone!

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