In the some of my early posts, I spent a considerable amount of time discussing open-source in terms of renewable-energy and some of the projects associated with it. While many people would argue that I am "Going Green", I once again assert that my interest has little to do with reducing my carbon-footprint. While that is a wonderful by-product, it is not the focus.
In most instances, I look at renewable-energy in terms of the small scale application. I am keenly interested in the so-called "off grid" applications. These are becoming more viable as commercial enterprise, and many companies crop up every day offering wind and solar energy-generation solutions. But my curiosity lays in the Do-It-Yourself (DIY), or shade-tree engineer side of the equation.
A comment that came back to me that pointed out one of the issues I could face was not necessarily in the generation of electricity, but in its storage. As have been seen in many projects, the electricity is often stored in deep-cycle lead-acid batteries. While these tend to have long lives, measured in years, the eco-friendliness of the battery is called into question. What happens to the batteries when they can no longer chemically store the electrical energy ? The answer can't be that good !
So this raises an interesting point - how DOES one store electricity without the use of chemical batteries ? One of the most promising methods is a technology that dates back thousands of years - the flywheel. The principle is straightforward: electrical energy is converted to kinetic energy when it is applied to the flywheel. The flywheel spins up, and then requires only a small amount of energy to keep it spinning. Then, once the energy-input is removed, the kinetic energy is re-converted back as the flywheel slows down.
This brief YouTube video shows the basics of how it works:
http://www.youtube.com/watch?v=mV_b5oMqc2M
OK - the science is somewhat more complicated, and the efficiency of such a battery is affected by such factors as friction at the bearing or friction of the air around the flywheel. These can be overcome, but require additional complexity be added to the solution. The use of magnetic-levitation bearings and vacuums are likely outside the abilities of most shade-tree engineers !
In the USA, a company called Beacon Power ( www.beaconpower.com ) has received a grant to build a 10MW battery in Stephentown, New York. The whole point is to provide a "smoothing" effect on the supply vs. demand curves of electricity in a state who is annually plagued by blackouts & brownouts.
But on a smaller scale, the use of a series of smaller flywheels could handle the storage of electricity for a reasonable amount of time. As we saw in the video above, the tiny flywheel kept the flashlight lit for a number of minutes. If we expand the solution to a reasonable limit, it should be possible to create an effective storage medium for smaller applications - say a home or a commercial building.
And the solution is thousands of years old.
The opinions expressed are purely those of the author. Opinions are like noses - everyone has one, and they are entitled to it !
2 comments:
The flywheel while a simple example of stored kinetic energy does not really have the ability to sustain power at a constant rate once the input is removed and frictional losses actually will cost you in the long run.
A better idea would be have natural resource like wind or solar produce electricity that does work when there is an excess of output like pump water up to a high reservoir and then at night or when the wind slows down use that stored kinetic energy to run a water turbine.
Yes the reservoirs would have to be huge at both ends but I think its more practical than a flywheel.
As anonymous points out, the flywheel has certain inefficiencies associated with it. In the large-scale implementations ( like Beacon Power's ), it is not being used as a long-term storage medium. It is intended to provide a smoothing effect for the power-grid. A common use would be to have the flywheel kick in to cover the "lag" created between when the principal power source (wind, solar, etc.) falters and the secondary power source (diesel generation, etc.) spools up. Indeed, it is a short-term stop-gap solution.
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