Simon has been a guest columnist here on Winds of Change before, and he recently sent me a piece worthy of another online slot. I believe in guest columnists, by bloggers or even folks (like Simon) without one. It's a good way of improving the diversity of views etc. offered by Winds of Change.
If you're interested in doing a Winds of Change Guest Column, contact me.
Storage
by M. Simon
Every one needs storage. I'm not talking about that garage so full of stuff you have to park your car on the street. I'm not talking your refrigerator with the half filled bowls in the back that are so full of life. I'm not even talking that closet full of clothes that will get worn again some day.
What I am talking about is energy storage. This is a problem that has so far proved so difficult that there has been no wide spread solution. This is about to change on a number of fronts. Let me tell you about one of those fronts, mechanical energy storage - the fly wheel.
Mechanical energy storage is just now coming on the market. This type of energy storage is not new. But, the current designs take this technology to a whole new level. One of those levels is space. Up till recently most satellites used batteries to store energy for those times when the solar cells couldn't produce enough electricity for the satellite. Times like when the satellite was passing through the earth's shadow. Batteries in space have the same problem as batteries on earth. They wear out after about 1000 heavy charge/discharge cycles, and while they are wearing out their capacity is continually reduced.
To the rescue comes the high speed flywheel. These are not your ordinary metal flywheels either. These flywheels run at 100,000 RPM and are made mostly of plastic and carbon fiber. They do not use ordinary bearings because they would wear out too fast. They use magnetic bearings which have no contacting parts. In addition the satellites use the gyroscopic forces generated by the flywheels to orient them to the receiving stations as the satellites rotate about the earth. With no air in space the main source of friction other than bearings is eliminated. The life of these flywheels is estimated at ten to one hundred times that of the batteries they replace.
This technology is now being brought to earth by such companies as:
The technology has advantages over batteries other than life.One of the advantages is that you don't have to replace worn out batteries. The flywheels also need no maintenance for their life. Another advantage is operation at full capacity over a wide temperate range. Batteries are most comfortable at room temperature. High temperatures reduce their capacity some and low temperatures reduce their capacity a lot. Charging and discharging batteries also reduces their capacity. Flywheels are much less limited in these respects. All of these things are obviously very important in space.
Another advantage of flywheels is the fact that they contain no large amounts of nasty chemicals and toxic or dangerous metals. Flywheels can also be recharged rapidly without significant increases in losses and there is no wear out mechanism from repeated deep discharges as there is with current chemical batteries. Finally, flywheels also have a ten to one weight and volume advantage over lead acid batteries, the most cost effective batteries for stationary energy storage.
The disadvantages of the flywheel are several. The first and most serious is that if one fails, the release of all the stored energy in a fraction of a second is explosive. The second disadvantage is the flywheel effect. These two problems are solved by using the flywheel only for stationary applications, and burying them in the ground. What is cost effective and useful for a satellite is not so good for a car. But might be good for the home, factory, or office.
The third problem is cost. Right now, the lifetime costs for a flywheel system makes them attractive for those who already must use a large number of batteries for energy storage. Telephone companies, cell phone base stations, and cable television operations will be the first targets for flywheel storage. Currently flywheels cost two to five times as much initially as an equivalent battery system, but this initial cost is earned back over time by the elimination of replacements and maintenance. Fortunately, the costs are declining. In five years, costs are estimated to be one fifth of what they are now.
There also technical problems to be overcome, one is the relatively high energy losses over time. You lose about two percent of the stored energy every day with current technology. Engineers are confident that they can reduce this to a few tenths of a percent a day or less.
The advent of cheap reliable dispersed "electrical" energy storage will make intermittent sources such as solar and wind economically feasible. In addition storage can be used for load leveling, eliminating peaking charges for businesses that have a lot of motors with their high starting currents. With reliable short term energy storage, we get a lot more effective generating capacity without adding any new generating plants.
(M. Simon is an industrial controls designer and Free Market Green)
Flywheels are one of the most promising technologies for replacing conventional lead acid batteries as energy storage systems for a variety of applications, including automobiles, economical rural electrification systems, and stand-alone, remote power units commonly used in the telecommunications industry. Recent advances in the mechanical properties of composites has rekindled interest in using the inertia of a spinning wheel to store energy.