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You may be surprised at some of the marvelous solutions a flywheel battery, being developed by RPM (Regenerative Power and Motion), can offer, as UPS (Uninterruptible Power Systems) and solar/wind power enabler and maximizer.
But simplistic flywheel notions persist. Costly fiascos result, when haste wins over sound engineering discipline. You need to start with basic flywheel physics long before you attempt preliminary, then detailed design, for a product development and test project. It requires a multi-disciplinary team, having extraordinary expertise in specialties like fiber composite material, rotor dynamics, strength of materials, magnetics, power electronics, position sensors, control systems, gas dynamics and viscosity, vacuum techniques (for zero windage loss), unique magnetic material and conductor configurations (for zero hysteresis and eddy loss), and abnormal event control (to protect people and property).
This work is definitely not for those with short attention spans. It requires sustained effort and dedication. Without that, you may not be able to discern engineering marvels (that can greatly improve all life on our planet) from fiascos (that can't work, or worse yet, can do great harm).
As you read about different projects below, you may want to try predicting outcomes, before learning how projects concluded. For some, I couldn't wait, to state my opinions. I apologize for that, if you are only interested in the facts; but prior reasoned opinions based on experience might save us from government embarking on even more costly and harmful fiascos financed by taxes.
Difference between low- and high-speed flywheels
Low-speed flywheels have been performing very useful functions for over a century. Punch presses and combustion engines are good examples. But they don't need to store much energy, and their power is delivered in a very short time span. The punch press may go thru a complete storage and delivery cycle in a second or so; and deliver its energy in a few milliseconds. Its maximum flywheel surface speed is about 20 ft/sec. A 1000-rpm 4-cylinder engine flywheel has a 15-millisecond storage and delivery cycle. Its maximum surface speed is about 50 ft/sec. Windage losses, for both, are not significant.
Low-speed (typically 3600-rpm with 2-ft diameter) flywheel power storage systems, offered currently by dozens of companies for UPS (Uninterruptible Power Supply) service, can deliver power for only 10 to 50 seconds. Its maximum surface speed is about 400 ft/sec. Windage losses are small, without vacuum enclosures, compared to friction, hysteresis, eddy, and winding losses of typically over 1-kw.
High-speed (up to 100,000-rpm with 0.7-ft diameter) flywheels are designed to deliver power at 1-kw or so for hours. Maximum surface speed can reach 3000 ft/sec. Windage losses at normal atmospheric conditions, and in a poorly maintained vacuum, would be about 1-kw. Hysteresis and eddy losses can be under 5-watts. So vacuum enclosures, and manufacturing processes to maintain vacuum, are crucial.
A few flywheel companies are developing high-speed flywheel UPS, with conventional motor/generator (some having conventional lubricated ball bearings) and magnetic bearing technologies. Idling losses, as might be expected from such a piecemeal approach, are high. Also, internal hot spots, vacuum loss, and bearing wearout, necessitate troublesome maintenance -- usually facilitated by gasket seals which compound vacuum loss problems.
Space satellite power storage and gyroscope -- a good job for flywheels
Space satellites powered by photovoltaics, especially the geo-stationary type used for communications and global position data, need both nocturnal power storage and inertial attitude control. Important advantages of high-speed flywheels here, over electrochemical batteries:
Giant solar reflector/concentrator in space (with or without flywheels)
This concept scared me, when I saw proposals over 30 years ago, for government funding. It advocated a giant solar reflector in space, that would beam concentrated solar power down to a solarthermal engine that would then drive an electric power generator. Quite apart from global warming, I was concerned about an apocalypse if its aim was not 100% reliable.
Flywheel enthusiasts may have advocated flywheel power storage for the generator and/or an onboard flywheel, for solar reflector attitude control. I'm sure flywheels were not a pivotal issue.
The proposed project was apparently not funded beyond a study contract. I hope it's dead and buried.
Giant PV and microwave converter in space, to beam microwave power to Earth...
The January 2001 PCIM (a magazine about power electronic systems) tells about recently revived interest in a DOE design for a 5210 km photovoltaic array, feeding a 2.45 GHz microwave converter, its output beamed to a power receptor on Earth. DOE concluded it might be feasible, on a scale a million times larger. What are they thinking? The only reason stated for not building it was its prohibitive expense.
I hope cost is not their only reason. Again, global warming, and frying any life caught by an errant microwave beam from such an absurd system, aren't trivial concerns.
Car powered by a flywheel via gears and clutch..
A totally mechanical flywheel powered car experiment was federally funded about 25 years ago. The high-speed fiber composite flywheel, with speed reducer gears, was in a vacuum enclosure. The gears were connected to a clutch by a shaft thru the enclosure having a rotary seal to minimize vacuum leak.
The flywheel was spun up when the vehicle was idle. When driving, it was supposed to power the car like an engine. This experiment was quietly abandoned, after an announcement that a flywheel disintegration test was to be conducted. I never heard how that went. With their rotary seal, I bet the vacuum didn't last an hour. This project was doomed from the outset.
The onboard flywheel powered EV with 400-mile range..
Do you remember the electric vehicle predictions, that onboard flywheels, recharged in minutes, could provide a range of 400 miles? The fast recharge is based on a very-high-power motor/generator, which is certainly possible, but not so practical. The 400 miles is based on the energy/weight ratio of modern fiber composites, compared to lead-acid batteries. But it fails to consider possible uncontrolled flywheel disintegration.
Let's do some easy math, based on physics explained by Isaac Newton (1642 - 1727) 300 years ago. For a 2000-pound EV, that cruises at about 60-mph, rolling friction force may be about 20 pounds, and aero drag about 30 pounds, for a total drag force of about 50 pounds. If all goes as planned, the flywheel can output 8 hp or 6 kw for up to 6.6 hours. To sustain a 50-pound thrust for 400 miles, energy stored by the flywheel must be 20,000 pound-miles. If the flywheel were to explode, its energy could blast a 2000-pound EV a height of 10 miles! That's not normally what would happen, because the blast would be multi-directional, not entirely an adiabatic and isothermal process, with much of it spent doing local damage, and aero drag on explosion fragments would be considerable, But it's a vivid way to characterize a possible uncontrolled energy release.
When this concept was promoted, it was argued that any possible explosion could be contained within the flywheel's vacuum enclosure. But such an enclosure would weigh far more than the flywheel. And in a collision, all bets are off. Moreover, they neglected idling loss, which is considerable for a flywheel with magnetic bearings that gets jostled a lot. I don't see recent claims about this onboard flywheel future; but many still hold onto this ill-conceived notion.
Vehicle with onboard flywheel for acceleration and regenerative braking...
This is the concept currently promoted by major auto companies with US government funding. An onboard flywheel would help accelerate the vehicle (fuel-burning engine "hybrid EV") by providing a 200-pound thrust for 10 seconds or so. For regenerative braking, thrust is reversed.
Although energy stored is far less here, collision hazard is still problematic. Plus, if the driving sequence involves long intervals between braking and acceleration, flywheel idling loss could dissipate so much of the stored energy, that the flywheel would not be effective.
Flywheel promoters with non-informational "product specifications" and non sequitur claims
I'm annoyed by flywheel company brochures that tout advantages of their flywheel UPS over conventional fuel-burning generators and lead-acid batteries -- but can't replace conventional UPS because their flywheels can sustain output power for only 10 seconds or so. Their promoters claim that adding their flywheel to conventional UPS improves battery life, by saving the batteries from relatively frequent short-term grid power outages. Experimental data does not support this claim, unless a 10-second discharge amounts to a significant part of the battery storage capacity, and grid outages occur almost daily.
Those brochures rarely include their flywheel UPS energy storage capacity, perhaps because it's usually equivalent to only 1 or 2 batteries. And they usually don't mention idling power, perhaps because it's over a kilowatt or so. They usually spec peak power, but it's not generally more than a battery bank can supply.
Maintenance is usually required, because these systems can have motor/generators with conventional ball bearings, and iron core laminations that get hot from hysteresis and eddy losses, while idling. If their flywheel is enclosed in a vacuum, it probably has gaskets to facilitate re-opening their enclosure for maintenance. And their manufacturing procedures may not include vacuum resin curing, or high temperature at high vacuum to remove internal and surface contaminants, that will outgas under long-term vacuum in excess of getter capacity to trap these molecules. Thus, in addition to vacuum leaks, they incur vacuum loss from outgassing.
However you measure it, life-cycle cost for their flywheel UPS is far higher than battery UPS. Reliability is not improved. Maintenance is not even reduced. No wonder lead-acid batteries command the lion's share of the world's electric power storage market.
RPM's on-site flywheel battery: UPS/storage for buildings and electric highways...
Let's examine a flywheel battery without the negative consequences of the preceding projects. It will weigh about 20% as much as equivalent energy lead-acid batteries. It will not need maintenance. It will have a dependable service life of more than 100,000 charge/discharge cycles, vs. 1000 cycles (and dropping dependability with use) for lead-acid batteries. This is a 100x improvement. RPM plans to offer a 20-year warranty. It will have a lower life-cycle cost than lead-acid batteries. It will not have environmental problems, with processing or disposal. It will be absolutely safe.
Briefly, this requires interdependent design constraints, imposed at the outset of RPM's product development program, on RPM's proprietary virtually zero power magnetic bearings, and proprietary motor/generator having minimal hysteresis and eddy losses. The greatest product development challenge is RPM's goal of only a few watts idling power, while maintaining rated energy storage. This is vital to cool temperatures within the flywheel enclosure, and certainly to acceptably low self-discharge rate (an electrochemical battery term). We don't think it can be achieved with a mobile flywheel such as onboard a road vehicle. RPM's flywheel battery is intended for applications that accommodate a stationary installation, preferably underground.
For an illustrated general description of RPM's flywheel battery and its UPS applications, click here.
For a detailed design and performance comparison with other flywheel UPS, click here.
For an illustrated description of electric highways, that can enable unlimited range EVs, powered by RPM's flywheel battery and solar/wind/grid sources, click here.
RPM's ongoing product development, for flywheel batteries like no other
Product development, that will continue as long as we value product and service excellence at minimum cost, is now mainly focused on flywheel power storage system (including its integration with various power sources and end users) reliability, manufacturability, testability, and cost reduction.
Along with product development, we are engaged in discussions with potential strategic partners (critical parts suppliers, end-product integrators/distributors, and companies in the power business).
For a pictorial essay, with facts, figures, and analysis, of building-integral solar and wind power system advantages, with on-site power storage provided by RPM's flywheel battery, please visit this page.
If you'd like to express your opinion, or ask questions, you can send me an email to fradella@earthlink.net.
See my comparison of RPM's flywheel battery page, to understand how RPM will achieve idling losses of only a few watts. That's phenomenal, compared to other flywheel batteries, with idling losses of 1 to 3 kilowatts. The others may return no energy, if they need to store it for more than 10 minutes.
Most electrochemical batteries have self-discharge rates that compare favorably to RPM's flywheel battery. But most electrochemical batteries fail after 1000 or so deep charge/discharge cycles. In stark contrast, RPM's flywheel battery should provide reliable service, with no degradation, after more than 100,000 equivalent spin up/down cycles.
Existing battery UPS is available, whose first cost is lower. Maintenance and replacement cost, poor reliability, environmental problems with processing and disposal, housing cost, and logistics, however, cause their life-cycle cost to be considerably higher than RPM's flywheel battery.
For RPM's plan, to prove our flywheel battery's exceptional performance, by building and testing several prototypes, then to manufacture and market flywheel batteries based on our extraordinary patented proprietary technology, click here.
For info on some of RPM's present resources, for executing our plan to produce and market our power storage systems, click here.
Is power storage and RPM's flywheel battery really so important?
My answer is "definitely, absolutely, certainly, and positively." One of my partners compares existing solar panel installations without power storage, to attempting to milk a cow without a pail. The imagery may be quite different, but it may help non-technical people understand the importance of storage to solar and wind power. Clearly, if power from these totally non-polluting and sustainable sources is not efficiently used and/or stored at the times it's available, it is lost. But please take time to look into it yourself. If we just accept what entrenched establishment spokesmen say, we get what we deserve.
The Electric Power Research Institute estimates that cost to critical manufacturing industries in the US alone, from power outages, is about $50 Billion yearly. RPM's flywheel battery UPS would prevent that loss. Also, our UPS could be powered by the grid during off-peak hours, presumably at far lower utility rates (because it can be generated from otherwise idle equipment), and reduce peak grid loading by generating power during peak hours (thereby eliminating the grid overloads, now responsible for power blackouts and brownouts in California).
Our on-site power storage also affords opportunities for stand-alone off-grid power. If you want electric power without air and water pollution, and global warming, that fuel-burning generating plants cause, you may be interested in new options we can enable:
Most solar panels are priced at $4000 down to $500 per kilowatt of power they can generate, typically for about 8 hours each day. Most are guaranteed for 20 years. So photovoltaic panels costing under $4000 that also serve as roofing, exterior walls, or windows for a building can yield (1-kw)(8-hr/day)(360-day/yr)(20-yr) = 57600-kwh lifetime electric energy output.
Power storage systems, that RPM plans to market at about $1000 for a 3 kwh model, and $10,000 for a 50 kwh model, guaranteed for 20-years, will be needed with the solar panels, to capture all the power the panels generate and provide uninterruptible electric power for the building as needed. The 50 kwh model would then cost ($10,000)/(20yr) = $500 per year. That's considerably less than typical service and maintenance fees for battery storage or fuel-burning UPS.
The equivalent energy cost for PV panels would amount to ($4000)/(57600-kwh) = $0.07/kwh. This is lower than prices in most regions of the US for grid power now (and utilities are not taxed for environmental damage they cause). Moreover, after several years in production, solar panel and storage system cost will decline, while grid power cost is expected to rise.
Although building-integral wind turbine/generators are rare, their power could cost even less than solar. Their energy yield calculations involve too many variables for an easy calculation example here. However, straightforward examples of practical building-integral installations (no towers needed) indicates that power from them would cost less than $0.01/kwh. An additional benefit of combining solar and wind power -- and any other sustainable source that may be available in a given location -- can be expected from a resulting lower peak-to-average power ratio. That would permit a lower capacity power storage system, which would cost less.
For illustrations and analysis of on-site solar and wind power systems, click here.
If you don't want hazardous nuclear waste, disastrous accidents, and uninhabitable land, that nuclear generating plants leave essentially forever, you should be interested in how we can show that such harmful and costly technologies are not needed.
If you want high-performance EVs having unlimited range, with dramatic driving convenience and safety features like self-steering and electronic collision avoidance, that don't pollute our air or water, cost far less than existing alternatives, and don't require you to stop for fuel or battery charging, you may be interested in new solar and wind powered electric highway options that RPM flywheel batteries can enable.
And if you don't like driving or riding costly autos that too often become incendiary bombs, paying for auto smog checks while their emissions continue to pollute our air, buying costly fuel that pollutes ground water with MTBE, you may be interested in alternative technologies proposed here.
We hope you are motivated like us, willing to do your homework on very important issues, and that you share our vision for a better future.
Your constructive comments, suggestions, or questions are most appreciated.
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