From the space station to power stations, the fast-spinning flywheel is about to revolutionize the way we store energy.

"Look at all these modern cars," Jack Bitterly says with an ironic smile, surveying the sedans on this dead-end street in Newbury Park, 50 miles northwest of Los Angeles. "The way they're designed, they should be driving backward. The most efficient shape is an airfoil, rounded at the front and tapering toward the back. These vehicles are the wrong way around."

Aerodynamics is second nature to Bitterly. As employee number 12 at the legendary Lockheed Skunk Works, he helped to develop the XP-80 experimental jet fighter. Later he was project aerodynamicist on the North American Aviation AJ-1, the Navy's first carrier-based nuclear bomber.

Bitterly finds it equally natural to question the status quo. Though he cuts a conventional figure in formal western style, with neatly pressed brown pants, brown leather jacket, highly polished brown shoes, and string tie, he's a quietly relentless radical. At 81, he's also more highly energized than people a quarter his age, working 50 hour weeks at a startup named US Flywheel Systems that he founded with the modest goal of revolutionizing one of the most fundamental processes in the industrial world: how we store energy.

Bitterly crosses the street to a single-story concrete building half hidden under a straggling cloak of ivy. This industrial backwater is so peaceful, a couple of rabbits are romping in the grass, while lizards bask on the curb.

Inside, the lobby has a well-worn, low-budget look. His office is more tastefully appointed, with a framed picture of the space shuttle on one wall, reference texts neatly arrayed on wooden bookshelves, and an iMac sharing his desk with a clothbound volume summarizing the inventions of Nikola Tesla.

He seats himself, ready now to explain why energy storage as we know it is about to be seriously changed.

At first glance, this is not a topic to set the heart racing. Energy storage has about as much sex appeal as solid waste disposal. Yet our methods for storing energy have become crucial to not only the old economy but the new. In industries from transportation to telecommunications, primitive energy storage technology is imposing huge hidden costs.

Semiconductor fabs, which cannot tolerate even momentary fluctuations in power, typically rely on duplicate supplies from separate sources, at great expense, because they can't store enough electricity to ride out an interruption. Automakers have been unable to build a viable electric car, mainly because batteries don't allow enough range, are too costly, and take too long to recharge. Even electric utility companies - supercharged by deregulated markets, distributed power generation, and accelerating demand - have no easy way to store electricity to meet peak requirements. As the business of load leveling, peak shaving, and resource sharing moves to the Internet - where the overall energy trade, according to Forrester Research, could reach $266 billion by 2004 - today's electric companies prepare for crunch periods by installing expensive spare generating capacity; some even stockpile thousands of batteries.

The always-on economy, by definition, depends upon continuous energy. Unsurprisingly, an uninterruptible power supply (UPS) - once a luxury for room-sized computer installations - is now a standard item both in home offices and all the networked tiers above, protecting servers and online service providers, Internet backbones, phone companies, and even cable TV networks.

Industrial-size UPS systems are built around arrays of lead-acid batteries - a device that Thomas Edison would recognize instantly if he were alive today. These archaic clunkers wear out within five years and are unreliable even in their prime, since they cannot tolerate high or low temperatures. They fail without warning, and are an ecological nightmare, loaded with toxic metal. Yet the lead-acid battery market, according to the staid Battery Council International, is increasingly bullish. Today's $1 billion-plus in annual North American sales should jump half again by 2003; UPS battery growth alone is forecast at a yearly 10 percent.

Jack Bitterly holds up a photo of giant lead-acid batteries stacked on heavy-duty industrial shelving. "These are maintained by an electric company in Puerto Rico," he explains. "The company isn't on a power grid, so it needs batteries in case its generators fail, or to satisfy peak demand. Now, each of those batteries weighs 460 pounds, and there are 6,000 of them. Twenty-five percent of them have to be replaced within three years." He shakes his head. "And this is considered highly successful."

Clearly, there ought to be a better way. And now, perhaps, there is.

Bitterly picks up a glittering black disc about 10 inches in diameter and 3 inches thick, with a circular center hole just big enough for his hand to slide through. The 25-pound disc is perfectly balanced and exquisitely finished, like a minimalist art object. It was fabricated here in this building, using equipment that Bitterly designed himself. This, he believes, is the upcoming revolution in energy storage: the wheel. More precisely, the flywheel - an elemental machine that historically has found a place in the potter's wheel, the steam engine, and the internal combustion engine. Now, Bitterly foresees, the flywheel will become the uninterruptible power supply that drives everything from station wagons to space stations.

Bitterly's vision seems oddly retro, a mechanical throwback in an era of solid-state electronics. But he's not alone in his view of the future. A patchwork of advanced flywheel companies is springing up across the country, from Newbury Park to New York State. With names like Active Power, they are beginning to test commercial markets still at a very early stage of development, building highly targeted products aimed at hybrid electric vehicles, or telecom UPS systems, or low Earth orbit satellites. Leading work in the fledgling flywheel industry is being done by Bitterly and company at US Flywheel Systems; San Francisco-based Trinity Flywheel Power; Beacon Power in Woburn, Massachusetts; and the Center for Electromechanics at the University of Texas in Austin. These players participate quarterly in a safety research program run by Hudson, Massachusetts-based Test Devices and cofunded by Darpa.

The underlying concept is simple, though the finished flywheel assemblies become increasingly complex. First you feed electricity to a motor, which accelerates the wheel to cruising speed. Riding on magnetic bearings inside a vacuum container that eliminates air resistance, the wheel can spin almost indefinitely after you cut the power. When you want to tap its energy, you draw electricity back out of the motor, which now functions as a generator. This imposes a load on the wheel, gradually slowing it as mechanical energy is converted back to electricity.

In this way, the flywheel can substitute for a battery, while offering features that no battery can match. Even the most exotic battery can be damaged if you charge or discharge it too quickly. A flywheel isn't affected by this treatment, and can operate at extreme temperatures, can contain 10 times a battery's power density, and - according to its advocates - should last for decades.

Naturally, the more energy you cram into a wheel, the more attractive it becomes. To increase the amount stored, you can make the wheel heavier, or spin it faster. Since you get four times as much energy if you double the speed, but only twice as much if you double the weight, clearly speed is the way to go - though this creates another problem. Doubling the speed generates four times the centrifugal force.

This is not a trivial matter. Your car is fitted with a simple steel flywheel to smooth the output of the engine between piston strokes. At a speed of 5,000 rpm, this wheel presents no safety hazard; but Jack Bitterly wants to spin a flywheel 20 times faster, at 100,000 rpm, producing 400 times the centrifugal force. That's more than enough to cause a steel wheel to self-destruct, spraying shrapnel at thousands of miles per hour.

Riding magnetic bearings inside a vacuum container, the wheel can spin almost indefinitely. When you want to tap its energy, it functions as a generator.

Bitterly, however, has never been afraid of technical challenges, even though his prolific research has not always led to commercial development. US Flywheel already has a prototype wheel running at more than 60,000 rpm, designed under contract for NASA, to replace batteries in the International Space Station. This is just a taste of the future that Bitterly foresaw when he first encountered the idea of flywheels for energy storage, almost three decades ago.

In the early 1970s, a nuclear fusion physicist named Richard Post used spare time away from his work at Lawrence Livermore National Laboratory to write an article forScientific American, speculating that new materials and control systems could revolutionize the lowly flywheel.

He proposed fabricating high-speed wheels from glass fibers or carbon fibers, which are stronger than steel; he suggested using magnetic bearings, which would eliminate wear and tear. These concepts were hard to realize, since the technology wasn't there yet. Still, when Bitterly read the article in 1973, he saw the potential.

Bitterly had entered the aerospace field back in 1940; from Lockheed he went to North American Aviation, then to the National Advisory Committee for Aeronautics, the forerunner of NASA. He designed space suit life-support systems for an Apollo moon mission, and he ran his own consultancy business in the fledgling field of space medicine. Perhaps because he doesn't suffer fools gladly and was impatient with the status quo, Bitterly tended to be a loner. "I spent probably half my professional career as an entrepreneur," he says. "Every once in a while I got itchy and started a company."

That's exactly what he did after reading Post's article. With a partner, he acquired a license to patents Post had filed, and began learning everything he could about flywheels and the technology he needed to make them happen. In 1975, the first incarnation of Bitterly's dream, US Flywheels, was born.

After two or three years, through an intermediary named Bill Lear, Bitterly obtained Department of Energy money to develop a flywheel-powered commuter car. Lear, however, lost interest and developed the Learjet instead. Bitterly regrouped and tried another angle, this time proposing an advanced flywheel to power a laser weapon - but Rockwell International got that contract, using a low tech steel wheel. "We struggled for a while," Bitterly recalls. "We never had enough support, and the government money stopped around 1980." Bitterly's R&D shop went into deep freeze; he returned to consulting, while his son Steve, who had participated in the business from the get-go, went to work on the Strategic Defense Initiative.

In the early '90s, a new Bellevue, Washington-based company called American Flywheel Systems recruited the Bitterlys, ultimately patenting a number of their designs and generating a fair amount of publicity. They soon parted ways, however, over reported differences about how to pursue R&D. Jack Bitterly today won't comment on the breakup; at the time he seemed disinclined to partner with large corporations to speed development of a commercial product. (By the late '90s American Flywheel had functionally fallen out of the flywheel picture.)

In 1992, Bitterly was contacted by an agent acting on behalf of actor Kevin Costner. Costner was seriously concerned about ecodoom; he was already planning his global warming movie,Waterworld, and had put a chunk of his personal fortune into Costner Industries, an outfit administered by his brother, Dan, to develop alternate-energy technology. In 1993, the Costners decided to capitalize a reorganized company under the new name US Flywheel Systems. They installed a new president, and Bitterly became chief scientist. "It was like winning the lottery," he recalls.

By this time technology finally had caught up with his ambitions. High-speed bearings rolled into the picture, as did carbon fibers with a tensile strength higher than the best steel, but with a much lower density - fibers 4 times stronger than steel that could store 16 times more energy per pound. Computers were cheaply available to control a winding machine that would place every turn of carbon fiber with absolute precision, reducing the amount of weaker epoxy resin needed to reinforce the fibers. The resulting wheel could be significantly stronger, perfectly balanced, and evenly stressed to withstand the huge centrifugal forces. Computers also could design, simulate, and record each refinement of every component in a flywheel assembly, while high-speed electronics could provide the servo control needed for magnetic bearings.

Initially Bitterly tried to sell flywheels to General Motors for its electric car, the EV1. "We put in a tremendous amount of effort preparing studies," he recalls. "We projected we could mount all the flywheels in the boxes designed for batteries, and they would store as much energy while weighing less."

It sounded good in theory, but Bitterly didn't have prototypes that would prove his assertions. He wanted GM to make a leap of faith based largely on projections of what should be possible if they spent enough money. At the Skunk Works back in 1940, Uncle Sam was happy to take a chance on crash programs that could win the war, but GM wasn't in a similar crisis. The corporation was doing well with conventional gasoline vehicles, had no incentive to take risks, and was developing the EV1 mainly to comply with federal and state regulations.

In 1994, Bitterly and his associates finally gave up on GM and retreated to more familiar, wide-open territory: the aerospace industry. "The beauty of the space program," he explains, "is that they'll accept something better, even if it wipes out previous technologies. Some of the greatest scientific changes have come from space, simply because in that environment a breakthrough is not just acceptable, it's mandatory."

He stands up behind his desk and takes me on a tour of the rest of the building. The no-frills look is everywhere; Costner Industries is the sole source of capital keeping US Flywheel's 16 employees - 12 of them technical - hard at work. Still, money has been spent where it's needed, on CAD workstations and on an elaborate test setup in a large, echoing space at the rear. Here, flywheels are spun inside steel enclosures to contain any debris from a catastrophic failure - although Bitterly assures me that this has never occurred. He picks up a sample wheel and points to hairline circular cracks, where centrifugal force has separated some of the layers of carbon fiber. "This is the worst that happens," he says with a shrug.

Technology caught up with Bitterly's ambitions. Carbon fibers 4 times stronger than steel can store 16 times more energy per pound.

Half a dozen guys in their twenties are crowding around video monitors in a large cubicle next to the flywheel test area. The monitors display data from sensors and lasers aimed at the rim of the test wheel, revealing even the slightest deformation as it accelerates to its design limit.

Back in the main section of the building, past a clean room where flywheels are assembled, Bitterly pauses by a workbench and shows me some component parts. The motor-generator is small enough to fit inside a coffee mug, yet he says it can put out 20 horsepower at 600 volts. "We can overload it to 50 horsepower for a minute," he says, weighing it in the palm of his hand. "Imagine four of these in a standard car. It would scream the tires off."

Space, though, has a more urgent need for flywheels, because every satellite orbiting the Earth suffers from an intractable energy storage problem. Solar panels can generate power only while they are in direct sunlight; batteries must maintain operation when the satellite passes through the Earth's shadow. Since even the most sophisticated batteries wear out after five or six years of this light-and-shade charge-discharge cycle, their life span limits the life of the entire satellite.

I'm introduced to Ray Beach, chief engineer of NASA's flywheel program at the Glenn Research Center in Cleveland. Beach has been involved with flywheels since the 1970s, and makes regular visits here to Newbury Park. He explains that NASA is interested in flywheels not only for energy storage but for attitude control. If flywheels are mounted in counter-rotating pairs, and more power is supplied to one wheel in a pair, a satellite will tend to turn in the opposite direction. A set of paired flywheels could eliminate the gyros or hydrogen-peroxide thrusters that have been used in the past to keep spacecraft pointing in the right direction.

When the International Space Station is finally launched, it will be fitted with special nickel-hydrogen batteries weighing a total of several tons, with a lifetime of just five years, requiring spares to be brought up from Earth at literally astronomical expense. These batteries could be replaced with 192 flywheels, which would be both lighter and more durable, outlasting the expected lifetime of the space station itself. The anticipated savings: $260 million.

NASA has paid US Flywheel Systems an initial $3 million, contingent on proof-of-concept demonstrations along the way. The first orbital test is scheduled for 2005.

Safety remains an issue, since a catastrophic failure could have terminal consequences for astronauts unlucky enough to be nearby. US Flywheel has addressed this issue at meetings of a flywheel safety consortium headed by Test Devices, which has decades of experience testing designs of spinning rotors such as the turbines in jet engines.

Eric Sonnichsen, who founded Test Devices in 1972, points out that a wheel created from carbon fibers is safer than a steel wheel, because even if a few fibers break, the wheel won't come apart. On the other hand, if a flywheel does disintegrate, says Sonnichsen, "it's more like potentially lethal lumps of coal coming at you, traveling at kilometers per second."

His company helped to develop containment vessels to mitigate this worst-case scenario. Sonnichsen's team has overaccelerated flywheels and dumped them off their bearings; in each case, the wheel skidded to a stop harmlessly inside its container. They finally figured out how to blow a speeding flywheel apart by firing a bullet into it. "I tend to be the Cassandra of the high-speed spin world," he says. "But at this point I am satisfied with the centrifugal safety of flywheels. In fact, they are much less hazardous than other storage methods we have now. A can of gasoline can be dangerous. Even a car battery can blow up, if you reverse polarity."

In space, though, flywheels won't have the same containment structures, because the shielding would weigh too much. A sudden failure could be disastrous. So wheels must demonstrate through cycle testing and spin testing that mechanical components will last many times longer than expected use. The wheels are then derated to - that is, run at - 50 percent of maximum speed.

Still, why take the risk?

Typically, Bitterly believes that in operation there will be no significant risk. Moreover, he views the challenge as a huge potential advantage. "Once people see that NASA is willing to place flywheels in space," he says, "then everyone will have to realize these things are safe to be used on Planet Earth."

In Massachusetts, Beacon Power has taken an opposite approach. Instead of pushing the technology with high rpms, it has opted for lower speed and higher weight. Instead of aiming for the skies, it's putting flywheels underground, where they can serve a strong existing demand. "We see a huge market in providing backup power for telephone, cable, and wireless networks," says Joe Saliba, vice president of marketing and sales. This is not an idle claim; Beacon has already placed working prototypes for evaluation by Bell Atlantic, Century Communications, and Telcordia Technologies. The San Diego Gas and Electric Company has ordered two commercial units, and another 100 will provide backup power for telephone service to 15,000 new homes in Mexico, where the hot climate degrades batteries.

On board low Earth orbit satellites, flywheels could do dual duty, storing energy and controlling orientation - maybe replacing fuel propellant.

A typical Beacon flywheel by itself weighs 150 pounds, rotates at 20,000 rpm, and sits inside a big cylinder that resembles a squat 55-gallon oil drum with a rounded top and bottom. It can supply one kilowatt for two hours, and you can buy one right now for about $15,000. "It should last 20 years," says Saliba. "And you shouldn't have to service it for six or seven. We put a foot or two of dirt on top of it, switch it on, and walk away."

Saliba previously worked at SatCon Technology, a satellite engineering company. He formed Beacon with a colleague, Bill Stanton, who became CEO. They recruited scientists from MIT, raised venture capital twice, and are going into a third round. Today Beacon has 35 employees and remains privately held, with SatCon owning a majority of the stock.

While Bitterly pursues a grand vision, Saliba is totally practical. "We're going after the telecommunications market first," he says, "including cable, telephone, and cellular phone systems. As a startup living off venture capital, you need revenue. I've got to go after the low-hanging fruit."

According to Saliba, Beacon's penetration of the broader $1 billion-plus battery market is mainly a matter of salesmanship. "Give us five minutes with a whiteboard," he says, "and we can show you a break-even point between three and five years." Still, he admits, the old product is firmly entrenched. "It's a different approach for people who currently accept batteries with all their faults."

The first Beacon prototype wheel was delivered in the fall of 1998 to WinDBreak Cable, a tiny cable TV company based in Gering, Nebraska. Bill Bauer, president and CEO, had participated in the development process. "I'm a member of CableLabs," he explains, "which does R&D for the whole industry. Six years ago, when cable companies saw they would be moving into information services, we commissioned a report by Arthur D. Little to consider alternatives for power backup. They looked at advanced batteries, flywheels, fuel cells, supercapacitors, natural gas generators, steam turbine generators - everything. They concluded that flywheels had a cost advantage, and probably could be developed fast enough."

When Bauer and two other cable guys went to the flywheel companies, Beacon seemed most ready to give them what they wanted. "We supplied specifications for a flywheel that would be a plug-for-plug replacement for the lead-acid batteries we were using in a typical installation," Bauer recalls. "A cable system is unlike the phone company, where power is centralized. We have little installations scattered all over, in people's backyards, or strapped to telephone poles. No one wants a generator in a backyard. In any case, a generator still requires batteries, to start it. A flywheel needs nothing at all, because it's always running."

Nebraska turned out to be a punishing environment for the Beacon wheel, as local temperatures plummeted from the 80s to below zero in just the first 30 days of operation. "We broke that first flywheel several times," Bauer says in an offhand style. "But that was OK. We wanted a catastrophic failure, so we could make it better."

On one occasion, the magnetic bearings failed and the flywheel mashed all the components underneath it. But the wheel itself remained intact, and Bauer dismisses concerns about safety. Today's Beacon system can be set to shut itself down if it deviates from perfect balance by a mere 10 microns.

Once the wheel is in place, it is monitored and controlled remotely via a local server plugged in to the Net, giving it a major advantage over batteries that have to be inspected in the field.

Bauer believes there's a market for 10,000 to 20,000 wheels per year, and expects the price to be halved after the first year, and then halved again as production ramps up. If he's right, this could be a boon for farms, cellular relay towers, and even off-the-grid mountain cabins. Solar cells and wind-driven generators can provide only intermittent power; a set of Beacon wheels would take over at times when the sun doesn't shine or the wind doesn't blow.

"Believe me, this is going to be a huge success," Bauer says. "In fact, I believe that flywheels will be one of the major advances in the new century. Lead-acid batteries will go by the wayside."

Trinity Flywheel Power maintains an engineering center near the Lawrence Livermore lab where pioneering theorist Richard Post still pursues flywheel research in his spare time. In fact, some of his funding comes from Trinity.

The privately held company hopes to market a wheel at the end of this year that will supply far higher amperage than the Beacon unit, over a much briefer time span. In the UPS world, this is known as a "ridethrough" system, built for applications where even a momentary interruption is unacceptable. It sounds like an esoteric item, but according to Don Bender, Trinity's mild-mannered vice president of engineering, the need for it is widespread. "In the Southwest and Florida," he explains, "you can have hundreds of brief outages per year, due to lightning strikes. For a large business online, the cost of a power interruption can exceed $1 million per minute. Financial institutions are also critical - and hospitals." Since batteries can be fatally damaged by a sudden, massive power surge, they're ill-suited for ridethrough systems, in which a flywheel functions without complaint. Also, while batteries can fail with no warning at all, remote polling of flywheels can tell you whether a unit is working.

Trinity's technology may also be used in a very different environment: the high tech battlefield, where laser weapons, railguns, and pulsed sonar could draw massive brief power surges from a flywheel that is then slowly recharged. Trinity has government contracts, but Bender says that "our clients haven't told us the precise applications."

A more mundane use would be in stop-and-go municipal vehicles. A bus, for instance, could be fitted with a small conventional engine that runs constantly, turning a generator, and feeding electric motors that drive the vehicle. The generator also brings a flywheel up to speed. When the bus pulls away from the curb, the flywheel supplies the necessary surge of power. When the bus cruises, the small engine is all it needs. When the bus stops, regenerative braking recharges the flywheel, so that it's ready to supply the next power burst. In this system, the engine is far smaller than what would be needed in a conventional vehicle, and can be optimized to run at its most efficient speed, minimizing pollution. Although a hybrid vehicle of this type would cost more initially, it could save money in the long term by running more efficiently, while reducing environmental impact.

Trinity has supplied some flywheels for testing by a Pacific Rim bus manufacturer - while another bus project is under way at the University of Texas' Center for Electromechanics (CEM).

Funded by sponsors ranging from Darpa to the Houston transit authority, CEM has tailor-made its own flywheel for mass transit. "Our system can supply 150 kilowatts of peak power, and 110 kilowatts of continuous duty," says project engineer Richard Hayes. He points out that vibration in a vehicle will be a problem, but the flywheel bearings have been designed to withstand three times the force of gravity. "We tested the bus yesterday," he says, "and on typical bumps we saw only 1 g. But potholes can inflict up to 5 gs. So, we have backup bearings. We're also building an electromagnetic suspension system that should provide a much gentler ride. I do believe there will be problems with vibration, but we'll solve them."

In the high tech battlefield, lasers, railguns, and pulsed sonar could draw massive brief power surges from flywheels that slowly recharge.

CEM is working on another system for the biggest ground vehicle of all: a train. Research engineer John Herbst is managing the Advanced Locomotive Propulsion System project, funded by the Federal Railroad Administration. Herbst envisions a locomotive driven by a gas turbine, with a massive 3-megawatt flywheel providing extra power for acceleration. "Fully electric locomotives are lightweight, powerful, and fast," he says, "but they require you to electrify the railroad. When you have a gas turbine supplemented with a flywheel, it can match the performance of an electric locomotive while eliminating the cost of electrification."

Considering both the various players and the variety of possible applications, it's clear that flywheels are no longer a purely speculative venture. Some are almost ready to roll out of the laboratory, into our daily lives. The only question is how far they'll go.

Richard Post, whose article inScientific American started it all, admits that he's a bit impatient. A half year older than Jack Bitterly, he says, "I still come into the lab here at Livermore because I want a chance to see some products emerging from my work - before I kick the bucket!"

Flywheels took far longer to develop than Post hoped and expected. "I was a science fiction fan when I was a kid," he recalls. "I read Robert Heinlein. I guess I'm a little disappointed that we haven't seen the kind of progress that those old writers predicted."

He cites financial realities as the major problem. "Most of the companies are still trying to find a market, a position where they can expand. A lot of the funding has to be from private capital; but this field has such a long history without achieving its goals, I believe that tends to put off investors."

Doesn't he feel the time is right?

"Well, yes, basically. All the elements of the technology are available. All it needs is to be taken seriously."

At Trinity, Don Bender is convinced that the demand is there - potentially. "Everybody who's in this business hopes to produce thousands of systems per year within a few years," he says. "We could see a market worth hundreds of millions of dollars within three years. I've seen studies putting the value much higher than that - but when you pay for a study, sometimes they just tell you what you want to hear."

Bender is skeptical about downsizing flywheels, because components such as magnetic bearings tend to remain expensive no matter how small the wheel is.

Post agrees that economics are the key factor preventing small-scale applications. "I mean, it would be impractical to put one in a flashlight," he says. But then he laughs. "Actually, I have one of those little flashlights containing a small generator. You work it by pressing a lever repeatedly with your thumb. Since that's an intermittent action, a small flywheel has to be attached to the generator, to keep it spinning."

Of all the advocates, Bitterly is least willing to accept size limits. "Some of the biggest flywheels were built in the industrial revolution," he says. "Since then, the trend is clear: They've been getting smaller and rotating faster. No one has beaten our pre-prototype for the space station, at 60,480 rpm, but you should be able to attain even higher speeds with smaller flywheels, and I foresee graphite fibers, in the next decade, that will be 10 times as strong, per pound, as they are now. I believe we'll be using those in the lab, and once something is in the lab, it always gets out of the lab if there's an advantage to it. Within 10 years I believe we'll see flywheels providing 10 times as much energy storage as they do today."

That still isn't the limit, though, as Bitterly looks ahead to replacing fibers with carbon nanotubes - ultrastrong microfilaments made by coaxing carbon atoms to form a seamless tube smaller than a human hair.

Talking about these future possibilities, Bitterly's enthusiasm is obvious. The past, though, has been marred by disappointments in several projects that Bitterly has tackled as an idiosyncratic inventor-entrepreneur. Before he ever started messing around with flywheels, he led an effort to develop a new, better space suit for lunar exploration. The suit was never used; the Apollo program ended too soon. Later Bitterly designed a suit to protect US Army personnel from biological weapons. His design was accepted, but Bitterly couldn't follow through on his subsequent plan to power the backpack's tiny air-conditioning unit with flywheels instead of batteries.

Today, despite its initial failure to win an order from General Motors, US Flywheel appears well positioned, with development money from NASA. Appearances, though, can be deceptive.

The current manager of flywheel energy storage for the International Space Station is Timothy Tyburski, who made some significant changes when he took control last July. A trained engineer and self-described cautious kind of guy, Tyburski has a doctorate in management; before coming to NASA he was a manager at the Ford Motor Company. And like the auto giant, the space agency appreciates economies of scale. "US Flywheel is not doing this on its own anymore," Tyburski says bluntly. "Once they supplied the 60,000-rpm demo" - in January, one year after the initial demonstration - "our cooperative agreement was over. We did want to encourage a small business, particularly because of their technical skills. But we really need someone like a TRW to provide systems integration, which US Flywheel is a little weak on."

Tyburski is concerned about integrating the flywheels with control systems, and with the space station as a whole; but TRW's involvement won't stop there. "Our current contract calls for TRW to do engineering model development," he says. "They've put together a team that includes CEM, at the University of Texas, and US Flywheel."

Bitterly hopes to replace flywheel fibers with carbon nanotubes. But the inventor-entrepreneur now finds himself competing with behemoths.

The flywheel that is developed by this team will be tested at a Boeing facility at the end of 2004. After that, NASA will hold the design rights and will invite aerospace contractors to build a product matching its specification. If US Flywheel wants to supply the finished wheels, it will find itself competing with industrial behemoths.

Bitterly sounds subdued when he talks about this scenario. "It's easier for large aerospace contractors that have decades of working with the government," he says. "However, we have been able to do things that the big corporations have not been able to do. We still could end up manufacturing the finished product."

No one said it would be easy for a startup company staffed by a small team of believers to create a state-of-the-art product and sell it to a huge government agency without losing control. Even if an aerospace conglomerate builds the devices that US Flywheel invented, Jack Bitterly will retain the honor of pioneering a field that is spinning off into areas far beyond the space program.

Even now, Bitterly remains convinced that flywheels could be viable in cars. "They would be absolutely practical," he insists. "It's not a technological problem, it's primarily a business problem, in that auto manufacturers would have to be persuaded to obsolete the equipment that they use now to build engines and drivetrains."

Practically speaking, how much would it really cost to develop automotive flywheels?

Bitterly pauses for a long moment. "A lot!" he says finally, laughing.