Plotting to Power: SuperPowers HTS
Date: Thursday , June 26, 2008
In the aftermath of the blackouts of August 2003 that left large parts of the northeastern United States and Canada in darkness, there was widespread consensus that something needs to be done to avoid the numbing power cuts that loom over the U.S. and a power-hungry world. Towards that end, Super Power Inc., a wholly-owned subsidiary of Intermagnetics General Corporation in Schenectady, NY is innovating to replace a key component of the power transmission world: copper.
Copper is fast becoming a painfully outdated way to transmit large amounts of power. Though its resistance is lower than many other metals, the amount of resistance is still significant enough to cause huge losses—some 7-8 percent of electricity is currently lost in transmission.
Superconductors can do the job a lot better. The U.S. Department of Energy (DoE) says that about half these losses could be avoided if superconductors were used. The money saved would amount to a whopping $16 billion every year. This would also mean a reduction in the amount of fossil fuels burnt, and the consequent reduction of atmospheric pollutions.
The DoE also estimates that the lower power losses inherent in superconducting power lines, for example, could eliminate the need for about 500 trillion BTU of coal-fired generation each year. That would mean about 131 million tons of carbondioxide, 24,232 tons of nitrous dioxide and 846,000 tons of sulphur dioxide would not be released into the atmosphere each year. In the U.S. alone, full implementation of superconducting technology could offset the emissions of the equivalent of 40 medium-sized conventional power generation plants.
BSCCO and YBCO
Take BSCCO, an acronym for the key elements that make up this ‘first generation’ high temperature superconductor (HTS). A demonstration version of a BSCCO cable produced by Sumitomo reduced resistive losses by 50 percent. Admirable though that may sound, that’s not quite good enough. For one, it costs an expensive $250 per KAmp meter—a meter of wire capable of carrying a thousand amperes of current would cost $250.
SuperPower is developing a ‘second generation’ comprised of yttrium, barium, copper and oxide, YBCO. The resistance this offers to current is a further 50 percent lesser than BSCCO.
Besides, it is far cheaper to produce too, at $50-100 per KAmp meter. (Copper, in comparision, costs a mere $10-20 per KAmp meter.)
One of the reasons for the lesser cost would be the fact that YBCO uses nickel instead of silver (used by BSSCO) to make the compound less brittle (as ceramics are wont to be). Besides, BSSCO production is a labor intensive process, and a low tech one, factors that also contribute to the increase in cost.
“In fact when SuperPower was formed in 2000, the main goal was to deliver second generation technology, a cutting-edge, automated continuous process, at a lower cost,” says Dr. Venkat Selvamanickam, leading the development work at Super Power.
All this needs some explaining. The phenomenon first: when certain materials are cooled (really cooled) they suddenly lose all resistance to electricity. These materials could be metallic or ceramic; and based on the ‘critical temperature’ at which the material becomes a perfect conductor of electricity, they could be high or low temperature superconductors.
It was in 1911 that the Dutch physicist Heike Kamerlingh Onnes, winner of the 1913 Nobel, discovered that the resistivity of solid mercury abruptly disappeared at 4.2 Kelvin (0 Kelvin is -273 degree Centigrade).
Liquid helium, which had been discovered not too long before, was used to cool the mercury down. It was to serve as a coolant for a long time after, till 1986, when it was found that even ceramics became superconductors. 1986 was in fact a major turning point in the field. The annual meeting of the American Physical Society was held in March that year, famously marked by a hastily convened midnight session that was later dubbed ‘the Woodstock of Physics’.
Researchers crowded in by the thousands, while their counterparts from over the world called in with findings that were sometimes barely hours old.
Till then, the highest temperatures attained for superconductors weren’t more than 23K. That year, researchers at IBM made a breakthrough, having got ceramics to superconduct at 38K.
Birth of a Superpower
All this triggered off renewed interest in the field. Dr. Gregory J. Yurek, a professor at the MIT, founded American Superconductor in his kitchen. Researchers at Intermagnetics General Corporation, which produces superconducting materials, also set about exploring these new avenues with gusto. Intermagnetics was a company that had been spun off from GE in 1971.
It has since then grown into a $150 million company, with over 800 employees. It went public [NASD:IMGC] in 1981. Intermagnetics has joint development efforts with—among others—the DoE, Department of Defense (DoD), National Laboratories, the New York State Energy Research and Development Authority (NYSERDA) and various commercial companies. Dr. Selvamanickam, then a graduate student at the University of Houston, a place noted for its cutting edge research in the field, was hired by Intermagnetics in 1994. He led the development work that, owing to Intermagnetic’s conviction of the commercial viability of such products, later took its distinctive identity as SuperPower, Inc.
A big advantage of the ceramic HTS is that liquid nitrogen is used for cooling instead of liquid helium. While helium liquefies only at around 4.2K, nitrogen does so at a far higher temperature of 77K. Not just that, liquid nitrogen is far cheaper than helium.
SuperPower is working on what is called ‘Thin Film’ technologies. It produces the tape in spools, just like magnetic tape. But unlike magnetic tape, “HTS tape” is far more complex to produce. It consists of several layers—between five to ten of them. Each of these layers require manufacturing equipment of their own. Over the past three years or so,
SuperPower has designed a variety of pilot equipment for the purpose. Though several systems are needed, they are all designed to work seamlessly, turning out meter after meter of the tape continuously. It starts off with the metal substrate that gives the tape its flexibility, which is then polished to a high degree of surface finish. They then proceed to deposit the various layers one over the other. “By the time we go through all the steps, we end up with multiple layers, capable of carrying more than a hundred times the current that copper wire can,” says Selvamanickam.
To date, the longest stretch SuperPower has produced measures 57 meters, a world record in its own right. “It’s primarily in its pilot production phase, and we expect it to become commercially viable by 2005.”
Who is Buying?
The first major commercial application of superconductors came with the invention of the clinical magnetic resonance imaging (MRI) some time in the early eighties. These operate with low temperature superconductors. Since 1986, the focus has been on developing the processes to produce HTS wire and producing longer lengths of tapes and wires with high performance. Crucially, these have to be flexible enough to be wound into transmission cables and coils for motors, generators, transformers, fault current controllers, and fault current limiters.
The first demonstration of the technology was realized using first-generation HTS (which are produced by metallurgical processes). This showed remarkable results, and enabled prototype demonstration units of all these devices to be designed, built and tested.
Second generation HTS technology, which is SuperPower’s focus area, is being taken through the next steps. Products like those under development at SuperPower have much better performance characteristics, and it would hardly be exaggerating to predict that they are going to revolutionise the power delivery infrastructure. (Intermagnetics and its SuperPower subsidiary have designed, manufactured and tested HTS subsystems for various companies. SuperPower collaborates with utilities, universities and system manufacturers, among others.)
SuperPower is developing a 350 meter long 34.5 KV HTS power cable in partnership with Sumitomo Electric Industries and The BOC Group. This is to be installed in the Niagara Mohawk power grid in Albany, NY. SuperPower’s first HTS cable project was in partnership with Southwire Company. SuperPower is also making a 5/10 MVA prototype HTS transformer in partnership with Waukesha Electric Systems, it has worked with GE on HTS generators, and with General Atomics on a fault current controller. The cost savings on these devices alone (not considering transmission losses) comes up to as much as $8 billion.
A rather groundbreaking application is what is called a “Matrix Fault Current Limiter,” device that provides the capability to limit damaging surges of high current, like when lightning strikes. Such a device, the likes of which does not exist today, would vastly improve the flexibility, and consequently the reliability of the power grid, while making it a lot safer.
Besides, as the August 2003 power outage showed, the nation’s power infrastructure is aging, and will have to be replaced with something better. And that demand is what companies in the space are aiming to satisfy.
The products they are offering are not only of higher efficiency than ever before, but also more compact and cheaper to maintain. “The transformers, for example, are a third of the size of the conventional ones,” says Trudy Lehner, Marketing Specialist with SuperPower. Not just that, she says, it is a lot easier to site the devices too, inside buildings, substations and so on, making them safe from terrorism or vandalism. The cooling medium is liquid nitrogen; no oil to start a fire or any other potential disasters.
The initial niche applications would be in places where there is no other practical solution. In densely populated, congested urban areas, for example, best use will have to be made of the existing ducts to supply larger amounts of power, without causing large scale disruption. Superconducting wires that can carry three to five times the power of the copper ones will suit the application well.
And it’s not just on paper—they have a pilot project in downtown Albany, one of their first prototypes. “Once that is demonstrated,” says Selvamanickam, “we expect the market to sit up and take notice. And prices would fall with increased demand. Our goal is to compete head to head with copper.” The initial project will end in 2007, and by then they would have enough wire available for sale to satisfy the demands that would come up.
Just in Time
What’s so amazing about a power grid is that power cannot be stored anywhere in the system: all the plants generate just what is required to satisfy the needs of the millions of customers. Now if a grid is running pretty close to its maximum capacity, and something causes a power plant to trip offline, then the other plants pick up the slack unless they are near full load too. Then to prevent a failure due to overload, they too will trip, causing the rest to fail too.
Estimates of the total costs of the outages range between $4-10 billion in the U.S.; in Canada, the Gross Domestic Product dropped 0.7% in that August, and there was a net loss of 18.9 million man-hours.
With SuperPower’s HTS, these losses could be mitigated—just in time.