Navigant Research Blog

Futuristic Glass Spurs Solar Innovations

— January 31, 2014

First invented in the Bronze Age, 5,000 years or so ago, glass is such an integral part of modern life that we rarely give much thought as to how it performs or is produced.  Today, though, the development of novel forms of glass promises to bring high-tech, low-cost advances to a range of applications, including solar power.

Glass has many advantageous qualities and one major disadvantage: it’s brittle.  It shatters on impact.  We long ago mastered the art of molding glass into many different curves and fantastical shapes, but once it’s set, it’s set until you take a hammer to it.

That is changing, as researchers at McGill University in Montreal have adapted structural characteristics from the shells of mollusks to give glass new resilience and flexibility.  The scientists found that the extremely tough and bendable nacre, or mother-of-pearl, that coats the inner shells of the creatures is made up not of an unbroken surface, but of millions of microscopic components or “tablets.”  When the shell is bent or deformed, the cracks between the tablets allow it to bend, yet remain intact.  Think of blocks of sea ice floating on a moving water surface; they rise and fall and compress and spread, but the overall surface of the ice remains the same.

Fractured Yet Flexible

In the same way, the McGill researchers found that they can pre-crack glass with lasers to create a puzzle-piece design.  The resultant microfractures are filled with polyurethane, creating a material that is weak at the boundaries of the tiny fragments, but resilient as a whole.  Flexible glass.

The immediate applications envisioned include less breakable smartphones, for instance.  But advances in making glass more flexible, resilient, and versatile will likely have implications for solar power, as well.

When a technology is as commoditized as solar panels, with prices halving in just the last few years, the tendency is to think that innovation in the materials has reached an apex; the only further development needed is to squeeze more cost out of the manufacturing process.  Solar panels with next-generation glass, however, could help drive the Murphy’s Law process of price reductions in solar technology while also producing panels with a wider range of possible applications.  Crystalline silicon solar modules, which require the rigid protection provided by glass, are more efficient than amorphous silicon modules.  Amorphous silicon (often used in thin-film solar coatings) has the benefit, however, of being flexible, making it applicable in a host of environments where conventional glass is less robust.

Spray On, Not Tan

Developed at the University of South Florida in alliance with the National Renewable Energy Laboratory and being commercialized under the mark SolarWindow by New Energy Technologies, a new glass with tiny transparent solar cells integrated is due to reach the market this year.  New Energy produces both flat glass for windows and structural glass walls and curtains for tall structures that have all the usual qualities of glass and also act as solar panels.  Made of organic polymers (thus grown, not manufactured), the transparent solar cells are the world’s smallest, the company says, measuring less than one-fourth the size of a grain of rice.  They are sprayed onto the glass in a novel process that does not require the high temperatures and vacuum chambers of other spray-on solar technologies.

Meanwhile, building off of NASA’s R&D on solar panels for deep space satellites, Entech Solar has developed a concentrating solar system called SolarVolt that uses tiny versions of Fresnel lenses – originally developed in the 19th century to focus the beams of lighthouses for many miles out to sea.  The miniature photovoltaic array has achieved a 20X concentration of the sun’s rays, enabling much smaller-sized systems per unit of energy captured.

These advances in the structure of glass, a 5-millenium-old invention, could help accelerate the solar revolution and bring closer the day when renewable energy is less expensive, by any measure, than fossil fuels.


A Possible Energy Storage Breakthrough

— May 21, 2013

In a recently published paper, Stanford professor Yi Cui revealed a new battery design that could, if it proves durable and effective in the real world, be a significant new technology in the energy storage market.  Like many experimental battery designs, Cui’s battery uses forms of lithium and sulfur.  However, the professor’s battery uses them in a completely novel fashion, sidestepping some of the problems that normally plague lithium sulfur batteries.

To understand why this battery holds so much promise, it’s important to understand the electrochemistry of sulfur.  When sulfur is used in a battery, it sometimes produces polysulfides, which can damage the inner workings of the battery.  When polysulfides collect within the electrolyte of the battery, they cause the other parts to degrade quickly.  That’s why traditional lithium sulfur batteries have such a low cycle life, sometimes lasting only a few dozen cycles.

Cui’s design turns the production of polysulfides on its head: the electrolyte is composed of a lithium polysulfide material.  When the battery is discharging, lithium ions leave a lithium cathode and bond with the lithium polysulfide electrolyte.  When it’s charging, the ions head back to the lithium metal cathode.  The result is a flow battery that, unlike any other flow battery, needs no ion-selective membrane.  Instead, a cheap passive coating of the lithium metal allows the correct ions to pass without leading to degradation of the cathode.

Multiple Breakthroughs

The Cui lab at Stanford will be familiar to readers who have read about previous battery work done there.  He seems to have an uncanny ability to turn out several new battery chemistry breakthroughs every year, ranging from yolk-shaped encapsulants to silicon nano-rods to dye-based batteries.  It seems inevitable that an innovation from the Cui lab will eventually rewrite the energy storage history books.

There’s reason to be hopeful for this particular concept.  This battery has two features that resonate with anyone who has tried to understand why flow batteries haven’t succeeded so far: the materials involved (lithium and sulfur) are relatively cheap and the absence of a membrane eliminates another large cost factor for most flow battery designs.  If the Cui battery can be scaled up from its small laboratory prototype and can withstand thousands of cycles, this concept could lead to a much cheaper form of energy storage than currently exists.

That’s a big “if.”  Many other promising experimental battery designs have proved to be too finicky or too expensive to manufacture to become real-world products.  Cui and his graduate student, Guangyuan Zheng, have shown data that their battery can endure 2,000 cycles without any noticeable degradation, which is a good start.  But the real proof of the system’s success will be in a commercially manufactured, scaled-up model.


One Step Closer to Quantum Cryptography

— March 4, 2013

Source: LANLIt sounds sci-fi but it really isn’t.  Los Alamos National Labs (LANL) announced that it has successfully demonstrated quantum cryptography, using a single photon to generate secure random numbers between devices.  LANL successfully tested this quantum crypto transmitter against an electric grid test bed.  (Perhaps the bigger surprise is that someone is actually developing a security solution not aimed at social networking.)

According to the press release, this marks “the first-ever demonstration of securing control data for electric grids using quantum cryptography.”  That gives me a mild case of heartburn:  cryptography is one method of protecting data, but to say that any cryptography on its own secures data is to overstate the accomplishment.  But this is genuine innovation – rare as hen’s teeth in grid cyber security – so let’s press on.

If this were just another way to encrypt data, I might say, “Neat!” and stop there.  But the most nearly intractable problem in securing smart grids is protecting legacy devices that sit side-by-side with modern IP- and Bluetooth-enabled devices.   The cryptographic transmitter, invented by LANL and called a QKarD, is tiny by comparison with other encryption devices and introduces line latency well within tolerances for a control network.  Testing was done on a 25-kilometer (15.5-mile) length of optical fiber.

New Intelligence Required

As Los Alamos points out, integrating renewable energy supplies into grids requires new techniques, and new telecommunications.  Most grids were built for the steady, predictable inputs from fossil-fired generation.  Adding variable rate inputs such as solar or wind requires new intelligence and new controls.  Those new controls assume that data received from the field is reliable and from a trusted source.

Cryptography can fulfill both of those functions.  While enterprise IT shops rely upon cryptography first and foremost for confidentiality, data integrity is more important for control networks.  Cryptography is not by itself a total security solution, but its role in preserving useful and accurate data is key.  LANL’s solution may move the industry one step closer to a painless way to protect all that data.

A recurring theme from my 3 years of research is that there is precious little innovation in cyber security.  Along with quantum cryptography, I have recently seen promising new approaches for network anomaly detection, network cleansing, and device ID protection, among other things.

Perhaps the tide is finally turning.


Algorithm Could Accelerate Advanced Batteries

— November 1, 2012

Innovation is what happens when we think our way out of a problem.  Engineers at the University of California, San Diego have developed sophisticated algorithms designed to run lithium ion batteries more efficiently and to do what chemistry can’t do:  reduce the cost of lithium ion batteries by up to 25%.  The algorithms would also be used to charge batteries up to twice as quickly.

Considering how many products use lithium ion batteries, the consequences for the market would be enormous.  Anxious to charge up your smartphone before a big day out?  What if you’re on a remote or fragile grid and need to charge a piece of critical equipment in a hurry? Nervous about driving your electric car on a long trip?

For that matter, what if there’s a superstorm approaching and you’ve got a limited amount of time to charge multiple devices?

Although the improved performance of lithium ion batteries could be a game-changer, so could lower costs, particularly in emerging markets like grid storage.  In a market where flywheels, advanced batteries, compressed air, and pumped storage are competing for market share, a system that’s more cost competitive on a power or energy basis will get much more attention and traction.

In the energy storage space, advanced batteries get a great deal of airtime but are typically dinged for two fatal flaws (depending on the chemistry involved): it’s difficult to eke out more efficiency and to reduce costs, and the batteries frequently need to be “oversized” to perform properly in applications that don’t quite align with the electrochemical limitations of the technology.

Undeterred, the researchers at UC San Diego are using mathematics to estimate where particles in the battery are so that the anode could be filled to capacity safely and efficiently (thus charging more quickly).  These innovators claim that the algorithms they have developed can estimate how a battery degrades over time and could reduce manufacturing costs for lithium ion batteries by up to 25%.

Thanks to the forward-thinking program managers at the Department of Energy’s advanced research arm, ARPA-E, this innovation will get a chance to be tested and demonstrated using a $460,000 grant and real batteries.


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