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A sheet of graphene is a mere atom thick and has low resistance and high mobility making it optimal for both semiconductor and capacitor applications.  (Source: University of Maryland)
Graphene ultracapacitors could double the storage of existing designs thanks to breakthrough

While the continual progress of efficiencies in solar and wind seem to make these technologies ideal candidates to eventually replace fossil fuels further into the future, one key element stands in the way of their adoption.  That element is variability of the power source.  While one solution would be to offset these power sources with continuous power sources such as tidal or geothermal, another option is storage.

Currently, two primary methods exist of storing power for later use -- rechargeable batteries and ultracapacitors (other exotic methods have also been proposed).  Ultracapacitors are a growing, but not widely known field.  Ultracapacitors can be mixed with fuel cells and batteries or used independently to provide power.  While expensive, ultracapacitors have numerous advantages over batteries, including higher power capability, longer life, a wider thermal operating range, lighter, more flexible packaging and lower maintenance.

Now a new breakthrough promises even better ultracapacitors.  A typical capacitor design features two sheets with an electrolyte between them.  Charge is developed and stored on the sheets.  The key to the new research is to use graphene as the capacitor sheet material. 

Graphene is a unique carbon molecule which is a one-atom-thick planar sheet of sp2-bonded carbon atoms densely packed in a honeycomb-like lattice.  The material has exceptional surface area, among other properties.  It also is a great conductor, and thus is being explored as a material for transistors

Rod Ruoff, a University of Texas at Austin mechanical engineering professor and a physical chemist who led the research describes, "Our interest derives from the exceptional properties of these atom-thick and electrically conductive graphene sheets, because in principle all of the surface of this new carbon material can be in contact with the electrolyte.  Graphene's surface area of 2630 m2/gram (almost the area of a football field in about 1/500th of a pound of material) means that a greater number of positive or negative ions in the electrolyte can form a layer on the graphene sheets resulting in exceptional levels of stored charge."

Professor Ruoff and his team used a chemically modified graphene sheet, and several widely used commercial electrolytes.  The resulting capacitor had a charge stored per weight (called "specific capacitance") rivalling the best available traditional ultracapacitors.  And Professor Ruoff is hopeful that the material's storage can be more than doubled with tweaking.  He states, "There are reasons to think that the ability to store electrical charge can be about double that of current commercially used materials. We are working to see if that prediction will be borne out in the laboratory."

His current team consists of graduate student Meryl Stoller and postdoctoral fellows Sungjin Park, Yanwu Zhu and Jinho An, all from the Mechanical Engineering Department and the Texas Materials Institute at the university.

Their impressive findings are reported in the forthcoming Oct. 8 edition of Nano Letters.

The U.S. Department of Energy has said advancing storage technologies is one of the most pressing needs of the renewable resource industry.  Other fields such as electric cars could also benefit from the research.  A graphene ultracapacitor equipped next-generation version of the Chevy Volt could get twice the range on a single charge or cut the battery weight in half.  It could even extend the life of laptop batteries.

Resources and funding for the project were provided by the Texas Nanotechnology Research Superiority Initiative, The University of Texas at Austin and a Korea Research Foundation Grant for fellowship support for Dr. Park.



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RE: Experiment
By alcalde on 9/18/2008 7:08:15 PM , Rating: 0
Wind doesn't produce radioactive waste that can kill you. You left out that wee little advantage of solar and wind vs. nuclear power. Oh, and then there's the drilling for fuel, the non-renewableness of nuclear, the fact that we don't have to worry about solar or wind falling into the hands of terrorists, etc., etc., etc.


RE: Experiment
By masher2 (blog) on 9/18/2008 11:34:40 PM , Rating: 4
Wind turbines do, however, have enormous spinning blades and weighty poles, both of which can most certainly kill you, especially in areas exposed to high winds-- which, coincidentally, is where such windmills tend to be built.

In fact, despite the small amount of power generated by wind at present, several people have already died from such accidents. How many have died from nuclear waste in the Western world? None whatsoever...in a half-century of operation.

So much for that theory.

Wind also requires the mining and production of vast amounts of steel and concrete, far more than nuclear reactors require...operations which have a number of toxic byproducts.

> "Oh, and then there's the drilling for fuel."

What drilling? We have enough fuel from spare nuclear weapons alone to power the nation for more than 200 years-- all without mining an additional ounce of uranium. And even after that, nuclear requires far less mining that wind power, due to the vastly smaller amount of resources it requires.

> "the non-renewableness of nuclear."

There's enough nuclear fuel on earth to last several times all of recorded human history. On that basis, nuclear is just as renewable as solar or wind. All three will run out eventually...but it's a problem so far in the future, we can't even conceive of it.

> "we don't have to worry about solar or wind falling into the hands of terrorists."

What would terrorists do with nuclear fuel? They certainly can't make a nuclear bomb out of low-enriched uranium. The plutonium generated is poisoned with so much Pu-240 that it's essentially useless as a nuclear weapon...and even refining it out is so complex and requires so much resources that one might just as well build your own reactor or enrichment plant (which is why nations like Iran, Pakistan, and North Korea chose just that route).

So that leaves a "dirty bomb" -- something more useful for generating irrational fear than any real damage. But if one wants radioactive material for such a bomb, it's much easier to get it from sources like medical radionuclides or even a large amount of discarded smoke detectors. Or -- if you're a smart terrorist -- you skip the idea entirely, and get something truly destructive, like a biological agent, or some much-more-deadly sarin, ricin, or other toxins.


RE: Experiment
By lco45 on 9/23/2008 3:53:35 AM , Rating: 2
Yes, but to be fair Masher, even if a whole field of wind generators failed at the same time it wouldn't render the entire region unlivable for hundreds of years, like Chernobyl did.
Having said that, fission is an excellent choice for power generation, and is orders of magnitude safer than mining for coal, or warring for oil control.


RE: Experiment
By Regs on 9/23/2008 10:55:32 AM , Rating: 2
You know what ticks me off?

The Sun goes away each day and doesn't let us know where it's going.

How can we work with this? Gawd damnit.


"My sex life is pretty good" -- Steve Jobs' random musings during the 2010 D8 conference














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