backtop


Print 52 comment(s) - last by Regs.. on Sep 23 at 10:55 AM


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.



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

RE: Energy storage
By Reflex on 9/17/2008 11:13:08 PM , Rating: 2
Probably because it would not have a significant impact. Keep in mind that our consumption of oil is enormous, building vehicles to run on a solution that is never going to hit economies of scale is just a waste of money.

Here's a good picture of just how much oil is consumed globally, and what it would take to replace that with a variety of power generation techniques: http://www.spectrum.ieee.org/jan07/4820/ncmo01

There is no easy answer.


RE: Energy storage
By Jaybus on 9/18/2008 12:39:26 PM , Rating: 2
I agree that there's no easy way. Therefore, we should be concentrating on using existing technology, rather than placing our hopes on future technology that may, or may not, someday materialize. I don't see how the new capacitor technology could much affect electrical power generation, even if it's the best thing since sliced bread.

According to the US DOE, the maximum capacity for the 1,493 coal-fired stations is 335,830 MW, or 51% of the US electrical power capacity. The capacity of the 104 nuclear stations is 105,585 MW, or 21% of the US electrical power capacity. The average nuclear station produces 4.5 times the power of the average coal-fired station. It would take 331 nuclear stations (more than 3 times the current number) to completely replace the current coal-fired stations.

By comparison, the maximum stated capacity of the 348 wind farms is 11,352 MW. So it takes at least 7 wind farms to replace 1 coal-fired station. It would take 10,451 wind farms, (30 times the current number) to replace the current coal-fired stations, regardless of battery/super-capacitor technology.

What I conclude from this is that coal-fired stations are not going away any time soon, and if even a few of the nuclear stations are forced to shut down due to their age, (the youngest of which is 30 years old), we are in serious trouble. I would prefer to build the nuclear stations now. They can be replaced later, should the great scientific discovery of a better power source finally come along.


“And I don't know why [Apple is] acting like it’s superior. I don't even get it. What are they trying to say?” -- Bill Gates on the Mac ads














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki