Light in a bottle

Tom James @ 29-07-2009

microresonatorScientists have developed a technique for confining light within a bottle:

Similar to the motion of a charged particle stored in a magnetic bottle, i.e., a particular spatially varying magnetic field, the light oscillates back and forth along the fiber between two turning points. For this reason, this novel type of microresonator realized by the physicists in Mainz is referred to as a bottle resonator. Tuning the bottle resonator to a specific optical frequency can be accomplished by simply pulling both ends of the supporting glass fiber. The resulting mechanical tension changes the refractive index of the glass, so that depending on the tension, the round-trip of the light is lengthened or shortened.

This could lead to the creation of a glass fibre quantum interface between light and matter, which in turn is an important component of hypothetical quantum computers and quantum communication systems.

[from Physorg][image from Physorg]


Graphene ultracapacitors

Tom James @ 16-09-2008

hexagonsMore developments in the field of ultracapacitors, this time using graphene (like a single layer of the graphite molecule, apparently), from researchers at the University of Texas:

“Through such a device, electrical charge can be rapidly stored on the graphene sheets, and released from them as well for the delivery of electrical current and, thus, electrical power,” says Rod Ruoff, a mechanical engineering professor and a physical chemist. “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.”

My understanding is that a key part of solving the two problems of anthropogenic climate change and the depletion of primary energy resources involves finding new and more efficient ways of storing energy.

Ultracapacitors are on option, synthetic petrol is another, or hydrogen fuel cells.

It will be interesting to see which technology (if any of these) becomes dominant as a means of storing energy.

[story from Physorg][image by procsilas on flickr]


Hydrogen Dreams

Tom James @ 09-06-2008

One of my bugbears is the constant implication in the popular press that the twin problems of anthropogenic global warming and peak oil will be solved by the mythical “hydrogen economy.”

Take this article in The Guardian newspaper:

The main fuels used in history form a nearly exact sequence, from ones having hydrogen_carless hydrogen to ones having more. Wood and charcoal were the earliest fuels, and have only a little hydrogen. Much of their burning is wasted in pouring out great gusts of carbon, which was needed to build up the tree from which the wood came, but doesn’t do much for the user burning that wood.

Coal has more hydrogen, and its burning can be cleaner. Oil – which dominated next – has yet more hydrogen per unit of carbon; natural gas has even more, and its burning is the cleanest and most efficient of them all. The trend line points pretty strongly to a pure hydrogen economy – but when that will occur is in the hands not of the scientists, but our wise political masters.

Hydrogen fuel cells have some promise as an energy storage medium, but you still need a source of energy in the first place: much of the commercial hydrogen produced today is actually produced from natural gas in a process which still produces carbon dioxide emissions.

Alternative methods using biological extraction have proven successful – but they still don’t tackle the nuclearfundamental problem of where the energy to extract the hydrogen comes from. With oil running out and our current industrial infrastructure reliant on dumping stored carbon dioxide into the atmosphere this is the problem that needs to be solved.

And if the basic problem is getting energy, wouldn’t it be better to concentrate on that and, once this problem is solved, use this source of hydrogen-producing energy to produce petroleum via the Fischer-Tropsch process and save £X trillions by avoiding upgrading our entire transport infrastructure to use hydrogen tanks and fuel cells?

My conclusion: every penny of research currently being poured into the hydrogen economy should be diverted into developing cleaner nuclear fission and synthetic petroleum fuel combined with hybrid electric-petrol vehicles.

Monday rant over.

[main article from The Guardian][other articles from PhysOrg][images from felixmolter and gavindjharper]


Where to store wind energy?

Jeremy Eades @ 17-10-2007

The weather is a fickle thing.  Typically, riding my bicycle to work is hard going and easy coming home because of wind patterns, but sometimes the wind decides to switch, or perhaps not blow at all, really messing with my commute.  Thus the problems with wind energy.  The wind doesn’t blow all the time, and it may decide to quit right at peak hours, or blow up a storm when no one’s using electricity.  So what to do?

A test wind park in Iowa, as described by Environmental Science & Technology, proposes to help solve these problems by using excess wind energy to store compressed air in underground aquifers until such time that demand rises.  This maximizes the turbines’ efficiency and allows companies to sell energy when they can make the most from it and when demand is highest – peak hours.

This could be a real boon to wind farms, making it more economical than it already has become to run turbines.

(via SciTechDaily) (image from article)