[getsmart-l] Renewable Energy - Great idea if it works!!

[John O'Gorman]

?RENEWABLE ENERGY 
?Sugar rush powers batteries 

?BY MICHAEL POLLITT Apr. 27/07 Globe and Mail 

?Researcher Shelley Minteer has experimented with soft drinks and table sugar in her quest to build a better battery. 

Her goal? A rechargeable one fuelled by sugar. 

Ms. Minteer is an assistant professor of chemistry at Saint Louis University in Missouri. She used to work with hydrogen fuel cells, but was always afraid of accidents. Eventually, she turned her attention to other types. 

"We got interested in sugar-powered fuel cells after developing ethanol fuel cells and realizing that, energetically, it made more sense to use the sugar directly than to turn sugar into ethanol and then use the ethanol," she says. 

Although using the sweet stuff to make electricity sounds surprising, it's actually not that novel. Researchers have put dead flies, sugar and even rotten fruit to use in efforts to develop renewable fuels. 

The first advantage of such power sources is avoiding the metals associated with traditional batteries. As an energy source, batteries are expensive and their manufacture consumes valuable resources, presents a disposal problem and can contaminate the environment. 

Ms. Minteer claims that her ?"sugar battery" is the longest lasting and most powerful of its type to date. Sugar (as glucose) powers all living things, with nature harnessing the available energy in a series of complex enzyme-driven reactions. 

Ms. Minteer tried soft drinks but found the best fuel for her biological fuel cell is ordinary table sugar. The main by-product of the electrochemical reaction? Water. 

The prototype sugar battery now sitting on her desk is being used to power a handheld calculator - and, she estimates, the battery has enough sugar left for several years. She says sugar batteries have the potential to operate three to four times longer on a single charge than conventional lithium-ion batteries. 

"Each cell gives a voltage of about 0.75 volts, but has three or four times the energy density of a typical battery, so the battery will last much longer." 

You have to stack two sugar battery cells together for a standard 1.5 volts - development work is needed before the physical size matches an AA battery. 

Ms. Minteer has spent 18 months working on the project, with another three to five years of work needed before commercial applications are developed. Her plan is to develop a mobile-phone charger powered by sugar. "This is a ?good first application, because it requires minimal engineering compared to something like a laptop battery that requires a great deal of engineering to get the fuel pumped to all parts of the battery," Minteer says. 

She'd like to see the technology used in other portable electronic devices. Funding by the U.S. Department of Defense is helping with the project - the idea of battlefield batteries rechargeable by easily obtainable sugar is an attractive one. 

Professor Phil Bartlett of Southampton University in the United Kingdom recently heard Ms. Minteer give a lecture about her work. Prof. Bartlett is an expert in electrochemistry and was unimpressed with her data .

"Technically [it] isn't going to cut it and it isn't leading-edge," he says. His calculations show that to provide two watts of peak power for a mobile phone from a sugar battery you'd need an effective electrode area of four square metres. 

The sugar battery's green credentials appear compelling, though. If carefully designed, it could be fully biodegradable and recyclable. Further research by Ms. Minteer will test the effects of temperature on performance and monitor the lifetime of the enzymes. 

Guardian News Service 
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