Apr 07 2009

Viral Batteries

The conventional wisdom these days is that battery technology will play an increasing role in our energy future. Electronic devices continue to proliferate, we have the technology to produce amazing implantable medical devices, and we are looking increasingly to green-energy sources for our cars, homes and the infrastructure of our civilization. All of this requires electricity, which needs to either be produces as needed, derived from a grid or external source, or stored in a battery.

It is not surprising, therefore, that hardly a week goes by when I do not come across some amazing battery breakthrough while perusing science news. Industry seems to be betting that battery technology is a worthwhile investment.

Of course, most of these breakthroughs will not pan out – they will not lead to a viable product that can be manufactured on an industrial scale. Also, many techniques are mutually exclusive – they apply only to a certain type of battery. For those that can work, it will likely take years for a product to actually be on the market. So reading this type of tech news is often an exercise in serial disappointment and delayed gratification. But it is interesting to see what might be coming down the pike.

One battery news item caught my eye this week – building batteries out of viruses. There are two components to this story that I find interesting (in addition to the battery angle) – using biology as a technology building block, and the increasing use of carbon nanotubes.

First, a quick overview of what these researcher did. They engineered a the M13 virus, which is a commong bacterial parasite, to act as a cathode, and also engineered another version to be an anode. The anode attracts cobalt oxide and gold to its outer coat. The cathode attracts iron phosphate. In order to create a circuit, the cathode also has to be conductive, so they attched the viruses to carbon nanotubes, which are highly conductive.

The result, they claim, is a battery that has the capacity and performance of existing lithium ion batteries. However, it also has one major disadvantage – the researchers say it can be recharged up to 100 times. That would render it useless for most appolications. Imagine a car, cell phone, or laptop battery you can only charge 100 times and then have to replace.  This may prove a fatal flaw to this approach if it cannot be improved at least a couple of orders of magnitude.

The major advantage of this technology is the production is easier – no toxic chemicals or high temperatures required. If it can be scaled up it may also be cost effective.

The researchers rightly caution that this development does not equal the development of a new battery that is viable for the market. This is purely in the experimental stage – fooling with new technology just as a learning exercise.

But, as I said, the new approaches here are interesting. Viruses are like little machines, and bacteria are little factories. They are the ultimate nanotechnology. We already engineer bacteria to produce drugs, and there is research into using bacteria to literally eat garbage and excrete fuel.

We already use viruses as vectors to insert genes for research purposes. There are efforts under way to use this technique to cure genetic diseases, although this research has run into some snags, specifically the viral vectors can cause bad infections.

What this highlights is that the technology of engineering viruses and bacteria is tricky, not risk free, and still in its infancy. But already there are clear indications of the power of this technology, and it is progressing steadily.

Also,  Craig Venter is developing completely artificial bacterial genomes. He claims he is close to doing just that. When this research is successful (and I think it is fair to say “when” and not “if”) that could mean not just altered viruses and bacteria, but ones designed from the ground up. Such organisms could then be designed for numerous potential applications. We could be seeing the beginning of a new type of technology, where our machines are grown instead of built.

The other component of this battery research I found interesting was the use of carbon nanotubes. These little guys are worthy of a series of blog posts by themselves, but the quicky is this: They are essentially sheets of carbon atoms rolled into tiny tubes.  Carbon nanotubes have two properties in particular that make them potentially very useful – they are extremely strong, and they are extremely conductive.

In this case they were used because of their conductive properties. They have a conductive carrying capacity of 1000 times greater than copper, although they are still semiconductors, and not superconductors. This means they are ideal for tiny electronics, because very small wires can conduct a great deal of electrons. In fact, researchers have developed a fully functional carbon nanotube radio.  Follow the link and you can hear the song Layla played over this nanoradio.

Carbon nanotubes seem highly likely, therefore, to be a major component of computers, batteries, and nanodevices in the near future.

Carbon nanotubes are also very strong – the strongest material yet created. From Wikipedia:

In 2000, a multi-walled carbon nanotube was tested to have a tensile strength of 63 gigapascals (GPa). (This, for illustration, translates into the ability to endure weight of 6300 kg on a cable with cross-section of 1 mm2.)

The challenge now is to develop manufacturing processes to make longer cables of nanotubes, as well as sheets of nanotube fabric and other useful forms.  This technology seems to be progressing at a good pace, and researchers remain enthusiastic about its potential. Carbon nanotubes could be for the 21st century what plastic was to the 20th.

It is exciting to see how this technology will all pan out in the future. While most of the announcements of amazing breakthroughs ultimately lead nowhere (see flying cars), many do see fruition. Some of the incredible gizmos I marveled at in technology magazines a decade ago are on my desktop, in my home, and clipped to my hip today.

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