Feature

CDs versus USB flash drives

G Magazine

Which portable data storage device is greener?

USB flash drive

Credit: iStockphoto

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Just what is the most environmentally responsible way to save your files?

Is it the older and bulkier CD or the newer, smaller USB flash drive (aka thumb drive, keychain drive, jump drive, pen drive and USB stick)?

Making it

The main component of a CD is petroleum-derived polycarbonate, a lightweight and break-resistant plastic.

Although plastic isn't considered green, in April of 2008, Toshiyasu Sakakura, a chemist with the Japanese National Institute of Advanced Industrial Science and Technology in Tokyo, announced that he had discovered a chemical pathway that turns carbon dioxide into polycarbonate or other plastics.

So CDs made from captured carbon dioxide might be a thing of the future.

The tiny size of a microchip inside a USB flash drive belies its environmental impact. Fabricating something so intricate requires very pure raw materials and a lot of energy to maintain that purity.

In 2002, scientist Eric Williams, from Arizona State University in the US, looked at the manufacture of a 32-megabyte microchip, similar to that found in a USB flash drive.

The 2-gram microchip required 72 grams of chemicals, 1.2 kg of fossil fuels, 32 kg of water and 700 g of gases to produce.

While microchip fabrication is becoming more efficient, the demand for more storage per chip means the amount of materials used in manufacture will remain steady over the years.

Capacity

It's hard to say which technology can store more files, as the two leapfrog each other with each techno-development.

One or two gigabyte (GB) USB flash drives are now ubiquitous, with 16 and 32 GB devices available at the top end of the market.

CDs can store of around 700 MB, while DVDs can store about 5 to 8 GB, or about six episodes of your favourite one-hour TV show.

The next improvement in optical storage is blu-ray technology, providing 25 to 50 GB of space per disc.

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