Thursday, June 18, 2009

Reducing water use for washing clothes

Washing the clothes is one of those core required energy and resource intensive things we do. Modern washing machines use a lot of water and electricity, as well as chemicals (laundry detergent) that may be creating unwanted environmental effects. Washing the clothes also involves drying them afterward, and this year I've been experimenting with energy efficient ways to dry my clothes (hint: clothes lines). Now a new process is becoming available that can use as little as a cup of water and use a different sort of detergent.

The product is by Xeros, a new company focused on the development of "virtually waterless" laundry cleaning. They are working from research by Professor Stephen Burkinshaw and the University of Leeds. (see Virtually waterless washing machine heralds cleaning revolution)

They claim to have developed a new way of cleaning clothes using less than 2% of the water and energy of a conventional washing machine. The process is based on the use of plastic granules (or chips) which are tumbled with the clothes to remove stains.

On Consumer Reports they explains that the chips, when in water, dissolves dirt and other stuff from clothes. The plastic chips somehow separate from the laundry and are collected by the machine, however I wonder just how the chips can be completely separated from the laundry. (see By the Numbers: Xeros hyperefficient front-loading washing machine)

The Xeros web site makes it clear this involves a specially designed washing machine, and that the machine still tumbles the laundry. One issue with modern laundry methods is that the machines damage clothes (but so does pounding clothes on rocks in a river). Their website makes it clear not all the beads will be removed from clothes by the machine.

The Xeros web site explains that the technology is applying the process of anchoring dyes in clothing, but doing it in reverse. The plastic chips absorb stains from clothes into the chips.

The nylon polymer has an inherent polarity that attracts stains. Think of how your white nylon garments can get dingy over time as dirt builds up on the surface despite constant washing. However, under humid conditions, the polymer changes and becomes absorbent. Dirt is not just attracted to the surface, it is absorbed into the centre. This is exactly what happens when Xeros nylon beads are gently tumbled with dampened garments.

They also talk about the savings potential:

There are multiple ways that Xeros will save you money. The dramatic water saving; reduction in electricity through shorter cycles; using less detergent. Even with the extra cost of the beads, we project Xeros has the potential to save up to 30% of direct operating costs. On top, there is the indirect cost savings of faster through-put, less effluent and no need to tumble dry.

Because the process uses so little water, there is little reason for machine based drying techniques. Hanging the clothes to dry them should be sufficient.

The Xeros product is not yet ready for consumer use. Their website repeatedly says it is in prototype development, then it will undergo testing. Further they are not immediately targeting consumer use, but instead industrial use. This includes hospitals, military, and the dry cleaning industry.

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