Mean green washing machine

This article here is interesting, about the invention of a washing machine that uses only a cup of water.   It works apparently by pounding the clothes with small plastic chips, using a fraction of the energy of a conventional washing machine.

Sound good?   I thought it did - until I read to the end.   It requires 20kg of plastic chips, which last for up to 100 washes, and therefore need to be replaced up to twice a year.

Now, I can understand the need to preserve water, but what about plastic?   It comes from oil, which is in even shorter supply.   And the process of making these plastic chips is presumably energy intensive.   I wonder what the comparison really is between a conventional washing machine and this one?