Trash to Treasure

Biofuels have become so tarnished in the public eye--they're uneconomical without government subsidies, using food (corn) for fuel defies common sense, biomass burning doesn't reduce CO2 emissions significantly anyway--that we are pleasantly surprised to hear any good news coming from that sector. And there is good news, albeit modest, from Brazil.

Photo from the Economist

In Brazil inedible rice husks, a waste byproduct of milling, are burned to generate electricity. All well and good, but the ash still must be disposed of. Pirelli, the tire maker, discovered that there was treasure in the trash:

Grasses contain tiny pieces of silica, called phytoliths (illustrated above), whose job is to discourage herbivores, both vertebrate and insect. Pirelli’s engineers realised that these defensive weapons are the ideal size to add to tyres in order to control hysteresis loss, and that a ready supply of them is available in the husks left over from the milling of rice.

What is hysteresis loss?

As the tyres bounce they convert kinetic energy into heat, thus wasting it. Hysteresis loss, as this is known, can be reduced by mixing a tyre’s rubber with powdered material that has strong chemical bonds in it.

The upshot is that the phytoliths from the rice ash will make "tyres" and cars more fuel-efficient.

In the opinion of your humble observer, it is just such smaller-scale projects that will lead to the success of the green-energy movement, not the showy failures that are rushed into production before the technology and markets are ready for them. © 2013 Stephen Yuen