Self-Cleaning Buildings to Fight Smog

bryan8m writes "Using technology already available for self-cleaning windows and bathroom tiles, scientists hope to paint up cities with materials that dissolve and wash away pollutants when exposed to sun and rain. The idea: UV rays hitting the titanium dioxide coated cement and concrete trigger a catalytic reaction that destroys the molecules of pollutants, including nitrogen oxides."

Comments

Re:Effective?

[Graymalkin]

Keyword here is catalytic reaction. A catalyst is a substance that initiates a chemical reaction but is not consumed itself in the reaction. The catalyst in the paint would stay in existence, it would simply break down pollutants when they came in contact with the material when UV radiation was hitting it. As long as the pollutants were reduced to innocuous materials there wouldn't be an issue with toxic waste disposal.

Re:Now, can we put DC on the transmission lines?

[Anonymous Coward]

Now, that high power solid-state switches ( hence, power converters ) are becoming do-able, is there any way we can start putting high-voltage DC on our power grids?

DC is horribly inefficient at delivering power. Besides, high voltage is high voltage. Power lines run just under the voltage needed to ionize the air. Once you ionize the air, then you set up currents, and those currents are sucking power, power that isn't being delivered, and could have been charged for.

Titanium dioxide has other problems

[domefreak]

The article explains that the smog-busting coating for buildings will contain titanium dioxide. They note that this compound is already prevalent in paints, but presumably this process requires a higher concentration than that. I searched GreenSpec for any existing paints that use this effect, and instead found this interesting fact:

The production of pigments can be a highly polluting process. When titanium dioxide is extracted from sand, large quantities of by-products are produced that have historically been disposed of by ocean dumping and/or deep-well injection. The process of refining titanium dioxide is also very energy intensive, with significant releases of carbon dioxide and sulfur oxides. The European Community considers these problems associated with titanium dioxide so serious that they have established limits on the amount of white pigment allowed, and limits on allowable emissions from pigment manufacture, for paints under consideration for the European Eco Label.

(from Environmental Building News, February 1999)