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Alcoa Building-Exterior Panels 'Eat' Smog From (A Few) Cars


Beijing smog

Beijing smog

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Pittsburgh-based aluminum giant Alcoa has developed a new coating for its aluminum building panels that passively sucks in airborne pollutants and transforms them into harmless substances.

Appropriately enough, the new panels are getting one of their first commercial tryouts at a new regional electronics recycling hub in Badin, North Carolina built by the company Electronics Recylers International, Alcoa announced last week.

Though the primary purpose of the coating is aesthetic - Alcoa is pitching it as a way to keep smog, bird droppings and other schmutz from collecting on exterior walls - the positive effect on local air quality is not insignificant, depending on the size and location of the building.

Alcoa claims that 10,000 square feet of the coating material - named EcoClean™ - has a “smog removal power” equivalent to about 80 trees, or enough to offset the airborne pollution emitted by four cars per day.

The coating is applied to Alcoa’s Reynobond® pre-painted aluminum panels.

The coating was launched last year as the result of a collaboration with the Japanese company TOTO. It is based on titanium dioxide, a common mineral used in everything from white paint to toothpaste and skim milk.

The “smog-eating” process itself is relatively simple: Titanium dioxide is a well known photocatalyst, and sunlight produces a reaction in titanium dioxide that energizes its electrons. When this energy is transferred to water vapor in the air, it forms oxidizers (free radicals) that attack particles of organic matter sitting on the panel’s surface, or floating nearby.

As far as airborne pollutants go, the substance in question is nitrogen oxide (NOx), which is a primary component of smog.

The reaction between titanium dioxide, sunlight and water vapor turns airborne nitrogen oxide into a harmless nitrate (nitrates are commonly used in fertilizer).

Another component of the coating makes the surface of the panel slick. When it rains, material on the surfaces slips off easily rather than collecting in beads of water.

The new coating, introduced last year, adds to Alcoa’s growing profile in the commercial sustainability sector.

The company began developing an aluminum-based concentrating solar power system with the National Renewable Laboratory in 2010, and its subsidiary Kawneer manufactured the wall of glass daylighting panels that contributed to the LEED Gold certification for the Pittsburgh Penguins’ new hockey stadium.

The choice of Electronics Recyclers International as an early adopter of the new coating also comes into play, since Alcoa owns a minority stake in the company.

As for titanium dioxide, the ubiquitous material is beginning to emerge as a player in the sustainability field. Though Alcoa has applied the process to opaque building surfaces, titanium dioxide could also be used to neutralize pollutants at other infrastructure vectors.

One example is a clear titanium oxide spray developed by the company Pureti, which began testing a titanium dioxide spray coating for road surfaces that could be used to reduce pollution from traffic. The company already markets a clear titanium spray designed for window glass and solar panels.

In addition, researchers at Lawrence Berkeley National Laboratory have been tweaking titanium dioxide as a foundational material for new energy technology. Among other uses, a more efficient form of titanium dioxide could be deployed as a catalyst to generate hydrogen from water for use in fuel cells, in combination with emission-free solar power.

This article, written by Tina Casey, was originally published on TalkingPointsMemo, an editorial partner of GreenCarReports.

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