For the moment, let’s put aside the fact that EcoClean – aluminum building panels that can “eat” smog – is produced by major aluminum maker Alcoa. If we’re going to have buildings that have aluminum siding (or siding at all) wouldn’t it be better if that siding could help clean the air? The most rational and effective solution would seem to be tackling the problem at its source (point source pollution), i.e. reducing pollution in the first place, especially the nitrogen oxides that make up the smog in most cities. But Alcoa is proposing panels coated in titanium oxide to neutralize pollution that is already in the air.
From an NPR story on the panels, the process works like this:
When sunlight strikes the titanium dioxide, its electrons transfer energy to oxygen and water in the air, creating free radicals. Alcoa says these free radicals then oxidize NOx molecules, and they’ll eventually wash away as nitrate. Alcoa had panels tested by an independent firm in Georgia, and the results “confirm that on a molecular level EcoClean neutralizes smog.
Alcoa claims that for a price 4 to 5 percent more than conventional aluminum panels, 10,000 square feet of the panels “hasAAe air cleansing power of 80 trees.” It would be great to reduce atmospheric NOx, but would the nitrates that are washed away then pollute water, possibly causing algae blooms? There are also shade benefits of trees (reducing the heat island effect), scrubbing of other pollutants in the air such as particulate matter and carbon monoxide, and water filtration and erosion prevention benefits that come with trees. To this end, Alcoa is apparently aiming to plant 10 million trees around the world by 2020.
The upshot seems to be that protecting forests and planting trees is the still the best bet, but an advance like Alcoa’s could be beneficial. This is especially true if the panels were used to replace old, non-pollution scrubbing panels on existing buildings instead of bulldozing to make room for new buildings.[Image]
