Entrepreneurs Fight Air Pollution With CO2-Reducing 'CityTrees' (cnn.com)

CNN is reporting on "CityTree", a unique 10-foot tall mobile installation which removes pollutants from the air." An anonymous reader quotes their report: Berlin-based Green City Solutions claims its invention has the environmental benefit of up to 275 actual trees. But the CityTree isn't, in fact, a tree at all -- it's a moss culture. "Moss cultures have a much larger leaf surface area than any other plant. That means we can capture more pollutants," said Zhengliang Wu, co-founder of Green City Solutions.

The huge surfaces of moss installed in each tree can remove dust, nitrogen dioxide and ozone gases from the air. The installation is autonomous and requires very little maintenance: solar panels provide electricity, while rainwater is collected into a reservoir and then pumped into the soil... "We also have pollution sensors inside the installation, which help monitor the local air quality and tell us how efficient the tree is." Wu said. Its creators say that each CityTree is able to absorb around 250 grams of particulate matter a day and contributes to the capture of greenhouse gases by removing 240 metric tons of CO2 a year... Wu also argued that the CityTree is just one piece of a larger puzzle. "Our ultimate goal is to incorporate technology from the CityTree into existing buildings," he said.
So far they've installed 20 CityTrees -- each of which costs about $25,000.

Comments

Re: CO2 is a global problem, not a city problem

[Entrope]

Particulate emissions and NO2 levels are largely local problems, especially when you look at health effects versus distance from source. You should want to clean up air in cities because there are lots of harmful emissions there, and because a lot of people live there. Especially in developing nations, along with China and India, it's wildly expensive to adopt the kind of environmental controls that the US and Europe use. I'm not sure that this gadget provides $25,000 worth of benefit, but I agree with the overall idea.

Re: This just in

[hey!]

Alright, time to drive a stake through the heart of this brain-dead water vapor meme.

There's one important fact about water which you are overlooking: it is wet. That is to say it can exist as a liquid (or a solid) at normal atmospheric temperatures and pressures. This means it can't diffuse throughout the entire troposphere like CO2 can before it exits the atmosphere as rain, snow, or dew.

And this is a good thing, because water is a potent greenhouse gas and all things being equal higher temperatures means more evaporation. If evaporation could drive warming the way CO2 does, we'd be looking at a runaway positive feedback loop that would end with the oceans boiling away.

Still, water doesplay a key role in anthropogenic climate change models. That's because CO2 can increase water evaporation in a global way that water vapor itself cannot. Water vapor basically doubles the impact of anthropogenic CO2.