Yule Heibel's Library tagged carbon_sequestering →  View Popular, Search in Google

Several studies recently, one claiming that cities aren't so green (whereas this one counterindicates it). I like this article because it argues for more trees.
QUOTE
While this news may just be common sense (trees are good!), it's another important argument for why urban planning needs to incorporate green space, particularly the shady kind. The human population is on track to add more than two billion people to our ranks in the next fifty years. Much of that growth will happen in urban areas, which currently shelter more than half of the globe. We'll need that urban land to absorb as much carbon as possible if we have any hope of fighting climate change.
UNQUOTE

good_mag cities environment carbon_sequestering ecological_urbanism

A company in Nova Scotia says it has developed a process by which manufacturers of precast concrete products can store 60Ts of CO2 in every 1000Ts of concrete product. This would be factory carbon dioxide (produced by heating the plant, running the machinery, etc.), which would be redirected onto the concrete, and absorbed (sequestered) by it, effectively negating the initial production of CO2. From the article:
QUOTE:
Concrete accounts for more than 5 percent of human-caused carbon-dioxide emissions annually, mostly because cement, the active ingredient in concrete, is made by baking limestone and clay powders under intense heat that is generally produced by the burning of fossil fuels. Making finished concrete products--by mixing cement with water, sand, and gravel--creates additional emissions because heat and steam are often used to accelerate the curing process.

But Robert Niven, founder of Halifax-based Carbon Sense Solutions, says that his company's process would actually allow precast concrete to store carbon dioxide. The company takes advantage of a natural process; carbon dioxide is already reabsorbed in concrete products over hundreds of years from natural chemical reactions. Freshly mixed concrete is exposed to a stream of carbon-dioxide-rich flue gas, rapidly speeding up the reactions between the gas and the calcium-containing minerals in cement (which represents about 10 to 15 percent of the concrete's volume). The technology also virtually eliminates the need for heat or steam, saving energy and emissions.
UNQUOTE
One of the comments to the article notes that carbonated concrete wouldn't be good for use in reinforced concrete buildings because the carbonation reduces the alkalinity of the product, and that in turn affects the durability and strength of the rebar/ steel, but that it would work well for sidewalks (and presumably cinderblock type materials?).

Interesting development, at any rate, as concrete production accounts for 5% of the world's human-caused carbon-dioxide emissions annually.

mit_techreview concrete carbon_emissions carbon_sequestering environment