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  • 02.17.09

Can We Just Bury Our CO2 Problem in The Sand?

A research project is underway in Illinois to perform a large-scale test on a solution to carbon dioxide pollution: The gas is being pumped underground instead of being released into the atmosphere. Sounds crazy, or irresponsible? Not really, if you look into the possibilities.

A research project is underway in Illinois to perform a large-scale test on a solution to carbon dioxide pollution: The gas is being pumped underground instead of being released into the atmosphere. Sounds crazy, or irresponsible? Not really, if you look into the possibilities.

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The process is called geological sequestration, and it’s a terrifically simple idea. Where CO2 is being produced in large quantities–say as waste gas from a coal-fired power station–you “harvest” the CO2 from the exhaust, pipe it to a special location and pump it under pressure to an underground storage facility. Here it permeates the rocks and, if the geology is favorable, stays there for thousands of years. 

The Illinois project is interesting for two reasons–it’s one of the largest attempts ever made to try the technology, and it’s exploiting a particularly promising geological formation. This is the Mt. Simon sandstone layer, a huge sheet of permeable sandstone around 6,000 feet down that underlies parts of Illinois, Indiana, and Kentucky. It’s interesting because of its size, and the fact that above it lies three separate impermeable layers that will effectively keep the CO2 pumped down there trapped in the sandstone.

The $84 million project will pump a million tons of CO2 down the well by 2012, and sophisticated tracking will determine how the CO2 moves through the rock layers, and test if it’s “leaking” out. A million tons is nothing compared to the annual CO2 output of the U.S.–predicted to be 8 billion tons by 2030–but this research project could blaze the trail for a commercial venture that would store 100 billion tons of CO2 down in the Mt. Simon sand.

But can we really just bury our CO2 problem?

Atmospheric CO2 is a potent greenhouse gas. Of course it’s a natural atmospheric component, but as our technology has advanced, we’ve been tipping the balance of atmospheric CO2 at an increasing rate–that is a potential component of global warming.

Think of burying CO2 as akin to burying waste nuclear products–it’s essentially a time-offset technique. We simply don’t have the technology (or money) to deal with the problem right now, so burying it for thousands of years makes it a problem for our distant descendants. Sequestering billions of tons of CO2 underground, if it proves successful, removes that gas from contributing to global warming, and by the time it leaks out (which it will) technology should have advanced enough to deal with it.

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There are a few problems in achieving deep-layer CO2 sequestration, of which the biggest are extracting the gas from exhaust gas flows, and finding the energy required to both extract it and pump it underground. The latter could take a surprising percentage of a power station’s output–but the cost could be met with a form of carbon tax.

Ultimately, does this sort of project make sense? Yes, it does. Though alternative fuel sources are being aggressively pursued nowadays, there’s still no sign of a fast, large-scale switchover to renewable energy. We don’t appear to be able to kick the coal and gas habit. Until we do so, any project that can efficiently dispose of the waste CO2–even if its just for a “temporary” thousand years–can only be a good thing for the environment.

[via Wired]

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