BP has proposed capturing carbon dioxide underground. A start-up in Texas called Skyonic says it can capture the gas and turn it into baking soda.
And now Carbon Sciences says it will turn carbon dioxide emissions from power plants and factories into calcium carbonate, otherwise known as limestone or chalk. The company combines the gas with fine calcium powders in a way that doesn't require a lot of heat and pressure, or that much calcium for that matter. For every ton of carbon dioxide, you only need three tons of raw materials, says CEO Derek McLeish.
The good news is that a lot of the raw materials exist as leftover tailings from mines, says McLeish. (Side note: McLeish also has set several land speed records at the Bonneville Salt Flats; it's a hobby.) So you are essentially taking environmental garbage, mixing it with pollution, and churning out a product that can then be sold to industrial manufacturers, who in turn won't have to ask miners to dig new holes in the ground to get calcium carbonate.
McLeish, in fact, showed us a prototype of how Carbon Sciences' system will work. It's in a van he drives around (See video). The chemical reaction that takes place in the van is powered by a solar panel on the roof.
Carbon sequestration will likely be inevitable--all three leading presidential candidates favor a cap-and-trade system, after all. The question now is how. Many believe that storing it underground will likely be the most practical way to do it, particularly when you think of the millions of tons of carbon dioxide that get produced. The gas will be liquefied before being inserted into the ground to increase storage.. However, a large percentage of the gas will just sit underground.
Converting carbon dioxide into solids does take raw materials and energy. McLeish (and Joe Jones of Skyonic), though, point out that the public isn't keen on storing a gas that can be hazardous to your health in large, underground caves. Still, carbon dioxide is a low-energy molecule. Converting it to other substances does require time, money, and energy. The efficiency of the processes will determine whether or not Skyonic or Carbon Sciences can become viable.
One sequestration technology you probably won't see, however, is using carbon dioxide to grow plankton in the ocean.