Carbon Capture

What is it?

Carbon capture and storage (CCS) involves trying to reduce the amount of carbon dioxide being released into the atmosphere by capturing it before it gets there and putting it somewhere else.

In some cases, it is also about trying to take the extra carbon dioxide in the earth’s atmosphere back out of it to try and reverse the process of global warming.

How are they trying to capture it?

In power stations, carbon dioxide is separated out from the mixture of gases that pass through the chimney stacks before they reach the air, or from steps earlier on in the process. It is then compressed and transported to a place it can be stored.

How are they trying to store it?

The carbon dioxide is being stored as a gas under the earth where it can be trapped underground by some rocks, or in old coal mines, oil and gas fields.
In the sea, the carbon dioxide will dissolve at low depths because of the higher pressures. You can also react it with limestone to make solid bicarbonates that will form sediments at the bottom of the oceans, or store it in other solid materials present on the ocean floor.

Carbon dioxide is being removed from the atmosphere using algae in the oceans to capture and store the energy from the air. When they die they sink and take the carbon with them.

What are the problems?

Carbon dioxide is a gas. It only turns into a solid at -78°C and only has a liquid phase at high pressures. It is a hard thing to store. Leakage is always a risk however you store it.
You are altering the natural balance of the earth’s ecological systems. Just in the same way that adding carbon dioxide to the atmosphere is making the greenhouse effect stronger, putting that carbon dioxide somewhere else will probably have an undesired effect wherever you put it. Dissolving it into the oceans, for example, would make the water more acidic and that could affect many other natural processes and reactions.
The effects of some of these solutions may not even show themselves for many years.

More information

SUPERGEN efficient power plants