What's the problem with Carbon Dioxide?

CO2 is a colourless, odourless gas found within the earth's atmosphere. It is the product of combustion and of respiration and is also utilised in the process of photosynthesis in plants. It has an interesting property in that it sublimes or changes from a solid (it freezes at −78 °C) directly into a gas at atmospheric pressure, without first becoming a liquid. This is why it is sometimes referred to as 'dry ice'. CO2 is produced commercially for use in fizzy drinks, dry cleaning and in de-caffeinating coffee. It can be transported or stored in liquid form, but only when held at a very high pressure.

CO2 is considered to be the most important of the greenhouse gases. With human activity, CO2 is emitted into the atmosphere whenever we burn organic matter as fuel. The carbon in the organic matter reacts with air to produce CO2 and energy. The largest sources of CO2 are fossil fuel powered power stations (those that use coal, oil or gas) and petrol or diesel powered transport (most cars and lorries).

It is the CO2 produced from these man made activities that is building up in our atmosphere and adding to the problem of global warming. We need to reduce our CO2 emissions by many millions of tonnes in order to lessen the effects of climate change such as sea level rise, ocean acidification and an increase in severe weather events such as drought, wildfire and flooding.

In order to store such large quantities of CO2 we can't just build big containers to hold it. We must use natural storage facilities. Some of the best natural containers are old oil and gas fields, such as those in the North Sea. They originally held the oil and gas for many millions of years, so logic dictates that they may be able to store CO2 for long periods of time. This storage of CO2 is referred to as carbon storage.