The idea works like this:
- First, you heat limestone to a very high temperature, until it breaks down into lime and carbon dioxide.
- Then you put the lime into the sea, where it reacts with carbon dioxide dissolved in the seawater.
The important point is that when you put lime into seawater it absorbs almost twice as much carbon dioxide as is produced by the breaking down of the limestone in the first place.
This has the effect of reducing the amount of carbon dioxide in the atmosphere. It also helps to prevent ocean acidification, another problem caused by the increase in the amount of carbon dioxide in the atmosphere.
If done on a large enough scale it would be possible to reduce carbon dioxide levels back to what they were before the Industrial Revolution.
The first step of the process – breaking down limestone into lime and carbon dioxide – seems counterintuitive as it uses a lot of energy and actually produces carbon dioxide. But this carbon dioxide can either be safely stored away or used to help grow crops in very dry areas. You can find out more about this here.
One of the questions I often get asked is: if this is so simple why hasn’t it been done before? The idea has been around for a number of years. It was first suggested by Haroon Kheshgi in 1995, but it was considered uneconomic as the process uses a large amount of energy. What we are interested in doing is using stranded energy to drive the process.
Stranded energy is energy that is remotely located, so it is not economically viable to exploit. For example, in a desert there is plenty of energy available, but it would cost too much to transfer the energy to where anyone wants it, so it never gets used. So, paradoxically, in a desert energy is abundant and cheap, but worthless. This process can use that stranded energy.
We couldn’t have got this far without the help of a large number of people who have been extremely generous with their time and expertise. We are developing this project in an open source way, so, if you are interested to help, please get involved.