The Idea

This is a brief description of the idea. If you prefer we also have a detailed description and a slideshow presentation on the process for you to see.

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.

 

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6 people have left a comment

Pierre Jones-Savard says: November 14th, 2008

Good end of day, i have learn from the forumer Yves Vinet( his pseudo is vinety) that in south América
many cultivators do dark soil by use of wood coal ;
they have only to spread the wood coal before the soil tillage.
The wood coal is carbon and in soil it is stable for a long time, salute.

Juana Banana says: November 20th, 2008

Have you herad about artifical Reef construction? It requires electric energy, which can be obtained from solar energy.
Reefs bind aswell a lot of CO2 and Ca. And reefs have a several positive effects for coastal communities, such as protecting coasts from adverse weather conditions, wave impact and flooding.
For each kilogramm of CaCO3 they bind aproximatley 450 gramms of CO2.
So instead of digging up a lot of rocks and throwing them into the ocean, why not “create” living rocks directly in the ocean. Reefs will be poblated by algae, which will then use additional CO2 for biomass production.
Probably will cost a lot less and have less impacts, but is based on the same mechanism.

Small Blue Planet » Blog Archive » Geo-Engineering - Science for the End of Days says: December 1st, 2008

[...] clipped from http://www.cquestrate.com [...]

Mike McFall says: January 17th, 2009

I have a very simple scientifically based idea on how to sequester Carbon from the atmosphere.
P.h.d.s have said it will work. As a father of three children I must watch out for the welfare of my family first, therefore I am simply waiting for a solid monetary offer from a corporation before revealing my idea. With the economy the way it is I need all the financial help I can get.
This method does NOT require the introduction / use of ANY material whatsoever. This will eliminate any enviro-groups complaints about anything.

Dan Breen says: March 1st, 2009

I am a chemical engineer, my business used lime and exhaust gas CO2 to preduce precipitated calcium carbonate. I struggle with two issues with your concept.

1. Lime requires a lot of energy to drive the limestone rock to 1000 deg C to drive it from CaCO3 to CaO. This evergy is currently generated by burning oil, gas, coal or pet coke. These fuel generate a lot of CO2. Also, a major factor here will be the evergy required to deliver and distribute the lime. Have you looked to see if the total CO2 required to produce and deliver you lime will not exceed what you believe it will do?

2. In my manufacturing experience, lime must be slaked to become hydrated lime (exothermic reaction). We then pass gasses with at least 8% CO2. This goes rapidly and efficiently to back to calcium carbonate (CaCO3). The evevated pH of the slaked lime, goes down to neutral as the CO2 is introduced and Calcium carbonate forms. How stable is the HCO3 you believe will form? Why wont it go back to CaCO3 as it does in the oceans such as the areas of forming limestone near Jamaica? If that accurs the result will be one CaO to one CO2.

Cquestrate « Kirstybooth’s Blog says: March 16th, 2009

[...] carbon dioxide issues would lie with limestone? After an hour with Chris Unitt, the developer of Cquestrate’s website, the advantages and potential draw backs of this seemingly obvious project became [...]

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