Mineral Sequestration
What is sequestration in mineral mines?
Sequestration in mineral mines involves reacting carbon dioxide with either magnesium oxide (MgO) or calcium oxide (CaO) to form stable carbonates, which are then reburied in the mines from which the original oxide was taken.
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| source: Lackner 10/7/2002 p.13 |
Who is working on it?
In the summer of 1998 a multi-lab working group, the DOE Mineral Carbonation Study Group, was created to develop mineral sequestration. [1] [2] The participants are:
What are its advantages?
- The carbonates formed are thermodynamically stable and the disposal is therefore permanent. There is no chance of the carbon dioxide escaping into the atmosphere.
- The mineral resources on earth far exceed need.
- Carbonate is the lowest energy state of carbon, not carbon dioxide. [3]
- "Mineral carbonation occurs naturally on a geological time scales and would eventually absorb all the additional carbon dioxide." [4] The process is just speeding up one that occurs in nature.
- The minerals are readily accessible in locations near high-density power generation centers. [5]
- There is potential to produce value-added byproducts. [6]
- The process is compatible with both technologies under development and current power systems. [7]
- Predicted cost is not unreasonable. [8] [9]
- Implementation without an external supply of heat is possible because the reaction is exothermic. [10]
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| source: Goldberg 7 |
What are its disadvantages?
- Carbonation plant must be at the site of the mine due to the large volumes of material required. [11]
- Volumes increase upon carbonation so in order to store the newly formed carbonates back in the mine some terrain alteration will be necessary. [12]
- Extensive mining operations necessary, which will have environmental impact.
- There is the potential for asbestos to be present in the mineral deposit. [13]
- Must be able to deal with ore impurities. [14]
When will mineral carbonation be operational?
Goldberg predicts a demonstrated scale carbonation system to be operational by 2007. [15]
Where will operations be located?
There are peridotite and serpentinite ore bodies, which are two magnesium silicate containing ores, located all over the world. [16] Major deposits of olivine, another magnesium containing ore, are found in Twin Sisters dunite, WA, Norway, and Japan. [17] "A single deposit in Oman contains over 30, 000 cubic kilometers of magnesium silicates, which alone could handle all of the world's coal." [18]
| Olivine Production, by country, (Thousand metric tons) (e) |
| |
1995
|
1999
|
| Norway |
5,850
|
6,300
|
| Japan |
900
|
900
|
| Spain |
500
|
500
|
| US |
90
|
90
|
| Italy |
50
|
50
|
| Others |
40
|
65
|
| Total |
7,430
|
7,945
|
| Note: (e) estimate |
[19]
What is the cost?
"Based on copper mining and milling cost, and the likely required plant size for chemical processing, a disposal cost of $15 to $20 per ton of CO2 would not be unreasonable. Even a recent IEA study agrees that mining, milling, and reclamation costs are low, around $7 to $10 per tonne of CO2.. The Albany process sidesteps concerns raised by the IEA in their report and suggests that with further R&D one could develop an implementation for the mineral carbonation process that including mining could be on the order of $15 to $20 per ton of CO2. With a power plant operating at 70% efficiency, this would be about 1 cent US/kWh of electricity." [20]
