Chapter 5 - The need and options available for permanent CO2 disposal

Abstract

This chapter focuses on the means of disposing CO2 from the combustion of fossil fuels at a cost that keeps fossil energy competitive with all major alternative energy sources. The carbonation reactions are actually part of the natural carbon cycle, and huge deposits of stable carbonates exist in the form of magnesium and calcium carbonates. Magnesium and calcium ions are also responsible for most of the CO2 storage in the oceans, without the otherwise associated lowering of pH. The silicates of alkaline earth metals are of particular interest because of their large abundance in the earth's crust. Magnesium silicates are available in huge deposits throughout the world. Furthermore, the magnesium silicate deposits contain a very large weight percentage of magnesium oxide, which is the basic component needed to form the carbonate. Magnesium silicates of interest are olivines and serpentines. The deposits are sections of the oceanic crust/upper mantle that were thrust up onto the land. The most prevalent useful silicate deposits are in the form of serpentinite, which is a relatively soft rock. The nature and hardness of the deposits make them suitable to open-pit mining.