New classification of CO_2 mineralization processes and economic evaluation

摘要

Ever increasing greenhouse gas emissions and global warming have brought greater focus to the areas of CO2 capture and storage/utilization. Carbon mineralization is one CCS/U technology that can capture large quantities of CO2 and convert it into stable carbonate products that can be stored easily. Several CO2 mineralization processes have been proposed, however there are no commercial scale projects because there are still significant issues that need to be improved upon before commercialization can take place. In this work, we perform a review of the available technologies and classify them into different groups. We have identified that a minimum of three inputs are required to a CO2 mineralization process. These can be in the form of two energy inputs and one chemical input or two chemical inputs and one energy input. When two forms of energy inputs are used, it is invariable to use electricity which is a poor form of energy i.e., CO2 emissions per unit of useful energy is higher than using heat as a form of energy. In view of this, we can qualitatively conclude that it may be worthwhile to develop technologies that use two chemical inputs and heat as a choice of energy rather than use both heat and electricity. It follows that the chemicals used must be regenerated using heat and not electricity. Further, we evaluate the economics of the most well-known type of mineralization process to date, the Direct Aqueous Carbonation (DAC) process, where the mineralization reaction takes place directly under aqueous conditions, high pressures and temperatures.