New Technique For CO₂ Mitigation--The Research Of CO₂ Sequestration In Soil

The development of world economy, the increase of energy consumption and the enormous emission of greenhouse gas, such as carbon dioxide, result in the questions that greenhouse effect is strengthening and the whole world climate is getting warm, and our ecosystem and economy are in challenged. So the ways of capturing, storing and mitigating of CO2, the major greenhouse gas, are researched and developed in many countries. Scrubbing the CO2 of combustion flue gas with ammonia to form ammonium bicarbonate and then sequestrating it in soil are a novel method of mitigation CO2. Ammonium bicarbonate (ABC) and long-effect ammonium bicarbonate (LEABC), which are used as nitrogen fertilizers in China, are water soluble carbon compounds. They can percolate into the earth's aquifer layer, and eventually be neutralized by the alkaline components in the aquifer. It means some of the carbon compounds in it can be permanently fixed in the earth, so that avoid them returning into atmosphere as greenhouse gas-CO2. This paper aimed at the percolation characteristics of ABC and LEABC. Simulative soil columns, which were fertilized with ABC and LEABC, respectively, were used to research the distribution and decomposition of the two fertilizers in soil under the natural condition in laboratory. It was found that concentrations of bicarbonate in the soil columns, fertilized with both ABC and LEABC were almost the same at the same depth of the soil after 7 days. But after two weeks, there were obvious differences between soil columns fertilized with LEABC and ABC, respectively. The concentration of the former was much higher than that of the latter at the same depth. And the irons of the former penetrated much deeper than those of the latter. The bicarbonate and carbonate irons of the former can percolate into the earth's aquifer layer, eventually be permanently fixed in the earth .So the results indicate LEABC is better than ABC to sequestrate CO2.Based on the experiment and theory, a model of solute transport was developed to simulate the transport process of the HCO3-ion in the porous media. The simulation results of the model are in agreement with the experimental results reasonably.