Energy and Environmental Analysis of Membrane-Based CH4-CO2 Replacement Processes in Natural Gas Hydrates

Abstract

Natural gas hydrates are the largest reservoir of natural gas worldwide. This paper proposes and analyzes the CH4-CO2 replacement in the hydrate phase and pure methane collection through the use of membrane-based separation. The investigation uses a 1 L lab reactor, in which the CH4 hydrates are formed in a quartz sand matrix partially saturated with water. CH4 is subsequently dissociated with a CO2 stream supplied within the sediment inside the reactor. An energy and environmental analysis was carried out to prove the sustainability of the process. Results show that the process energy consumption constitutes 4.75% of the energy stored in the recovered methane. The carbon footprint of the CH4-CO2 exchange process is calculated as a balance of the CO2 produced in the process and the CO2 stored in system. Results provide an estimated negative value, equal to 0.004 moles sequestrated, thus proving the environmental benefit of the exchange process.

Mathematical Model of Carbon Dioxide Injection into a Porous Reservoir Saturated with Methane and Its Gas Hydrate

“…The process of CH4-CO2 exchange in the methane hydrate occurs with the reservoir heating. We also performed a comparison with the experimental data presented in [55]. In this work, the process of the replacement of methane in CH 4 hydrate with CO 2 in a dispersed medium is considered, and the dynamics of temperature changes for this process is presented.…”

“…At the second stage of the experiment, the process of methane replacement with carbon dioxide in the hydrate saturated sand sample was studied. The initial methane hydrate saturation was 10%, the sample porosity was 34%, and the initial temperature in the reactor was 275 K. Figure 4 shows a comparison of the results of numerical study and experimental data, given in [55], for changes in temperature over time. As can be seen from Figure 4, energy is released due to the replacement; after the completion of the CH 4 -CO 2 replacement process, the sample temperature returns to the initial one.…”

“…It is worth noting the satisfactory agreement between the experimental data and the calculation results using the proposed model. [55]. The solid line is the numerical study results according to the proposed model, while the points are the experimental data.…”

“…The process of CH4-CO2 exchange in the methane hydrate occurs with the reservoir heating. [55]. The solid line is the numerical study results according to the proposed model, while the points are the experimental data.…”

Energy Analysis in Ice Hockey Arenas and Analytical Formula for the Temperature Profile in the Ice Pad with Transient Boundary Conditions

“…All in all, very different types of solutions can be realized for promoting the energy saving by increasing the overall system efficiency, see e.g. Castellani et al (2017) for solar energy storage and Castellani et al (2019) for pure methane collection.…”