Professor James Economy's Group
Potential Application of Gas Hydrate for Sea Water Desalination
Gas Hydrates are formed in systems of water and small molecules by low temperature and high pressure. From a scientists point of view, gas hydrates are cages of water (host) molecules that surround gas (guest) molecules and at the same time exclude the salt. Gas hydrates are ice-like crystalline structures and can exist at temperatures above the freezing point of water and elevated pressures. It is estimated that there is more methane in the form of hydrate sitting on the bottom of the ocean there all of the oil ever discovered. In this study, we propose, for the first time, to examine the use of gas hydrates (clathrates) as a source of clean water. We expect to be in a position to design and evaluate a process for actually preparing potable water from seawater.
Gas hydrates were formed in our laboratory using a high pressure liquid propane or CO2 or at lower pressure using ethane gas, with simulated sea water at 1-4 oC. The initial results show that gas hydrates display significant desalination, but the salt concentration is still higher than the potable level.
Our Research Plan is : 1). Develop an understanding of the conditions required for gas hydrate formation accompanied by salt separation; 2). Identify approaches to catalyze the formation and decomposition of gas hydrate; 3). Try to find out which of these systems is appropriate for use at shallow depths for economical recovery of potable water and the working gas 4). Eventually, try to access the methane hydrate sitting at depth of several thousand feet to recover streams of clean water and methane ( a source of fuel).
Figure 1. Structures of gas hydrates
Figure 3. Forming and Instant Melting of Ice-like Sample
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2. Ripmeester, J.A., et al., Nature, 1987, 325, 135
3. E. D. Sloan, Jr, Geological, 1998, 137, 31-50