Methane Hydrates: An Abundance of Clean Energy?

Abstract

The discovery that gas hydrates (also called clathrate hydrates) can crystallize (Figure 1) as a solid by the combination of water and several types of gases exposed to low temperatures and elevated pressure goes back to the 1800s. French researchers were the frst to report the formation of methane, ethane, and propane hydrates.1 Results of these studies remained as scientifc novelties until the mid-1930s, when it was discovered in Germany that gas hydrates forming as solids above 0°C in gas pipelines blocked the fow of natural gas.2 This observation initiated a furry of activities both in Europe and in the United States to fnd various inhibitors to prevent hydrate formation in gas transmission lines. During the mid-1960s, it was recognized that nature, over millions of years, has deposited vast amounts of methane hydrates along most of the continental margins in the ocean sediments, as well as along the permafrost regions in Alaska, Canada, and Russia.3 Figure 2 shows the presence of methane hydrate deposits in the ocean sediments and in the permafrost regions of the world. These deposits are byproducts of microbial decomposition of organic matter or of Earth's geothermal heating distributed worldwide where temperature and pressure are suitable for hydrate formation. The distribution of organic carbon in Earth's crust as methane