Combustible ice holds promise

Combustible ice — a natural gas hydrate existing as ice crystals with methane gas locked inside — is usually formed under high pressure and low temperature in permafrost or under the sea.

When exposed to normal air pressure, the hydrate breaks down into water and methane, with 1 cubic meter of the compound releasing about 160 cubic meters of gas, making it a highly energyintensive fuel.

It is regarded as a clean energy option with high energy density and huge amounts of reserves. It releases less than half the amount of carbon dioxide when burned as does oil or coal.

China’s natural gas hydrate research started in the South China Sea, home of the biggest reserve in the country, with an estimated 80 billion metric tons of oil equivalent — the bulk of China’s total 100 billion metric tons.

In China, the hydrate has been widely detected in permafrost in areas such as the Qinghai-Tibet Plateau, and below the South China and East China seas.

No country has been able to produce gas commercially, despite its promising potential, due to the challenging conditions of harvesting the hydrate, including worries about potential pollution.

China started research on the energy source in the late 1990s. Its first gas hydrate samples were collected in the South China Sea in 2007.