Uncertainties Shadow Combustible Ice Mining Breakthrough

The snowcapped Qilian Mountains in Qinghai province seem a world apart from the subtropical South China Sea – yet both are home to a curious, methane-containing substance known as “combustible ice” that could replace traditional fossil fuels.

Areas of the world from mountains to sea floors contain so much combustible ice – an estimated 20 quadrillion cubic meters combined, according to the U.S. Department of Energy – that the substance could potentially meet the world’s energy needs for centuries.

On May 18, the China Geological Survey (CGS) announced that a Chinese ocean-mining crew in the South China Sea had completed the world’s first successful, extended-period extraction of combustible ice, which is also called methane hydrate. The fuel was pulled from beneath the sea floor over eight consecutive days.

China’s State Council and the Communist Party hailed the feat as a “landmark achievement.”

Moreover, the Chinese miners outperformed a rival team from Japan, a country with which China has been competing for years in a technological race aimed at unlocking the vast potential of combustible ice.

Just two weeks before the CGS announcement, Japanese sea-floor miners extracted 35,000 cubic meters of methane from combustible ice deposits within a 12-day period.

But China’s eight-day drilling operation extracted 120,000 cubic meters – far more than the Japanese.

China’s “mining operation used a lot of groundbreaking, core technology,” Pan Xilu, marketing manager at China International Marine Containers, a state-owned company that designed the semi-submersible drilling rig used in the South China Sea operation, told Caixin.

Pan said the rig platform, called Lanjing 1, holds the current world record for drilling depth – 15,240 meters beneath the ocean floor – among vessels of its kind.

And China lays claim to some of the world’s largest combustible ice reserves. CSG says methane hydrate lying beneath the waters of the South China Sea holds the combined energy equivalent of 70 billion tons of oil.

Uncertain Future

Japanese miners in 2013 were the first to successfully extract undersea combustible ice. But the project was cut short because seabed sediment clogged drilling equipment.

The Japanese setback laid bare one of the many uncertainties about the future of China’s combustible ice ambitions.

Researchers and industry sources told Caixin that a variety of technical hurdles must be overcome before the process of mining combustible ice and extracting its methane is commercially viable.

Moreover, they said, mining operators must carefully consider the environmental impact of every combustible ice extraction effort in order to avoid a possible ecological disaster.

And not to be overlooked is the fact that methane releases carbon dioxide when burned, just like other fossil fuels.

Combustible ice mining presents far more technical challenges than conventional fossil fuel extraction operations, a CGS staffer told Caixin. Combustible ice deposits are usually found in the loose sediment at the edge of continental shelves, which is a technically difficult medium for mining because the substance is frequently found on steep seabed slopes. And methane hydrate decomposes easily, which poses a challenge because miners must prevent methane seepage while mined solids are transported to the ocean surface.

Sources told Caixin that Chinese and Japanese mining teams in May used a technique called “depressurization,” through which pressure near the drill site is reduced to trigger a breakdown of combustible ice into water and methane gas. The technique is relatively inexpensive and suitable for mining combustible ice over a wide area.

But depressurization presents challenges, as its use over time could damage the geological structure of a seabed and cause underwater landslides, said Wang Pinxian, a professor of marine geology at Shanghai’s Tongji University.

More worrying is that large amounts of methane from combustible ice mining operations could contaminate seawater and the air, damaging ocean ecosystems as well as the atmosphere, according to a World Ocean Review report published by Maribus, a German non-profit group.

Long Way to Go

Formed under low temperatures, high pressure conditions, combustible ice is found in permanently frozen tundra and deep-sea sediment. As a fuel source, it has a high-energy density.

Combustible ice was first mined in Russia’s Siberia in the 1960s. China and Japan kicked off national programs aimed at commercializing undersea reserves in the 1990s.

In 1999, the Guangzhou Marine Geological Survey found evidence of combustible ice reserves in the South China Sea. Two years later, Japan’s Ministry of Economy, Trade, and Industry announced an 18-year plan to explore commercial options for undersea combustible ice.

In 2007, Chinese miners collected their first combustible ice samples by drilling near Saint Esprit Shoal in the northern South China Sea. A year later, samples were extracted from permafrost in the Qilian Mountains.

Combustible ice was also found in the Pearl River Delta near Shanghai in 2013.

In the wake of the latest success, CGS officials said they expect to launch the next trial extraction operation within five years. The ultimate goal is to begin commercial mining of combustible ice by around 2030, CGS said.

No one denies that the path to commercialization will be long and difficult.

The latest “historic breakthrough is still a rudimentary experiment, focused on testing the safety of the process,” Dong Xiucheng, a professor at the China Oil and Gas Center, at China University of Petroleum, told Caixin. “We’re still a long way from thinking about its economic dimension and doing real commercial mining.”

And even if methane can be extracted from the world’s vast deposits of combustible ice, experts say environmental challenges must not be ignored.

“We’re currently treading on thin ice, exercising extreme caution,” said a source who participated in the latest mining project. “There’s still a long way to go.”