Japan is heavily reliant on foreign imports for its energy, with few reserves and most of its nuclear fleet still mothballed following the 2011 Fukushima disaster. But as Japan’s second test extraction of subsea methane hydrates begins, the country could be moving one step closer to an abundant domestic power source.

Methane hydrates – colloquially known as fire ice – are giant reserves of gas trapped in ice crystals that have been discovered off the coasts of Japan, America, India and China. The energy-dense substance looks similar to ice and when burned, one cubic metre of the methane hydrate can contain 160 cubic metres of hydrocarbon gas.

Although the Chinese, US and Japanese governments have been actively pursuing methane hydrates for years, with initial tests of a Japanese reserve taking place in 2013, the resource has proven incredibly difficult to extract. Located either in the shallow sediments of the deepwater continental shelves or beneath permafrost, it disintegrates if it is not kept under great pressure, releasing methane into the atmosphere.

Gas hydrates, once thought to occur rarely in nature, are now known to be bountiful, making them a potentially valuable resource. “The most recent estimates of gas hydrate abundance suggest that they contain perhaps more organic carbon that all the world’s oil, gas, and coal combined,” the US National Energy Technology Laboratory has said.

If the newest Japanese tests prove successful and economically viable this could lead to  a whole new energy alternative for resource-poor Japan, but has technology advanced enough to extract the complex water molecule lattices?

Japan’s second extraction test

Japan’s newest test began in May, 49.6 miles south of the Atsumi Peninsula in the Nankai Trough off Japan’s south-east coast. Two wells have been drilled using the deepsea drilling vessel Chikyu, to reach the methane hydrates that lie 300m below the seabed, at a water depth of 1,000m.

Each well is using a different system to avoid sand disrupting the wells, which has forced production to cease in previous tests. Memory polymers of various shapes will be used to stop the inflow of sand and monitoring wells are being drilled nearby to record changes in temperatures and pressures in different seabed layers.

"Japan’s newest test began in May, 49.6 miles south of the Atsumi Peninsula in the Nankai Trough off Japan’s south-east coast."

The Japanese Agency for Natural Resources and Energy (ANRE) said: “In light of the results of the second offshore methane hydrate production test, ANRE will continue efforts for methane hydrate production by advancing research and development regarding long-term and stable production, cost-effectiveness, environmental impact and other elements, while monitoring the international situation, so as to launch private-led projects for commercialisation around the mid-2020s according to the Basic Plan on Ocean Policy.”

It is not just Japan that is pushing forward with exploration and development of this tricky substance; China has also successfully extracted gas from methane hydrates. In May the country managed to extract 113,200 cubic meters from the South China Sea, with 99.5% methane content. Another test is underway on the US off the Gulf Coast, run by the University of Texas.

High-pressure challenges

Gas hydrates have often been seen as a problem, not a potential power source. Because they often form around deepwater oil and gas drilling wells, the management of gas hydrates are an essential part of project planning for underwater operations as failing to do so can hinder the well and the pipeline. Until recent years, the lion’s share of research has gone into the mitigation of flammable ice, rather than its development.

One key challenge facing methane hydrate extraction is the potential damage of uncaptured methane. Natural gas is one of the cleaner fossil fuels, creating 50% less CO2 when burned than coal, one of the aspects that has contributed to the success of shale gas. However, unburned methane is substantially more damaging than CO2 so it must be captured before it has a chance to become either depressurised or warm.

"Natural gas is one of the cleaner fossil fuels, creating 50% less CO2 when burned than coal."

Traditional drilling equipment can destabilise the seabed, releasing the methane into the surrounding ecosystem and the atmosphere. The methane must therefore be captured before it is taken out of the sea. Unlike oil or conventional gas reserves, however, it is not situated in just one place but often spread out over a vast area. In order to capture it, extraction equipment needs to be able to move along the seabed, picking up, depressurising and collecting the hydrates.

What could methane hydrates mean for Japan?

The discovery of methane hydrates off the coast of Japan arguably means more to the islands than it does for China or the US.

Following the closures of Japan’s nuclear plants in 2011, coal and LNG imports skyrocketed to keep the country’s lights on. In 2015, 114.145 million tonnes of coal were imported, a vast increase from just 60 million in 2000.

There is an estimated 40 trillion cubic feet (1.1 trillion cubic metres) of methane hydrates located in Japan’s eastern Nankai Trough alone. If it is possible to commercially capture this, it could meet Japan’s total energy demand for eleven years. The Ministry of Economy, Trade and Industry has announced that it intends to create a private commercial gas hydrate sector by 2027, but there are still many challenges to be overcome and tests are in very early stages, so it may be too soon to trumpet the rise of a new domestic energy source for Japan just yet.