Japan plans to capture a sixth of its carbon dioxide pollution and store the gas underground in a bid to tackle climate change, according to a report on Monday.

The proposals would see Japan bury some 200 million tons of carbon dioxide each year by 2020, a huge increase on the scale of existing schemes, the largest of which store about 1 million tons annually.

Masahiro Nishio, an official at the Ministry of Economy, Trade and Industry, said the underground storage could begin as soon as 2010. But several hurdles remain, he admitted.

The technology is expensive, costing up to 6,000 yen (US$54) per ton of stored carbon dioxide. The new initiative aims to halve that cost by 2020, Nishio said. "It's very expensive, so we have much to study."

Capture and storage of carbon dioxide, also called sequestration, has become a key technology in recent years as industrialized nations battle to control their greenhouse gas emissions.

Japan, the world's second largest economy, expels 1.3 billion tons of carbon dioxide a year, making it one of the world's top offenders.

The technology is also seen as the only realistic way to allow developing nations to burn their abundant stocks of coal without provoking runaway global warming.

That would require so-called "clean coal" technology, which is able to separate the carbon before or after the coal is burnt.

Nishio said the first target would be the carbon dioxide produced during natural gas production, but that emissions from steel mills, power plants and chemical factories would follow.

The gas would be made into liquid and squeezed into underground reservoirs, gas fields or gaps between rock strata. Concerns have been raised that carbon dioxide could leak, but geologists monitoring existing schemes say there are no signs of escapes.

John Davison, of the International Energy Agency's greenhouse gas programme in Cheltenham, said Japan's plans were ambitious: "To be capturing and storing that amount of carbon dioxide by 2020 is a very large ramp-up rate."

Stuart Haszeldine, a carbon storage expert at Edinburgh University, said Japan could have trouble finding enough underground space. "Japan doesn't have access to large scale carbon dioxide storage reservoirs like the UK does in the North Sea."

At present, the most high profile carbon storage project is in the North Sea, where Norwegian oil company Statoil disposes of about 1 million tons each year.

Source: China Daily