An experiment to store carbon dioxide, a global warming gas, 1.1 km underground is under way in Nagaoka, Niigata Prefecture.

The experiment, conducted at the Iwanohara oil storage site of Teikoku Oil Co., is led by Research Institute of Innovative Technology for the Earth, a Kyoto-based foundation established in 1990 as a research hub primarily for technologies to counter global warming.

The five-year project, the first in Japan, is aimed at developing technologies to store a large amount of carbon dioxide gas collected from large-scale emission sources such as thermal power stations and chemical plants.

The gas will be stored in an aquifer made of sandstone and rich in moisture. A typical aquifer is topped with a 100-meter layer of cap rock, known as an impermeable formation, that keeps liquids and gases trapped.

The experiment at Iwanohara involves injecting carbon dioxide into onshore and offshore aquifers through wells and monitoring the movement of the gas through three observation wells.

A typical car belches roughly 4 tons of carbon dioxide a year.

Engineers at Iwanohara are pumping about 20 tons of carbon dioxide a day into the aquifers, and the plan is to inject 10,000 tons in the next 18 months.

Officials at the research institute say the experiment is safe and there is no fear that the carbon dioxide stored in the aquifers will leak back to the surface.

Shigeo Murai, project leader, said the experiment will need to be done in a larger scale in the future, and cutting down the cost of operation will also be their future agenda.