Japanese heavy industries are pushing ahead with technology aimed at lowering costs of natural gas and helping promote greater use of the environmentally friendly energy source.
Mitsui Engineering & Shipbuilding Co. and Mitsubishi Heavy Industries Ltd. are among the Japanese companies developing commercial uses for natural gas hydrate, a frozen powdery material of high gas concentration.
Natural gas hydrates had previously been considered troublesome as they clog up pipes and cause accidents in pipelines and petrochemical complexes, but a rethink by scientists has caused them to be seen as a useful form of natural gas.
"We have almost managed to solve the technological problem," said Tatsuya Takaoki, deputy chief of Mitsui Engineering's NGH project team. "The remaining challenge is early commercialization."
Natural gas emits less carbon dioxide -- regarded as the main cause of global warming -- than fossil fuels such as coal and oil, but the prevailing technology for transporting and storing it in liquefied form is costly.
Particles of NGH have a spherical wickerwork structure ranging from tens of micrometers to several millimeters in diameter.
Although its gas concentration level falls short of the 600-fold level of liquefied natural gas, NGH can be stabilized at minus 15, compared with LNG's minus 162.
This characteristic allows companies to cut costs for storing, transporting and investment in production of NGH by 20 percent to 30 percent from those for LNG, according to industry officials.
The low cost could prompt businesses to tap relatively small gas fields in Southeast Asia and Oceania that have been abandoned due to production costs exceeding revenues.
Natural gas hydrates require no pipelines and are easy to store and handle, making them suitable for use in small power stations and electric generators, the officials said.
The heat-absorbing effect of their being converted back into gas, and the release of high-pressure gas may also be applied to air conditioning and power generation, they said.
There are several ways to produce NGH. Mitsui Engineering is developing a hydrating process of mixing water and natural gas under a temperature of 2 degrees and 50 times standard atmospheric pressure.
Mitsubishi Heavy has opted to spray water on natural gas and then remove the excess water. The product dissolves at the surface but stabilizes as the detached water particles freeze, providing an overcoat.
Mitsui Engineering has jointly developed with Osaka University and other partners a technology to make the powder into high-density pellets more tolerant to changes in temperature and easier to transport and store, Takaoki said.
The company plans to set up a pilot plant somewhere in Japan in the near future for trials ranging from production to converting the product back to gas, he said.
MHI officials meanwhile said the company expects to before long expand the output capacity of its pilot plant to 100 tons a day from 1 ton at present.