NKK Corporation, Taiheiyo Coal Mining Co., Ltd. and Sumitomo Metal Industries, Ltd. announced today that their joint synthesis tests of dimethyl ether (DME), a new source of clean energy, have made steady progress at a test plant in Kushiro, northern Japan. The three companies are working on the commercial development of low-cost DME mass production technology jointly with the Center for Coal Utilization, Japan. The project is sponsored by MITI's Agency of Natural Resources and Energy, with a grant for promoting coal utilization technology. Tests are ongoing at the five ton-per-day test plant completed in August this year at the Kushiro Colliery of Taiheiyo Coal Mining by using coal-bed methane, which is generated where coal is mined.

   Major facilities at the test plant built on a 3,000m² site include a synthesis gas (major components: hydrogen and carbon monoxide) production/ purification system, a 20m-high DME synthesis reactor and DME purification columns. About 30 researchers are engaged in R&D and test operations at the research center newly set up in the Kushiro Colliery.

   To date, the partners have conducted two sets of DME synthesis tests. The first set, conducted in September, involved production tests of synthesis gas (CO, H₂) alone, but the second set, which took place in October, were DME synthesis trials that lasted 300 hours. The latter showed that the test plant was extremely stable in operation, and, after one week, led to the world's first successful synthesis of DME from coal-bed methane. The tests produced 80% of the designed capacity of DME, at a purity of 97%. These results were excellent, reproducing almost perfectly the results of tests previously conducted using a small (50kg per day) bench plant and the process simulations. Throughout the test period, no deterioration was detected in the activity of the catalyst.

   The partners plan to hold one more set of tests this fiscal year, running from late November through December. In fiscal 2000 further tests will be held once each in June and July, followed by a two-month continuous operation trial in September through October. The DME produced during these tests is to be used in diesel engine tests.

   The aim of the various tests this fiscal year and next is to optimize the process and establish its reliability. In fiscal 2001, the project's final year, a design concept for a 500 ton-per-day commercial-scale plant will be developed and an overall system evaluation will be conducted.

   China and other countries simply release their coal-bed methane into the atmosphere. This methane accounts for one percent by volume of the world's consumption of natural gases. Since methane has 21 times the greenhouse effect of CO₂, the large-scale release of coal-bed methane is not only a waste of natural energy resources, but also is a problem in view of the need to curb global warming. The recovery and efficient use of coal-bed methane is a matter of urgency. The fact that the new process led to the world's first synthesis of DME from coal-bed methane, despite still being at the test plant stage, is a significant step toward resolving these problems.

   The process enables use of not only coal-bed methane, but also coal-gasified gas (including gas from low-grade coal, which is abundantly available throughout Asia), natural gas from small gas fields and associated gas from oil fields, as the raw material for the DME synthesis. The partners believe that through growing applications of DME, the process will play a major role in resolving the energy resource and global warming problems in the coming century.