According to the results obtained by the operation, it has been confirmed that the output gas mixture possesses the properties indicated in Fig. 12. As shown in the figure, high-calorie gas featuring 15-18MJ/Nm3, that could not be achieved by gasification by "Norin Green No. 1" test plant through partial oxidation (ca. 10 MJ/Nm3; using O2 and H2O as gasifying agents) or conventional gasification using air as a gasifying agent (ca. 5 MJ/Nm3), can be produced when the reaction temperature is 800-900°C, H2O/ C mole ratio is lower than 5.0, and the reaction time is ca. 2 seconds. In addition, this gas mixture contains over 20% hydrogen (H2). This value is higher than the threshold value of 10% for applicability in terms of ignition and combustion rate for gas engines and micro gas turbines, which indicate that the gas mixture is a high-quality gas fuel. Besides, given that the compositional ratio of H2 to CO is higher, the threshold combustion temperature is 90°C higher than that of methane. Figure 13 explains a comparison of theoretical combustion temperatures of this gas mixture and various fuels, such as methane, gasoline, propane, methanol and ethanol.

Biomass means any form of lignocellulosic materials.

3. Conclusion

As the gas mixture generated with "Norin Green No. 1" test plant and high-calorie gas produced with "Norin Biomass No. 3" test plant using the high calorie gasification technology is temporarily stored in a cold gas state, it can be used in a manner similar to natural or city gas, with widespread applications.

Obviously, since "Norin Biomass No. 3" plant, which efficiently converts biomass into high calorie gas mixture with a small system, can be easily used as a fuel for gas engines and micro gas turbines, it can also be used for small-scale power generation and co-generation. Accordingly, high-efficiency and small-scale power generation can be achieved.

The potential applications of the gas mixture generated by gasification through high-calorie gas production are as follows;

1. Co-generation in buildings, hospitals, industrial parks, factories, etc.

2. Commercial power (targeted efficiency of 25-35%, with at least 1 million kWh/year)

3. Peak cut (reduction of contracted power) and emergency use for large-scale factories

4. Gas fuel for industrial parks (e. g. ceramics and porcelain)

5. Supplementary fuel for incinerator (dioxin countermeasure for industrial waste processing)

6. Fuel for boilers of greenhouse agriculture

7. Fuel for food processing industries by the use of residues produced in the process.

8. Synthesis of biomethanol for BDF production, for batteries of direct methanol fuel cell (DMFT), and a liquid fuel mixed with gasoline for flexible fuel vehicles (FFV).

Three "Norin biomass No. 3" plants processing 4-6 dry t/day of biomass feedstock are under construction by private companies and local government with the 50% financial support from the Government.

This study demonstrates that the gasification of readily available biomass materials both by partial oxidation technology and by high calorie gasification technology could be optimized for generation of gas mixtures primarily composed of H2, CO and producing methanol yields ranging theoretically from ca. 40 to 60% by dry weight. A test plant utilizing gasification through partial oxidation with 2t/day gasifier can achieve a methanol yield of ca. 20% from the biomass raw material (by weight). This creates an opportunity to utilize a wide range of high yielding with low sugar and starch content such as Erianthus and Miscanthus. Non-palatable lignocellulosic byproducts such as sawdust and crop residues such as straw and husks of rice from various industries would also have suitable application. Sawdust, rice bran, refuse of sugarcane mills (bagasse etc.) and rice husks are particularly attractive and provide a ready-to-use biofuel resource. It is anticipated that the cultivation and utilization of biomass crops will be attractive as carbon neutral biomass feedstocks for biofuel production in the future.

The potentially positive economic impact of biomethanol production on Japanese farming and social systems from planting grasses and trees in unutilized land is immense (Nakagawa 2001; Harada 2001). Reduced CO2 emissions, recycling of abandoned upland and paddy field and woodland in mountainous areas, and recycling of wastes of agricultural products would all be possible by promoting biofuel production system based on the gasification technologies. This technology is particularly attractive since biomethanol can be produced from a wide range of biomass raw materials.

4. Acknowledgements

Authors would like to express their sincere thanks to Dr. Bryan Kindiger, USDA-ARS, Grazinglands Research Laboratory for his critical reading of the manuscript.

This researches were supported by a grant from Ministry of Agriculture, Forestry and Fisheries of Japan, named "Development of sustainable ecosystem for primary industries towards the 21st century" (2000-2002), "Bio-recycle of wastes from agriculture, forestry, and fisheries" (2003-2005), and "Rural Biomass Research Project, BEC (Biomass Ethanol Conversion)" (2006-2010).