Because about 70% of the national land in Japan is covered with forests, Japan has abundant potential energy of woody biomass (WB). However, the energy use of WB is not advanced sufficiently. The cost of power generation by WB is higher than that of grid, and the supply and demand balances for the energy use is not established. In this study, we focused on the three types of power generation by WB, i.e., direct combustion, gasification, and chemical-looping combustion (CLC) which is one of the promising energy conversion technologies from carbon fuels based on the cyclic reduction and oxidation of metal oxide particles and with reduced energy for CO2 capture. We designed each power generation process, calculated the energy efficiency and power generation cost by the detailed bottom-up approach, and suggested the technological scenario to show innovation pathways to be solved and / or conditions to utilize more WB. We found that it was important to improve the energy efficiency of steam cycle by higher temperature and pressure with the cost reduction of WB itself, and thus power generation cost decreases less than ￥25 /kWh – target cost in this study, and CO2 sales by CLC is effective to reduce cost.
Waste biomass may contain artificial compounds added during the intermediate treatment process of biomass, as well as natural inorganic matter and compounds discharged by human activity. Carbonized biomass produced for the purpose of fuel utilization for example, may affect self-heating characteristics depending on the compound added. In this study, in order to evaluate the effect on self-heating characteristics by iron compounds produced by carbonization, poly ferric sulfate was selected as a compound to be added, and elemental speciation of iron compounds and thermal behavior by oxidation reaction of carbonized biomass were analyzed. As a result, it was found that carbonized biomass containing poly ferric sulfate may have decreased self-heating characteristics by retaining under air atmosphere for several days. From elemental speciation analysis of iron compounds, it was confirmed that hydrates of FeSO4 exists in carbonized biomass immediately after production and become Fe(OH)SO4 after oxidation reaction. As a result of analysis of thermal behavior of carbonized biomass, it was found that heating value due to oxidation reaction tended to increase according to the amount of poly ferric sulfate. When the amount of poly ferric sulfate is large, it could greatly affect heating value of the whole of carbonized biomass.
Fallen leaves of cherry and pine were put in a side-arm flask with zeolite. It was heated gradually by an infrared heater until 540 °C to generate ethylene gas. The amount of ethylene was measured by gas chromatography. Lignin reagent, filter paper, and newspaper were also used for comparison. The same experiment without zeolite was also conducted to check the effect of the zeolite. Ethylene gas began to generate at approximately 400 °C. 3.6% of the fallen leaves of cherry and 3.1% of the fallen leaves of pine turned into ethylene gas. The amount of ethylene gas generated from lignin reagent was about two-thirds of that from fallen leaves. The amount of ethylene gas generated from filter paper was little. The amount of ethylene gas generated from newspaper which was thought to contain lignin a little was larger than that from filter paper. By using zeolite, the smell of the phenolic compound were gone and the amount of ethylene gas increased.
Oil palm residue is expected as a prospective alternative to fossil fuels for mitigating greenhouse gas emissions. Coal and biomass co-firing power generation is introduced in Japan as cheaper biomass option. This study aims to design a sustainable empty fruit bunch (EFB) utilization system for co-firing fuel considering international transportation from Malaysia to Japan, and to evaluate the system performance based on energy balances, costs and environmental impacts. The EFB utilization system consists of six processes such as resource collection, raw EFB transportation from resource generation point to preprocessing facilities, preprocessing, produced bio-fuel transportation from preprocessing facilities to exporting ports, and international transportation. The transportation pathways in the Malaysia is optimized using the geographical information system (GIS) based on the actual road network. As preprocessing technologies, pelletizing, carbonization, and ethanol production are considered. The results show that the CO2 reduction cost in the case that EFB is pelletized in the distributed preprocessing facilities in the target area has negative value -4.35 USD/t-CO2 that shows the EFB pellet supply cost is cheaper than the coal. The CO2 reduction costs in the case that EFB is carbonized 141 USD/t-CO2, and that the bio-ethanol is produced from EFB 393 USD/t-CO2 are also cheaper than the domestic wood pellet supply system in Japan. In the sensitivity analysis, it is shown that the available amount of raw EFB has the effect on the CO2 reduction cost of the carbonization and the bio-ethanol production. On the other hand, it has small effect on the pelletizing.