Biomass utilization has been introduced from the viewpoint of electricity generation in the last decade, but its price has not been reduced at all. When compared with photovoltaics and wind turbine, it is still expensive, and its introduction will force people to pay more for electricity. Considering the popssibility of supplying electricity from solar power and wind, we need to consider the provision of carbon for steel making, jet fuel, and plastic. Difference of biomass from other renewable energy is that it takes form of organics, and can supply carbon to these use. Domestic biomass can provide 26 Tg of carbon, which is sufficient for carbon needs in Japan.
In Japan, the biogas generated by methane fermentation is mainly used for power generation and heat. However, there are other uses for biogas, such as city gas feedstock and car fuel. There are also growing expectations for methane production using hydrogen derived from renewable energy sources. In this study, we will re-evaluate the methane fermentation process through the re-evaluation of the value of biogas with regard to biomass wastes, which have been incinerated so far despite the fact that they are a carbon-neutral resource. As a result, it was found that the CO2 emission factor of electric power use and the addition rate of propane for calorific value adjustment are significant factors in the CO2 reduction effect. In addition, as a result of comparing the LCCO2 between hydrogen-oriented methane and biogass-oriented methane from biogass, the latter (LCCO2:-0.796kg-CO2/m3) was superior in terms of the environment.
In recent years, a lot of support and research have been carried out for the purpose of reducing forestry costs. The purpose of this study was to clarify the economic effect of mechanization and advanced ICT system on the entire flow in the forestry flow including forest survey, thinning, main cutting, and timber distribution flow. As a result, it was found that the production cost of thinning was higher than the profit as a woody biomass fuel material even if mechanization and “smart” distribution using demand matching system were introduced. However, by introducing both mechanization and “smart” distribution, overall profits increased by about 34 million yen per year.
Giant Miscanthus (Miscanthus × giganteus), a hybrid species between Miscanthus sacchariflorus and Miscanths sinensis, is a promising biomass crop for temperate regions. Its origin was Japan, but it is commercially cultivated in Europe and north America countries, particularly in UK. It has many advantages for high biomass production with some environmental benefits such as high rate of carbon sequestration and efficient nutrient recycling. Our present research revealed that it shows high biomass potential in Hokkiado region from our local field trials.
Climinate change caused by global warming becomes currently major problem. We need alternative energy of traditional fossil fuels to solve this problem. Biomass is one of the solutions. Sewage sludge, one of the biomass, has potentials as fuels and fertilizer due to its large amount and phosphorus content. However, since the calorific value is very low, it is rarely used as industrial energy sourse. In this study, to increase the use of sludge as fuel, we investigate the pyrolysis and combustion characteristics of sewage sludge. In addition, we analyzed the phosphorus contained in sewage sludge ash and pyrolysis residue.
The optimal utilization balance of woody biomass between material and energy was examined based after analyzing the amount of forest resources and demand and supply of woody biomass, as a case study of the Tohoku area, Japan. The forest stock in Tohoku area is about 630 million m3, which can supply fuel equivalent to about 24 years of household electicity consumption and about 40 years of fuel demand from woody biomass power plants in the Tohoku area. All of these values are calculated assuming that woody biomass is used for fuel purposes only. Nevertheless, it was quantitatively clarified from the viewpoint of resource quantity that biomass power plants operating in the Tohoku area would make sustainable supply difficult if the forestry operation cycle was set to 60 years.
We are now developing a gas-solid reaction process for producing syngas from biomass for power generation. Although any biomass can be used for this purpose, bamboo is more suitable than wood because the former has the world's highest greenhouse gas absorption capacity i.e., organic carbon production rate（kg/ha/year）. In this study, bamboo infiltrated with a catalyst solution was fed into a horizontally rotating cylindrical furnace equipped with a gas-solid contact function (called Hybrid kiln).
Currently, from the viewpoint of global warming countermeasures, reduction of fossil fuel consumption is required. Therefore, it is expected that the use of biomass fuel will be expanded. However, biomass fuel has the problems of low energy density and high transportation costs. In this research, we focused on biomass gasification technology. The gasification of biomass char, which controls the gasification reaction of biomass, was analyzed by thermogravimetric analysis. Gasification experiments of woody biomass char by H2O were conducted to investigate the effects of temperature and gasification agent concentration on the gasification behavior. As a result, it was confirmed that the temperature dependence was high and the gasification rate increased as the concentration of the gasifying agent increased. In addition, it was found that the gasification rate increased as the reaction progressed and had a maximum value.
Direct carbon fuel cells (DCFCs) are expected to be useful devices that effectively utilize carbon resources. We have proposed novel tubular molten carbonate-type direct carbon fuel cells (TMC-DCFCs). In this study, effects of fuel compositon on the cell performance of TMC-DCFCs were investigated. Continuous power generation tests were conducted using activated carbon or carbonized wood as carbon fuel. Although carbonized wood included volatile matter and ash, the cell performance was as high as that using activated carbon. Effects of carbonate concentration in fuel were investigated by I-V measurements. Cell performance was low when carbonate was not included in fuel because of poor accessibility and CO generation. Sufficient carbonate concentration leads to high cell performance, but exessive carbonate may induce electrode flooding.
We have applied the combination of thermogravimety and solid phase microextraction (TG-SPME) to qualitative analysis of evolved gases on pyrolysis and combustion of tea or coffee waste. The SPME fiber was inserted directly into the gas outlet of the TG instrument to extract evolved gases. After extraction, the SPME fiber was transferred to the injection port of the gas chromatography/mass spectrometer (GC/MS). The TG curves of tea waste showed two mass loss transitions during heating under inert atmosphere, whereas two mass loss transitions with combustion were observed under oxidizing atmoshpere. The evolved gases were extracted by the SPME fiber and identified by GC/MS.
For the efficient utilization of waste biomass in Saga city, the economic and environmental impact of the process for producing sohorolipids (SLs) were quantitavively evaluated. The SLs yield and input energy were calculated to estimate the production cost and CO2 emission for plant operation through process simulation. The process consisted of three unit operation including enzymatic hydrolysis, fed-batch fermentation that required additional carbon sources, and purification. Waste biomass such as household food waste and business food waste were selected as feedstock, and the capaicty of the process was approximately 20 t-carbohydrates/d. Process simulation indicated that the SLs was obtained at 52.3t/d. The production cost was ¥1107/kg-SLs and the CO2 emission was 10,475t/y.
The current deoxygenation reaction of vegetable oil consumes a large amount of high-pressure hydrogen deriving from the fossil resouces. To solve this problem, the hydrothermal deoxygenation reaction of vegetable oil was tested in the presence of Pt/activated carbon catalyst. The test reaction was operated at 593K in the initially charged 4MPa N2. Alos, the cesium-substituted heteropolyacid was additionally supported on thePt-supported carbon, and its effect on the product distribution xygenation investigated. As a result, it was clarified that the hydrocarbon yield depends on the hydrogen production by the aqueous phase reforming, and the acidity of the catalyst makes the deo reaction more efficient.
We have been studying catalytic cracking of cellulose using hydrocarbons as a solvent to produce alternative fuels. Comprehensive use of biomass requires an understanding of the catalytic cracking behavior of hemicellulose. Therefore, the catalytic cracking of rice straw-derived hemicellulose was investigated. As a result, hemicellulose decomposed at 230°C and was easily condensed to form a solid component. However, as the reaction temperature increased, the solid component was decomposed to form a solvent-soluble component.
Microwave irradiation accelerated hydrogen production by catalytic pyrolysis of crystalline cellulose and bamboo via Ni-SiO2-Al2O3. The Debye-Waller factor measured by microwave in situ XAFS suggested that the reaction was accelerated due to the localized high temperature of Ni nanoparticles formed by microwave irradiation. We demonstrated that synergy of the microwave-enhanced pyrolysis of biomass and localized high temperature of Ni nanoparticles accelerate the catalytic pyrolysis of lignocellulose to produce hydrogen.
Reaction behaviors of cellulose and glucomannan isolated from Japanese cedar (Cryptomeria japonica) in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) at 120°C were investigated, aiming for elucidation of the differences in reactivity between cellulose and softwood hemicellulose. GPC and HPLC analyses indicated that the depolymerization of glucomannan and cellulose takes place via cleavage of their β-1,4-glycosidic bonds. Glucomannan was found to depolymerize than cellulose. This result is against the general idea that hemicelluloses are more readily to degrade than cellulose in various biorefinery processes. Our further investigation on the reaction behaviors of a mixture of cellulose and glucomannan suggested that glucomannan significantly retard the cellulose degradation.
Spent coffee grounds discharged from beverage makers, coffee shops, convenience stores, homes, etc. are plant-derived biomass resources and must be effectively utilized. Coffee grounds still contain caffeine and chlorogenic acid, palmitic acid and other fatty acids. After extraction of these useful chemicals, we propose the sheet forming of the waste coffee grounds using a cellulose derivative: hydroxypropylmethyl cellulose (HPMC) as a molding aid. It was confirmed by a capillary rheometer that the extrudability of ethanol-extracted coffee grounds was almost the same as that of raw coffee grounds. Using a kneading vacuum extrusion molding machine, ethanol-extracted coffee grounds with citric acid and glycerin was successfully molded to give a flat sheet. The obtained sheet was flexible and could be hot press molded. Further heating was able to suppress water absorption.
In woody biomass or waste to energy plants, high temperature corrosion of boiler tubes, such as active oxidation which is caused by alkali chlorides has become a serious problem. In this study, the active oxidation of metal specimens by NaCl was evaluated with Thermogravimetry - Differential Thermal Analysis (TG-DTA) to elucidate the mechanisms and establish the highly practical solutions for the corrosion. As a result, the active oxidation had a dependency of the metal composition, and there was a correlation between increments of metal specimens with TG isothermal tests and decrements with immersion corrosion tests.
This paper reported that the effect of the atmosphere on the ash melting behavior analysis of various woody biomass fuel samples and the evaluation method as a biomass gasification fuel. It was found that the ash melting behavior with high potassium content differed significantly between air and CO2 atmospheres. Most of the samples with CaCO3-K2CO3 molar ratios below 0.6 showed low DT and HT in the reduction atmosphere, and most of the samples with CaCO3-K2CO3 molar ratios around 0.6-0.8 showed high DT, but there were some samples with low DT/HT (less than 800 degrees). This may be due to the content of Al2O3 and SiO2. The CaCO3-K2CO3 molar ratio tended to be higher in European and American woody species than in Japanese conifers, and the average value for Japanese conifers was around 0.6.
In the combustion boilers and gasifiers of woody biomass, clinker formation and ash deposition occur in the furnace and heat recovery section, which hinders stable operation. In the case of ash with high potassium content, the generation of melt due to CaCO3-K2CO3 eutectic was confirmed in the temperature range of 750-850°C in the combustion atmosphere with CO2 in addition to the gasification atmosphere. Since the viscosity of the melt is lower than that of the glassy melt, the melt is considered to play the role of a binder for clinker formation.
We are studying a resource recycling type algae biomass system. In this system, algae are cultivated using wastewater, exhaust gas, and waste heat discharged from facilities such as factories. The cultivated algae are converted into fuel and used up in the facility. In order to realize this system, we first built a facility that can carry out the entire process of cultivation, harvesting, concentration, dehydration, and fuel conversion. Next, we are working to reduce the energy consumption of each process.
A Biomass CHP system was completed by Bamboo Energy Co., Ltd. in Nankan Town, Kumamoto Prefecture, in March 2019, as the first full-scale Organic Rankine Cycle in Japan using bamboo for biomass. It has a capacity of about 1 MW electricity, 2.8 MW thermal oil supply, and 4 MW warm water supply, with total energy efficiency of about 70%. The well-known difficulty of burning bamboo has been successfully solved by burning it with bark based on fundamental research for a long time. In this report the operation result of demonstration is outlined.
The purpose of this study is to investigate the role of biomass in a decarbonized energy system for Akita Prefecture. Previous study has shown that Akita Prefecture has the potential for wind power generation that exceeds its primary energy consumption, and that decarbonization is possible in quantitative terms. However, even if all of the wind power potential were installed, there would still be a shortage of electricity from renewable energy sources for more than 1,000hours per year, and large-scale storage battery would be required. It made energy supply cost be relatively high. In this study, the effect of the operation method of the power generation facility on the energy supply cost when using the woody biomass existing in the prefecture for electricity is clarified, and the use of biomass suitable for a decarbonized energy system in Akita Prefecture is discussed.
This study calculated incomes and expenditures such as silvicultural and harvesting as well as stumpage prices on the Japanese cedar, cypress, pine, and larch forests using the silvicultural prescriptions set based on the regional forest plans and operation systems set based on topographic conditions such as slope angles and height differences with GIS. Then, this study estimated the availability of unused materials for woody biomass power generation plants under operation with FIT at the end of June 2020 as the supply potential from the profitable subcompartments. Considering the subsidy rate of 100% to secure the reforestations, the availabilities met the demands in Japan as a whole.
Woody biomass is attracting attention as an energy source that does not compete with food supply. However, cellulose, one of the main components of woody biomass, is difficult to hydrolysis to glucose, since it exhibits high crystallinity with numerous hydrogen bonds. Use of ionic liquids has been proposed as one of the solutions. Dissolving cellulose in certain ionic liquids reduces crystallinity and facilitates hydrolysis to glucose. On the other hand, wild-type Saccharomyces cerevisiae (S. cerevisiae), which has high ethanol fermentation capacity, has low tolerance to ionic liquids and cannot ferment xylose, one of the sugar components of woody biomass. In this study, we attempted to develop S. cerevisiae that is tolerant to ionic liquid by using our genetically modified xylose-fermenting yeast. We also investigated ethanol production from glucose and xylose using the yeast in the presence of ionic liquids.
In the study, first, the effect of the addition of hydrogen to the simulated syngas, produced from the steam gasification of woody biomass, on the product gas composition is examined. Next, the effect of the addition of hydrogen to the steam gasification of carbon particles with a purity of 99.9% or woody biomass on the product gas composition is investigated using a fixed-bed continuous reactor. In the gas phase reaction, the introduction of hydrogen at the temperatures of 600-700°C is the most effective way to reduce CO2 emissions. In the carbon particle surface reaction, the introduction of hydrogen inhibits CO2 production, while also inhibiting the carbon reaction. At 900°C, while ensuring the suppression effect, the carbon reaction rate is also greatly improved.
We think that now is a good time to expand the options for de-carbonization technology and focus on the liquid fuel derived from woody biomass that can be used in conventional automobiles. In this study, hydrogen, which is expected to be produced in excess with the development of renewable energy power generation, is introduced into the gasification reaction field. At the same time, we design a process up to the synthesis of liquid fuel, methanol, through woody biomass steam gasification, which has the potential to reduce CO2 production, and evaluate the environmental and economic efficiency. The CO2/methanol productions in/via the steam gasification of 10t/day wood with 0.4t/d H2 result in a 15% reduction/20% increase in that without hydrogen, being made mostly of a compressor in a part of capital cost breakdown.
Recently, Stable securing of wood fuel is an issue by increasing demand for woody biomass. In this research, focusing on the use of willow as a fuel for small gasification combined heat and power. Effect of willow and cedar blend on copyrolysis and co-gasification reactivities and on environmental impacts of willow chip fuel manufacturing system were clarified. With the use of thermogravimetry and differential thermal analyzer, blend of willow char and Japanese cedar char resulted that a synergistic effect was observed in the latter half of the reaction. Also, SRPM estimated the instantaneous reactivity with the highest accuracy in the other char gasification reaction rate models. However, SRPM has unsteady term and requires complex fitting. In the future, a proposal of a simple and highly accuracy model is necessary for the willow reactivity estimation.
In this study, Japanese cedar powder pulverized by vibration mill with ring media was blended with ABS and molded into filament for fused deposition modeling 3D printer. The Japanese ceder powder was either pulverized only or acetylated. The content of pulverized and acetylated powders were varied in the mold experiments. The results showed that as the pulverized powder content in the blended filaments increased, the average diameter increased and the strength decreased. The acetylated powder suppressed these changes. Cross-sectional observation showed clumping of pulverized powder. The blending conditions are considered to be inadequate, so this is an issue for the future.
Installation planning and evaluation of the decarbonization effect of woody biomass combined heat power plant and related facilities were studied in the Hamadori area damaged by the 2011 earthquake and nuclear power plant accident. The decarbonization effect was evident as the decreased emission of CO2 due to the use of renewable electric power and heat. The recovery in the Hamsadori area featured a large decarbonization effect up to 4% of the total emission from the studied town. The scale up merit (number of combined heat power plants) was confirmed.
In recent years, the demand for fuel has been increasing due to the growing use of biomass power generation, and a stable supply of domestic woody biomass is an issue. We focused on the energy use of tomato stems and leaves, which are mostly discarded agricultural residues in the region. In order to clarify the co-pyrolysis characteristics of tomato stover and cedar blends, the effect of tomato stover blending on co-pyrolysis was investigated by comparing kinetic parameters and thermodynamic properties calculated using the iso-conversion method. It was found that the activation energy of a mixture of 30% was lower than that of a mixture of 0% (cedar only) at conversions below 0.8.
Chitin represents a resource for sustainable functional materials. However, traditional β-chitin production methods involve alkaline treatment at approximately 90°Ｃ for its separation from the protein, thus not suitable as a functional peptide, as it is mixed with an alkaline aqueous solution. This study examined the conversion of squid pen into solid β-chitin and water-soluble peptides using only water at temperatures of 150–250°Ｃ for 30–120min. Solid β-chitin was converted to its nanofiber form and the physicochemical properties of the β-chitin nanofibers were almost the same as those produced by the traditional method. promising environment-friendly technique for complete utilization of squid pen components, including β-chitin and protein.
Vegetable and fruit residues generated at house kitchen were dried at ambient condition. The primary purposes of the present study are to (1) obtain the drying rate data of representative vegetable and fruit residues and (2) propose the drying kinetics, whice may be useful for suppressing the amount of high moisture trashes at each house. The mass of vegetable and fruit residues was measured at intervals of around ten hours till the equilibrium moisture content (EMC) was attained. The time course data of the mass were analyzed by a first order kinetic equation, in which the drying rate becomes zero at the EMC. The drying rate constant ranged from 0.01 to 0.09 h-1, and most of them were around 0.03-0.04 h-1. It was found that the reciprocal of the rate constant was approximately proportional to the representative size of the residues with a proportionality constant of 3.3 h/mm.
In this study, we attempted a simultaneous pulverization and acetylation of wood powder (Japanese cedar) by mechanochemical grinding using a vibration mill with ring media. Acetic anhydride was used as the acetylation reagent to be added during pulverization, and the input ratio of acetic anhydride was set to 50, 75, and 100% for 200 g wood powder. For the evaluation, the particle size distribution, and the degree of acetylation by the weight increase rate (WPG) were measured and powder state was observed by a scanning electronic microscope to confirm the effect of the pulverization time. As a result, the highest WPG of 17.5% was obtained in 60 min pulverization in which the acetylation reagent was 75%. On the other hand, although the decrease in powder particle size was suppressed by increasing the amount of acetylation reagent added, the effect of suppressing wood powder agglutination was also confirmed.
In this study, we investigated the adhesion of cedar powder burning ash to the metal surface and the melting behavior of cedar ash. For adhesion to the metal surface, a flat flame with an equivalent ratio of 0.7 was used, and the metal was burned for 70 minutes with the filling amount as a parameter. As for the melting behavior, the samples were raw cedar and cedar ash, and the temperature was raised from room temperature to 1400°C at a heating rate of 10°C / min using heating combustion with a heater. As a result, the amount of adhesion on the metal surface was positively dependent on the amount of cedar powder filled. As for the melting behavior, raw melted completely at a higher temperature.
Composting process of livestock waste produces a strong odor containing high concentrations of ammonia and carbon dioxide. In this study, we aimed to develop a system to deodorize the odor and utilize the ammonia and carbon dioxide as nutrient sources by aerating it into a culture tank of microalgae (Botryococcus braunii), which is a promising biofuel source. Continuous cultivation was conducted by aerating air mixed with ammonia and carbon dioxide to clarify the effect of ammonia aeration conditions on the growth. The microalga did not grow when the same amount of nitrogen as in the control area (nitrate-nitrogen) was supplied by ammonia, but it showed similar growth rate when double the amount was supplied. Also, when the amount of nitrogen supplied in the control area was doubled, nitrate nitrogen accumulated in the culture medium because it could not be fully absorbed. However, with ammonia supply, almost no ammonia nitrogen was detected in the exhaust gas and culture medium. Therefore, it was assumed that the amount of nitrogen absorbed by the alga would be higher in ammonia aeration culture. The actual amount of absorbed nitrogen calculated from the growth rate and nitrogen content was about half of that estimated by subtracting that in the exhaust and culture medium from that supplied. It was suggested that the remaining half of the nitrogen was fixed as organic nitrogen in the algal secretions or symbiotic bacteria.
Torrefaction experiments were conducted in the bamboo packed bed. The higher calorific value (HHV) of the torrefied bamboo powder increased with the average temperature in the packed bed. When the average temperature was about 580K, the HHV achieved to 25MJ / kg which was comparable to the higher calorific value of coal. It was also found that the particle size of torrefied bamboo powder decreased with the increase of the average temperature. Furthermore, we investigated the grindability and the characterization of the torrefied bamboo powder.