Although extremely high numerical targets have been set for energy conservation and decarbonization in the household sector, has Japan's household energy consumption structure been as energy-wasting as has been suggested?. Energy consumption per household has already started to decline since the mid-1990s. The fact is that the growth in the number of households has far exceeded the decline in per-household consumption, and as a result, the energy consumption of the household sector as a whole has been rising. Even that value has been declining since the mid-2000s. The most anticipated and emphasized scenario for going carbon neutral in the residential sector (hereafter CN) is that CN will be achieved as if it were easy to achieve by electrifying all uses. In reality, however, it is not so easy to achieve this, as there will still be at least 20 million existing housing units in 2050. Most of these hot-water systems use gas as their heat source. Replacing these systems with heat-pump water heaters called "Eco-Cute" is very difficult because there is no space to replace them in most cases. If this is the case, we should take immediate measures to supply decarbonized energy by utilizing existing gas pipelines at the same level as we did for electrification. In addition, although it is hoped that energy prices will not rise even if CN is realized, current price estimates suggest prices of at least 30 to 50%, and in some cases more than double the current price. Currently, the share of utility costs borne by households is about 6%. Even this level is extremely high compared to 3.3% in the U.S. and 2.5% in the U.K. In the northern country of Hokkaido If this ratio exceeds 10%, it is considered a danger zone and may become a social problem called "Fuel Poverty" (energy poor), as pointed out by Prof. Brenda Boardman, former professor at Oxford University in the UK. In fact, this issue has topped the list of consumer energy policies in the U.K. In Hokkaido, a price increase of 20% may cause the entire population of Hokkaido to fall below this level. What is the price level that can be achieved? There is a mountain of issues that we cannot take our eyes off of regarding CN from the consumer's viewpoint.

In the future systems of carbon recycling and biomass utilization, gasification is expected to play roles of syngas production integrating various types of biomass and biomass-derived wastes into syngas (CO/H₂). In this lecture are discussed requirement of gasification for maximized syngas yields, and also introduced emerging technologies and concepts.

In recent years, tetra-n-butyl ammonium bromide (TBAB) clathrate hydrate has been identified as a phase change material that possesses an appropriate phase change temperature of 5 to 12°C. Moreover, depending on conditions, TBAB hydrate may form a slurry. The hydrate slurry can be transported directly and has a high heat transfer rate. In order to utilize the slurry in the thermal energy storage systems, it is important to reveal not only fundamental thermal properties but also flow and heat transfer characteristics of the slurry. In this study, the fundamental properties of the hydrate and its slurry were outlined to use the TBAB clathrate hydrate as PCM based on the author's past studies.

In response to multiple approaches of the international community, such as carbon neutrality by 2050, CE, marine plastic problems and others, Japanese government enforced on April 1, 2022, Law for the Promotion of Plastic Materials Circulation, aiming at acceleration of highly advanced plastic circulation through the entire life cycle of plastic products and parts, which is fundamentally different from the traditional approach of other recycling-related laws. The program under the new law includes a guideline for design for environment, reduction of single use plastic, changeover from energy recovery to mechanical recycling and/or feedstock recycling and more. There are some concerns about meeting ambitious goals.

University of Yamanashi has been promoting research on fuel cells since the 1960s, and has been researching a wide range of themes related to fuel cells, such as alloy catalysts, catalyst supports, electrolytes, separators and coating methods for catalyst inks. In order to transfer these research results to regional companies to promote new hydrogen and fuel cell related industries, a three-party agreement was signed between Yamanashi Prefecture and the Yamanashi Industry Support Organization. Based on the agreement, University of Yamanashi has been supporting regional companies. This presentation introduces examples of activities related to new product development support utilizing the research results of the university and human resource development of regional companies.

Ammonia is regarded as one of the alternative fuels because of the physical properties of Ammonia are suitable for transportation and storage as the “hydrogen carrier”. On top of those preferable characteristics, the high amount of mass productivity can be achieved through Haber-Bosch process. However, there are some issues of ammonia fuel based on the combustion characteristics to be solved for applying ammonia to the industrial combustion furnaces, such as the low laminar burning velocity, the low flux of radiative heat transfer and also the large amount of Fuel NOx formation. These features of ammonia fuel may lead on the instability of the system operation, and quality of the material in the industrial combustion furnaces. Therefore, it is necessary to know the fundamental characteristics of ammonia flame and to find the way how to improve those issues and how to apply ammonia as the fuel in the industrial combustion furnaces. In terms of those requirements, the fundamental characteristics of ammonia/N₂/O₂ laminar premixed flame and the effects of oxygen enrichment were experimentally investigated.

The "Energy Studies" ("Energy-Gaku") division was established in 2007, and 21 years have passed since the predecessor study group was launched in 2001. The situation surrounding energy is changing drastically, and changes are required in all aspects of how we act regarding energy. Thus, it is important to have a comprehensive viewpoint on energy issues, including not only technical aspects but also humanities and social science perspectives. This paper describes the author's opinion on "Energy Studies". It is necessary for people from many academic fields to gather together to discuss and exchange opinions on various energy-related issues, which will lead to the construction of a sustainable society and the realization of a carbon-neutral society by 2050.

Biomass can be seen as an energy source creating new industries and employment through regional activation. Herein we describe how to sustainably utilize the enormous unutilized biomass resources in the Southeast Asian region. Establishing a sustainable, carbon-neutral energy procurement method from unused biomass with Japan's technological and engineering capabilities will lead to infrastructure exports to developing countries and international cooperation in addressing Japan's energy security issues and global warming in developing countries. This presentation will focus on the following topics: the current efforts under the SATREPS (Science and Technology Research Partnership for Sustainable Development) project “sustainable replantation of oil palm by adding value to oil palm trunk through scientific and technological innovation.”

The recent approaches by the author and co-workers in understanding the involved chemistry and physics toward numerically simulating the chemical reactors are presented. The processes will include the gasification of solid fuels, coal tar reforming, and Sabatier reaction for producing carbon neutral synthetic methane.

The authors started a research project since 2021 for developing a poly-generation system utilizing various fuels with CO₂ capture. The system is composed of a gasifier, a gas clean-up system, a power generation system, and a chemical synthesis system. The gasifier is based on an O₂/CO₂/H₂O blown gasifier developed in a previous project for developing an Oxy-fuel IGCC system, and it will be upgraded in the present project to treat various carbonaceous feedstock, such as plastic wastes as well as coal. This presentation shows mass and heat balances of the whole system in the case of producing methanol as a chemical material. The calculations indicated that the total efficiency has a maximum value for syngas recycling ratio 0.7 in the methanol synthesis island. Additionally, plastic-waste has positive effect on the total efficiency.

The Osaki CoolGen Project is aiming to realize the revolutionary low carbon coal fired power generation through the combination of Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC). This project consists of three steps. In the first step, a demonstration of oxygen-blown Integrated Coal Gasification Combined Cycle (IGCC) has been successfully completed. In the second step, oxygen-blown IGCC with CO₂ capture is currently demonstrated. In the third step, IGFC with CO₂ capture is demonstrated from 2022.

A β-zeolite-containing hierarchical catalyst having micropores on the inside and mesopores on the outside was prepared in one step by the simultaneous generation of β-zeolite and mesoporous silica using the gel skeletal reinforcement method. Furthermore, their reactivity in the catalytic cracking reaction of n-dodecane was investigated. From the results of XRD and N₂ adsorption/desorption measurements, GSR-4.5HS-H-Beta and GSR-5HS-H-Beta showed the existence of both β-zeolite and mesoporous silica and developed the hierarchical pore structure in the simultaneous preparation of β-zeolite and mesoporous silica using the gel skeletal reinforcement method. In GSR-5HS-H-Beta, a pore diameter reached 50nm, suggesting that not only mesopores but also macropores would also have developed. In catalytic cracking of n-dodecane using GSR-4.5HS-H-Beta, the conversion reached 73% with high RON value. GSR-4HS-H-Beta gave rather low conversion of n-dodecane while the selectivity for gasoline fraction was higher.

Multiscale measurement is suitable for samples with a hierarchical structure and provides the structural information from small scale as a crystal structure to large scale as a higher order structure. Powder samples of tetra-n-butylammonium chloride (TBAC) semiclathrate hydrate were investigated by neutron scattering for multiscale structure analysis. Neutron scattering profiles showed flat-like backgrounds and Bragg diffraction peaks in the high q region and decreases in the background in the middle q region. In the low q region, increases in the scattering profiles were observed proportional to q^-4, reflecting spherical particles or grain boundaries. Furthermore, it has become clear that these behaviors are temperature dependent.

In a previous study, the problem that solution often tends to be supercooled was solved by applying voltage and the factor was the metallic product that was generated from the electrodes after applying voltage. Also, it was revealed that they were mixtures of certain metallic materials by analyzing the electrode products. In this study, the relationship between metal particles and crystal structure was investigated by observing the crystals of hydrate produced by adding these metal particles to the TBAB solution. The experiment focused on the influence that the addition of the metal particles gives to the crystal forms．

A large degree of supercooling is necessary to form the tetra-n-butylammonium bromide (TBAB) semiclathrate hydrate. Developing an effective method to suppress supercooling is essential to use semiclathrate hydrates as potential thermal storage media. We have already reported the relationship between the memory effect and the solution structures in the TBAB semiclathrate hydrate reformation, based on the scanning electron microscopic observation. In this presentation, we report a dynamic stimulation method as a means of supercooling suppression. We would like to discuss the relationship between the conditions of dynamic stimulation and crystallization.

Semiclathrate hydrates are host–guest materials that form from water and ionic guests. As ionic guests, tetra-n-butylammonium (TBA) and tetra-n-butylphosphonium (TBP) salts are widely used. The semiclathrate hydrates can capture small gases such as CO₂ and CH₄. Recently, unique gas selectivity of these materials was found. In the most widely used TBA Br (TBAB) hydrate structure, CO₂ was efficiently captured in a particularly shaped cage that was distorted by TBA and CO₂ itself. On the other hand, based on gas separation tests it is also reported that the TBA Cl (TBAC) hydrate which is also widely used one has a superior gas selectivity. In this study, we performed single crystal X-ray diffraction measurements on TBAC + CO₂ hydrate. The superior gas selectivity was discussed based on the determined structure.

Clathrate hydrate is a compound in which guest molecules are encapsulated in a cage structure under low-temperature and high-pressure conditions. The guest molecules are not only simple molecules but also cyclic molecules. Many cyclic molecules have multiple conformations, but there are still few studies on whether changes in conformations occur within the cage structure and their selectivity. In this presentation, we will report on the conformation of guest molecules in the cage structure.

Argon hydrate, one of gas clathrate hydrates, is known to change its initial cubic sII phase to hexagonal sH, tetragonal sT, and orthorhombic sO phases successively under pressure. In the present study, high-pressure Brillouin scattering measurements have been performed for single crystalline argon sII and sH phases grown in a diamond anvil cell, and their ratios of elastic constants to density have been determined as a function of pressure. Interestingly, C₁₁/ρ in the sII phase is obviously insensitive to pressure in comparison with methane hydrate sI, which probably reflects the instability of the large cage in the sII phase.

High-pressure X-ray diffraction and Raman scattering measurements of hydrogen sulfide have been performed up to 2 GPa at room temperature. From the X-ray diffraction measurements, it is found that the initial cubic structure I is transformed into a structure H (hexagonal) at 0.9 GPa and dissociated into Ice VI and the plastic phase of hydrogen sulfide at 1.65 GPa. The pressure dependence of Raman shifts for the symmetric stretching vibration of guest hydrogen sulfide shows negative slopes at respective low-pressure region of sI and sH phases, which is indicative of the existence of the hydrogen-bond interaction between water and hydrogen sulfide molecules.

High-pressure X-ray diffraction and Brillouin measurements have been made for sI and sH Krypton hydrate phases up to 1.7 GPa at room temperature. Although the obtained pressure dependence of the lattice volume in the sH phase shows no obvious change at 1.0 GPa where the visual change occurs in the sH phase, the ratios of elastic constants to density indicate abrupt decreases at 1.0 GPa. These results suggest that the occupation number of krypton atom in the large 20-hedron cage of the sH increases at 1.0 GPa.

It has been reported that linear alkanes longer than ethane are enclathrated into the urea clathrate under low-temperature and high-pressure conditions. To thermodynamically demonstrate the proof-of-concept of the propane/propylene separation via urea clathrates, we investigated the equilibrium relations of propane and propylene binary mixtures in the (propane+propylene)/urea clathrates. The results reveal that propane is concentrated in the urea clathrate and that the separation of propane and propylene via urea clathrates is feasible from the thermodynamic viewpoint.

Methane (CH₄) hydrate is a kind of inclusion compound, a crystal that encapsulates methane in a cagelike structure formed by a hydrogen bonding network of water molecules. The CH₄ hydrate has been developed for use as a transportation and storage medium for natural gas to replace liquefied natural gas. Conventional methods have made it possible to store methane hydrate for more than one month in an atmosphere of atmospheric pressure and 273 K. However, if storage at even higher temperatures becomes possible, CH₄ can be transported and stored more efficiently.

We have shown that CH₄ hydrate can be preserved more efficiently than conventional techniques by immersing CH₄ hydrate in cyclopentane liquid. In this presentation, we will present the preservation phenomenon and its mechanism.

Natural gas hydrates have been recovered off Hidaka (Hokkaido, the Pacific Ocean) in the framework of practical education of Kitami Institute of Technology. We retrieved hydrate-bound sediment cores from gas seep sites using T/S Oshoro-maru of Hokkaido University. Plate-like gas hydrate crystals were found in the core of C114-GC2104, located around 155 cm beneath the sea floor. Crystallographic structure of the samples belonged to the structure I, and hydration number, cage occupancies of large and small cages were estimated as 6.00, 0.97 ± 0.00, and 0.93 ± 0.01, respectively. Molecular and isotopic composition of hydrate-bound gas suggested microbial origin via CO₂ reduction. δ¹³C of ethane also indicated microbial.

We tested the performance of various hydrate crystal growth inhibitors (HCGIs). We used a tetrahydrofuran (THF) sII hydrate system using a unidirectional growth apparatus. We selected the polyvinylpyrrolidone (PVP) K-90 and polyvinylcaprolactam (PVCap) as a strong HCGIs. The tetrapropylammoniumbromide (TPrAB), tetrabutylammoniumbromide (TBAB), tetrapentylammoniumbromide (TPeAB), tetrahexylammoniumbromide (THexAB) are selected as a weak HCGIs. The weak HCGIs is known to have synergy effect on strong HCGIs. The HCGI concentration c = 0.5 wt%, and growth rate V is variable. These results enhance the persuasiveness for the model that the HCGI effect is explained by the residence time on the crystal surface of HCGI, τ, and duration time t* of crystal growth. We determined the threshold growth rate of THF hydrate for examining HCGI performance on sII gas hydrate. In addition, we tested the synergy effect of weak HCGIs on strong HCGIs by mixing both HCGIs solutions.

The development of methane hydrate commercialization is underway, and in recent years, the impact of decarbonization has been considered. In this study, a new development concept was generated by systematically organizing and combining technological elements using a morphological matrix based on the proposed development concept. An evaluation model was developed to evaluate and compare the development concepts quantitatively, and tradeoffs were identified based on economic efficiency and energy balance.

Hydrogen production from hydrogen energy carrier, such as ammonia, is endothermic reaction. On the hand, methane synthesis from carbon dioxide with hydrogen is intensive exothermic reaction. From this point of view, the authors suggested methane synthesis from carbon dioxide with ammonia, called “Ammonia-Methanation”. In this study, ammonia methanation catalyzed by a hybrid catalyst composed of Ni/Al₂O₃ and Ni/CeO₂ was investigated. It was found that the above mentioned hybrid catalyst had high activity for methane synthesis through ammonia methanation.

Tokyo Gas is working on the social implementation of methanation, which can achieve carbon neutrality of gaseous energy while effectively utilizing existing city gas infrastructure, with the aim of realizing a carbon neutral society by 2050. The activity include a small scale demonstration of methanation in our facility, development of innovative methanation technology that is expected to improve higher efficiency of methane synthesis than conventional technologies, and also studies of supply chain to introduce a large amount of synthetic methane from overseas.

In hydrothermal carbonization, which is a kind of hydrothermal treatment process, biomass is treated in high temperature and high pressure water to produce solid product called hydrochar. The properties of the solid and liquid products change depending on the conditions including reaction temperature, time, and heating rate, which also affects the yield of hydrochar. However, the relationship between conditions and its effect differs from one researcher to another and has not been clarified. Therefore, we investigated the reaction characteristics of hydrothermal carbonization. We used glucose as the feedstock to investigate the behavior of char formation from water based solution. We considered a reaction model from previous studies and calculated the carbon yield of some substances using high performance liquid chromatography. The experimental values agreed with the calculated ones. The results of hydrothermal carbonization of glucose solution in a batch reactor are reported in terms of the product yields as a function of reaction temperature and time.

A novel process for the production of levulinic acid (LA) from glucose using an AlCl₃ catalyst in an aqueous choline chloride solution was designed. In this process, the catalyst and formic acid (FA), which is a byproduct of the process, were recovered and reused. Organic waste (humins) was used as a heat source, thereby minimizing energy input and waste disposal. Furfural, octanol, and toluene were used as extractants for the purification process of LA and FA based on the solubility with water, and partition coefficient between water and LA or FA, respectively. The energy requirements of the process were determined based on literature data for a glucose feed rate of 100 kg/h and reaction times of 90, 120, and 180 min. The minimum selling price (MSP) of the product was calculated based on the capital and operating costs required to produce LA and FA at an internal rate of return of 6.1% over 20 years. The results show that the energy required for this process was 40.6–44.5 MJ/kg-LA, which is significantly less than the conventional methods, and the MSP was 6.47–8.80 USD/kg, which is lower than the market price of LA. Part of the energy required (12.2–24.7%) can be supplied by a furnace that combusts humins, accounting for 21% of the total capital cost, which is considered economically feasible for an industrial process. Overall, we found that a reaction time of 90 minutes was the most favorable condition in terms of both energy requirements and economics.

Cellulose is efficiently decomposed by fast pyrolysis. However, because the generated mist products drift for a long time in the gas phase, it is difficult to recover the products efficiently. In this study, we tried to recover the mist products efficiently by the addition of static electricity using corona discharge treatment. With this method, the mist products, the major compound was levoglucosan, were rapidly aggregated and recovered as a condensate. In addition, the levoglucosan purity was improved probably due to the higher content of levoglucosan in the mist. Large amounts of the aldehyde-type by-products may exist as gaseous products.

Fast pyrolysis of cellulose gives a large amount of levoglucosan, which can be saccharified under mild conditions. This fast-pyrolysis-based saccharification can be applied for the production of polylactic acid (a bioplastic) via lactic acid fermentation. However, we already found that aldehyde-type by-products inhibited the lactic acid fermentation. In this study, we tried to use reduced pressure conditions in fast pyrolysis of cellulose to reduce the by-production of aldehydes by suppressing the secondary degradation of levoglucosan. As a result, the aldehydes production was efficiently suppressed under the reduced pressure conditions. The levoglucosan yield increased when we used Avicel power and high purity pulp sheet (both from wood), while the yield rather decreased in pyrolysis of Whatman cellulose filter paper (from cotton). It was found that such difference originated from the sheet structure. Yield of levoglucosan was reduced under reduced pressure in the pyrolysis of pulp samples in which fine fibers filled the voids in the sheet.

When cellulose is heated at a constant temperature, the weight-loss rate becomes maximum after an inductive time after reaching a predetermined temperature. This phenomenon has been explained by the generation of “Active cellulose”. In our laboratory, we have studied the molecular mechanism corresponding to this activation process. Since blocking the reducing end delayed the initiation process of cellulose, it has been suggested that the thermal degradation reactions at the reducing end is related to the activation process. In this study, we focused on the generation of the IR signals at 1700 cm^-1 (carboxyl C=O) and 1600 cm^-1 (conjugated C=C) in isothermal heating of two types of cellulose, Avicel PH-101 and Whatman CF-11, in the temperature range of 220-280°C. The formation of these structures was kinetically investigated, and the activation process of cellulose during pyrolysis is discussed.

Excellent decomposition and extraction of lignin from Japanese cedar were achieved by water-added supercritical methanol (SCM) treatment at 270°C/30 MPa, producing soluble products with a wide range of molecular weight distribution. To further decompose such lignin-derived macromolecules into monomers, subsequent water-added SCM treatment or catalytic hydrogenolysis was studied. The additional SCM treatment failed to yield more monomers due to recondensation, while the catalytic hydrogenolysis successfully depolymerized lignin macromolecules into aromatic monomers with high selectivity.

Hydrogen production from saccharides and alcohols was studied by in-liquid plasma generated in vapor bubbles in water. Highly volatile alcohols exhibited significant gasification, producing mainly H₂ and CO, while low volatile alcohols and saccharides were slower to gasify, with H₂ and CO₂ the main gases produced. This may be because the gasification of low volatile substances can occur only at the interface between the bubbles (plasma region) and the liquid-phase water, where the water-gas shift reaction of CO also underwent, resulting in higher ratios of CO₂.

A Zn-exchanged ZSM-5-Al₂O₃ composite support was prepared by the conventional kneading method, and noble metals Pt or Ru was introduced by the impregnation method. Using the catalyst, the dehydrocyclization-cracking of methyl oleate was performed at hydrogen pressure 0.5MPa and 500°C. Using 0.8Ru/Zn (16) Z (24) 60A catalyst, aromatic yield was as high as 15wt% while the selectivity of C5-18 liquid fuel fraction reached 69%. In contrast, Pt based catalysts produced not only larger amounts of gaseous products but also larger amounts of aromatics, suggesting that the Pt-based catalysts would give aromatics through aromatization of gaseous products whereas the Ru-based catalysts would give aromatics through direct aromatization of longer hydrocarbons than gaseous ones.

We have been researching the catalytic reaction to hydrodeoxygenate plant oil under the hydrothermal condition. Since the catalytic reaction causes the in-situ hydrogen production from glyceryl group of plant oil, it is possible that drop-in fuel is produced without the external hydrogen supply. The current target to verify the production of drop-in fuel is to isomerize simultaneously the straight-chain hydrocarbons produced from plant oil under the hydrothermal condition. Thus, in the present work, the plant oil hydrodeoxygenation catalyzed by Pt supported on zeolite was tested at 593 K with autoclave batch reactor, in the expectation that acidity of zeolite is active in formation of carbonium ion as the isomerizing intermediate. H-Y and H-ZSM5 were employed as the zeolite support, and the prepared Pt/zeolite catalysts brough about production of the branched hydrocarbons. Also, Pt/H-ZSM5 resulted in the higher isomerization ratio than Pt/H-Y. This seemed to agree with order of the zeolite acidity.

Ash deposition behavior that causes corrosion of heat transfer tube differs in biomass-fired boilers and coal-fired boilers. In this study, we conducted biomass ash deposition experiments to a test piece simulating the heat transfer tube using an electrically heated drop tube furnace. A mixture of KCl and kaolin was used as the biomass-simulated ash. After the experiments, the ash adhesion interface was observed and analyzed by SEM-EDX. We also performed thermodynamic equilibrium calculations and considered ash deposition characteristics experimentally and theoretically.

In this study, we have investigated the influences of alkali and alkaline earth metals (AAEM) on the redox reactivity of an oxygen carrier in a chemical looping process. Calcium and Potassium, typical AAEM components in biomass ash, were selected and were physically mixed with an oxygen carrier, ilmenite. The redox reactivity of the ilmenite with Ca and K was evaluated by a thermogravimetric analysis in reduction-oxidation cycles with different reaction times. The results showed that the addition of Ca and K significantly influenced the redox reactivity of ilmenite.

An updraft type biomass gasification furnace has an advantage of being able to gasify even biomass with a high moisture content. However, a relatively large amount of tar is usually generated, so that utilization of tar is important. On the other hand, biomass bottom ash generated in the process is often disposed of as industrial waste. In this study, heavy tar (HT) collected by an actual biomass gasification plant was mixed with bottom ash (BA) or simulated bottom ash containing potassium or calcium salts and then gasified in a tubular reactor by increasing the temperature up to 600°C under nitrogen atmosphere containing steam. Tar and gaseous products collected in sections of 50°C each were compared to elucidate the active components for tar degradation in bottom ash.

A three tower circulating fluidized bed cold model was built with a scale equivalent to 300 kWth to develop a technology of chemical looping combustion poly-generation. Circulating rate of Ilmenite oxygen carrier between the three towers was measured and attrition rate was evaluated.

The BDF used in diesel engines has a higher oxygen content than gas oil. Therefore, the oxygen is supplied by fuel during combustion when BDF is used. In previous studies, performance tests using mixed fuels of gas oil and BDF in a small diesel engine to which EGR is applied was performed. And, it has showed that the using fuel with a high BDF mixing ratio increased PM emissions are suppressed under combustion conditions of reduced oxygen concentration. However, the oxygen contained in gas oil and BDF is extremely small compared to the oxygen contained in intake air. This study conducted performance tests using gas oil and BDF in a small diesel engine with EGR applied, confirming the effects of oxygen contained in intake air and fuel on exhaust gas characteristics.

To reduce energy consumption of the microalgal biofuel production, an oil extraction method without drying and cell disruption process is required. In this study, liquefied ammonia (NH3(l)) was attempted to use as an extraction solvent of oil from wet microalgae. Wet Isochrysis lutea sample was placed in a pressure-resistant vessel, and NH3(l) was passed through the sample at 10 cm³・min^-1 at about 0.85 MPa at room temperature (20°C). 28.1 wt.% of dry microalgae as the crude oil was extracted when the ratio of NH3(l) to sample (wet basis) was 16:1. Fatty acid methyl ester components which is suitable for biofuel production were synthesized through transesterification of the NH3(l) extracted crude oil. These results showed that fatty acids were extracted from wet microalgae using NH3(l) without drying and cell disruption.

Bamboo, which has been left unmanaged and has expanded in Japan in recent years, can be a good candidate for the feedstock for bioenergy production to replace fossil fuels to reduce greenhouse gas emissions. However, it contains a high concentration of alkali and alkali earth metals such as potassium and sodium, leading to slagging and fouling problems during the combustion process. This study investigated the effect and mechanism of methanol leaching pretreatment of bamboo ash at different liquid flow rates. The packed bed reactor was used at temperature and pressure of 20°C and 0.1 MPa, respectively. The results indicate that the removal efficiency increases with the flow rate, and then it becomes stable. There was probably a change in the mechanism of mass transfer. The methanol leaching pretreatment can effectively remove the potassium and ash content with the highest removal percentage of 48.5% and 80.5%, respectively, with almost no loss of organic matter.

We are developing a process for obtaining syngas from bamboo using a horizontal rotary kiln that combines pyrolysis and reforming functions. Bamboo fed into the kiln is pyrolyzed into gas (dry gas, water vapor, and tar vapor) and solid (char) in the first half of the kiln, and the tar and char are steam-reformed into hydrogen and carbon monoxide gas (syngas) in the second half.

An experimental plant with a diameter of 300 mm and a length of 750 mm was used to operate at a pyrolysis temperature of 700°C and a steam reforming temperature of 750°C. As a result, it was confied that the reforming rate of tar and char reached 90%, and furthermore, the shift reaction progressed by 70%.

Bamboo is the most land productive plant in the world. and can be grown in many parts of the world. Bamboo power plants are expected to become a key technology for a decarbonized society in 2050.

In order to clarify the effects of disk rotational speed of disk chipper and wood feed rate on consumed energy and productivity in wood chipping, sugi (Cryptomeria japonica) lumber were chipped under different rotation speeds and feed rates. The results showed that both energy consumption and productivity increased with increasing rotational speed, but were not influenced by feed rate.

Since small-scale gasification CHP of wood chips has strict conditions for fuel properties, it is necessary to ensure the quality of fuel components, shape, moisture, and strength, etc. for stable operation. However, when wood chips are manufactured and dried on a small scale at individual on-site where gasification CHP is introduced, the problem is stabilization of quality and reduction of manufacturing cost of wood chips. Therefore, in this research, we examined the possibility of reducing the manufacturing cost of high-quality chips at a large-scale production base.

Carbon-neutral fuel is expected to reduce CO₂ emissions in the transportation sector. In order to develop a gasification process that biomass can be converted to syn-gas with high efficiency, hydrogen was introduced into steam gasifier of biomass. In this study, the effect of hydrogen-rich conditions on gasification products was investigated by evaluating gas composition and product yield. By adding H₂ into gasification process, concentration of CO₂ was decreased while concentration of CO was increased due to water-gas shift reaction. Furthermore, methane formation was also facilitated by introduced H₂. In addition, tar and char yields were increased under the condition of 700°C. These results indicated that decomposition reactions of tar and char such as water-gas reaction were inhibited in hydrogen-rich conditions.