This work investigated influence of concentration of ammonium bicarbonate on the activity of rutheniumencapsulated porous hollow silica sphere catalyst for hydrogenation of ammonium bicarbonate into formic acid. From the analyses of the reaction solution by total carbon dioxide meter and HPLC, almost all the carbonate species in the reaction solution before and after the reaction is bicarbonate ion up to saturated concentration of ammonium bicarbonate, while certain amount of carbonate ion existed in the solution over saturated concentration probably because of the solution pH values. The tendency reflected formic acid yield, and the highest yield of formic acid was obtained in the solution with saturated ammonium bicarbonate solution.
The effect of essential oil (EO) addition to the oxidation stability and odor preference change of biodiesel was investigated. The oxidation stability of biodiesel at 25 degrees C increased from 24 to 200 days with addition of 1 wt% EO from clove, thyme thymol, and cinnamon leaf. The combustion characteristics of a fuel (B10), a blend of diesel and EO added biodiesel, were evaluated. The cetane number for B10 clove EO achieved the standard number 51, however B10 without EO failed. The change of flash point and kinetic viscosity caused by the addition of EO was negligible. In application to diesel engines, the hydrocarbon contents in exhaust gas decreased with the addition of EO. Based on odor monitoring results, the fuel odor classification of B10 changed toward unpleasant odor with addition of EO of 1wt % clove. After combustion, the odor of the exhaust gas between B10 and B10 with the clove was at a closed value.
In this study, a mechanochemical treatment was investigated in which pulverization and acetylation of Japanese cedar (Cryptomeria japonica) powder were simultaneously performed using a vibration mill with ring media. Dried cedar powder (200 g) was treated with acetic anhydride (AA) at weight ratios of 30%, 40%, 50%, 75%, and 100% relative to the powder, and the effects of milling time on particle size distribution, weight percent gain (WPG), morphological changes, and thermal degradation characteristics were evaluated. The results indicated that, within the range of conditions investigated in this study, the AA50% condition, in which the amount of acetic anhydride was equivalent to half the weight of cedar powder, exhibited the highest efficiency in simultaneous particle size reduction and acetylation, achieving a maximum WPG of 17.8%. Changes in particle size distribution and SEM observations under this condition revealed fragmentation similar to that observed in dry milling, which exposed hydroxyl groups within the particles and promoted acetylation. Furthermore, thermogravimetric analysis (TGA) indicated that the onset temperature for thermal degradation at 95% weight retention increased by up to 16 degrees C compared to untreated powder. In contrast, at AA75% and above, adhesion to the inner wall of the milling vessel was observed, leading to reduced reaction efficiency. This method demonstrates potential for rapid and efficient chemical modification of wood powder.
This study investigates the actual conditions and awareness of consumers regarding home solar power systems. A web screening survey was conducted targeting individuals in their 30s to 60s living in their own houses in Tokyo and the surrounding three prefectures, followed by a detailed survey focusing on solar power system owners, considerers and non-considerers. The results revealed that approximately 12% of respondents were owners, with a notably higher proportion among those in their 30s and 40s. Many purchasers cited economic benefits as their primary motivation, and satisfaction levels were high, mainly due to savings on electricity bills. Conversely, approximately 32% of non-owners expressed an intention to purchase. Reasons for not purchasing included high initial costs and concerns about the expected payback period. These findings suggest that to increase adoption among non-purchasers, it is important to provide services that alleviate anxieties and inconveniences during the purchase consideration phase, along with clear explanations of subsidies and operational simulations. Overall, the findings contribute to a better understanding of key factors to promote the adoption of home solar power systems.
CO2 deposition under low-pressure conditions plays a key role in sublimation-based CO2 separation processes; however, numerical studies on this phenomenon remain limited. In this study, CO2 deposition behavior was investigated using a combination of a global tank-scale model and a local model that resolves the growth of the dry-ice layer. The global model evaluated heat transfer and fluid flow inside the tank using CO2 properties corresponding to 100 kPa and 1 kPa, while the local model analyzed the growth of the deposited layer and its influence on the near-wall temperature. Experiments conducted under reduced-pressure conditions provided two key datasets-the temporal evolution of gas temperature near the cold plate and the growth of the dry-ice layer-which were used as reference indicators for comparison with the simulations. Although the simulations reproduced the initial temperature decrease, they failed to capture the subsequent temperature rise observed experimentally, suggesting that heat release associated with CO2 deposition significantly affects the thermal behavior. When this heat release was incorporated as an additional boundary condition, the characteristic temperature rise observed in the experiments was successfully reproduced. These results clarify the respective roles and limitations of the global and local models in representing CO2 deposition behavior and provide guidance for developing more accurate numerical models.
To ensure the safe transportation and handling of ammonia borane (AB) as a hydrogen source, its fundamental safety-related properties, which include toxicity, corrosivity, flammability, and storage stability, were evaluated in both aqueous solution and powder. Toxicity tests on an AB aqueous solution indicated carcinogenicity, highlighting the need for precautions to avoid ingestion, penetration into the skin, and contact with the eyes. Immersion tests with AB aqueous solution showed corrosion and surface deposition on several metal plates. The flash and ignition points of an 8 mol/L AB aqueous solution were 56.5 and 129 degrees C, respectively, while the flash point of the AB powder was 84.0 degrees C. AB powder retained its purity after four years of storage at room temperature with air exposure. AB powder absorbed moisture at >80 RH% at 25 degrees C and did not degrade when the absolute humidity was <= 4.4 g/m3 at temperatures below 50 degrees C. AB powder in the container with low humidity maintained its purity for one week outdoors during summer (below 50 degrees C). These findings provide a comprehensive dataset to support safety design, risk management, and regulatory guidelines for the practical use of AB in hydrogen systems.
This study formulates the uncertainty associated with future deployment levels of variable renewable energy (VRE) as a stochastic programming problem. The uncertainty is incorporated into a capacity and operation planning model, which is then solved to evaluate the energy mix required to achieve carbon neutrality in 2050, taking into account the utilization of imported hydrogen and synthetic methane. The results indicate that, regardless of the level of VRE deployment, carbon neutrality can be achieved by positioning VRE as the primary energy source in combination with various decarbonization technologies. Among these options, synthetic methane is found to be more economically viable than hydrogen, primarily due to its compatibility with existing infrastructure, which enables the continued use of current assets. Furthermore, distributed energy systems such as SOFC-CGS, which operate on synthetic methane and feature short lead times for deployment, are identified as promising technological options under uncertain conditions. These results underscore the importance of incorporating uncertainty into long-term energy planning and suggest that flexible, infrastructure-compatible technologies play a crucial role in developing a resilient and cost-effective energy system that supports the realization of carbon neutrality by 2050.
Methane gas recovery from a methane plume on the seafloor in the Sea of Japan was conducted to demonstrate the highly efficient continuous recovery system. The demonstration site was located northeast offshore Sado Island at a water depth of approximately 150 m. The recovery system consisted of a bubble collector, a riser tube, a submersible pump, and a gas-liquid separator. Results showed that the recovery system was operated continuously while recovering gas seeping from the seafloor as well as entrained seawater. It was found that the gas composition analysis confirmed that the gas collected at the outlet of the gas-liquid separator on the research vessel contained methane at a measurable concentration. The methane was considered to have originated from the gas plume seeping on the seafloor.
Sugarcane production generates field trash, including fresh leaves, dry leaves, and tops. Field trash by sugarcane varies between 11 and 21 t/ha, depending on the variety and quality of growth. Consequently, an enormous amount of crop residue is produced every year. However, the crop residues are poorly managed. They are either burnt or left in the field, thus causing environmental pollution. A feasible alternative is to convert this field trash into densified fuel briquettes, changing low-bulk-density biomass into high-density, energy-concentrated fuel. This study aimed to develop fuel briquettes using sugarcane dry leaves (field trash) and investigate their physicochemical and thermal properties. The influence of pressing time (30, 60, and 90 s), binder content (5, 10, and 15 % wt/wt), and briquette height (3, 4, and 5 cm) on the physical and mechanical properties of the briquettes were examined using the Response Surface Methodology to achieve the maximum bulk density, shatter resistance, abrasive resistance, and compressive strength. Results showed that the optimal conditions were 80 s pressing time, 15 % wt/wt binder content, and 5 cm briquette height, resulting in briquettes with a bulk density of 340 kg/m(3), 99.6 % shatter resistance, 80.2 % abrasive resistance, and 230.2 kPa compressive strength, respectively. The fuel briquettes contained 23.7 +/- 0.6 % volatile matter, 41.5 +/- 0 % fixed carbon, and a calorific value of 16.59 +/- 0.06 MJ/kg. It took 3.1 +/- 0.2 min to ignite and 12.5 +/- 1.8 min to boil 1.59 L of water, with an average burning time of 79.7 +/- 4.7 min. The average thermal efficiency of PHilMech fabricated cooking stove using the optimized carbonized sugarcane dry leaves-based fuel briquettes was 31.5 +/- 3.3%.
This study investigated the influence of solution and thermal treatments of porous silica-alumina particles on their activity in the hydrolytic dehydrogenation of ammonia borane. Most of the residual sodium in the sample after preparation of the silica-alumina precursors was removed by treatment with aqueous hydrochloric acid. The treated sample exhibited high hydrogen evolution from the aqueous ammonia borane solution, probably because of an increase in the number of protonic acid sites on the surface of the porous particles due to the solution treatment. The soaking time during the calcination process to obtain porous silica-alumina particles also influenced their activity in the dehydrogenation reaction, and the activity increased with increasing soaking time. The sample calcined at 673 K for 9 h, followed by treatment with aqueous hydrochloric acid, exhibited the highest dehydrogenation activity.
Cellulose nanofibers (CNFs) are materials produced from cellulosic pulp derived from renewable woody biomass and fibrillated to the nano size in width, and is expected to be alternative to fossil-based plastic gas barrier packaging materials. There are many reports of gas barrier films made by coating with chemically modified CNFs such as a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized CNF, however low drying efficiency is one of the problems. On the other hand, although the mechanically nanofibrillated CNF has relatively high drying efficiency with chemically modified CNFs, there are few examples of its use as a gas barrier material. To produce the gas barrier thin films, a thin film transfer method based on the formation of wet paper of mechanically fibrillated CNF using paper-making technology was established, and the effect of CNF thin film on gas barrier properties were investigated. The paper-making technology was applied to the formation of a mechanically fibrillated CNF thin film with a basis weight of 7.5 g/m(2 )and its transfer onto a filter paper substrate, enabling the formation of sheets with an oxygen barrier property. This study shows that thin films of mechanically fibrillated CNF with oxygen barrier properties can be fabricated by the papermaking method using paper as the base material. In addition, the fact that there were sheets with high oxygen barrier properties even when mixed with unfibrillated fibers suggests that the formation of mechanically treated CNF thin films by this method will lead to higher efficiency in the nanofibrillation, dewatering, and drying processes.
Chlorella, a genus of green algae, exhibits rapid growth and high lipid accumulation as self-defense against adverse conditions. This study aimed to identify optimal conditions for the growth and lipid accumulation of Chlorella sorokiniana in a two-stage process for biofuel production. In the first stage, C. sorokiniana grew best in BG11 medium with 3 g L-1 NaNO3 and 10 g L-1 glucose, achieving highest dry cell weight (DCW) of 2.87 +/- 0.35 g L-1 and lipid content of 23.25 +/- 0.15 % DCW after 4 d of cultivation. The second stage cultivation reached a C. sorokiniana biomass concentration of 2.18 +/- 0.08 g L-1 and lipid content of 40.78 +/- 0.61 % DCW with the addition of 30 g L-1 NaCl, 6 g L-1 NaHCO3 and a light intensity of 150 mu mol m-2 s(-1) after 2 d cultivation in 1 L Erlenmeyer flasks. C. sorokiniana cultured in 20 L, 50 L, and 300 L closed photobioreactors (PBRs) achieved DCW ranging from 1.35 +/- 0.06 to 1.94 +/- 0.04 g L-1 and lipid contents from 33.21 +/- 0.67 % to 38.48 +/- 0.76 % DCW, respectively, after 4 d in the first and 2 d in the second stage under optimal conditions of cultivation. Fatty acids profile, including C16:0, C18:2, and C18:3, indicated high-quality biodiesel, meeting 4-5 out of 5 parameters according to US and European standards. Therefore, C. sorokiniana is a potential feedstock for biodiesel.
