This paper attempts to shed light on the factors driving fluctuations in returns on U.S. ethanol futures prices over the past 15 years using time series analysis based on Markov processes. The empirical results reveal that the U.S. ethanol futures market consists of two distinct regimes. Regime 1, representing a stable state, exhibited a structure positively correlated only with corn prices returns. In contrast, Regime 2, representing an unstable state, was characterized by long-memory properties reflecting past ethanol futures movements, showing a positive correlation with returns on renewable energy investments and a negative correlation with returns on global stock indices. Thus, the results suggest that while ethanol futures correlate only with corn prices during normal times, it tends to correlate with financial markets during periods marked by increased uncertainty stemming from both raw material price volatility and the uncertain outlook for U.S. biofuel policy. The findings are expected to contribute as decision-making for ethanol procurement planning or as market forecasting.

抄録全体を表示

In Japan, the decarbonization of the automobile sector, which accounted for 16.5% of the nation’s CO₂ emissions in fiscal year 2023, is critically dependent on electrification. However, due to challenges such as high vehicle prices, insufficient charging infrastructure, and usability issues in cold climates, the widespread adoption of electric vehicles (EVs) has not yet been realized. Consequently, during the transitional period, expectations are rising for policy measures such as improving the efficiency of internal combustion engines, expanding hybrid vehicle adoption, using low-carbon fuels, and, especially, the effectiveness of carbon pricing policies. These challenges underscore the necessity of evidence-based policy design for the road transport sector. In response, this study aims to estimate the price elasticity of fuel demand—a key factor influencing the impact of carbon pricing—by vehicle category, including hybrid vehicles, standard passenger cars, compact cars, and mini vehicles.

抄録全体を表示

This study quantitatively evaluates energy efficiency in local AI deployment under single-GPU constraints, analyzing 14 open-source LLMs across four model families (DeepSeek-MoE, DeepSeek-R1, Qwen3, Gemma3) with parameters ranging from 4B to 32B. We systematically assessed the impact of MoE architecture versus Dense models, quantization techniques (FP16→Q8→Q4), knowledge distillation, and reasoning mode activation on energy consumption across three task types: benchmark evaluation (Arena-Hard, LiveCodeBench, GPQA), long-text generation, and workflow processing. Results demonstrate that Qwen3 30b-a3b(MoE) consistently reduced power consumption by 13–87% compared to Qwen3 32b(Dense), while quantization from FP16 to Q4 achieved 50% energy reduction. Reasoning mode increased consumption 2–8× depending on task complexity (e.g., 4–8× in LiveCodeBench). Notably, Gemma3-4b Q4 achieved optimal energy efficiency (300% power variance), requiring careful power management. QAT models showed comparable efficiency to PTQ but with higher power fluctuations. These findings provide actionable guidelines for enterprises to balance energy efficiency with performance in local AI deployment, particularly for small businesses and research labs operating under hardware constraints.

抄録全体を表示

Agrivoltaics is gaining attention for balancing agriculture and renewable energy in Japan, with greenhouse cultivation showing high potential due to its inherent energy demand. However, designing systems that ensure sufficient crop yields while managing complex environmental controls remains a challenge. This study proposes a design method for greenhouse strawberries, focusing on optimizing ventilation, CO₂ enrichment, and shading to maximize photosynthesis. Using a simulation based on FvCB and Two-Leaf models, canopy photosynthesis was estimated under semi-transparent solar panels. Verification results revealed that around noon, photosynthesis rates with panels are comparable to those without, as conventional methods also require shading to maintain CO₂ levels. Under a PPFD transmittance of 62.3%, both the monthly photosynthesis from November to March and the total over five months met the MAFF’s 80% yield requirement. The results also indicate that considering environmental control is essential for accurately estimating crop yields when installing solar panels. However, several issues remain, including the need for further analysis of morning and evening photosynthesis, humidity effects, and environmental dynamics.

抄録全体を表示

High penetration rates of photovoltaic power generation (PV) are increasing the output curtailment rates of PV, and the decrease of revenue from PV is potentially hindering its introduction. Demand response (DR) and energy storage system (ESS), including pumped hydro and storage battery, is very effective to lower the curtailment rates. If the temporal CO₂ emission intensity, 30 minutes intervals for example, is fairly calculated and announced, together with the introduction of carbon pricing mechanism, the electric energy price difference between daytime and nighttime is enlarged, and then DR and ESS introduction will be more active. Though the temporal intensity in ten areas covering all Japan is already announced on some website, the calculation ignores interregional power flow through tie-lines and the time shift effects by ESS. Therefore, we propose a fairer method to calculate the temporal intensity considering tie-lines and ESS. The basic idea is that the virtual CO₂ gas is carried and stored together with electric power flow, and the gas is emitted where and when electric energy is used. We show trial calculation results of temporal intensity using open data in FY2024 in Japan. We analyze the fairness and introduction effects of our calculation method.

抄録全体を表示

To achieve carbon neutrality by 2050, expanding photovoltaic (PV) generation requires demand-side management using heat pump water heater (HP) and lithium-ion battery (LIB). This study proposes a method to estimate net electricity demand at a regional level to quantify the impacts of these energy resources. The proposed method models the operation of daytime water-heating HP and residential LIB. Case studies under a 2050 deployment scenario in Aichi Prefecture show that the impact of HP and LIB adoption on total city-level net electricity demand is limited, with reductions of approximately 0.4% in Midori Ward, Nagoya, and 0.5% in Toyohashi City. In contrast, shifting the HP water-heating start time from 9:00 to 11:00 reduces reverse power flow during midday hours: the share of community units with no reverse power flow increases from 26% to 41% in Midori Ward and from 30% to 58% in Toyohashi City. These results suggest that analyzing net electricity demand at a detailed regional level is important for the large-scale deployment of PV, HP, and LIB.

抄録全体を表示

This study aims to estimate the life-cycle environmental impact of about 100 buildings in Japan, focusing on structural frames and finishing materials at the early design stage. Based on the analysis results, dominant factors were identified, and environmental impact reduction measures were proposed. The findings quantitatively revealed the variability in environmental burdens due to differences in design conditions and structural types by building use. Key materials such as steel and ready-mixed concrete were identified as dominant contributors. Furthermore, hotspot analysis clarified major impact processes during material production. Based on these insights, specific mitigation strategies were proposed, including decarbonization of manufacturing processes and material-efficient design. This study contributes to promoting the effective application of LCA in the early design phase and advancing low-carbon strategies in the building sector.

抄録全体を表示

This study quantitatively evaluates greenhouse gas (GHG) emission changes associated with the introduction of synthetic methane (e-methane) into the LNG supply chain of city gas utilities. Using publicly disclosed data, GHG emissions were analyzed in accordance with the GHG Protocol (Scope 1–3). Utilities were categorized into two groups based on the presence or absence of LNG-fired power generation to reflect differences in emission structures.
For utilities with power generation facilities, total Scope 1–3 emissions were reduced by 44.1% under a low-carbon case reported in previous studies (24.3 g-CO₂/MJ-HHV), but only by 9.8% under Japan’s Hydrogen Society Promotion Act (44.4 g-CO₂/MJ-HHV). For utilities without such facilities, the corresponding reductions were 60.9% and 33.3%, respectively.
These results indicate that while the magnitude of emission reduction varies with business structure, the effectiveness of e-methane is primarily determined by its carbon intensity. The findings highlight the importance of evaluating decarbonization strategies based on both emission structure and carbon intensity.

抄録全体を表示

The yellow phosphorus producing reaction behaviors and the cost calculation in the commercialized yellow phosphorus generation process using an electric furnace were analyzed. The yellow phosphorus producing reaction behaviors were derived by applying the electric furnace operating technology (the heating and melting using a plasma arc) to the operation data, and the cost was calculated.
The yellow phosphorus production weight was set at 5,000 tons/year. The blending ratio of charge materials (phosphate rock, silica rock and coke) was determined, and the slag, metal and dust weights and exhaust gas volume were calculated using the material balance. As a result, for the yellow phosphorus production weight of 5,000 tons/year, the slag and metal weights were calculated as 41,900 tons/year and 600 tons/year, respectively.
The result of cost calculation shows a deficit. Due to the high purchase weight and price of coke, this process is deemed difficult to turn a profit. This is because the process involves the melting phosphate rock which has a high CaO content at high temperatures.

抄録全体を表示