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Existing climate change mitigation scenarios for attaining the 1.5°C goal generally phase out hydrocarbon use through decarbonization of the energy system to eliminate fossil fuel usage. However, they require rapid changes in energy-demand technologies and human behaviors or extensive reliance on bioenergy for carbon dioxide removal (CDR). Carbon capture and utilization (CCU) presumably could support to alter such energy systems, considering recent technological advancements in direct air capture (DAC) and renewable-based hydrogen. Here, we developed a CCU-based scenario under the 1.5°C climate goal using a global energy system model. In the scenario where CCU is mainly introduced by limiting demand-side electrification, bioenergy, and CDR, CCU-based synthetic fuel reaches 30% of global energy demand to achieve net-zero emissions by 2050. In contrast to existing 1.5°C scenarios, this CCU scenario is characterized by greater availability of hydrocarbons in energy demand, reaching 280 EJ in 2050, whereas fossil fuel and bioenergy supplies decrease to 60 EJ and 100 EJ, respectively. Despite moderate demand-side electrification, this scenario involves rapid upscaling of renewable energy and DAC, which reach 600 EJ and 10 Gt-CO2 per year by 2050, respectively. While the CCU-based scenario involves multiple challenges on energy supply transformation and associated energy investments, it provides an alternative mitigation option that considers the difficulties in rapid demand-side changes and the risks of bioenergy and CDR.

The Japanese power system has unique characteristics with regard to variable renewable energies (VREs), such as higher costs, lower potentials, and less flexibility with the grid connection compared to other major greenhouse-gas-emitting countries. We analyzed the role of renewable energies (REs) in the future Japanese power sector using the results from the model intercomparison project Energy Modeling Forum (EMF) 35 Japan Model Intercomparison Project (JMIP) using varying emission reduction targets and key technological conditions across scenarios. We considered the uncertainties for future capital costs of solar photovoltaics, wind turbines, and batteries in addition to the availability of nuclear and carbon dioxide capture and storage. The results show that REs supply more than 40% of electricity in most of the technology sensitivity scenarios (median 51.0%) when assuming an 80% emission reduction in 2050. The results (excluding scenarios that assume the continuous growth of nuclear power and/or the abundant availability of domestic biomass and carbon-free hydrogen) show that the median VRE shares reach 52.2% in 2050 in the 80% emission reduction scenario. On the contrary, the availability of newly constructed nuclear power, affordable biomass, and carbon-free hydrogen can reduce dependence on VREs to less than 20%. The policy costs were much more sensitive to the capital costs and resource potential of VREs than the battery cost uncertainties. Specifically, while the doubled capital costs of VRE resulted in a 13.0% (inter-model median) increase in the policy cost, the halved capital costs of VREs reduced 8.7% (inter-model median) of the total policy cost. These results imply that lowering the capital costs of VREs would be effective in achieving a long-term emission reduction target considering the current high Japanese VRE costs.

With the shift of climate debate from understanding to actions, the use of integrated assessment models (IAMs) is gradually expanding. Since IAMs produce least-cost pathways, technoeconomic parameters constitute one of the basic parameters. Traditionally, IAMs dealt with technologies with slowly-changing, relatively homogeneous manner. Since technologies are rapidly evolving, and the pattern of technological development is regionally heterogeneous, the IAM community must embrace a new strategy to treat their underlying technoeconomic parameters. Here we illustrate such challenges by reviewing the treatment and performance of IAMs with respect to some of the rapidly changing technologies (e.g., solar, wind, and batteries). Our review shows that IAMs have difficulty in updating the cost of the rapidly changing technologies. We then articulate a new strategy, drawing upon the lesson from the current model intercomparison projects and climate sciences. We argue that a loose network of modeling groups across the globe should create a database of technological parameters in a standardized format and standard evaluation tool, perhaps to be facilitated by the IAM Consortium. Such a framework would contribute to the review of the progress toward the Paris Agreement goals.

Japan is the sixth largest greenhouse gas emitter in 2016 and plays an important role to attain the long-term climate goals of the Paris Agreement. One of the key policy issues in Japan's energy and environmental policy arena is the energy system transition to achieve 80% emissions reduction in 2050, a current policy goal set in 2016. To contribute to the ongoing policy debate, this paper focuses on energy-related CO2 emissions and analyzes such decarbonization scenarios that are consistent with the government goals. We employ six energy-economic and integrated assessment models to reveal decarbonization challenges in the energy system. The modeling results show that Japan's mitigation scenarios are characterized by high marginal costs of abatement. They also suggest that the industrial sector is likely to have a large final energy share and significant residual emissions under the 80% reduction scenario, though it is generally thought that the transport sector would have large decarbonization challenges. The present findings imply that not only energy policy but also industrial policy may be relevant to the long-term environmental target. Given the high marginal costs exceeding those of negative emissions technologies that could place a cost ceiling, further model development would be crucial.

In June, 2019, Japan submitted its mid-century strategy to the United Nations Framework Convention on Climate Change and pledged 80% emissions cuts by 2050. The strategy has not gone through a systematic analysis, however. The present study, Stanford Energy Modeling Forum (EMF) 35 Japan Model Intercomparison project (JMIP), employs five energy-economic and integrated assessment models to evaluate the nationally determined contribution and mid-century strategy of Japan. EMF 35 JMIP conducts a suite of sensitivity analyses on dimensions including emissions constraints, technology availability, and demand projections. The results confirm that Japan needs to deploy all of its mitigation strategies at a substantial scale, including energy efficiency, electricity decarbonization, and end-use electrification. Moreover, they suggest that with the absence of structural changes in the economy, heavy industries will be one of the hardest to decarbonize. Partitioning of the sum of squares based on a two-way analysis of variance (ANOVA) reconfirms that mitigation strategies, such as energy efficiency and electrification, are fairly robust across models and scenarios, but that the cost metrics are uncertain. There is a wide gap of policy strength and breadth between the current policy instruments and those suggested by the models. Japan should strengthen its climate action in all aspects of society and economy to achieve its long-term target. Supplementary Information The online version contains supplementary material available at 10.1007/s11625-021-00913-2.

This study investigated insights into reducing energy-related CO2 emissions in households by examining individual socio-economic drivers at a sub-national level. Specifically, the logarithmic mean Divisia index technique was used to decompose CO2 emission trends into six drivers in all 47 prefectures of Japan during the period from 1990 to 2015. Drivers included the change in the number of households (household effect), distribution of households (distribution effect), household size (size effect), per-capita household energy consumption (consumption effect), household energy choice (choice effect), and sectoral CO2 emission intensity (intensity effect). The results showed that, in contrast to size and the distribution effects, the number of households had a positive, significant effect on CO2 emissions, indicating that recent demographic trends are responsible for the increase in CO2 emissions observed in most of the prefectures during the study period. With regard to effects related to consumption and choice, CO2 emissions due to changes in lifestyle dropped in only seven prefectures and reductions due to changes in sectoral energy choice were seen in only two prefectures in 2015. The intensity effect boosted the emissions of these prefectures the most in 2015 because of the shutdown of nuclear power plants due to the Great East Japan Earthquake. Further, we identified those prefectures that needed to reduce their per-capita energy consumption level in order to attain the reduction targets for household CO2 emissions in 2030 from 2015, given projected changes in demographic trends and recent and projected emission intensities. In order to achieve reductions in total CO2 emissions in line with the Paris Agreement, it is important to prioritize national and local policy interventions for the transfer of new household energy technologies, upgrade household appliances, and encourage people to limit energy consumption in light of the differences in these key drivers in each prefecture., Applied Energy, 228, pp.2321-2332; 2018

A secure energy supply is indispensable for Japan's economic activity, but it is becoming more difficult to attain, due to increasing energy demand in emerging countries. The pattern of socioeconomic development and the achievement of a low-carbon society are also strongly related to energy security. This study evaluated energy security performance in Japan under alternative scenarios of future socioeconomic and energy conditions by applying three energy security indicators derived from the Shannon-Wiener diversity index. The 2050 Japan Low Carbon Navigator was used to estimate energy structures under five socioeconomic scenarios and three selected combinations of effort levels toward producing a low-carbon society. It was found that the effort levels were the most influential factors in determining energy security performance, because they greatly affect energy supply and demand. The choice of socioeconomic scenario was also influential, although the impact of this choice was less significant than the choice of effort level. However, the impact of country-risk indicators is less substantial than the above two factors. The energy security performance of Japan will improve in the future, compared with the current level. However, if the country pursues further economic growth, its energy security performance will not greatly improve. Consequently, increasing efforts to achieve a low-carbon society will contribute to the realization of a highly energy-secure society with respect to Japan's current and future socioeconomic situation.

The curtailment and storage associated with the fluctuation of electricity supplied by variable renewable energy (VRE) may limit its penetration into electricity systems. Therefore, these factors need to be explicitly treated in the integrated assessment models (IAMs). This study improves the representation of curtailment and storage of VRE in a computable general equilibrium (CGE) model. With the data generated from an hourly power sector model, curtailment and storage of VRE electricity are treated as a function of the shares of solar and wind in the electricity mix. This relationship is incorporated into a CGE model and we also updated the VRE costs and resource potential. The results show that with such improvement, by 2100, in a 450 ppm atmospheric CO 2 equivalent concentration (henceforth ppm) scenario, some electricity generated from VRE is either curtailed (2.1%) or needs to be stored (2.9%). In contrast, if VRE fluctuation is not considered, the long-term global economic cost of carbon mitigation is significantly underestimated (by 52%) in the same scenario. Conversely, updating the VRE costs and resource potential leads to a decrease in mitigation costs. Our simulation implies that the fluctuation of VRE cannot be ignored and needs to be incorporated into CGE models. Moreover, in addition to storage with batteries, many other options are available to reduce curtailment of VRE. The top-down type CGE model has limitations to fully incorporate all aspects due to its limited spatial, temporal, and technological resolution.

This study investigated the factors behind the historical changes in CO2 emissions of the Japanese manufacturing industry as a whole and by sector at the prefectural level. We decomposed the changes of CO2 emissions in 47 prefectures from 1990 to 2013 into four factors (carbon intensity, energy intensity, structure, and activity effects) using the logarithmic mean Divisia index method. We found that energy intensity, structure, and activity effects were more influential in the changes of emissions than the carbon intensity effect, although the most influential factor varied by prefecture. Among the eight considered industrial sectors of Japan's manufacturing industry, the changes in the chemistry and metal sectors were particularly complex. Thus, improvements of the energy intensity and production in these two sectors should be prioritized. We also conducted detailed analysis of the decomposed factors in three selected prefectures based on cluster analysis.

Power plants are one of key energy sources for industrial symbiosis complexes. However, decarbonization of the power sector, including decommissioning of existing fossil-fuel power plants, aggregation of power plant sites, and capacity augmentation of carbon-free power plants, is necessary to achieve low-carbon societies in the long term. Decarbonization results in declining advantage for industrial symbiosis complexes that rely on fossil-fuel power plants. To establish sustainable industrial symbiosis complexes, we used a quantitative model to analyze optimal locations and scales for power plants in Japan considering CO2 emissions reduction targets and several demand scenarios. Our results showed that even with a target of 80% CO2 emission reduction, almost half of Japan's electricity generation could come from fossil-fuel power plants in 2050 if CCS technology were deployed widely. Fossil-fuel power plants would be developed mainly in the regions of high electricity demand and little wind power potential, such as Tokyo, Chubu, and Kansai. From an intra-regional perspective, fossil-fuel power plants could be constructed in areas of high electricity demand. In addition, except for the above areas, generation from fossil-fuel power plants would vary in accordance with the availability of renewables and electricity demand. Our results indicate that future climate policy, regional electricity demand, and availability of regional renewables should be considered when planning the development of industrial symbiosis complexes.

The road transport sector accounted for 18.8% of global CO2 emissions in 2016. Regional efforts are indispensable for reducing automobile emissions, especially considering the diversity in regional transportation systems. Existing studies of automobile emissions have focused on nationwide transportation systems or differences in city size without considering regionality and long-term changes in vehicle occupancy. In this study, we decomposed national and regional automobile emissions in Japan between 1990 and 2015 by the Logarithmic Mean Divisia Index method. Statistical data that took vehicle occupancy into account were used. Results showed that nationwide vehicle occupancy increased (due to increased vehicle size and vehicle ownership), which increased emissions by 15.2% compared to 1990 levels. In highly populated regions, fuel efficiency decreased earlier than other regions thanks to the strengthening of ordinances regarding air pollution. In Western Japan, which includes less-populated prefectures, the rising popularity of mini-vehicles resulted in increased vehicle ownership and a decrease in occupancy but also led to improvements in fuel economy. To reduce automobile CO2 emissions, it will be essential to improve fuel efficiency and to increase vehicle occupancy through mechanisms, such as ridesharing and vehicle right sizing.

This study examined which socio-economic drivers contributed to energy-related CO2 emissions in Japanese households in all 47 prefectures since 1990. We adopted the logarithmic mean Divisia index technique to decompose the prefectural trends in CO2 emissions during the period 1990-2013 into six drivers: change in the number of households (household effect), distribution of households (distribution effect), household size (size effect), per-capita household energy consumption (consumption effect), household energy choice (choice effect), and sectoral CO2 emission intensity (technology effect). The results showed that, in contrast to the size effect, the household effect and the distribution effect both had positive and significant effects on CO2 emissions, indicating that these recent demographic trends were responsible for the increase in CO2 emissions observed in most of the prefectures during the period. Regarding the consumption effect and the choice effect, i.e., changes in CO2 emissions due to changes in lifestyle and technology, only ten and seven prefectures reduced their CO2 emissions in 2013, respectively. Thus, in order to further reduce CO2 emissions through these key drivers among prefectures, it is considered necessary to prioritize the transfer of new household energy technologies, upgrade household appliances, and encourage people to limit energy consumption.

After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE). However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan’s NDC (nationally determined contribution) assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price). Our result clearly shows that consumers’ electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%–6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2–2.26 MtCO2 (−4.5% on average compared to the zero-ECE case). The time-varying ECE is necessary for predicting Japan’s electricity demand and CO2 emissions after the earthquake.

A secure energy supply is important for Japan, but it is becoming difficult to attain due to increasing energy demand in emerging countries. In addition, the achievement of a low-carbon society is strongly related to energy security. This study aims to evaluate energy security performances in Japan under different socioeconomic and energy conditions in the future by applying three energy security indicators, based on the Shannon-Wiener diversity index. The 2050 Japan Low Carbon Navigator was used to estimate energy structures under five socioeconomic scenarios and three selected combinations of effort levels toward a low-carbon society. We found that the effort levels were the most influential factor in assessing energy security performances because energy supply and demand are greatly affected by the effort levels. The choice of socioeconomic scenario was also influential, although the impact of this choice was less significant than that of the effort level. On the other hand, the impact of country risk indicators is less significant than the above two factors. The energy security performances of Japan will be higher in the future, compared with the current level. However, if the country pursues further economic growth, its energy security performance will not greatly improve. With respect to Japan’s situation, which significantly depends on imported energy, increasing efforts to achieve a low-carbon society will contribute to the realization of a high-energy security society.

Objectives. The purpose of this study was to assess the effect of myocardial sympathetic denervation on the chamber-specific alteration of beta-adrenergic signaling in left ventricular failure in rabbits. Background. Local abnormalities in sympathetic nerve terminals, including the neuronal reuptake of norepinephrine, are thought to be responsible for the chamber-specific regulation of beta-adrenergic signaling in heart failure. Methods. Sixteen rabbits were given 6-hydroxydopamine, 25 mg/kg body weight intravenously on days 1 and 2 and 50 mg/kg intravenously on days 7 and 8. Another 16 rabbits received vehicle. Aortic regurgitation was induced in eight of the 6-hydroxydopamine—treated and eight of the vehicle-treated rabbits on day 14. Another eight of the 6-hydroxydopamine—treated and eight of the vehicletreated rabbits underwent a sham operation. The hearts were excised for biochemical analysis on day 21. Results. Hemodynamic characteristics on day 21 showed left ventricular failure in both the aortic regurgitation groups. The plasma norepinephrine concentration on day 21 was higher in both the aortic regurgitation groups than in the sham groups. The beta-adrenoceptor densities and isoproterenol plus 5′guanylylimidodiphosphate-, 5′-guanylylimidodiphosphate- and sodium fluoride-stimulated adenylyl cyclase activities were decreased only in the failing left ventricle of the vehicle-pretreated aortic regurgitation group, but in both ventricles of the 6-hydroxydopamine-pretreated aortic regurgitation group. The basal and forskolin-stimulated adenylyl cyclase activities were similar in both the aortic regurgitation groups and in the sham groups. Conclusions. Sympathetic denervation prevented chamberspecific alterations in beta-adrenergic signaling in acute left ventricular failure. Local loss of sympathetic nerve endings, and especially the defective neuronal norepinephrine reuptake, are likely to be responsible for the chamber-specific alteration of the beta-adrenoceptor-G protein-adenylyl cyclase system in heart failure in rabbits.

Out of 71 patients admitted to the National Kurihama Hospital and a related hospital for alcoholics or hepatic dysfunction, we studied the histopathology of alcoholics with HCV infection. Liver biopsies were divided into three groups depending on whether or not the patient was an alcoholic and anti-HCV antibody positive. The three groups were: (1) 30 HCV-antibody negative alcoholics, (2) 17 HCV-Ab positive alcoholics, and (3) 24 HCV-Ab positive non-alcoholics. Alcoholics developed specific hepatic fibrosis with a solid appearance, and the HCV-Ab negative alcoholics had relatively less lymphocytic infiltration. In contrast, patients with type C virus developed fibrosis with a loose appearance with more lymphocytic infiltrates including lymphfollicular accumulation. HCV-Ab positive alcoholics showed mixed features such as more fibrosis and less piecemeal necrosis and lymphocytic infiltration, especially in follicle formation, than HCV-Ab positive non-alcoholics. Changes of hepatocytes, such as hydropic swelling, fatty change and acidophilic body, increased in severity in the alcoholics compared with the non-alcoholics with viral hepatitis. These findings suggest that the combined exposure to both alcohol and HCV enhances hepatocellular damage, but suppresses inflammatory reactions such as lymphocyte infiltration and follicle formation seen in type C hepatitis.

Background: Right ventricular myocardial infarction (RVMI) is the major cause of hypotension and/or shock (HpS) after acute inferior myocardial infarction (inferior AMI). It is, however, unclear how RVMI affects the acute hemodynamic course. Methods and Results: In the present study, 153 patients with inferior AMI caused by right coronary artery occlusion were examined. Associations between in-hospital outcome and HpS before admission (preER-HpS) or HpS after admission (postER-HpS) were assessed using multivariate logistic regression analysis. Multivariate analysis was also conducted to determine a predictor for postER-HpS, including clinical findings in the emergency room as independent variables. HpS developed in 48.4% of patients with inferior AMI. Patients with RVMI more frequently had HpS than their counterparts in the first 6 h after infarction onset. RVMI was, however, not associated with preER-HpS, but was independently with postER-HpS (odds ratio (OR): 10.1; 4.0-27.7), whereas left ventricular failure was associated with preER-HpS, but not with postER-HpS. Furthermore, RVMI (OR: 9.4; 3.6-27.1) identified at presentation predicted postER-HpS. Conclusions: Independent of concomitant left ventricular involvement, RVMI was significantly associated with postER-HpS, but not with preER-HpS. These findings highlight the importance of identifying RVMI immediately after admission in the setting of inferior AMI. (Circ J 2010; 74: 148 - 155)

Right ventricular infarction occurs in conjunction with inferior myocardial infarction caused by proximal occlusion of the right coronary artery. However, right ventricular infarction occurs infrequently, and the reasons for this are uncertain.We retrospectively assessed the association between preinfarction angina and right ventricular infarction, as well as the short-term outcome, in 113 patients with a first acute inferior myocardial infarction caused by right-coronary-artery occlusion. The association between the timing of angina during the week before infarction and the clinical outcome was also assessed.The absence of preinfarction angina predicted the development of right ventricular infarction (odds ratio, 6.3; 95 percent confidence interval, 2.7 to 15.1; P0.001), complete atrioventricular block (odds ratio, 3.6; 95 percent confidence interval, 1.4 to 10.3; P=0.01), and combined hypotension and shock (odds ratio, 12.4; 95 percent confidence interval, 4.5 to 40.6; P0.001). Angina 24 to 72 hours before infarction was most strongly associated with reductions in the rates of right ventricular infarction (adjusted odds ratio, 0.2; 95 percent confidence interval, 0 to 0.8; P=0.02) and combined hypotension and shock (adjusted odds ratio, 0.1; 95 percent confidence interval, 0 to 0.5; P=0.02).Preinfarction angina was an independent predictor of the absence of right ventricular infarction in patients with acute inferior myocardial infarction. The patients with preinfarction angina also had better short-term outcomes than those without preinfarction angina.

Background Pump failure after acute myocardial infarction (AMI) can be predicted by several indices that estimate infarct size. However, there are few indices that predict infarct expansion and cardiac rupture. We focused on the prognostic significance of serum C-reactive protein (CRP) after AMI. Methods and Results Serum CRP levels were measured every 24 hours in 220 patients with a first Q-wave AMI. In-hospital complications, predischarge left ventriculographic findings, and long-term prognosis were assessed in relation to peak CRP levels. Peak levels of both CRP and creatine kinase (CK) were higher in patients with pump failure than in those without pump failure. In patients with cardiac rupture, peak CRP levels were higher than in those without rupture ( P =.001); peak CK levels were not predictive. Higher CRP levels were found in patients with left ventricular aneurysm ( P =.001 versus those without), aggravated heart failure ( P =.03 versus those without), and cardiac death ( P P =.004), left ventricular aneurysmal formation (relative risk, 2.11; P =.03), and 1-year cardiac death (relative risk, 3.44; P Conclusions Cardiac rupture, left ventricular aneurysmal formation, and 1-year cardiac death were associated with an elevation of serum CRP early after AMI, suggesting that elevation of CRP levels after AMI may predict infarct expansion.

Understanding the hourly electricity profile and the electricity consumption by each appliance is essential for encouraging energy-saving measures in the household sector. There are two methods for identifying energy consumption for households in existing studies: the engineering and the statistical methods. Both methods have strengths and limitations. In this study, we developed a hybrid method based on the statistical method by combining following three steps using knowledge of the engineering method; externalizing the electricity consumption for the refrigerator, adding the number of at-home-and-awake members as explanatory variables, and restricting appliance usage hours. The proposed hybrid method could adequately reproduce the total hourly electricity consumption and seasonal variation compared to the engineering method, and could decompose major appliances, some of which that were not disaggregated by the statistical method. For the quantitative analysis of the model improvement, we calculated Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE) for each method with direct metering data. For most of appliances, RMSE and MAE of hybrid model were improved from 11% to 71% compared to the existing methods. The collection of more samples to increase the accuracy of the estimation and application to areas of low statistical data availability are future steps.