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In order to develop a system to estimate a country-scale soil organic carbon stock change (SCSC) in agricultural lands in Japan that enables to take account effect of land-use changes, climate, different agricultural activity and nature of soils, a spatially- explicit model simulation system using Rothamsted Carbon Model (RothC) integrated with spatial and temporal inventories was developed. Future scenarios on agricultural activity and land-use change were prepared, in addition to future climate projections by global climate models, with purposely selecting rather exaggerated and contrasting set of scenarios to assess system's sensitivity as well as to better factor out direct human influence in the SCSC accounting. Simulation was run from year 1970 to 2008, and to year 2020, with historical inventories and future scenarios involving target set in agricultural policy, respectively, and subsequently until year 2100 with no temporal changes in land-use and agricultural activity but with varying climate to investigate course of SCSC. Results of the country-scale SCSC simulation have indicated that conversion of paddy fields to croplands occurred during past decades, as well as a large conversion of agricultural fields to settlements or other lands that have occurred in historical period and would continue in future, could act as main factors causing greater loss of soil organic carbon (SOC) at country-scale, with reduction organic carbon input to soils and enhancement of SOC decomposition by transition of soil environment to aerobic conditions, respectively. Scenario analysis indicated that an option to increase organic carbon input to soils with intensified rotation with suppressing conversion of agricultural lands to other land-use types could achieve reduction of CO2 emission due to SCSC in the same level as that of another option to let agricultural fields be abandoned. These results emphasize that land-use changes, especially conversion of the agricultural lands to other land-use types by abandoning or urbanization accompanied by substantial changes in the rate of organic carbon input to soils, could cause a greater or comparable influence on country-scale SCSC compared with changes in management of agricultural lands. A net-net based accounting on SCSC showed potential influence of variations in future climate on SCSC, that highlighted importance of application of process-based model for estimation of this quantity. Whereas a baseline-based accounting on SCSC was shown to have robustness over variations in future climate and effectiveness to factor out direct human-induced influence on SCSC. Validation of the system's function to estimate SCSC in agricultural lands, by comparing simulation output with data from nation-wide stationary monitoring conducted during year 1979-1998, suggested that the system has an acceptable levels of validity, though only for limited range of conditions at current stage. In addition to uncertainties in estimation of the rate of organic carbon input to soils in different land-use types at large-scale, time course of SOC sequestration, supposition on land-use change pattern in future, as well as feasibility of agricultural policy planning are considered as important factors that need to be taken account in estimation on a potential of country-scale SCSC. [ABSTRACT FROM AUTHOR]

This paper explores the role of negative emissions technologies (NETs) in energy systems, bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC) with geological carbon storage (DACCS) in particular, using a bottom-up energy system model TIMES-Japan that participated in the 35th study of the Stanford Energy Modeling Forum (EMF 35 JMIP) focusing on the energy transitions for the long-run climate goals. Modeling results show that large-scale deployment of NETs is essential to achieve the net-zero vision of Japan's long-term strategy, however, these NETs might not be enough in the case of the highest energy service demands. Within the feasible solution space, earlier deployment of BECCS with domestic biomass can contribute effectively to achieve the target with the support of the DACCS at the later period if both technologies are available. It shows feasible results without DACCS only in the lowest energy service demands, implying the importance of urgent research, development, and deployment of DACCS. Furthermore, this study shows that earlier deployment of DAC system with CO2 utilization in fuel production is a cost-effective way to lead the large-scale deployment of the DAC as NETs. [ABSTRACT FROM AUTHOR]

This paper assesses challenges for social impact assessment (SIA) for coastal and offshore infrastructure projects, using the case study of the Tomakomai Carbon Capture and Storage (CCS) Demonstration Project in Hokkaido, Japan. Interest in SIA and linked concepts such as social licence to operate is growing, yet marine environments also have potential to raise additional complexity in project governance. Drawing on qualitative research conducted in Tomakomai and Japan more widely across the project development and implementation phase, the paper argues that building an understanding of the social, cultural and historical relationship between the community, industry and the sea is crucial to understanding the neutral or cautiously supportive response of the citizens and stakeholders in Tomakomai to the project. Moreover, effective SIA in coastal regions needs to find a way to account for – or at least make visible – these complex relations between society and the sea. Based on the findings, it is suggested that developers or policymakers overseeing SIA in coastal regions ought to pay extra attention to the extent to which developments like CCS are viewed by communities as 'new' as opposed to a continuation of existing activities in the sea; to the importance of engagement on monitoring during the project operations phase; and to the non-economic values such as pride and identity which communities and stakeholders may derive from the sea. [ABSTRACT FROM AUTHOR]

In this paper, the significance of CO 2 -free hydrogen is discussed using a long-term global energy system. The energy demand–supply system including CO 2 -free hydrogen was assumed, though there are still large uncertainties as to whether a global CO 2 -free hydrogen energy system will be deployed. System analysis was conducted using the global and long-term intertemporal optimization energy model GRAPE under severe CO 2 emission constraints. Applied global CO 2 constraints for 2050 were a 50% reduction from 1990 levels. CO 2 constraints accounting for Intended Nationally Determined Contributions (INDCs) in each region were also considered. A variety of energy resources and technologies were considered in this model. Hydrogen can be produced from low-grade coal or natural gas with CO 2 capture and electricity from renewable energy. The hydrogen CIF (cost, insurance, and freight) price for Japan was about 3.2 cents/MJ in 2030. Hydrogen demand technologies considered in this paper are hydrogen-fired power plants, direct combustion, combined heat and power (fuel cells, gas engines, and gas turbines), fuel cell vehicles, and hydrogen internal combustion engine vehicles. The majority of CO 2 -free hydrogen was deployed in the transportation sector. CO 2 -free hydrogen was utilized in the power sector, where deployment of other zero emission technology has some constraints. From an economic viewpoint, CO 2 -free hydrogen can reduce the global energy system cost. From the viewpoint of a localized region, such as Japan, deployment of CO 2 -free hydrogen can improve energy security and environmental indicators. [ABSTRACT FROM AUTHOR]

This paper examines the life-cycle greenhouse gas (GHG) emissions reduction and associated marginal costs (MC) in Japan when the government enhances the transition to battery electric passenger vehicles (BEVs) by implementing a rapid investment regime for charging stations and fossil-fueled vehicle bans. Important factors affecting BEV emissions are battery performance, battery production technology, electricity generation mix and battery minimum state of charge (SOC min). We find that in addition to a rapid investment regime, a fossil-fueled vehicles ban policy is necessary to significantly increase the uptake of BEVs and achieves the deepest reduction in life cycle GHG emissions. Under this policy, with carbon neutral electricity by 2050 and a low SOC min charging regime, life-cycle GHG emissions are reduced by 48% and the MC by 53% in 2060. A carbon neutral light transport fleet in 2050 will require carbon capture and storage to offset 24 million tonnes-CO 2 equivalent of emissions even if electricity is carbon neutral by 2050 and users adhere to a low SOC min charging regime. [Display omitted] • Enhanced infrastructure development has a little impact on the uptake of BEVs. • The more stringent vehicle ban reduces life cycle GHG emissions the most. • Battery charging regime is crucial to GHG emissions reduction and associated cost. • Improving battery and vehicle production is crucial to GHG emissions reduction. • Carbon neutral light vehicle transport by 2050 requires carbon capture and storage. [ABSTRACT FROM AUTHOR]

In this paper we draw up future roadmaps for technologies, policies, and optimal investment timing toward the achievement of a low-carbon society (LCS) in Japan by 2050. Future pathways for Japan to follow are calculated using an analytical model based on a backcasting methodology. Early actions can lead to pathways for minimizing the costs toward a LCS in Japan. However, to take early actions, large investments will be needed at the initial stages. The investment requirements for the residential and commercial sector and transportation sector will be especially costly: The former reaching 2.5 trillion JPY annually from 2010 to 2025 and the latter reaching 2.5 trillion JPY annually from 2010 to 2015. There are four main advantages to early actions. (1) Technologies have learning-by-doing effects: The additional cost of reducing CO2 emissions will fall as the technologies spread. (2) If actions are delayed, learning-by-doing effects may fail to work sufficiently, resulting in higher total investment requirements for achieving a LCS. (3) No infrastructure can be built immediately; hence it would be difficult to switch suddenly to a LCS in the years just before 2050. (4) Future technological development has several uncertainties. If the development of one of the currently dominant technologies falls behind schedule, it will fail to spread as expected and CO2 emission targets will not be met. Early actions will open up new opportunities for the spread of alternative actions toward the LCS should a dominant technology fail in some way. [ABSTRACT FROM AUTHOR]

This study investigated cost‐effective energy strategies for realizing net zero CO2 emissions in Japan by 2050, employing an energy system optimization model with hourly electricity balances. The detailed temporal resolution enables the model to capture the intermittency of variable renewable energy (VRE) and the costs of system integration measures. Siting constraints on VRE, such as prohibiting solar PV and onshore wind developments in forests and offshore wind developments inside fishery rights areas, are incorporated in the model to reflect the environmental protection and social acceptance perspectives. Simulation results imply that a well‐balanced power generation mix, combining renewables, nuclear, gas‐fired with carbon capture and storage, as well as ammonia‐fired, would contribute to curbing mitigation costs. In contrast, a simulation case with very high VRE penetration poses economic challenges. The average shadow price of electricity in 2050 in a 100% renewables case (RE100) is projected to be more than doubled from a reference case which is based on middle‐of‐the‐road assumptions. Marginal CO2 abatement cost in 2050 increases from 49,200 JPY/tCO2 in the reference case to 75,300 JPY/tCO2 in the RE100 case. The economic viability of high VRE penetration is improved by relaxing the siting constraints, although it may raise environmental and social concerns. [ABSTRACT FROM AUTHOR]

By considering trade-offs and complementarity between carbon removal from the atmosphere by forests and emission reduction by wood use, we developed a forest-sector carbon integrated model for Japan. We discuss mitigation measures for Japan based on model projections. The integrated model included the forest model and the wood use model. Based on three scenarios (baseline, moderate increase, and rapid increase) of harvesting and wood use, the integrated model projected mitigation effects including carbon removal by forests and emission reduction through the wider use of wood, until 2050. Results indicate that forests will not become a source of net carbon emissions under the three scenarios considered. The baseline scenario is most effective for mitigating climate change, for most periods. However, the sum total of carbon removal in forests and carbon emission reductions by wood use under the rapid increase scenario exceeded the one of the moderate increase scenario after 2043. This was because of strong mitigation activities: promoting replanting, using new high-yield varieties, and wood use. The results also indicated that increases in emission reduction due to greater wood use compensated for 67.9 % of the decrease of carbon removal in 2050, for the rapid increase scenario. The results show that carbon removal in forests is most important in the short term because of the relative youth of the planted forests in Japan, and that mitigation effects by material and energy substitution may become greater over the longer term. [ABSTRACT FROM AUTHOR]

This study considers the emissions implications of co-combusting imported ammonia in coal-fired power stations. The study adopts a supply chain approach, estimating the emissions reduction potential of 20% ammonia co-combustion in coal-fired power stations in the country of use, and the emissions associated with ammonia production in the country of origin. The paper considers the emissions implications of using different ammonia production technologies: Haber-Bosch (HB) ammonia production with hydrogen generated from steam methane reforming using natural gas (SMR), with and without carbon capture and storage (CCS); Haber-Bosch ammonia production with hydrogen generated from renewable sources; and fully renewable electricity generated ammonia. The empirical setting of the study is an ammonia supply chain encompassing Japan and Australia. The results show co-combustion of ammonia produced with SMR-HB provides no net benefit for the combined country emissions, as ammonia production related greenhouse emissions in Australia are equivalent to the emission reductions in Japan. In contrast, co-firing ammonia produced from fully renewable sources reduces emissions in the two countries in 2030 by 43 MT per annum. SMR-HB processes with varying levels of CCS reduce annual emissions by 16–34 MT. Based on the results, different policy options are suggested for managing the emissions associated with a Japan-Australia ammonia supply chain. • Japan actively pursuing ammonia/coal co-combustion to reduce power sector greenhouse gas emissions. • An Australia-Japan ammonia supply is examined at a country boundary emissions basis. • Choice of ammonia manufacturing approach has significant impact on emissions. • 40 MT pa saving in Japan offset by 39 ± 11 MT pa increase in Australia from Best Available Technology. • Only a fully renewable ammonia manufacturing process reduces emissions in both Australia and Japan. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a rock physics model describing the relationship between resistivity and CO2 saturation at the Nagaoka CCS test site in Japan. 10.4kt CO2 were injected at Nagaoka between July 2003 and January 2005, with repeated logging performed both during and after the injection period. The target reservoir at Nagaoka is shaly sandstone, in which the conductance of clay minerals has a significant effect on log resistivity. We analyzed open-hole log data in order to estimate shale volume and distribution, and applied Waxman–Smits model to fit the data. For the known observables in the model we used the resistivity log and water saturation derived from the neutron log, with the saturation exponent and the correction value for shale conduction then obtained using the time-lapse logging data. According to the modeled results, the area characterized by smaller saturation exponents corresponded to that with minor changes in resistivity. Dissolved CO2 was also found to reduce the resistivity of formation water. Model modification taking this effect into account was thus carried out, although the essence of the original Waxman–Smits model was retained. The performed analyses provide evidences of successful residual and solubility trapping currently in progress at Nagaoka. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to develop independent and systematic criteria for assessing CCS policy in terms of its level of policy integration. We believe that we should assess CCS policy in terms of the distance to an ideal integrated CCS policy in order to keep track of its trajectory toward sustainable development. After reviewing the existing literature of environmental policy integration, an assessment framework for integrated CCS policy is developed based on Arild Underdal''s notion of ‘integrated policy’ then, its usefulness is demonstrated by applying it to CCS policies in Japan and Norway. In the final part, we summarize the findings of the cases and conclude with some observations regarding explanatory factors of the difference in terms of the achieved level of policy integration between Japan and Norway''s CCS policies, and some policy implications derived from the analysis based on the framework. [Copyright &y& Elsevier]

Abstract: To evaluate the probable storage volume of CO2 in Japan, the Research Institute of Innovative Technology for the Earth (RITE) and the Engineering Advancement Association of Japan (ENAA) collected and organized a wide range of geological information on Japanese sedimentary basins, and estimated a CO2 storage capacity during a period between 2006 and 2009 . In an attempt to optimize the investigation efforts and to share the information, the vast amount of geological data collected were then reorganized into a database system where the investigation results could be readily accessed and browsed. This paper represents the outline of the database system. [Copyright &y& Elsevier]

Abstract: This paper presents the results of careful considerations on the surface facilities at one of the most promising CCS (Carbon dioxide Capture and Storage) candidate sites in Japan in regards to process, economy and energy consumption. This site has been selected to demonstrate the feasibility of CCS total system in which CO2 is captured from natural gas processing plants, transported to the injection site (100 km away from the plants), and then stored in the saline aquifers underneath the seabed of the Japan Sea. Four technical issues have been reviewed for the surface facilities, namely CO2 transportation, removal of impurities in the CO2 gas, the liquefied CO2 heater models and the shaft seal system for CO2 pumps. As for the CO2 transportation method, tanker trucks transportation is selected compared to pipelines because of the merits in a construction period, economy, and local citizen’s understanding and acceptance which are crucial for the realization of the project. Concerning process building, removal of impurities contained in the CO2 gas has been considered first. CO2 gas separated from natural gas contains hydrogen sulfide, mercury, and BTX in addition to water. These impurities must be eliminated prior to liquefaction of CO2 because they could interfere with the process as well as for environmental considerations. The adsorption method is found to be effective for removing all these impurities. However, it is also found that adsorbent consumption rate depends largely on the process sequence with which the impurities are eliminated. After reviewing the results, it is found that the most economical sequence to eliminate these impurities is in the order of mercury, hydrogen sulfide, BTX, then water. Liquefied CO2 heater models have been considered to reduce CO2 emission. After transportation to the injection site, the liquefied CO2 is pressurized and heated from −10 °C to a super critical state of 40 °C in order to avoid phase transition inside the injection tube. Using a heat pump to utilize the heat in the air to improve the energy efficiency, CO2 emission is substantially reduced by approximately 70% compared to the conventional method using hot water from a boiler that uses heavy fuel oil. A centrifugal pump will be selected for CO2 pumps because it can handle large volumes. An effective shaft seal system is the tandem formation using vapor-liquid seal and dry gas seal for the first and the second stages respectively. However, since we have limited experience of this formation at CO2 pumps in Japan, it is identified as a critical item in the demonstration project. [Copyright &y& Elsevier]

Abstract: Carbon Dioxide Capture and Storage (CCS) is a technology for reducing the amount of CO2 to be emitted into the air, by storing the CO2. However, a CCS project itself emits some CO2. Therefore, to estimate CCS’s net CO2 reduction effect, it is effective to apply life cycle assessment (LCA) to CCS projects. In this paper, we assumed a number of CCS project models to be feasible in Japan, and estimated the amount of CO2 emissions to store one ton of CO2 by applying LCA to the CCS projects. As a result, depending on the model case, 50% or more of the CO2 amount to be stored was emitted. The study also revealed that approximately 80% of the CO2 emissions at CCS-applied facilities derived from the energy consumed to re-heat the liquid absorbent that absorbed CO2. The study also indicated that a substantial amount of CO2 emissions can be reduced if heat integration is conducted between the production equipment and the CCS equipment for energy utilization, such as bleeding CO2 from a power station and other production equipment. [Copyright &y& Elsevier]

Abstract: Monitoring is essential to assess whether sequestered carbon dioxide (CO2) behaves as expected and a variety of monitoring techniques have been proposed and examined. Although those techniques provide useful information, such as CO2 migration and distribution, individual information yields only limited insight into CO2 behavior in geological reservoirs. To deepen our understanding of migration and containment of sequestered CO2, a monitoring framework must be established to comprehend the individual sources of information. This paper describes the monitoring framework that was applied to a pilot project of CO2 storage conducted at an onshore site in Nagaoka, Japan. The target aquifer was the early Pleistocene sandstone bed, around 60m thick and 1100m below the ground surface. During the 554-day injection period, around 10,400tonnes of CO2 were sequestered. Three monitoring wells were completed around an injection well and several monitoring schemes, including continuous measurements of pressure and temperature, well logging, crosswell tomography, and in situ fluid sampling, were applied. Based on the individual monitoring results, meso-scale as well as macro-scale migration of sequestered CO2 was examined. These multi-scale observations on CO2 migration were not in contradiction with each other but were consistent as a whole. In particular, the compositional analysis of in situ fluid samples in conjunction with time-lapse well logging played an important role in understanding meso-scale migration of CO2, and flow simulation provided remarkable insights into the process of macro- and meso-scale migration. This study discusses monitoring and simulation studies for assessing multi-scale migration, with emphasis on the importance of comprehensive analyses, since they can bridge the gap between the individual monitoring outcomes. [ABSTRACT FROM AUTHOR]

Abstract: With the development of distributed generation (DG) technologies and the implementation of policies to encourage their applications, building combined heat and power (BCHP) is expected to play a greater role in the commercial buildings in the future. BCHP is a promising efficiency improvement and carbon mitigation strategy, but careful selection of technology and operation mode is required to achieve a reasonable system performance according to energy consumption characteristics of buildings and technical features of equipments. This paper analyzed energy consumption characteristics of four typical commercial buildings in Japan and simulated the energy system performances of four mostly widely adopted DG technologies under different operation mode conditions for the four buildings studied. Various scenarios were evaluated and compared regarding energy utilization efficiency, energy saving and environmental effects, as well as economic efficiency. Results show that the hotels and hospitals are more attractive for BCHP because of their stable thermal load demands and a favorable heat-to-power ratio, which is the most compatible match with available DG technologies. Furthermore, some DG technologies are more suitable for a certain type of building than others because of their technical features more matching with the building’s energy consumption characteristics, as well as the user’s motivation of selecting BCHP. In Japan, during selecting DG technologies, the prior order is gas turbines (GT), gas engines (GE), diesel engines (DE) and phosphoric acid fuel cells (PAFC) for the hotels, PAFC, GE and GT, DE for the hospitals, PAFC, DE, GE and GT for the stores, as well as DE, PAFC, GE and GT for the offices. [Copyright &y& Elsevier]

Abstract: This paper presents results from a survey on stakeholder attitudes towards Carbon Capture and Storage (CCS). The survey is the first to make a global comparison across three major regions; USA, Japan, and Europe. The 30-question survey targeted individuals working at stakeholder organizations that seek to shape, and will need to respond to, policy on CCS, including electric utilities, oil & gas companies, CO2-intensive industries and non-governmental organizations (NGOs). The results show generally small differences across the regions and between the different groups of stakeholders. All believed that the challenge of significant reductions in emissions using only current technologies was severe. There is a widespread belief both that renewable technologies such as solar power and CCS will achieve major market entry into the electricity sector within the next 10 to 20 years, whereas there is more skepticism about the role of hydrogen and especially nuclear fusion in the next 50 years. All groups were generally positive towards renewable energy. Yet, there were some notable areas of disagreement in the responses, for example, as expected, NGOs considered the threat of climate change to be more serious than the other groups. North Americans respondents were more likely to downplay the threat compared to those of the other regions. The Japanese were more concerned about the burden that would be placed on industry in the coming decade as a result of emissions constraints and NGOs were more likely to believe that the burden would be light or very light. NGOs believed CCS to be far more attractive than nuclear fusion power but much less than renewables. As expected, the risk for leakage from reservoirs was ranked number one of the risk options given. [Copyright &y& Elsevier]

Abstract: A public survey was conducted concerning carbon capture and storage technology (CCS) in the months of February and April 2007 in Japan, Previously another CCS survey took place in December 2003, and a set of the questions asked in the 2007 survey were purposely the same as that used in the 2003 survey, Japanese adults were randomly selected to answer a questionnaire either in printed format or in online format. Several versions of the questionnaire were used, and each contained a different educational part, imparting relevant CCS information. 334 people successfully responded to our paper survey in Tokyo and Sapporo while 2156 people completed our online survey across the nation. The questionnaire for the survey contained 5 sets of different information package on CCS and questions asking pros and cons on CCS implementation to analyze influence of information provided on CCS. Based on the results of survey we found: that not many people still know about CCS. Those who have knowledge on CCS show a preference for CCS implementation, however; preference was decreased after obtaining information which we considered was neutral on CCS. These results suggest a possibility that information on negative aspects of CCS (risks, etc.) would not be well known in the general public. We also found that preference for CSS decreased slightly after providing different information on CCS to respondents in the group with the newspaper articles which we considered neutral in comparison with other groups. The newspaper articles contained the information on negative opinions against CCS besides risk-related information as well as information based on an IPCC Special Report: it is assumed that such negative opinions may have influenced opinion formation of respondents. Since CCS is new technology, information about how other people or entities evaluate CCS would influence public opinion. In the sub-sample provided with industrial and natural analogues of preference on geological storage, the views were slightly more positive about CSS in comparison with reported opinions of other groups. This implies information on natural or industrial analogue would help manage perception of risk in a positive way. The result of path analysis to data of a public survey identified four factors, (1) risks and leakage, (2) effectiveness of CCS, (3) responsibility, and (4) fossil fuel use. We found that the factor of understanding the effectiveness of CCS is most positively influential for general acceptance of CCS. I Implementation of geological storage and the factor of risks and leakage become much more influential negatively in the implementation of geological storage compared to general acceptance of CCS, implying that implementation of CC2 geological storage also needs careful communication of risk. [Copyright &y& Elsevier]

Mangrove forests are characterized by high rates of carbon sequestration, with much of this carbon being derived from fine roots. In this study, we sought to estimate the dynamics of the fine (<2 mm) and small (≥2 mm) roots of Kandelia obovata, one of the mangrove forest species found on Okinawa Island, southern Japan, and to evaluate annual root production considering root decomposition estimated using root litterbags. To estimate root production and mortality, we applied two approaches, sequential soil core sampling and ingrowth core methods. We found that annual root production determined by sequential soil core sampling was 3.2 times higher than that estimated by ingrowth core methods. The annual production of fine roots (545 and 294 g m−2 year−1 for sequential soil core sampling and ingrowth core methods, respectively) was higher than that of small roots (536 and 44 g m−2 year−1 for sequential soil core sampling and ingrowth core methods, respectively). The results obtained using sequential soil core sampling indicated a high proportion of fine root necromass to total fine root mass (81%), most of which comprised very fine roots (<0.5 mm). We also established that the decomposition ratio of fine roots was lower than that of small roots. Collectively, our observations indicate that the slow rate of decomposition and high rate of production of fine roots contribute significantly to the accumulation of fine root necromass, particularly that of very fine roots, in the mangrove forest. [ABSTRACT FROM AUTHOR]

Organisations attempt to contribute their share towards fighting the climate crisis by trying to reduce their emission of greenhouse gases effectively towards net zero. An instrument to guide their reduction efforts is internal carbon pricing. Next to choosing the right pricing tool, defining the exact value of an internal carbon price, especially against the background of potential regulatory external carbon prices, and assessing its impact on business units' energy systems poses a challenge for organisations. The academic literature has so far not examined the impact differences of an internal carbon price across different countries, which this paper addresses by using an optimisation model. First, it analyses the energy system cost increase of a real-world facility based on an internal carbon price compared to a potential regulatory carbon price within a country. Second, we evaluate the energy system cost increase based on an internal carbon price across different countries. The results show that with regard to internal carbon prices the additional total system cost compared to potential external carbon prices stays within 9%, 15%, and 59% for Germany, Japan, and the United Kingdom, respectively. The increase in the energy system cost in each country varies between 3% and 93%. For all countries, the cost differences can be reduced by allowing the installation of renewables. The integration of renewables via energy storage and power-to-heat technologies depends on the renewable potentials and the availability of carbon capture and storage. If organisations do not account for these differences, it might raise the disapproval of internal carbon prices within the organisation. [ABSTRACT FROM AUTHOR]

Japan's mid-century strategy to reduce greenhouse gas (GHG) emissions by 80% by 2050 requires rapid energy system changes, which may lead to stranded assets in fossil fuel-related infrastructure. Existing studies have shown that massive stranding of assets in the energy supply side is possible; few studies have involved economy-wide stranded asset analysis. In this study, we estimated stranded investments in both the energy supply and demand sectors in Japan in the context of near-term goals for 2030 and the mid-century strategy. To this end, multiple emission scenarios for Japan were assessed based on various emission reduction targets for 2030 and 2050. The results show that stranded investments in the energy supply sectors occur mainly in coal power plants without carbon capture and storage (CCS), especially in scenarios without enhanced near-term mitigation targets. Increases of stranded investment in demand sectors were observed primarily under stringent mitigation scenarios, which exceed the 80% reduction target. In particular, investment for oil and gas heating systems in the buildings sector may be stranded at levels up to $20 billion US between 2021 and 2050. We further simulated a scenario incorporating a subsidy for devices that do not use fossil fuels as a sector-specific policy; this reduced the amount of stranded investment in the buildings sector. We confirmed the benefit of enhancing near-term mitigation targets to avoid generating stranded investments. These findings support the importance of inclusive energy and climate policy design involving not only pricing of carbon emissions but also complementary cross-sector economy-wide policies. [ABSTRACT FROM AUTHOR]

• We estimate parameter and predictive uncertainty of a soil respiration model in a cool-temperate forest ecosystem based on Bayesian inversion approach. • We use a Gaussian innovative residual error model with a generalised likelihood function that accounts for correlated, heteroscedastic, and non-normally distributed residual error. • We demonstrate that the Bayesian inversion approach is useful as a means by which to evaluate effectively parameter and predictive uncertainty of a soil respiration model with precise representation of residual errors. Careful modelling of soil carbon sequestration is essential to evaluate future terrestrial feedback to the earth climate system through atmosphere–surface carbon exchange. Few studies have evaluated, in bio- and geo-applications, parameter and predictive uncertainty of soil respiration models by considering the difference between observations and model predictions; i.e. residual error, which is assumed neither to be independent nor to be described by a normal (i.e. Gaussian) probability distribution with a mean of zero and constant variance. In this paper, we use 2-year observations of soil carbon flux from 2017 to 2018 (hereafter referred to as 'long-term simulation') obtained with two open-top chambers to estimate parameter and predictive uncertainty of a simple soil respiration model based on Bayesian statistics in a cool-temperate forest in western Japan. We also use a Gaussian innovative residual error model in which a generalised likelihood uncertainty estimation that accounts for correlated, heteroscedastic, non-normally distributed (i.e. non-Gaussian) residual error flexibly handles statistics varying in skewness and kurtosis. Results show that the effects of correlation and heteroscedasticity were eliminated adequately. Additionally, the posterior distribution of the residuals had a pattern intermediate to those of Gaussian and Laplacian (or double-exponential) distributions. Consequently, the predicted soil respiration rate, and range of uncertainty therein, well-matched the observational data. Furthermore, we compare results of parameter and predictive inference of the soil respiration model from the long-term simulation with those constrained of short-term simulations (i.e. 4-month subsets of the 2-year dataset) to determine the extent to which the approach used affects the estimation of parameter and predictive uncertainty. No significant difference in parameter estimates was found between the long-term simulation versus any of the short-term simulations, whereas short-term simulation analysis of the uncertainty at 50 %—i.e. between the lower (25 %) and upper (75 %) quartiles of the probability range—indicated distinctive variations in model parameters in summer when more vigorous activity of trees and organisms promotes carbon cycling between the atmosphere and ecosystem. Overall we demonstrate that the Bayesian inversion approach is useful as a means by which to evaluate effectively parameter and predictive uncertainty of a soil respiration model with precise representation of residual errors. [ABSTRACT FROM AUTHOR]

CCS projects involve a complex legal mechanism. The IPCC (2005) clearly indicated that installations of CCS technology require 'long-term management' by: ensuring careful site selection; monitoring systems; regulations; and remediation and liability measures. While a large volume of legal study on CCS has been undertaken, a variety of SEA and EIA and their possible mixed approaches are also being considered for designing an effective policy and legal framework for CCS (e.g. IEAGHG, 2007; and Koornneef et al. 2008, 2011). Yet, the best practice of the mixed approach to assisting a policy, legal and regulatory framework is unclear, due to the lack of experience and the varied levels of comprehension. Japan intends to commercialise CCS technology in the future. This paper provides an analysis of examining: whether the key roles and elements of SEA and EIA in response to long-term management are being covered in the current CCS law in Japan. The outcome of this study creates a novel framework of legal analysis, an application of the framework that articulate insights into Japan's legal issues, and a set of potentially useful lessons for the future design of policy and legal framework for CCS projects. [ABSTRACT FROM AUTHOR]

Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment (as of 2018) in Japan. Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages (≤ 3 years), the positive complementarity effect was explained by enhanced growths of early- and mid-successional species in the mixture. Later on (≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer. Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies. [ABSTRACT FROM AUTHOR]

The influence of the long-term combination of rice straw removal and rice straw compost application on methane (CH4) and nitrous oxide (N2O) emissions and soil carbon accumulation in rice paddy fields was clarified. In each of the initial and continuous application fields (3 and 39−51 years, respectively), three plots with different applications of organic matter were established, namely, rice straw application (RS), rice straw compost application (SC) and no application (NA) plots, and soil carbon storage (0−15 cm), rice grain yield and CH4 and N2O fluxes were measured for three years. The soil carbon sequestration rate by the organic matter application was higher in the SC plot than in the RS plot for both the initial and continuous application fields, and it was lower in the continuous application field than in the initial application field. The rice grain yield in the SC plot was significantly higher than those in the other plots in both the initial and continuous application fields. Cumulative CH4 emissions followed the order of the NA plot < the SC plot < the RS plot for both the initial and continuous application fields. The effect of the organic matter application on the N2O emissions was not clear. In both the initial and continuous application fields, the increase in CH4 emission by the rice straw application exceeded the soil carbon sequestration rate, and the change in the net greenhouse gas (GHG) balance calculated by the difference between them was a positive, indicating a net increase in the GHG emissions. However, the change in the GHG balance by the rice straw compost application showed negative (mitigating GHG emissions) for the initial application field, whereas it showed positive for the continuous application field. Although the mitigation effect on the GHG emissions by the combination of the rice straw removal and rice straw compost application was reduced by 21% after 39 years long-term application, it is suggested that the combination treatment is a sustainable management that can mitigate GHG emissions and improve crop productivity. [ABSTRACT FROM AUTHOR]

Gravimetric techniques are used for monitoring the distribution and migration of CO2 stored in geological formations. Superconducting gravimeters (SGs), because of their high sensitivity, can enable continuous ground‐based monitoring of offshore CO2 storage. For offshore monitoring purposes, gravity stations should be located near the seashore to maximize the signal of interest. We observed gravity continuously with an SG near the seashore at the Tomakomai carbon dioxide capture and storage demonstration site in Japan to assess variation of the observed gravity and to evaluate the applicability of this technique for monitoring of large‐scale offshore storage. Strong noise caused by strong winds and ocean waves was removed by low‐pass filtering. The noise did not fundamentally affect long‐term gravity changes. The observed gravity was affected strongly by shallow groundwater level changes but the effects were sufficiently corrected by expressing their effects as a summation of linear functions of groundwater level changes. Considering all possible effects on gravity, the standard deviation of the gravity residuals during 85 days of observation was minimized to 7.5–8.2 nm s–2. Based on the model setting of the Tomakomai site, the estimated annual gravity changes caused by industrial‐scale injection (1 MtCO2 year–1) into a hypothetical offshore formation (1 km depth) were –2.8 to –3.3 nm s–2 under different saturation conditions. The estimated changes exceed the observed standard deviation in 2.3–2.9 years. These results suggest that injection‐induced gravity changes can be detected using SG within a few years. Therefore, the present ground‐based gravimetric technique can contribute to long‐term monitoring of offshore storage. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study assesses Japan's emission pathways aimed at net-zero emissions by 2050, as implied by the Paris Agreement's global climate goal of pursuing efforts to limit the temperature rise to 1.5 °C. Based on a scenario analysis performed using AIM/Enduse [Japan], Japan's energy supply sector requires a radical transformation, including reliance on carbon dioxide removal options such as bioenergy with carbon capture and storage (BECCS) to attain net-zero emissions by 2050 without substantial social changes. By contrast, the gap between the 1.5 and 2 °C scenarios is relatively moderate in demand sectors. The building sector may need to be decarbonized even in the 2 °C case, whereas the transportation sector will face additional challenges, such as electrification and penetration of biofuel, in the 1.5 °C case. Reaching net-zero emissions by 2050 is a huge challenge, since the price of carbon in the net-zero emissions case increases by a factor of four or five over that in the 2 °C case. Moreover, the absence of early action as well as limited use of low-carbon energies would considerably add to the burden. Given these challenges and uncertainties, the potential of other mitigation options, such as drastic social change, large-scale afforestation and international emissions trading, merits consideration. [ABSTRACT FROM AUTHOR]

In order to estimate a country-scale soil organic carbon (SOC) stock change in agricultural lands in Japan, while taking into account the effect of land-use changes, climate, different agricultural activities and the nature of soils, a spatially explicit model simulation system was developed using Rothamsted Carbon Model (RothC) with an integration of spatial and temporal inventories. Simulation was run from 1970 to 2008 with historical inventories. Simulated SOC stock was compared with observations in a nation-wide stationary monitoring program conducted during 1979-1998. Historical land-use change, characterized by a large decline in the area of paddy fields as well as a small but continuous decline in the area of orchards, occurred along with a relatively large increase in upland crop fields, unmanaged grasslands, and settlements (i.e. conversion of agricultural fields due to urbanization or abandoning). Results of the simulation on SOC stock change under varying land-use change indicated that land-use conversion from agricultural fields to settlements or other lands, as well as that from paddy fields to croplands have likely been an increasing source of CO2 emission, due to the reduction of organic carbon input to soils and the enhancement of SOC decomposition through transition of soil environment from anaerobic to aerobic conditions. The area-weighted mean concentrations of the simulated SOC stocks calculated for major soil groups under paddy fields and upland crop fields were comparable to those observed in the monitoring. Whereas in orchards, the simulated SOC stocks were underestimated. As the results of simulation indicated that SOC stock change under managed grasslands and settlements has been likely a major sink and source of CO2 emission at country-scale, respectively, validation of SOC stock change under these land-use types, which could not have been accomplished due to limited availability or a lack of measurement, remains a forthcoming challenge. [ABSTRACT FROM AUTHOR]

No tillage (NT) fosters carbon (C) sequestration, increases soil organic matter (SOM) stock, and improves soil health. However, its effect on SOM accumulation in Andosol, which has high OM stabilization characteristics due to its specific mineral properties, remains unclear. In this study, we evaluated the effect of NT on SOM content and its distribution by the physical fractionation method and assessed the quality of accumulated SOM in each fraction. We collected soil samples at 0–2.5, 2.5–7.5, and 7.5–15 cm depths from NT and conventional tillage (CT) plots in a long-term (19 years) field experiment of Andosols in Ibaraki, Japan. The soil samples were separated into light fraction (LF), coarse-POM (cPOM: 0.25–2 mm), fine-POM (fPOM: 0.053–0.25 mm), and silt + clay (mOM: <0.053 mm). The C, nitrogen (N), and organic phosphorus (Po) contents of each fraction were analyzed. The C content of cPOM and fPOM in NT at 0–7.5 cm was higher than in CT, while there was no clear difference in the mOM fraction or deeper layer (7.5–15 cm). NT increased the C, N, and Po contents in the labile POM fractions at the surface layers but did not increase the stable fraction or change the quality. [ABSTRACT FROM AUTHOR]

CO2 sequestration of the forests in Oita Prefecture, Japan, was estimated using satellite remote sensing data. First, hybrid classification of the optical LANDSAT ETM+ data was performed using GIS to produce a detailed land cover map. CO2 sequestration for each forest type was calculated using the sequestration rates per unit area multiplied by the forest areas obtained from the land cover map This results in 3.57 MtCO2/yr for coniferous, 0.77 MtCO2/yr for deciduous broadleaf, and 2.25 MtCO2/yr for evergreen broadleaf, equivalent to a total of 6.60 MtCO2/yr for all the forest covers in Oita. Then, two different methodologies were used to improve these estimates by considering tree ages: the Normalized Difference Vegetation Index (NDVI) and the stem volume methods. Calculation using the NDVI method shows the limitation of this method in providing detailed estimations for trees older than 15 years, because of NDVI saturation beyond this age. In the stem volume method, tree ages were deduced from stem volume values obtained by using PALSAR backscattering data. Sequestration based on tree age forest subclasses yields 2.96 MtCO2/yr (coniferous) and 0.31 MtCO2/yr (deciduous broadleaf forests). These results show the importance of using not only detailed forest types, but also detailed tree age information for more realistic CO2 sequestration estimates. In so doing, overestimation of the sequestration capacity of forests could be avoided, and the information on the status and location of forest resources could be improved, thereby leading to sounder decision making in sustainable management of forest resources. [ABSTRACT FROM AUTHOR]

The article offers information on the topics regarding energy and environment. It discusses the carbon finance which includes the wasted 78 billion dollars on global warming project of Japan, and the installation of wind farms in Spain. It also mentions the climate and energy policy including the carbon market payment rise in California, trillion-euro energy plan in Europe, and the delay fund for solar power, carbon capture and storage projects in Australia.

We estimated the carbon (C) sequestration potential of organic matter application in Japanese arable soils at a country scale by applying the Rothamsted carbon (RothC) model at a 1-km resolution. After establishing the baseline soil organic carbon (SOC) content for 1990, a 25-year simulation was run for four management scenarios: A (minimum organic matter application), B (farmyard manure application), C (double cropping for paddy fields) and D (both B and C). The total SOC decreased during the simulation in all four scenarios because the C input in all four scenarios was lower than that required to maintain the baseline 1990 SOC level. Scenario A resulted in the greatest depletion, reflecting the effects of increased organic matter application in the other scenarios. The 25-year difference in SOC accumulation between scenario A and scenarios B, C and D was 32.3, 11.1 and 43.4 Mt C, respectively. The annual SOC accumulation per unit area was similar to a previous estimate, and the 25-year averages were 0.30, 0.10 and 0.41 t C ha−1 year−1 for scenarios B, C and D, respectively. The system we developed in the present study, that is, linking the RothC model and soil spatial data, can be useful for estimating the potential C sequestration resulting from an increase in organic matter input to Japanese arable soils, although more feasible scenarios need to be developed to enable more realistic estimation. [ABSTRACT FROM AUTHOR]

To evaluate the carbon (C) sequestration function of grassland soils in Japan, soil C stocks were measured in 24 grasslands (3–43-year-old pastures) across 14 livestock farms nationwide. Soil C stocks varied among soil types, and the values in the upper 25 and 50 cm were higher in Andosols (mean, 12.4 and 19.3 kg m−2, respectively) than in Brown Forest soils (7.5 and 13.7 kg m−2) and other soil types (5.5 and 7.5 kg m−2). At the same time, C stocks varied among pastures within each soil type. Compared to data from the published work on the C content shortly after pasture establishment, aged pastures had decreasing C concentrations as the soil depth increased, suggesting substantial C accumulation in the top soil layers during pasture aging. This C accumulation caused grassland soils to store as much C as adjacent forest soils. Although the C stocks in the grassland soils were not statistically different from those in the adjacent native forest soils, some grassland areas stored greater amounts of C than the forests, indicating a possibility of increasing soil C stocks through improved grassland management. [ABSTRACT FROM AUTHOR]

Hydrogen and its energy carriers, such as liquid hydrogen (LH2), methylcyclohexane (MCH), and ammonia (NH3), are essential components of low-carbon energy systems. To utilize hydrogen energy, the complete environmental merits of its supply chain should be evaluated. To understand the expected environmental benefit under the uncertainty of hydrogen technology development, we conducted life-cycle inventory analysis and calculated CO2 emissions and their uncertainties attributed to the entire supply chain of hydrogen and NH3 power generation (co-firing and mono-firing) in Japan. Hydrogen was assumed to be produced from overseas renewable energy sources with LH2/MCH as the carrier, and NH3 from natural gas or renewable energy sources. The Japanese life-cycle inventory database was used to calculate emissions. Monte Carlo simulations were performed to evaluate emission uncertainty and mitigation factors using hydrogen energy. For LH2, CO2 emission uncertainty during hydrogen liquefaction can be reduced by using low-carbon fuel. For MCH, CO2 emissions were not significantly affected by power consumption of overseas processes; however, it can be reduced by implementing low-carbon fuel and waste-heat utilization during MCH dehydrogenation. Low-carbon NH3 production processes significantly affected power generation, whereas carbon capture and storage during NH3 production showed the greatest reduction in CO2 emission. In conclusion, reducing CO2 emissions during the production of hydrogen and NH3 is key to realize low-carbon hydrogen energy systems. [ABSTRACT FROM AUTHOR]

We attempted to obtain carbon sequestration maps of deciduous forests in Japan using detectable parameters from the Moderate Resolution Imaging Spectrometer (MODIS) sensor and to determine how the spatial pattern of carbon sequestration differs within the same forest ecosystem type. For this investigation, we firstly parameterized the MODIS algorithm at one flux tower site, Takayama, for the years 2002–2003. The MODIS algorithm could link flux-based net ecosystem productivity (NEP) with simple functions controlled by a thermal infrared band and a vegetation index. Second, the performance of the MODIS algorithm was validated through comparisons with the flux-based NEP at another flux tower site, Hitsujigaoka. The MODIS-based NEP at Hitsujigaoka was also within an accuracy of a flux-based NEP with R 2 of 0.879 and root mean square error of 1.64 gC m−2 day−1, regardless of canopy structure and age. The MODIS algorithm was noteworthy for its general applicability in different locations. Finally, we used the MODIS algorithm for the same forest ecosystem type in Japan for regional extrapolation of NEP. The MODIS-based NEP of deciduous forests in Japan showed great variance with 347 ± 288 gC m−2 year−1 in 2002, according to the stand structure and climatic condition of the year. Studies for quantification of ecosystem carbon balance need to consider variance, frequency and spatial distributions of NEP. Satellite remote sensing demonstrated the potential for the large-scale mapping of NEP. [ABSTRACT FROM AUTHOR]

The addition of biochar to the forest floor should facilitate efficient carbon sequestration. However, little is known about how biochar addition effects litter decomposition, which is related to carbon and nutrient dynamics in forest ecosystems. This study evaluated the effect of biochar addition on leaf litter decomposition in a forest ecosystem. To examine whether leaf litter decomposition was stimulated above and below biochar, litterbag experiments were carried out for about 3 years in a field site where biochar was added at the rate of 0, 5 and 10 t ha−¹ (C0, C5 and C10 plots) to the forest floor in a temperate oak forest, Japan. Biochar addition at C10 significantly enhanced litter decomposition below biochar for 2 years after treatment and above biochar for 1 year after treatment. Litter water content in biochar plots tended to increase under dry conditions. Biochar addition enhanced litter decomposition because of increased microbial activity with increased moisture content and accelerated the decomposition progress rather than changing the decomposition pattern. However, the carbon emission through changing leaf litter decomposition was small when compared with the carbon addition by biochar, indicating that biochar could be an effective material for carbon sequestration in forest ecosystems. [ABSTRACT FROM AUTHOR]