明石 修

This study analyzes the potential to reduce air pollutants while achieving the 2 degrees C global temperature change limit target above pre-industrial levels, by using the bottom-up optimization model, AIM/Enduse [Global]. This study focuses on; 1) estimating mitigation potentials and costs for achieving 2 degrees C, 2.5 degrees C, and 3 degrees C target scenarios, 2) assessing co-benefits of reducing air pollutants such as NOx, SO2, BC, PM, and 3) analyzing features of sectoral attributions in Annex land Non-Annex I groups of countries. The carbon tax scenario at 50 US$/tCO(2)-eq in 2050 can reduce GHG emissions more than the 3 degrees C target scenario, but a higher carbon price around 400 US$/tCO(2)-eq in 2050 is required to achieve the 2 degrees C target scenario. However, there is also a co-benefit of large reduction potential of air pollutants, in the range of 60-80% reductions in 2050 from the reference scenario while achieving the 2 degrees C target. (C) 2014 Elsevier Ltd. All rights reserved.

Energy efficiency is one of the main options for mitigating climate change. An accurate representation of various mechanisms of energy efficiency is vital for the assessment of its realistic potential. Results of a questionnaire show that the EMF27 models collectively represent known channels of energy efficiency reasonably well, addressing issues of energy efficiency barriers and rebound effects. The majority of models, including general equilibrium models, have an explicit end-use representation for the transportation sector. All participating partial equilibrium models have some capability of reflecting the actual market behavior of consumers and firms. The EMF27 results show that energy intensity declines faster under climate policy than under a baseline scenario. With a climate policy roughly consistent with a global warming of two degrees, the median annual improvement rate of energy intensity for 2010-2030 reaches 2.3 % per year [with a full model range of 1.3-2.9 %/yr], much faster than the historical rate of 1.3 % per year. The improvement rate increases further if technology is constrained. The results suggest that the target of the United Nations' "Sustainable Energy for All" initiative is consistent with the 2-degree climate change target, as long as there are no technology constraints. The rate of energy intensity decline varies significantly across models, with larger variations at the regional and sectoral levels. Decomposition of the transportation sector down to a service level for a subset of models reveals that to achieve energy efficiency, a general equilibrium model tends to reduce service demands while partial equilibrium models favor technical substitution.

In this paper, we assessed the technological feasibility and economic viability of the mid-term (until 2050) GHG emission reduction target required for stabilization of radiative forcing at 2.6 W/m2. Given the apparent uncertainty surrounding the future deployment of nuclear and CCS technologies, we intensively investigated emission reduction scenarios without nuclear and CCS. The analysis using AIM/Enduse[Global] shows the emission reduction target is technologically feasible, but the cost for achieving the target becomes very high if nuclear and CCS options are limited. The main reason for the cost rise is that additional investment for expensive technologies is required in order to compensate for emission increases in the steel, cement and power generation sectors in the absence of CCS. On the other hand, if material efficiency improvement measures, such as material substitution, efficient use of materials and recycling, are taken, the cost of achieving the emission reduction target is significantly reduced. The result indicates the potentially important role of material efficiency improvement in curbing the cost of significant GHG emission reductions without depending on nuclear and CCS.

The feasibility of two low-carbon society (LCS) scenarios, one with and one without nuclear power and carbon capture and storage (CCS), is evaluated using the AIM/Enduse[Global] model. Both scenarios suggest that achieving a 50% emissions reduction target (relative to 1990 levels) by 2050 is technically feasible if locally suited technologies are introduced and the relevant policies, including necessary financial transfers, are appropriately implemented. In the scenario that includes nuclear and CCS options, it will be vital to consider the risks and acceptance of these technologies. In the scenario without these technologies, the challenge will be how to reduce energy service demand. In both scenarios, the estimated investment costs will be higher in non-Annex I countries than in Annex I countries. Finally, the enhancement of capacity building to support the deployment of locally suited technologies will be central to achieving an LCS. Policy relevance Policies to reduce GHG emissions up to 2050 are critical if the long-term target of stabilizing the climate is to be achieved. From a policy perspective, the cost and social acceptability of the policy used to reduce emissions are two of the key factors in determining the optimal pathways to achieve this. However, the nuclear accident at Fukushima highlighted the risk of depending on large-scale technologies for the provision of energy and has led to a backlash against the use of nuclear technology. It is found that if nuclear and CCS are used it will be technically feasible to halve GHG emissions by 2050, although very costly. However, although the cost of halving emissions will be about the same if neither nuclear nor CCS is used, a 50% reduction in emissions reduction will not be achievable unless the demand for energy service is substantially reduced.

Every possible technology is pursued in order to achieve strict radiative forcing targets. Nuclear energy and Carbon Capture Storage (CCS) are regarded as important mitigation options. However, harsh criticisms have been directed at Japanese nuclear energy policy after the Fukushima nuclear accident, and the Japanese government will be required to re-evaluate not only its energy policy, but also the GHG reduction target itself. Like nuclear energy, CCS might not be regarded as a suitable option for GHG mitigation because its long-term safety has not been revealed. In this paper we analyze the energy policy response to an absence of nuclear energy and CCS, especially focusing on Japan, China and India. We find that the appropriate energy strategies against the unproven technologies differ between regions due to the uneven pre-existing nuclear energy, CCS potential and renewable energy potential, and the resource endowments and the levels of economic development. We also find that the strict mitigation target can be achieved even if nuclear energy and CCS are not available. In such a case, however, significant enhancement of renewable energy is needed, as well as particular fossil fuel alternatives based on region-specific availabilities and costs. (C) 2012 Elsevier B.V. All rights reserved.

In this paper, we explore GHG emission scenarios up to 2050 in Asia and the world as part of the Asian Modeling Exercise and assess technology options for meeting a 2.6 W/m(2) radiative forcing target using AIM/Enduse[Global] and AIM/Impact[Policy]. Global GHG emissions in 2050 are required to be reduced by 72% relative to a reference scenario, which corresponds to a 57% reduction from the 2005 level, in order to meet the above target. Energy intensity improvement contributes a lot to curbing CO2 emission in the short-term. Meanwhile, carbon intensity reduction and CO2 capture play a large role for further emission reduction in the mid to long-term. The top five key technologies in terms of reduction amount are CCS, solar power generation, wind power generation, biomass power generation and biofuel, which, in total, account for about 60% of global GHG emissions reduction in 2050. We implement additional model runs, each of which enforced limited availability of one of the key technology. The result shows that the 2.6 W/m(2) target up to 2050 is achievable even if availability of any one of the key technologies is limited to half the level achieved in the default simulation. However, if the use of CCS or biomass is limited, the cumulative GHG abatement cost until 2050 increases considerably. Therefore CCS and biomass have a vital role in curbing costs to achieve significant emission reductions. (C) 2012 Elsevier B.V. All rights reserved.

In this article we examine the technological feasibility of the global target of reducing GHG emissions to 50 % of the 1990 level by the year 2050. We also perform a detailed analysis of the contribution of low-carbon technologies to GHG emission reduction over mid- and long-term timeframes, and evaluate the required technological cost. For the analysis we use AIM/Enduse[Global], a techno-economic model for climate change mitigation policy assessment. The results show that a 50 % GHG emission reduction target is technically achievable. Yet achieving the target will require substantial emission mitigation efforts. The GHG emission reduction rate from the reference scenario stands at 23 % in 2020 and 73 % in 2050. The marginal abatement cost to achieve these emission reductions reaches $150/tCO(2)-eq in 2020 and $600/tCO(2)-eq in 2050. Renewable energy, fuel switching, and efficiency improvement in power generation account for 45 % of the total GHG emission reduction in 2020. Non-energy sectors, namely, fugitive emission, waste management, agriculture, and F-gases, account for 25 % of the total GHG emission reduction in 2020. CCS, solar power generation, wind power generation, biomass power generation, and biofuel together account for 64 % of the total GHG emission reduction in 2050. Additional investment in GHG abatement technologies for achieving the target reaches US$ 6.0 trillion by 2020 and US$ 73 trillion by 2050. This corresponds to 0.7 and 1.8 % of the world GDP, respectively, in the same periods. Non-Annex I regions account for 55 % of the total additional investment by 2050. In a sectoral breakdown, the power generation and transport sectors account for 56 and 30 % of the total additional investment by 2050, respectively.

In this study, we simulate global CO2 emissials and their reduction potentials in the industrial sector up to the year 2030. Future industrial CO2 emissions depend on changes in both technology and industrial activity. However, earlier bottom-up analyses mainly focused on technology change. In this study, we estimate changes in both technology and industrial activity. We developed a three-part simulation system. The first part is a macro economic model that simulates macro economic indicators, such as GDP and value added by sector. The second part consists of industrial production models that simulate future steel and cement production. The third part is a bottom-up type technology model that estimates future CO2 emissions. Assuming no changes in technology since 2005, we estimate that global CO2 emissions in 2030 increase by 15 GtCO(2) from 2005 level. This increase is due to growth in industrial production. Introducing technological reduction options within 100 US$/tCO(2) provides a reduction potential of 5.3 GtCO(2) compared to the case of no technology changes. As a result, even with large technological reduction potential, global industrial CO2 emissions in 2030 are estimated to be higher as compared to 2005 level because of growth of industrial production. (C) 2010 Elsevier Ltd. All rights reserved.

本研究では, 全世界の鉄鋼部門を対象に特別な対策を行わない場合の2050年までのCO₂排出量を推計した. はじめに, マクロ経済モデルおよび国内・国際の市場の均衡を考慮した国際分業モデルにより各国の生産量を推計し, その後, 技術積み上げ型CO₂排出量推計モデルを用いてCO₂排出量を推計した. 結果, 2050年には世界全体の鉄鋼生産量は2324Mtonとなり, CO₂排出量は, 2000年比2044MtCO2増加の3717MtCO₂となると推計された. このとき, 既存技術の導入による排出量削減量 (技術固定ケースからの排出削減量) は1360MtCO₂となることが示された. また2000年-2050年における世界の排出増加量2044MtCO₂の内, 中国・インド両国における排出増加量は75%を占めることが示された.

本研究の目的は, 都市旅客交通からのCO, NO_x, PM, CO₂排出を対象に, 環境負荷量と都市構造との関連に関する都市横断的知見を得ることである. まず, 世界の都市において環境負荷量が異なる要因を解析した. 結果, すべての物質について, 交通量が環境負荷量の都市間差異を最も説明することが示された. 続いて, 交通需要量を人口密度, 都市面積等の変数を用いて説明する交通需要モデルを構築した. 交通需要モデルおよび排出係数モデルを用いた感度分析の結果, 人口密度を20%増加させた場合, 面積あたりNO_x排出量は6.2%～25.8%増加し, 一人あたりCO₂排出量は3.1%～11.3%減少することが示された. 一人あたりCO₂排出量減少率は, 乗用車トリップ分担率が60%程度の都市で大きいことが示された.

Reducing CO₂ emissions is one of the biggest environmental issues which is captivating international concern. CO₂ emissions from transportation sector are increasing in both developed and developing countries. In this research we focused on four countries in Asia such as Japan, China, India and Thailand which are thought to be on the various stage of economical development. We conduct long-term projection on CO₂ emissions from transportation sector for those four countries. For the first step, we estimate transportation demand for each country using passenger transportation demand model and freight transportation demand model. Passenger transportation demand model reflects time use constraint which is the limitation of time spends to transportation activity of one person in one day. Freight transportation demand model is a simple model which estimates future value using current trends. Second, we estimate the CO₂ emission using bottom-up type model. This model describes technology choice using linear programming method. As a result, we could conduct long-term projection on CO₂ emissions from transportation sector for each country in the different socio-economical situation.