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The objective of this paper is to analyze the most up-to-date data available on total greenhouse-gas emissions of a LNG fuel supply chain and life-cycle of city gas 13A 1 based on surveys of the LNG projects delivering to Japan, which should provide useful basic-data for conducting life-cycle analyses of other product systems as well as future alternative energy systems, because of highly reliable data qualified in terms of its source and representativeness. In addition, the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 were also predicted, taking into account not only the improvement of technologies, but also the change of composition of LNG projects. As a result of this analysis, the total amount of greenhouse-gas emissions of the whole city-gas 13A chain at present was calculated to be 61.91 g-CO2/MJ, and the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 could be expected to decrease by about 1.1% of the current emissions.

The dispersion of input-coefficients in input–output (I–O) tables and the effect on LCA results are evaluated, utilizing the data for compiling the I–O tables. CO2 emission intensity and its variance with each commodity and service categorized in the I–O tables are estimated and applied to the LCA of a specific passenger car. Calculated results show that coefficients of variation (CV) of CO2-emission intensity are about 0.8 for the intermediate commodities which are frequently assessed in LCA. CO2 emissions induced by the production of the passenger car and the CV of the emissions are estimated at 1.3 Mg–C and 0.14, respectively. The value of CV is smaller than that of the most intermediate commodities since the CV of total emissions decreases as the number of components of the passenger car increases. Although emission intensity itself given by I–O tables has large variance, I–O tables are still useful tools for LCA if the number of components of a product is large enough.

Clean development mechanism (CDM) is expected to facilitate technology transfer from developed to developing countries and to reduce greenhouse gas emissions economically. This article evaluates a CDM project utilizing photovoltaic (PV) systems. For this purpose, we first estimated life cycle CO2 emissions of PV and other power generation systems based on an input-output table for environmental analysis. The cost of the PV systems was also evaluated, taking into consideration the effect of mass production. Next, two dynamic scenarios were developed to disseminate PV systems. One is a scenario only for domestic dissemination, and the other includes a CDM project utilizing PV systems as well as domestic dissemination. We then evaluated a net present value of the CDM as well as CO2 reductions in the dynamic scenarios. A net present value of the CDM project was estimated to be negative at 5% of the discount rate. At the same time, it was shown to be much higher at a lower discount rate and at higher prices of certified emission reduction by the CDM. Accordingly, we proposed new schemes to make the CDM viable. In particular, we discussed how to lower project risks with CDM.

An analysis was conducted on greenhouse gas emissions from the liquified natural gas (LNG) chain and life cycle of City Gas 13A [caloric value: 46 MJ/Nm3(11,000 kcal/Nm3)], which is produced from LNG. The analysis was based on highly reliable data which are qualified in terms of source and representativeness. Actually, the latest data for CO2 and CH4 emissions from the natural gas field and liquefaction plant were obtained from field studies. Moreover, the analysis includes CO2 emissions during the LNG transportation from exporting countries to Japan, city gas production and distribution stage in Japan and the manufacturing of facilities associated with the production of natural gas overseas to final domestic consumption. The reduction effect of CO2 using LNG cryogenic energy was also considered. The evaluation showed that the level of greenhouse gas emissions and energy consumptions in the modern natural gas production and liquefaction plants were lower than those previously reported due to improvements in the production process. The results of the analysis also provide basic data essential for conducting life cycle analyses in many fields using natural gas.

The clean development mechanism (CDM) is expected to facilitate technology transfer from developed to developing countries, as well as to economically reduce greenhouse gas emissions. This article aims at evaluating strategies in CDM, in which developing countries can improve industrial energy efficiency with financial support from developed countries. First, we investigated characteristics of the systems utilizing game theory. Analytical results revealed that technology transfer through the system might be considerably diminished, depending on the shapes of the marginal cost functions for reducing CO2. Next we estimated actual marginal cost curves of countries involved in CDM, in order to know the cost-effectiveness of CO2 reduction options. Input-output tables were utilized in this analysis, since these are established in developing countries as well as in developed countries. We have transformed one country’s input-output table to be adjusted against another country, taking the difference in goods prices into consideration. As far as data on the economy and industry are concerned, we used those from Japan and China, since China has been rapidly increasing its economic scale and greenhouse gas emissions. However, the implications from these analyses are useful also for other countries.

Degradation of the global environment and depletion of resources are threatening sustainable development of mankind. In particular, climate change caused by increasing greenhouse gases is one of the most serious issues in analyzing energy systems. This paper aims at proposing frameworks to investigate sustainability and at evaluating technologies for sustainable energy systems. For this purpose, we first define the index of sustainable limits on resource depletion and emissions. Sustainability of mineral and energy resources is evaluated based on the index. Estimations indicate that energy resources and CO2 are unsustainable, and that we should introduce technologies to reduce energy consumption and CO2 emissions. Life cycle energy requirements are assessed for photovoltaic systems as representatives of the technologies. Through the life cycle assessment, we quantitatively evaluate measures to improve life cycle energy requirements and capital costs. At the same time, we clarify the direction of research and development required for technologies to realize sustainable energy systems. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 25–31, 2000

This paper aims at clarifying key points for realizing sustainable energy supply under restrictions on resource and environment. For this purpose, we first developed a database to estimate life cycle efficiencies and greenhouse gas emissions for various energy systems. Then on the basis of this life cycle assessment, we quantitatively define the concept of ‘Sustainability Limitations’ on resource depletion and environmental emissions. From this concept, present world is judged to be unsustainable both from resource and environmental viewpoints. At the same time, we clarify how far present world is from Sustainability Limitations. Then we describe our mathematical model simulating global energy supply and demand in ultra-long term. In this model, the concept of Sustainability Limitations is utilized so as to impose economic incentives to make energy system shift to a sustainable one in long term. Sustainability limitations of resource depletion and CO2 emissions are taken into consideration. As energy resources, this model includes coal, oil, natural gas, other unconventional fossil fuels, uranium and renewable resources. As energy technologies, it includes major technologies of mining, transport, conversion and final utilization. Computed results have shown that present energy system, which is judged to be unsustainable, shifts to a sustainable system in the ultra-long term with appropriate incentives.

Depletion of the fossil fuels and climate change caused by the greenhouse effect is threatening the sustainable development of mankind. Since the CO 2 produced by burning fossil fuels is the dominant source of anthropogenic greenhouse gas emissions, CO 2 disposal is expected to be an effective option for mitigating climate change. However, if we took the option of CO 2 disposal and continued relying on fossil fuels, it could not be the sustainable use of energy resources. Therefore we need some theoretical framework for realizing the sustainable development. In this paper, we have developed a model to demonstrate the way of sustainable use of energy resources under constraints on CO 2 emissions. Computed results have shown that present energy system based on fossil fuels shifts to the system based on renewable resources in the ultra-long term with appropriate incentives. CO 2 disposal plays an important but a transitional role in this analysis.

Publisher Summary This chapter evaluates the potential for reducing fluorocarbon emissions as a measure for the abatement of global warming by enforcing new laws: the Law for Recycling of Specified Kinds of Home Appliances and the Law for Recovering and Decomposing of Specific Fluorocarbons. The chapter focuses on the three different kinds of fluorocarbons: CFCs, HCFCs, and HFCs, and targets refrigerant use because of the availability of relevant data. The Kyoto Protocol regulated the emissions of six types of greenhouse gases (GHGs): CO2, CH4, N2O, hydrofluorocarbons (HFCs), sulphur hexafluoride (SF6), and perfluorocarbons (PFCs). Under the protocol, Japan committed a 6% reduction from the level of equivalent CO2 emissions in 1990. However, it is a difficult task for Japan to achieve this reduction target by reducing the energy-related CO2 emissions, as its energy efficiency has already reached the world's highest level. Therefore, by considering the large effects on global warming caused by fluorinated GHGs, measures for reducing emissions of non-CO2 GHGs can be regarded as one of the important strategies to comply with the Kyoto Protocol. The restrictions for emissions of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have been omitted in the Kyoto Protocol, because CFCs and HCFCs have already been regulated as ozone depleting substances (ODSs) under the Montreal Protocol.

This paper aims at evaluating technologies to realise a sustainable energy system within the constraints of resources and environment. For this purpose, we first developed a database to estimate life cycle efficiencies and greenhouse gas emissions for various energy technologies. Then, on the basis of this life cycle assessment, we quantitatively define the concept of sustainability limitations on resource depletion and environmental emissions. From this concept, the present energy system of the world is judged to be unsustainable from both resource and environmental viewpoints. Then, various mitigation measures such as disposal of CO2 and solar power generation are evaluated utilising the concept. The evaluated result showed how sustainability influences cost–effectiveness of the measures. At the same time we clarified the key points to realise a sustainable energy scenario in ultra–long term.