Yasunari Matsuno

Integration of Life Cycle assessment and population balance model for assessing environmental impacts of product population in a social scale case studies for the global warming potential of air conditioners in Japan

ScopeIn this study, a dynamic model was built in which LCA and PBM were integrated to quantitatively assess the total environmental impacts induced by the product population in a society over time. Specifically, a determination was carried out concerning how Japan’s air conditioner population is used (lifetime distribution, number of units, etc.) and an assessment was made concerning the Global Warming Potential (GWP) associated with the air conditioner population.MethodsThe proposed dynamic model was applied to air conditioners for analyzing the total GWP caused by the air conditioner population in Japan from 1990 to 2010. To create a trend forecast model for future environmental load, scenarios for air conditioner production up to 2010 were formulated and the total GWP from the air conditioner population was predicted. Conducted also were sensitivity analyses whose parameters were air conditioner performance, lifetime and the rate of refrigerant recovery when retired units are processed.Results and DiscussionApplying the PBM to the air conditioner population in 2000, it was found that 81.5 million units consumed 5.94 x 10p10 kWh in that year, which was a 6.1 % increase in the total annual power consumption in 1990. In both a stationary scenario and a steady growth (1.5% annual increase), it was found that the total GWP would be 27.7% higher than in 1990 under the stationary scenario and 37.8% higher under the steady growth scenario. The improvements in air conditioner performance will have a small effect on reducing the total GWP from that population. Furthermore, in connection with the average lifetime, it was found that the GWP, due to refrigerant releases when units are disposed of, would be relatively large in 2000 and the following years.ConclusionsThus, shorter product lifetimes will spur a replacement of air conditioners with new units, a situation that will only lead to the reduction of GWP if the recovery rate of refrigerant is to be achieved to more than 50% under the stationary scenario.Recommendations and OutlookTo meet COP3 targets for Japan in 2010 (i.e. to reach the same level as in 1990 for household appliances), our study shows that it will be vital to raise the refrigerant recovery rate. If the number of air conditioners in use remains unchanged, recovery would have to be 45.7%, but under the steady growth scenario it would have to be at least 60.4%. Therefore, it will be difficult to meet COP3 targets unless the refrigerant recovery rate is strongly increased. This method is applicable to assess not only the GWP of air conditioners, but also other environmental impacts caused by a variety of product populations, which will be quite effective for setting targets of products’ performance, policymaking, etc.

Development of life cycle inventories for electricity grid mixes in Japan

Since most industrial processes consume electricity, it is quite important to develop reliable inventory data for electricity. There is, however, a problem that only a few figures concerning emissions related to electricity have been reported. In this work, process models of power plants were developed for the Japanese situation which simulate the mass flows and estimate the missing figures of emissions dependent on technical parameters of the plants and fuels. In Japan, electricity is supplied to the various regions by 10 electric companies. Therefore, life cycle inventories for the electricity grid mixes of the 10 electric companies in 1997 were developed. The functional unit is 1 kWh of electricity distributed to electricity users in each region. The emission of CO2, SO2, NOk, CH4, CO, non-methane volatile organic compound (NMVOC), dust (all particulates) and heavy metals (Ni, V, As, Cd, Cr, Hg, Pb, Zn) from power stations as well as those from fuel production and transport were investigated. Other pollutants into air, emissions to water, solid wastes, radiation and radioactive emissions from atomic power stations were not included due to a limitation of the available data. Direct CO2 emissions related to 1 kWh of electricity distributed by companies ranged from 0.21 to 1.0 kg/kWh (average value: 0.38 kg/kWh). Direct emissions of SO2 and NOx from power stations related to 1 kWh of electricity are 2.5* 10-4 and 2.2* 10-4 kg/kWh on the average, respectively. SO2 emissions calculated in this work were somehow large compared with those reported by electric companies. Detailed information concerning total sulfur content in oil consumed in each oil-fired power station are required for an exact calculation of SO2 emissions from oil-fired power stations. In addition, the ratio of sulfur that goes into slag in combustion must be investigated further. The average amounts of CO, CH4, NMVOC and dust emissions were 5.0*10-5, 8.2*10-6, 1.8*10-5 and 6.8 * 10-6 kg/kWh, respectively. Heavy metal emissions from power stations were on the order of 10-9 to 10-8 kg/kWh. Detailed information concerning heavy metal content in oil and coals consumed in fossil fuel power stations are further required for an improved assessment of heavy metal emissions. Contribution of fuel production and transport to total CO2 emission was relatively small. On the other hand, contributions of fuel production and transport to total SO2 and NOx emissions were relatively large. In the case of CO, NMVOC and dust, emissions in fuel production and transport were predominant to total emissions. Heavy metal emissions into air during production and transport of fuels were on the order of 10/-8 to 10-9 kg/kWh.

Modeling In-Use Steel Stock in China’s Buildings and Civil Engineering Infrastructure Using Time-Series of DMSP/OLS Nighttime Lights

Abstract: China’s rapid urbanization has led to increasing steel consumption for buildings and civil engineering infrastructure. The in-use steel stock in the same is considered to be closely related to social welfare and urban metabolism. Traditional approaches for determining the in-use steel stock are labor-intensive and time-consuming processes and always hindered by the availability of statistical data. To address this issue, this study proposed the use of long-term nighttime lights as a proxy to effectively estimate in-use steel stock for buildings (IUSSB) and civil engineering infrastructure (IUSSCE) at the provincial level in China. Significant relationships between nighttime lights versus IUSSB and IUSSCE were observed for provincial variables in a single year, as well as for time series variables of a single province. However, these relationships were found to differ among provinces (referred to as ―inter-individual differences‖) and with time (referred to as ―temporal differences‖). Panel regression models were therefore proposed to estimate IUSSB and IUSSCE in consideration of the temporal and inter-individual differences based on a dataset covering 1992–2007. These models were validated using data for 2008, and the results showed good estimation for both IUSSB and IUSSCE. The proposed approach

Exploring and estimating in-use steel stocks in civil engineering and buildings from night-time lights

Steel is the most widely used metal in the world, and numerous studies have investigated its stock and flow. Two basic methods for analysing material flow and accounting for stock are the top-down and bottom-up approaches. Their applicability, however, largely depends on data availability. To overcome this limitation, we have contemplated using satellite imagery as a proxy for missing data. In a previous study, we confirmed the correlation between night-time light radiance and civil engineering/building in-use steel stocks in Japan. In this study, the scope of the investigation was expanded to a global scale, examining correlations in different regions of the world. We found that night-time light radiance and in-use steel stocks have region-specific linear correlations, which are influenced by construction styles, which in turn depend on climate, seismic activity, cultural preferences, etc. The results were then applied to countries in the various regions whose in-use steel stocks were previously unreported. This technique produced an estimate of the global civil engineering/building in-use steel stock of around 9 × 109 tonnes (9 Gt), with 1.24 Gt being previously unreported. As a further step, this study shows the spatial distribution of civil engineering/building in-use steel stock in each region.

Current status of weighting methodologies in Japan

In Japan, requirements for the development of valuation methodology are very stringent. Several methodologies have been proposed to meet these demands in recent years. These methods, however, are quite different in many points such as selected impact categories, the numbers of substances considered, and basic concepts for the environment. The results of LCA are fully dependent on the goals of LCA practitioners and commissioners. If they misunderstand the concept of method and use it, the result may not fit for the purpose. Consequently, it is important to characterize the methods selected by the practitioner in accordance with their LCA goals. In this paper, weighting methodologies proposed in Japan have been introduced with a comparison between the results of case studies for common industrial products. Furthermore, we considered the present situations and future directions of valuation methodologies in Japan. This consideration is carried out based on the results of investigations performed by the Impact Assessment Committee of the National LCA Project of Japan

Characteristics of three-phase fluidized-bed electrodes for an alkaline fuel cell cathode

Abstract The characteristics of three-phase fluidized-bed electrodes have been studied in an alkaline fuel cell cathode of 51 mm i.d. and 300 mm height at 333 K. Raney silver particles of 0.6 mm diameter and sintered silver particles 1–3 mm in diameter were employed as the working electrode in the three-phase fluidized bed with a nickel perforated plate used as a current collector. Both oxygen gas and electrolyte (25 wt% potassium hydroxide solution) were fed into the working electrode at velocities of 2.9–12 and 2.9–14.5 mm/s, respectively. For polarization below 120 mV, activation polarization was predominant, giving a single steady-state polarization curve independent of both gas and liquid velocities. Above 120 mV, the polarization decreased with the increase in both gas and liquid velocities. A homogeneous potential distribution in the bed of electrode particles was observed except for the region near the current collector.

Elementary analysis of mobile phones for optimizing end-of-life scenarios

The metals contained in various mobile phones were analyzed. More than 20 elements were detected and their net amounts were found to increase year by year. The environmental and economic impacts were assessed based on an elemental analysis. The CO2 emissions generated by the incineration of plastics were estimated to be almost the same as those avoided by recovering the metals. Gold had the biggest economic impact. However, the amount of gold is decreasing and an eco-design for improved recycling is an urgent problem.

Improvement in electrode performance of three-phase fluidized-bed electrodes for an alkaline fuel cell cathode

An improvement in electrode performance of a three-phase fluidized-bed electrode for an alkaline fuel cell cathode has been carried out in a 51 mm i.d., 300 mm high half-cell at 333 K. Platinum-coated Raney silver particles of 0.6 mm diameter were employed as the working electrode in the three-phase fluidized-bed electrode. A dimpled nickel plate current collector was used to reduce the electrical resistance between the current collector and the electrode particles. A significant improvement in electrode performance was achieved for the platinum-coated Raney silver particle system with the dimpled current collector, where the polarization resulted mainly from diffusion resistance.

Analysis of the potential for a comprehensive approach towards LCA and EMS in Japan

Sustainable development can only be achieved if industry adoptsboth product related and organisation related environmental management tools, such as Life Cycle Assessment (LCA) and Environmental Management Systems (EMS). In Japan, EMS (ISO 14001) is more widely applied than LCA (ISO 14040). Therefore,one means by which Japanese industries could be motivated to adopt and use LCA is to relate LCA-activities to the policies and instruments of ISO 14001. The potential of such a comprehensive approach was analysed by a survey of 270 Japanese enterprises (response rate 45%). The results indicate that 19% of the responding representatives had responsibilities for both LCA and EMS, while the remaining only work in one of both fields. A statement in the company’s/ plant’s Environmental Policy of ISO 14001, stating that LCA is to be used as part of the EMS, was found in 42% of all companies. A surprising number (39%) either already use, or plan to use, LCA and EMS as combinated/integrated tools. A strong argument for the establishment of a comprehensive approach can be seen in the perception of the usefulness of LCA, which was rated significantly higher in companies that acknowledged the complementary potential of LCA and EMS.

Electrode performance of fixed and fluidized bed electrodes for a molten carbonate fuel cell anode

Abstract The electrode performance of molten carbonate fuel cell (MCFC) anodes using three-dimensional electrodes has been studied to validate the potential of such electrodes for MCFC systems. Polarization characteristics of three-dimensional electrodes have been investigated experimentally in a half cell of 42 mm i.d. and 500 mm height with an air/CO2/gold reference electrode at 923 K. In the fixed-bed electrode, polarization consisted of mainly diffusion polarization. In the fluidized-bed electrode, there was less diffusion polarization by virtue of the high mass-transfer rate. A one-dimensional model was used to analyze the effective resistance of the particle phase, ϱm, in the three-dimensional electrodes. The effective resistance of the particle phase in the fluidized-bed electrode was found to be three to four times larger than that of the fixed-bed electrode. It was found that the electrode performance of three-dimensional electrodes was competitive with that of porous gas diffusion electrodes.