Tomohiro Tabata

Life cycle assessment of integrated municipal solid waste management systems, taking account of climate change and landfill shortage trade-off problems

Steps taken to counter the climate change problem have a significant impact on the municipal solid waste management (MSW) sector, which must tackle regional environmental problems such as the shortage of sanitary landfills, especially in Japan. Moreover, greenhouse gas emissions and final disposal have a trade-off relationship. Therefore, alleviation of both these environmental problems is difficult, and Japanese local municipalities are anxious for action to solve these problems and reduce treatment costs. Although ambitious waste management measures have been enacted in many countries, they appear to lack a holistic view and do not adopt a life cycle approach. Therefore, it is important to reconstruct the MSW management system, taking into account environmental and economic aspects. In the present study, life cycle assessment and mathematical modelling were used to seek ways of redesigning the MSW management system in order to minimize environmental impacts and/or reduce treatment costs. One economic block was selected as the study area (Iwate Prefecture in Japan). The life cycle inventory and costs data for every MSW transportation and treatment process in this region were collected and processed. Then, taking account of geographic information, an optimal solution for the minimization of environmental impact or treatment costs was derived. To solve the trade-off problem, a sensitivity analysis was conducted to find optimal reduction targets for climate change and final disposal.

Waste-to-energy incineration plants as greenhouse gas reducers: A case study of seven Japanese metropolises

Municipal solid waste (MSW) incineration is a greenhouse gas (GHG) emitter; however, if GHG reductions, achieved by accounting for waste-to-energy, exceed GHG emissions, incineration can be considered as a net GHG reducer. In Japan, only 24.5% of MSW incineration plants perform energy recovery despite 80% of MSW being incinerated; therefore, there is great potential to extract more energy from MSW. In this study, the factors that should be considered to achieve net GHG reductions from incineration were analysed from a life cycle perspective. These considerations were then applied to the energy supply requirements in seven Japanese metropolises. Firstly, the carbon footprints of approximately 1500 incineration plants in Japan were calculated. Then, the incineration plants with negative carbon footprint values were classified as net GHG reducers. Next, the processes that contribute to the carbon footprint were evaluated, and two processes—plastic burning and electricity savings—were found to have the greatest influence. Based on the results, the energy supply requirements were analysed and discussed for seven metropolises (Sapporo, Tokyo, Nagoya, Osaka, Kobe, Takamatsu and Fukuoka) taking into account the energy demands of households. In Kobe, 16.2% of the electricity demand and 25.0% of the hot water demand could be satisfied by incineration to realise a net GHG reducer, although urban design for energy utilisation would be required.

Environmental and economic evaluation of pre-disaster plans for disaster waste management: Case study of Minami-Ise, Japan.

Although it is important that disaster waste be demolished and removed as soon as possible after a natural disaster, it is also important that its treatment is environmentally friendly and economic. Local municipalities do not conduct environmental and economic feasibility studies of pre-disaster waste management; nevertheless, pre-disaster waste management is extremely important to promote treatment of waste after natural disasters. One of the reasons that they cannot conduct such evaluations is that the methods and inventory data required for the environmental and economic evaluation does not exist. In this study, we created the inventory data needed for evaluation and constructed evaluation methods using life cycle assessment (LCA) and life cycle cost (LCC) methodologies for future natural disasters. We selected the Japanese town of Minami-Ise for the related case study. Firstly, we estimated that the potential disaster waste generation derived from dwellings would be approximately 554,000t. Based on this result, the land area required for all the temporary storage sites for storing the disaster waste was approximately 55ha. Although the public domain and private land area in this case study is sufficient, several sites would be necessary to transport waste to other sites with enough space because local space is scarce. Next, we created inventory data of each process such as waste transportation, operation of the temporary storage sites, and waste treatment. We evaluated the environmental burden and cost for scenarios in which the disaster waste derived from specified kinds of home appliances (refrigerators, washing machines, air-conditioners and TV sets) was transported, stored and recycled. In the scenario, CO2, SOx, NOX and PM emissions and total cost were 142t, 7kg, 257kg, 38kg and 1772 thousand USD, respectively. We also focused on SOx emission as a regional pollution source because transportation and operation of the temporary storage sites generates air pollution. If the treatment of all waste were finished in 3years, the environmental standard would be satisfied by setting work duration to 4.8h/d.

Life cycle assessment and life cycle costs for pre-disaster waste management systems

This study develops a method of environmental and economic evaluation of an integrated disaster waste management system that considers the spatial scale of removal, transport, and treatment of disaster waste. A case study was conducted on combustibles, which is a type of disaster waste derived from dwellings, in Mie Prefecture, Japan. First, we calculated the quantity and the spatial distribution of disaster waste derived from dwellings and tsunami debris produced as a result of a large-scale earthquake. The quantity of disaster waste was estimated as 7,178,000t with functioning flood-preventing facilities and 11,956,000t without functioning flood prevention facilities. Ensuring resilience in the face of earthquakes and tsunamis by renovating flood-preventing facilities is extremely important in decreasing the production of wastes, especially in coastal regions. Next, the transportation network for transporting combustibles in disaster waste to temporary storage sites, incineration plants, and landfill was constructed using an optimization model. The results showed that if flood-preventing facilities do not function properly, the installation of temporary incineration facilities becomes essential. Life-cycle emissions of CO2, SOx, NOx, and PM and the costs of removal, storage, and treatment of combustibles were calculated as 258,000t, 618t, 1705t, 7.9t, and 246millionUSD, respectively, in the case of functioning flood-preventing facilities. If flood-preventing facilities do not function, the quantity of environmentally unfriendly emissions and the costs increase. This result suggested the significance of renovation in order to maintain the conditions of flood-preventing facilities to decrease the environmental burden and costs as well as keep the production of disaster waste at a minimum.

Heat supply from municipal solid waste incineration plants in Japan: Current situation and future challenges.

The use of waste-to-energy technology as part of a municipal solid waste management strategy could reduce the use of fossil fuels and contribute to prevention of global warming. In this study, we examined current heat and electricity production by incineration plants in Japan for external use. Herein, we discuss specific challenges to the promotion of heat utilisation and future municipal solid waste management strategies. We conducted a questionnaire survey to determine the actual conditions of heat production by incineration plants. From the survey results, information of about 498 incineration plants was extracted. When we investigated the relationship between heat production for external use and population density where incineration plants were located, we found that regions with a population density <1000 persons (km2)-1 produce <500 MJ t-1 of heat. We also found that external use of such energy for factories, markets, and related use, was noted in cities with a population density of 2000 to 4000 persons (km2)-1. Several incineration plants have poor performance for heat production because there are few facilities near them to provide demand for the energy. This is the result of redundant capacity, and is reflected in the heat production performance. Given these results, we discussed future challenges to creating energy demand around incineration plants where there is presently none. We also examined the challenges involved in increasing heat supply beyond the present situation.

Using a Rebound Matrix to Estimate Consumption Changes from Saving and its Environmental Impact in Japan

We investigate the extent to which Japanese people can change their consumption and the corresponding environmental impact. We propose a new analytical framework with a rebound matrix that captures the monetary flow from potential savings to their respending (referred to as rebound). A questionnaire is used to derive the matrix. On average, respondents spent 3.4 million Yen annually, resulting in 12.4 tons of carbon dioxide (CO) emissions in their daily lives. The survey results suggest that acceptable spending reductions would correspond to a CO emissions reduction of nearly 6%. However, the CO emissions would increase by nearly the same amount when the respondents respend their savable money (rebound CO emissions). The annual CO emissions and the annually reducible CO emissions both increase with the increase in annual expenditure. Consequently, the net CO emissions also increase with the increase in annual expenditure. The rebound spending is approximated using the rebound matrix. Finally, it is suggested that the net CO emissions can be reduced through lifestyle changes whereby spending on energy items is reduced and the resulting savings are spent on telecommunication, clothes, shoes, education, and housing.

Environmental Impacts of Utilizing Woody Biomass for Energy: A Case Study in Japan

Abstract The first part of this chapter provides information about current and potential uses of woody biomass for energy in Japan, using country reports. Also included is a discussion of various challenges Japan faces in promoting woody biomass energy utilization since the Great East Japan Earthquake in 2011. The second part of this chapter provides information about the environmental impacts of utilizing woody biomass for energy by conducting a life cycle assessment (LCA). The steps used for the LCA were the following: (1) identify current and potential spatial distributions of woody biomass using geographic information systems; (2) make an inventory of data collected from the various life cycle stages, such as tree trimming, transportation, and energy production; and (3) calculate the environmental impacts, particularly greenhouse gas emissions. These are then followed by the results from the LCA using a case study of coal cocombustion with woody biomass in Japan.