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11. Efficient energy recovery through a combination of waste-to-energy systems for a low-carbon city

Author

Makoto Ohata, Minoru Fujii, Satoshi Ohnishi, Tsuyoshi Fujita, and Inaba Rokuta

Subjects
Economics and Econometrics, Energy recovery, Engineering, Municipal solid waste, Mobile incinerator, Waste management, business.industry, 020209 energy, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, Incineration, Waste-to-energy, Waste treatment, 0202 electrical engineering, electronic engineering, information engineering, Cleaner production, business, Waste Management and Disposal, Refuse-derived fuel, 0105 earth and related environmental sciences
Abstract

Innovative and efficient use of municipal solid waste as a source of energy is an important way to promote the transition to low-carbon cities. One key strategy to improve energy efficiency is to create a network of multiple sectors that can produce and utilize energy from waste. This mechanism has already been adopted at the urban scale in several developed countries as a way to enhance environmental efficiency and reduce adverse impacts. However, to use waste efficiently, it is necessary to examine the supply chain of wastes as a source of materials with potential to generate energy. Such an examination can inform the design of an efficient waste-to-energy process that will create a symbiosis between industry and the waste management sector. In this paper, we describe a model that evaluates energy recovery efficiency by considering the costs and benefits of an innovative waste-to-energy system. In the model, we also consider the material and energy flow of wastes in accordance with the quantity and quality of waste emissions, the separation system, treatment technologies and combinations thereof, and energy recovery and use in other sectors. The scenario was designed by identifying waste management options, including waste quantity/quality; the separation system; the treatment technology model for wet or dry methane fermentation; incineration; a combined system that involves superheating with exchanging heat between the incineration plant and fermenter; and use of refuse paper and plastic fuel (RPF). The results revealed that energy recovery efficiency was most dependent on the effective use of RPF with a relatively high lower heating value and superheating of boiler steam by methane gas in the combined system. An important conclusion was that the most efficient system was a combined system in which paper, plastic, and RPF were separated from 80% of the waste, and 20% of the waste was incinerated and used for wet methane fermentation. The amounts of energy recovered from that system was 54.5 kWh/t, and the efficiency was 33.4%. Analytical results indicated that it is possible to create the critical technology and to develop policy insights needed to make efficient waste management systems for the transition to low-carbon cities.

Published
2018

20. Conference Report on the 9th International Conference on EcoBalance (EcoBalance2010) (Detail report)

Author

NANSAI, Keisuke, primary, KUDOH, Yuki, additional, HONDO, Hiroki, additional, HAYASHI, Kiyotada, additional, MATSUBAE, Kazuyo, additional, NAKAJIMA, Kenichi, additional, MURAKAMI, Shinsuke, additional, MOTOSHITA, Masaharu, additional, HASHIMOTO, Seiji, additional, HARA, Minako, additional, NAKAJIMA, Michiyasu, additional, INABA, Rokuta, additional, MATSUNO, Yasunari, additional, and SHINOHARA, Yoshikazu, additional

Published
2011
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41. Hybrid life-cycle assessment (LCA) of CO2 emission with management alternatives for household food wastes in Japan.

Author

Inaba, Rokuta, Nansai, Keisuke, Fujii, Minoru, and Hashimoto, Seiji

Subjects
SOLID waste, SENSITIVITY analysis, WASTE management, INCINERATION
Abstract

In this study, we conducted a hybrid life-cycle assessment (LCA) to evaluate reductions in CO2 emissions by food waste biogasification of household food wastes in Japan. Two alternative scenarios were examined. In one alternative (Ref), all combustible municipal solid wastes (MSWs), including food waste, are incinerated. In the other (Bio), food waste is biogasified, while the other combustible wastes are incinerated. An inventory analysis of energy and material flow in the MSW management system was conducted. Subsequently, the inventory data were summarized into an input-output format, and a make-use input-output framework was applied. Furthermore, a production equilibrium model was established using a matrix representing the input- output relationship of energy and materials among the processes and sectors. Several levels of power generation efficiency from incineration were applied as a sensitivity analysis. The hybrid LCA indicated that the difference between the Bio and Ref scenarios, from the perspective of CO2 emissions, is relatively small. However, a 13-14% reduction of CO2 emissions of the total waste management sector in Japan may be achieved by improving the efficiency of power generation from incineration from 10% to 25%. [ABSTRACT FROM AUTHOR]

Published
2010
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42. Evaluation Method of Mechanical Recycling and Case Studies Based on Life Cycle Inventory Analysis.

Author

Fujii, Minoru, Hashimoto, Seiji, Nansai, Keisuke, Murakami, Shinsuke, Inaba, Rokuta, Osako, Masahiro, and Moriguchi, Yuichi

Subjects
WASTE recycling, CARBON dioxide mitigation, ALUMINUM, POLLUTION prevention, CONSERVATION of natural resources, WASTE management, RECYCLED products, WASTE products, AIR pollution
Abstract

The article presents a study on the use of life cycle inventory analysis to study mechanical recycling methods. It examines closed-loop recycling and open-loop recycling with consideration for carbon dioxide reduction effect. The study mentions that closed-loop recycling including methods used for aluminum cans involve evaluations of recycling rate and carbon emissions. Open-loop recycling requires unit functions to assess the carbon emissions after materials change properties during recycling. The study also recommends the use of a performance ratio in examining open-loop recycling. An overview of the study is provided

Published
2008

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