Designing a Small-scale Infra-free (IF) System for Community Applications: Managing Energy, Water and Waste

Abstract

This paper explores alternative infra(structure)-free (IF) scenarios at a community level to promote machizukuri (community/neighborhood planning), a bottom-up decentralization approach improving citizen' and municipality involvement in city planning in Japan. Demographic analysis in Japan shows that the population is becoming more urbanized, with an increasingly centralized infrastructure, but that per capita waste generation is increasing because the number of people in each household is decreasing; therefore, integration of the energy, water and waste (EWW) cycles becomes more important. For residents who are unconnected to centralized sewage treatment in Japan, mainly concentrated in municipalities whose population is less than 100,000, there is a lack of alternatives for wastewater treatment, except the current technically-demanding 'joukasou' on-site treatment system. The authors evaluated the 30-year life-cycle cost performance of three current systems with alternative (integrated-technology) IF scenarios focusing on wastewater treatment for a small community (20 households). These systems are; wastewater gardens with biogas production, an anaerobic digester gas system integrated with fuel cell technology and a heat and power unit (CHP) combined with a biogas-producing reed bed system, all of which treat wastewater and result in useful end products-, closing the life cycle with low maintenance, a lower environmental load-, and two to four times smaller development cost than centralized options in both rural and urban communities.

Management of a small-community waste-food cycle on an inhabited island in Kushimoto town to address Japanese sub-urban shrinking city problem

“…Although the population tends to decrease, calculations show that the amount of waste increases due to the increase in one-person households [10]. The potential waste increase would not only be from the local sources, but also from the increase in the number of overnight tourists that we estimate to increase but which are currently one third of day trips, as shown in Fig.l.…”

A decentralized/self-sustaining (infra-free) kitchen-system proposal with a home incinerator and Sabatier reactor-integrated waste management utility

“…Integration of a closed-hydrogen loop could further decentralize a HH by reducing stress on physical and social solid waste management infrastructure, decreasing greenhouse emissions and improving resource integration. Using a prefab wall unit could reduce the required installation area to less than 1m 3 . Further research will focus on integrations of different sub-system architectures and decentralization by integrating wastewater with solid waste management system in order to propose a completely self-sufficient IF-House.…”

“…IF projects an increase of approximately 2.2 million tons of solid waste in 2020 in Japan, even with the population trends set to decrease in the future, the trend of increasing single or one-couple HH will produce more waste than now [3]. This paper focuses on increasing single HH, which generates 941g/ person/ day compared to a four-person HH, which is 440g/ person/ day, in which a study on solid waste reduction could lead to a new type of decentralization.…”

“…Units adding into the total weight of the kitchen are 4.85kg (excluding the hydroponics unit) and require an installation space of 1.93m 3 (with the hydroponics unit). Warm stale air cools the exothermic reactor to maintain the optimum temperature and supplies excess home-air as clean fuel.…”

“…The home incinerator and hydroponics unit are the most space consuming elements, each requiring 0.6m 3 . The incinerator can basically replace the space reserved for garbage boxes under the sink.…”