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

Abstract

abstractThis paper explores alternative infra(structure)-free (IF) scenarios at a community level to promote machi-zukuri (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.