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SummaryPlant-derived renewable resources have the potential to enable the simultaneous generation of high-value-added products, such as foods, with energy, such as electricity and thermal power. Much of the heat cogenerated from renewables in power plants has been discarded because of the geographical and temporal gaps in heat supply and demand. In this study, we aim to devise an effective industrial symbiosis (IS) for a regional combined heating and power (CHP) plant utilizing local renewable resources. For the actual region of IS, the island of Tanegashima in Japan was adopted, where sugarcane is planted as a base industry. Through a thermodynamic analysis of the energy flows in a sugar mill, it was demonstrated that large amounts of heat were discarded from the sugar mill, even though the quality of heat was high enough for power generation or other energy demand. This is partly because some of the renewables have been regarded as wastes in the production of foods or other high-value-added products. At the same time, scenarios were defined and analyzed on the integrated use of locally available lignocellulosic biomass to increase the operation ratio of an existing bagasse-based CHP system. Through both periods with and without sugar production, additional heat and power can be made available by decreasing the energy loss and through IS. Keywords:bagasse boiler and power generator heat and power industrial ecology island system renewable resources sugarcane Supporting information is available on the JIE Web site

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SummaryDistributed energy sources, such as self-power generation, steam boilers, and combined heat and power production (CHP), are operated to manage the supply of energy by optimizing the costs of meeting the demand for electricity and heat. This article was written in conjunction with reports by the United Nations Environment Program's International Resource Panel that quantifies and compares the environmental and natural resource impacts and benefits of using demand-side efficient technologies for greenhouse gas mitigation scenarios from now until 2050. In this article, we examine the potential of using distributed energy sources in future energy systems. First, we reviewed the existing research into several energy technologies, especially into cogeneration systems for CHP, using a bibliometric analysis. The current energy supply/demand in the demand-side sectors in Japan is also reviewed using available statistical data, and an investigation into the energy requirements of industrial manufacturers was performed. After systematizing the results of our review on progress in current research, a scenario analysis was conducted on the potential of distributed energy sources to clarify the contribution of the various technology options. A mismatch between the quality of energy produced, especially heat, or any benefits arising from scale from other energy technologies, can decrease the incentive to implement distributed energy technologies. As a requirement of a regional energy system design and management, distributed energy sources should be considered so that the appropriate technology options can be adopted for the desired energy supply in the demand-side sector. The possibility exists to replace conventional single-generation technologies, such as boilers or power generators, with multigeneration technologies. A change in the grid power mix is one of the most sensitive parameters affecting the performance of cogeneration technologies.

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Japan is faced with sustainability challenges such as resource security and depopulation. Well-coordinated, multifaceted actions including a shift from imported fossil to locally available renewable resources and empowering of rural areas are vital in tackling these challenges. Here, we present our co-learning approach to practice the multifaceted actions with a case study on Tanegashima, an isolated Japanese island. In these actions, thorough understanding of the feasible technologies, the locally available resources, and the socioeconomic aspects of the local community should be shared among the stakeholders to acquire the momentum for a change. In addition to the technoeconomic analysis, several other analyses were conducted to reveal the concerns of respective stakeholders, share the understandings on the possibilities of technology options, and their socioeconomic implications on local sustainability. Tools such as the life cycle assessment, input-output analysis, and choice experiments based on questionnaire surveys on the residents' preferences are used for the analyses. The stakeholders were provided with the results during a 5-year period, through more than 30 co-learning events, e.g., symposiums, seminars, and workshops. A total of ca. 1400 participants from residents, local industries, public organizations, and a high school joined these events. These opportunities gradually converted the concerns of the local stakeholders on their future regional energy systems into expectations and yielded constructive alternatives in technology implementation that can use the locally available resources. The changes in residents' mind set through the co-learning processes induced by the contributions of the outsiders, providing professional insights acquired from the analyses and through the interactions with local stakeholders were examined in this study. This study demonstrates that the holistic incorporation of scientific technology assessments into co-learning can help coordinate the collaboration between researchers and local stakeholders toward regional transformation.

Sugar production is the main industry in Tanegashima, Japan. Whilst the sugar mill recycles sugarcane bagasse as a fuel, it concurrently generates large amounts of unused 200 °C heat during operation. Raw sugar is shipped to a refinery in Osaka for the final stages of production, which uses a city gas boiler to continuously generate a large quantity of 150 °C heat. However, factories in Tanegashima need a continuous supply of process steam at temperatures of up to 120 °C. To resolve this spatial and seasonal mismatch of heat, we propose a thermal energy storage and transport system using a zeolite adsorption/regeneration cycle. A process flow diagram of the sugar mill has been developed, and the amount of available heat, the potential storage capacity, and the transportable amount of heat have been calculated. Two scenarios were analyzed, in which the stored heat is shipped to Osaka, or used on the island. This was achieved by calculating the rate-based storage capacity of zeolite, based upon an adsorption and regeneration test. The transportable quantity of zeolite determines the feasibility of using waste heat. In the first case, transport of heat to the sugar refinery in Osaka has little possibility of being implemented. In the second case, transport of heat to a liquor factory in Tanegashima can potentially reduce its usage of heavy oil by 83 %, equivalent to 33 kL/year.