Studies on Regional Recycling System of Energy & Resources Based on Chemical Heat Pump Utilization (2005)
Master's Thesis, Chiba University Graduate School of Science and Technology
Chemical heat pump (CHP) systems could become an effective way to use thermal energy for sustainable development in the near future. The CHP can store thermal energy in the form of chemical energy, and release it at various temperature levels. Especially, the authors studied a calcium oxide/water CHP and a calcium sulfate/water CHP. Each of these CHPs has its merits and demerits, so the form of apparatus and system design suitable for the situation are very important.
In this study, our group firstly focused on waste heat from engineering plants as heat sources. The amount of the waste heat has already been estimated, however, some amount has not been measured yet, especially, waste heat from the surface on pipelines and walls. The surface temperature was measured by field research in an industrial complex using an infrared thermograph.
Secondly, we proposed thermal energy recycling utilization systems, from heat sources to heat applications, using CHPs and other technologies of thermal energy utilization such as absorption heat pumps and adsorption heat pumps. As heat sources, unutilized energy such as waste heat from engineering plants and incinerators, surplus exhaust heat from a decentralized cogeneration system and renewable energy such as solar thermal and geothermal energy are considered. As heat applications, space heating/cooling, hot/cold water supply, drying, dehumidification, and ice production are considered. We calculated the energy conversion, the total energy efficiency, and cost estimation in these case studies with our original software.
Furthermore, based on the life cycle assessment (LCA) method, the authors study the life cycle of CHP systems from raw material acquisition to waste disposal.
As a result, it was found that the amount of resource energy is found to be recovered, converted, transported and used in heat supply application effectively. It can be seen that the total running cost and CO2 emission are mostly affected by transportation process. The CHP utilization system needs less energy in operation, however, it needs more energy in the system construction in some cases. Also, the CHP system enables offline energy transportation of the chemically stored heat materials and the decrease of energy consumption and CO2 emission.
Keywords: Sustainable development, Accountability, Thermal energy recycling utilization system, Unutilized energy, Chemical heat pump (CHP), Life cycle assessment (LCA)