Analysis of Distributed Energy Supplying Technologies From the Viewpoint of Waste Heat

Yutaka Nagata, Central Research Institute of Electric Power Industry

Keywords

Abstract

In Japan and other countries cogeneration systems have attracted attention because of their dramatically increased efficiency. However, these systems consume fossil fuels and there is the fear of worsening the heat island phenomenon, if they are installed in city areas. On the other hand, heat pump technology has been applied to various energy services. Because heat pump technology is quite efficient and if its energy is delivered from the outside of city area, the waste heat in city area is expected to be much less than cogeneration systems even though the loss of generation and transmission is taken into account. This study examined the characteristics of waste heat from various urban energy supplying systems by the reference survey; also, energy consumption and the amount of waste heat from a model house in summer season were estimated. The result shows: 1. The forms of waste heat differ greatly according to the cooling methods of energy supplying systems in commercial use, 2. There are various theories about the influence of latent heat on the heat island phenomenon, 3. Energy consumption is the lowest with the fuel cell cogeneration system (high waste heat recovery), but, the smallest amount of waste heat is exhausted in the city area with a combination of grid electricity and a heat pump water heater. The amount of waste heat from a gas engine cogeneration system and a fuel cell cogeneration system are even larger than that from the combination of grid electricity and an efficient gas water heater.