ASABE Technical Library - Abstract

Abstract.

This study was conducted to verify the possibility of binary power generation using composting fermentation heat recovered by a full-scale suction-type aeration composting system (SACS). SACS is different from ordinary composting system aerated by blowers. In SACS, air is sucked from the bottom of composting material by blowers, and fresh air is supplied from the surface of the material so that exhaust gas gathered at the bottom of compost contains gases as ammonia and heat in high density is generated during composting process. Binary power generation was carried out at full scale SACS (Tochigi city, Tochigi, Japan), which had a volume of 400 m³. The temperature of the exhaust gas in this facility is 64.2 °C on average. Water warmed by this exhaust gas was used for a high-heat source and agricultural water (16.1 °C on average) was used for a low-heat source for a binary power generator (ECOR-3-Ft; ADVANCE RIKO, Japan). Firstly, the layout of the heat exchanger for recovering exhaust gas heat was investigated. Next, we attempted to maintain a continuous power generation and clarified issues of it. As a result, using an exhaust gas heat of 5.2 GJ/day (= 60 kW), a power of more than 700 W was generated. The energy conversion efficiency in this power generation process was approximately about 5%. When the compost material was turning over, the heat of the exhaust gas temporarily decreased. Due to this, power generation stopped 1 or 0.5 days after turning over, but it remained stable during other times.