A compost heating solution for a greenhouse in north-eastern Poland in fall

Abstract

Abstract Biological waste generated by households, including the organic fraction of municipal solid waste and garden green waste, is collected by municipal services and processed. These operations require additional energy carriers, such as fuel for waste transport. This study proposes a method for on-site composing of household waste in line with the zero waste strategy. The largest amount of heat is generated in the thermophilic phase of the composting process, and in the proposed method, excess heat was used to heat a greenhouse. The proposed solution relies on passive heating without additional equipment. The greenhouse was supplied with the heat generated by 136\xa0kg of composted biological waste between 19 October and 2 December. An identical, but unheated greenhouse was set up to determine the efficiency of the proposed heating system. Air temperature, pressure and humidity were measured in both greenhouses. On average, the temperature inside the heated greenhouse was 2.3\xa0°C higher than in the unheated greenhouse and 3.1\xa0°C higher than ambient temperature throughout the experiment. The net heat gain from the composted waste was determined with the use of the laws of thermodynamics at 32.5\xa0MJ. The proposed solution decreased the quantity of biological waste collected from the household by 136\xa0kg, thus reducing primary energy consumption. The designed solution was used to heat the greenhouse in fall. During the thermophilic phase, the temperature inside the heated greenhouse did not drop below 0\xa0°C, whereas below zero temperatures were noted on three occasions in the unheated greenhouse. Artificial neural networks were used as a tool to predict the temperature inside a heated greenhouse to predict if temperature would fall below the permissible value.